The BSA A7-A10 Forum
Technical (Descriptive Topic Titles - Stay on Topic) => A7 & A10 Engine => Topic started by: adunham1 on 29.09. 2019 01:01
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Hi everyone,
I'm getting ready to rebuild my 61' SR engine and was hoping for some advice on things to look out for, things to change/inspect "while I'm in there," and anything else related to re-assembly. Currently it's completely apart and I've got some anxiety about seeing all the bits laying around! It has already had the sludge trap replaced with SRM Allen head caps.
Currently I'm planning on new 8:25:1 +.040" pistons as the current bores are just a bit too large for the current .030" pistons. Probably GPM or Gandini (are they the same?). It seems my alternative are JP pistons, which are notoriously heavy. I don't mind sending the crank to get balanced, but would prefer not to if the new pistons are similar weight. Speaking of the bottom end, as long as I don't see any cracks or other signs of wear, is it OK to re-use the old con rods? New big and small end bearings, though.
Other than that, the bronze bushings for each side of the crank look OK, so I wasn't planning on doing anything there.
This is my first time really into the bottom end of a BSA, so I'm definitely a little apprehensive and want to make sure I take my time to do it right. Sorry for such an open ended question!
Other than that, I need to find someone in the US to rebuild the Magneto. The bike will be converted to 12v electronics, an SRM oil pump, external filter, and some Eddie Dow front fork parts.
Again, thanks for any insights you might be willing to share. I would really appreciate it!
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Some weights of pistons are given in this thread link below, JP are not particularly heavy? Some manufacturers make one size of casting then machine them down, which means the over sizes are particularly heavy, but not the std size. Note some gudgeon pins can weigh a lot!
https://www.a7a10.net/forum/index.php?topic=6086.msg41598#msg41598
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G'day Andrew.
Replace the anti siphon ball & spring.
Check the cam bushes, cam journals and lobes, cam followers for wear.
Old rods are OK if straight and crack tested (I polish mine). New bolts would be good.
Drive side main should be a C3 grade. Replace the timing side bush with a solid one and line ream to suit crank journal and check the crankcase hole for out of round (if it is a new bush has to be made to suit.
Trial fit crank in cases (without the cam) to check end float and shim behind the inner race.
That'll keep you going for a day or two.
Cheers
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Old rods are OK if straight and crack tested (I polish mine). New bolts would be good.
Also make sure the big end holes are round & to correct size. They can be elongated ( stretched/ out of round)
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Muskrat has correctly detailed the important things to look at, I would lke to attach great importance to his first line the anti syphon ball and spring this is behind the small screw inside the crankcase next to the timing side main bearing, but make sure you get the correct parts mainly the spring. This ball and spring does to some extent help with wet sumping, in my case on my A7 before I renewed them I had to drain the sump once a week or I ran the risk on start up of having oil come out of the breather onto the garage floor. After renewal the bike does still wet sump but I have left it for over 3 weeks and started it without oil coming out or smoke from the exhausts.
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To add to former posts, new nuts and big end bolts are desirable but pricey. Existing Bolts are probably OK for further use, it depends on the nuts previously used, some locking types ruin the thread for further use. The problem with new ones are that many are not up to the job, even from trusted suppliers. As ironhead recommends, get the big end eyes checked for ovality. Any machine shop can do this.
The basic weakness in the design is the oil feed to the big ends, using the timing side bush to feed oil into the crank. The bush needs to have a good seal around the periphery where it mounts into the crankcase, a leak here will vent oil, rather than it going into the crank. Wear on the bush and crank journal will also reduce the oil to the big ends. Suggested running clearance here when new is 1-1.5 Thou. Plenty on the forum about this bush, choices, modifications, installation, sizing.
The sludge trap on your later crank is a removable tube. Folks take out the plugs, clean the hole they can see, leaving sludge on the outside of the tube. Remove the flywheel radial bolt and the tube will come out, revealing more sludge. The radial bolt should be replaced with a new one, Loctited in place for security, as a failure here wrecks the motor.
The wear limit on the journals is 2 Thou, they usually wear oval, so measure diameter in several places, and each side for taper. If the big end journals are reground, remove the sharp edge around the oil feed holes, blending them into the journal surface, otherwise they can cut a neat groove in your new shells. Con rods are the same forging, drive side/clutch side one has a small bleed hole from the big end eye, this should face to the flywheel, putting the bearing shell tab slots on the rods towards the front of the engine.
Pistons and rings.... Hepolite pistons, now distributed by Wassell, and only related by name to the originals, have yet to establish themselves as a viable alternative, so are best avoided. New old stock AE/Hepolite are OK, they were the standard when the bikes were new. Gandini rings have a good reputation, curing oiling and smoke problems when fitted to pistons otherwise considered to be at fault. In your part of the world, Hastings rings would be a good choice.
The small ball in the valve on the scavenge pipe in the sump needs to have reasonable movement, the ball often gets stuck by carbon and sludge, and the pipe needs to be secure and sealed into the crankcase.
BSA Service sheets are available in the Literature Section of the forum.
Good stuff there from birthday boy Musky.
Swarfy.
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Has anyone mentioned cleaning out the sludge trap, (in the middle of the crankshaft)?
Swarfy got his post in before I posted.
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Hi GB, tried here to pass on some hard won experiences......All the best.
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Hi guys, sorry for the late reply and thank you for all of yours!
I got nervous about re-using old rods and seeing as how I only want to do this once (hopefully!) went ahead and ordered some MAP cycle rods: http://www.mapcycle.com/performance-parts/connecting-rods/map7068-a-bsa-a10-late-4340-h-beam-connecting-rods-6-5.html I think I'm going to pair them with some 8.25:1 GPM pistons from wherever I can find them. TMS Nottingham seems to have them.
KiwiGF, that's a very informative thread. Thank you for sharing. I was messing about with weights and balance yesterday, but this is sort of a comprehensive guide so that's great. I will use this closer when the new bits arrive. I'll try to post an update with the weights of my new pistons, rods, etc when I get them.
Muskrat... you're right that'll keep me going for a day or 2, or 10! I've heard the solid bushes are a good replacement. Do you know of a good source for one? I've got a couple of good machinists that could do the work for me. Pardon my ignorance, is that C3 grade Bronze?
biker bob, yes I have read quite a bit about the anti-wet sump valve on many BSA models... so I guess I infer its importance. I had seen them on SRM's site, but do you think any NEW one would be fine or is there a preferred one? I'm not trying to break the bank here, but I want to fit good quality parts while I'm in this far.
Swarfcut, great name! I actually just re-assembled my crank with the new sludge trap this evening. I did NOT replace the bolt (but I have new ones... doh!) Interestingly enough, someone had cleaned the sludge trap recently as there was little to nothing in there. That was a little annoying, as it was the reason for pulling the engine! I will remove the bolt, replace it and loctite it in. Thanks for the spec on the timing side bushing, I'll relay this to the machinist that works on it. I had no idea about the ball in the scavenge pipe. I will have to take a look and research that a bit.
Thanks again everyone. I'm really looking forward to making some real progress! My Dad is helping me, so I'm sure he's excited to have it off his bench. This is only our second full engine rebuilt. We rebuilt a 1974 Moto Guzzi Eldorado last year, so it's very interesting to see how things are different, yet all the same.
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C3 denotes internal radial clearance of mains roller bearing.
The A10 engine was stripped and rebuilt using basic tools and facilities and are fairly bullet proof, they need regular engine oil changes and need to be ridden with respect like you would treat any old girl.
I would try to reuse as many original parts as possible, certainly theres some rubbish pattern items now available. SRM are a very good source for new replacement items and offer support and backup.
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.............Pardon my ignorance, is that C3 grade Bronze?...
In addition to B-b's comment, my take on that is the clearance between the rollers/ balls, and the inner/ outer race(s)...
......... We rebuilt a 1974 Moto Guzzi Eldorado last year, so it's very interesting to see how things are different, yet all the same. ....
Well- that sure garnered my attention... I'd be really happy if our A10's were that easy...I did my model T in ~'96 and totally stoked; there must be a way.....
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Here are a couple of photos of the bike finished.
(https://i.imgur.com/DKOuMBS.jpg)
(https://i.imgur.com/awkvbaL.jpg)
And yes, I wish they were as easy! Everything easily accessible and straight forward. The hardest part was learning some Italian to know which way round to put some parts!
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........The hardest part was learning some Italian to know which way round to put some parts!...
That's a bonus- just think of the mayhem you can acheive on your next Euro trip *smile*
The bit that baffled me is the ignition- red for right and green for left....me thinking it must be to do with navigation colours from their aviation background, but that went west when saw airplanes overhead with red left and green right....(I'm obviously not a boaty even though I did a navigation course)...turns out it's to do with the flag- but my argument is it depends which way I look at it *pull hair out*
Looking at the centre stand, it looks a fair bit far forward which would be loading the pivots up a lot and also not lifting wheels high enough- I had that on my T, so built up the stops with some 'trick' welding *work*
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my tip would be to ream out the conrod bolt holes . no binding or tight spots. reuse good conrod bolts.
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........The hardest part was learning some Italian to know which way round to put some parts!...
That's a bonus- just think of the mayhem you can acheive on your next Euro trip *smile*
The bit that baffled me is the ignition- red for right and green for left....me thinking it must be to do with navigation colours from their aviation background, but that went west when saw airplanes overhead with red left and green right....(I'm obviously not a boaty even though I did a navigation course)...turns out it's to do with the flag- but my argument is it depends which way I look at it *pull hair out*
HA! Just imagine me running down the streets yelling, "SINISTRA O DESTRA?!" (left or right!) over and over again.
Perhaps you have an ultra rare MEXICAN Guzzi? I can't remember what the stock wiring was; we ended up fitting a custom wiring harness with an alternator upgrade replacing the old magneti marelli generator.
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Reaming out conrod bolt holes....please don't do it. Cap and rod are matched, altering the hole will add an extra variable.
Although it can be a pain getting the caps on and off easily, the shoulder on the bolts gives a fixed location to the cap relative to the rod, so is best left alone. Once again heating the big end eye and cap with the hot air gun will expand the alloy enough for the bolts to slip through the hole relatively easily.
But I will agree with edboy and reuse serviceable bolts with new nuts. The way I ride is a bit more sedate and with a lot of mechanical sympathy for the old machine. When you think about it, the bolts and rod are only under extra tension on the induction stroke. Rest of the time the rods experience different compression loads.
Swarfy.
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Good move on the MAP rods, they are a quality product and that is a very reputable company, I have known them decades and they race and test their products before its ever sold to a customer.
Read up and or ask them for proper specs on how to fit those rods and how to measure rod bolt stretch. Bolts have a modulus of stretch to them and the factory # for Ft pounds is just an approximation. True torque is actually measured by the rod bolts stretch. (You use a micrometer and measure the bolt) Trust me, Marino and his crew at MAP will happily supply you the data needed.
I cant say on modern H beam steel rods as I have yet to rebuild an engine that used them, But on stock rods, if its been torqued and ran at all, the rod must be resized. They go out of round. This is easy to check with decent measuring tools. Have yet to see any that didnt need it. The procedure uses specialty tools, they mill a little off the cap or mating surfaces, then machine back to round with the cap torqued in place and then placed on a specialty hone (Usually a sunnen hone machine) and carefully honed to desired spec.
As to reusing rod bolts,, I have, but I am pretty careful about it. Again I measure by stretch, and a bolt that does not stretch is junk, fit for the scrap bin. I will agree that replacements are a problem getting quality made rod bolts. As to the nuts, it depends, some are a pinch nut and only servicable once. Scrap after that.
As to rod failure,, I have seen some fracture due to detonation, Also lubrication failure, a few bent or cracked due to hydraulicing but surprisingly the experts say most rods dont fail on compression.
https://www.onallcylinders.com/2015/09/11/rod-school-how-to-choose-the-right-connecting-rods/
" Depending on the application, different types of stresses are applied to the connecting rods. For example, large amounts of torque will yield heavy compression and bending loads on the rods. High rpms, on the other hand, cause mostly tensile-loading or stretching forces. In most cases, connecting rods don’t fail on the compression stroke; rather, they break apart on the exhaust stroke at high-rpm operation due to tensile loading.
“This (tensile loading) is also much harder on rod bolts than horsepower and torque,” Davis said. “Other factors to consider are piston weight and the stroke of the crankshaft. Also, different fuel and nitrous use will have a different effect on combustion and how the load is delivered to the rods.”
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Regardless,, If strictly a show bike, I suppose it wont matter but if you want to ride it all, Im a broken record here. But a DYNAMIC BALANCING is mandatory. You can static balance a motor and it helps, but there is no replacement for a good dynamic balance job. The difference is night and day. You will swear its a sewing machine smoothness and wonder how it was even rideable before.
Plus there is rocking couple which no way to fix other than dynamically.
Finding a good shop to do the balancing is tricky. I have 2 locally, One is outstanding, the other is good but not optimum. You can help in the process. Start by weighing everything.
Rods, big and small ends, pistons, rings, pins, clips, Equalize everything.
I have found OEM hepolite pistons variable by grams on a scale LtoR,, as well as dimensionally, I dont have a high opinion of Cast Hepolites. However aftermarket pistons are variable,, but Cycle Craft, now EMGO have been overall outstanding quality considering the parameters of being a casting. I have also found remarkable consistency except once on dimensions and weights. **, what is surprising is the pins on the repops vary but they are easy,, hone the ID of the pin to equalize.
Now,, pistons are graded. Turn them over and generally on the pin boss but could be anywhere you should find small paint dots. Red-blue or green. The better the quality the better the grading.
When made, they are rough cast,, they are then machined to size. Then checked and separated by grades...they then match them to equals to make a pair. Once in a great while you will find a mismatch pair. I did once and we believe it was at the distributor or wholesaler level and someone got into a box and didnt return them to the right box. I had to buy 3 sets to get them all equal,, most people NEVER check!
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HA! Just imagine me running down the streets yelling, "SINISTRA O DESTRA?!" (left or right!) over and over again.........
*dunno*....dunno but sounds impressive
.......Perhaps you have an ultra rare MEXICAN Guzzi? ...
I bought it from a guy who imported it from Michigan in '92....Michigan/Mexico- sounds similar *whistle*
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if you have to heat the conrods up to slide the conrod bolts through the conrod then logically you should heat up the conrod when torque setting. the conrod holes always burr up and i wasnt suggesting going oversize. but its a free country- your choice. [ except brexit ]
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edboy yes I found mine had closed up at the bolt heads and washers on the caps so I just eased those bits out and jobs a good en
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I'll have to purchase a socket to tighten the MAP conrods, but that should be easy. New bolts with them as well. I think I read on the ad it specified .005 - .0055" stretch on the bolts, but supposedly they send an instruction sheet.
Sluggo, good to hear about your good fortunes with them. I feel like I don't read much about then people fit new parts. It sort of sounds like, "it depends on a lot of factors" when considering Conrod failure. I do agree in that the tensile loading seems like it might be tougher on the rod especially if its pushing a heavier piston.
I am absolutely planning on sending everything to someone to have it dynamically balanced. Do you guys know anyone in the US that does it? Preferably fairly close to Ohio. I'm going to weigh everything when I get it; for my records and perhaps it will help whoever does the balance. It's definitely going to get ridden! What percentage do you suggest? I've read 54-65%... but the higher seems to be for more racing applications. I would assume that the percentages are based on the RPM's you intend to ride at; if that's the case. I will be 55-70 mph or so.
I'm definitely going to get a set of 8.25:1 pistons, but finding anything other than GPM seems to be difficult. They're probably fine. I've emailed TMS Nottingham about a set as it is a few dollars cheaper than Draganfly sells them, but haven't heard back in a few days. I will measure and weigh them upon receiving as part of the balance process.
Looking forward to getting going on this. I get distracted with other things too easily!
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I have yet to use the new MAP conrods but hope to soon. But I have been using their products since the early 1990s. I have used many of their Unit Triumph belt drives for both myself and shop customers when I was still running a shop. Other parts as well, They have been a staple for both stock and customs for a long time.
(They have some very informative tech papers on stage tuning, cyl heads, valve train and general racing and street performance they used to publish and include with their catalogs. I asked last year if they would dig them out and publish them or offer them for sale, Still super helpful material,, The carb tuning stuff is something I used to photocopy and hand out to customers, saved me loads of grief, and educated end point user is a wonderful thing)
I think it would be great for you to post up pix and details of your build and be a help to others.
As to balancing, thats a complicated topic. There is a auto based shop in Gresham Oregon we have used, and they are well respected in the Race car and hot rod community, They did fine on several builds a few years ago. We had another guy, Dan Halls 5 point automotive who also did Dynamic balancing and specialized in British bike cranks and rods as well (Many shops wont touch them) but he passed away and the guy who took it over was a disaster.
So my preferred guy is an old Oregon Hippy who does airplane propellers and industrial applications. No website and has a small specialty shop up in the hills But I usually boxed things up and ship to him, but I have a cabin we visit so we pass right by.
Its name is E.V Lewis Dynamic balancing and he does the bike stuff on the side as there is not enough of it to run his business on. But he is well regarded in the vintage Bike community and many shops secret weapon. So on balance factor, He can discuss that and advise, But goes about it differently than many discussions you will see. You can find the percentage %s hotly debated on many forums, But my experience is dont get hung up on specific numbers. You DO want to record and keep a journal on all your specs, weights and numbers so, lets say down the line you have to replace pistons? Just consult your specs and you can deal with it.
But heres what I do. I box up everything that will rotate, after the rods are machined/resized, Journals ground or polished and Crank has been checked (Cracks, straightness, tolerances) then the pistons, pins, clips, rings and even the sludge trap plug (On some models there is a plug on the side of the crank). Optional is clutch basket, or Alternator rotor
(On some models that rotor is a huge weight flopping around on the end of a crank and can unbalance the whole she-bang,, Ernie charges generally $10 to balance them and worth it. Some come back with 3-4 dimples, others are so out of whack they look like a swiss cheese grator on one side) Some people balance trans mainshafts and layshafts and timing gears but thats a big OCD.
Now, Ernie will ask a series of questions. What type of frame, RPMS you generally ride at, and takes measurements. He fixes Rocking couple (Which is a complicated topic, but its a vibration wobble in laymans terms) but then corrects your weights and then moves the worst vibration to where you rarely run at RPM wise. Low, or high...
Now, some cranks and Rot. assys balance easily, Some are a real PIA. But sometimes,, there is a real problem. Early BSA Cranks have pretty full crank flywheels and cheeks,, LOTS of material to work with. But later Triumph and Nortons the cranks are cut down, and you remove weight opposite where you have the imbalance, But sometimes there is no material THERE. (Nothing to machine/drill) So he calls and runs my options. A few times we had to add what is called Mallory metals, which he machines a hole, plugs it with super heavy Mallory metal (Ballast) and tack welds it into place. Thats the only way to balance some cranks. I think I still have some photos of some Norton and Triumph ones,, Ill look. But years ago, we experimented with a BSA A65 and tried out the Capt Dirt suggestion.
Ill add this here, but if you feel its too off topic to your discussion Ill remove it.
Capt Dirt used to build some super competitive TT and Flat track BSAs, He told me the Unit Twins had the best cyl heads and better than Triumph or Nortons. He also liked the BSA cams, and correctly pointed out the stock A65 cams profiles are what Triumph copied for their race/sports models. But Capt said the BSA had too heavy of a flywheel. So, besides the oiling system mods and the rod mods I explained he said go out and weigh the lightest Triumph twin crank and then match that on the BSA and you will have a rocket ship.
So Triumph played with crank weights up and down over the years, Part of their vibration was also manifested in frame design (A real problem on the duplex mdls 60-62) but I think 1966 was the lightest cranks,, I would have to check my notes to be sure so dont quote me,, But IIRC it was around 16-17 pounds total weight. BSAs we measured were around 22-24 pounds? So, in late 69 to 73 BSA had 3 different flywheels and weights. (including the A70 twins, the A50 and 2 weights for the A65) So I have NOS flywheels so we picked the lightest one, and had it machined. We COULD NOT get it to the target weight but I think we got around 17-18? Which was a lot less than the stock weights. But Ernie had a heck of time balancing it. But he succeeded (He found the project FUN! *smiley4*).
So, there was some blueprinting issues with the cases as well (Cases were out of whack, both crank and cam center lines as well as the cyl deck) We also used a SRM 357 Cam and some other tweaks. So I built the motor and it went into a hard tail bobber frame. The owner freaked out a little bit. It revved like a 2 stroke and was freakishly quick. Zero to go to jail MPH super fast. (We geared it for the street not the track) So it was a super fun bike. But,,, not good for long distance cruising or relaxed putt putt in the country. It was a beast. I enjoyed the project and well learned a lot. However I dont think for most bikes super light cranks are a good idea. The BSA Unit is a good all around plodder and hooligan blasts, so the heavier crank works well.
I have pictures in my office of that build and on my list of things I want to put up here that might be informative.
I have no input on other balancing shops besides my regional ones. But I have a friend in Alaska who builds a bike every winter and he ships his bottom ends to Jaye Straight? Brittech. I never dealt with him so no opinions. Maybe others can advise.
My old guy, Dan,, felt Ernie was too cheap, He felt he should charge more. Dan was anywhere from $125 to 250 depending on difficulty which is fair. Ernie was much less,, $75 to $150 in most cases, and add ons such as timing gears and alternator rotors were cheap,, often $10 per part. Prices might have changed since and problem projects scale accordingly.
But Ernie, Should anyone want to use him, Is located in Creswell Oregon not far from Interstate 5. He will meet in town or at the small airport, But can do shipping as well. #541-895-2287
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Well, I received the MAP cycle rods and wow... they do look and feel amazing. Very, very good quality. I weighed them and they came in at 439 grams (with bolts and nuts only.) (https://i.imgur.com/ZfVHFrV.jpg?1)
(https://i.imgur.com/GtyTaIN.jpg?1)
(https://i.imgur.com/Gu5h8BE.jpg)
(https://i.imgur.com/ypErk1f.jpg)
I've also ordered a set of the 8.25:1 pistons from Draganfly in the UK; so hopefully they will arrive in a week and a half or so. Amazing shipping times these days. I will post some more photos of the rebuild as soon as I get organized. I've got bits laying everywhere right now.
Great advice on keeping a journal with specs, weights, etc for the current setup. It would indeed make any changes much easier. I don't suppose I'll have much trouble with plenty of material on this crank; it looks (and feels!) pretty dense. I would love to see a photo or two of the mallory metal fix in action. That seems pretty interesting.
Interesting point on the BSA/Triumph/Norton info there. I've had 4 BSA's now and have always felt that the upper end felt fantastic, but the lower rev areas were lacking a bit. Makes sense with the cam. You're spot on with at least my crank weight; 22.7 lb. I'm surprised you were able to remove enough material to get it down to 17-18 pounds. That's a ton of weight!
I purchased a alloy clutch pressure plate from Britech New England (Jaye) and it was a nice piece for an A50. I'll have to contact him again. Otherwise, Ernie sounds like he might be the man for the job if he's up for it.
Thank you for all the information; it's very interesting. I really cannot wait to get on the bike for a ride. I don't think you'll find anyone with a bigger smile... if it all goes well!
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.......... You're spot on with at least my crank weight; 22.7 lb. I'm surprised you were able to remove enough material to get it down to 17-18 pounds. That's a ton of weight! ...........
*eek* geez....5lb in a ton- at that rate I'm bringing my scrap iron over there *smile*, and not even a dram of contraband else I'll rot in a dark dank cell.... *contract*
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Well, I received the MAP cycle rods and wow... they do look and feel amazing. Very, very good quality. I weighed them and they came in at 439 grams (with bolts and nuts only.) (https://i.imgur.com/ZfVHFrV.jpg?1)
(https://i.imgur.com/GtyTaIN.jpg?1)
(https://i.imgur.com/Gu5h8BE.jpg)
(https://i.imgur.com/ypErk1f.jpg)
I've also ordered a set of the 8.25:1 pistons from Draganfly in the UK; so hopefully they will arrive in a week and a half or so. Amazing shipping times these days. I will post some more photos of the rebuild as soon as I get organized. I've got bits laying everywhere right now.
Great advice on keeping a journal with specs, weights, etc for the current setup. It would indeed make any changes much easier. I don't suppose I'll have much trouble with plenty of material on this crank; it looks (and feels!) pretty dense. I would love to see a photo or two of the mallory metal fix in action. That seems pretty interesting.
Interesting point on the BSA/Triumph/Norton info there. I've had 4 BSA's now and have always felt that the upper end felt fantastic, but the lower rev areas were lacking a bit. Makes sense with the cam. You're spot on with at least my crank weight; 22.7 lb. I'm surprised you were able to remove enough material to get it down to 17-18 pounds. That's a ton of weight!
I purchased a alloy clutch pressure plate from Britech New England (Jaye) and it was a nice piece for an A50. I'll have to contact him again. Otherwise, Ernie sounds like he might be the man for the job if he's up for it.
Thank you for all the information; it's very interesting. I really cannot wait to get on the bike for a ride. I don't think you'll find anyone with a bigger smile... if it all goes well!
Out of interest are the rods you bought OEM length? Some (USA) rods listed for A10s are 6.5” long, but OEM is actually slightly less than that, something like 6.47” from memory, longer rods may be an issue if you are going high compression as well *dunno*
Billet alloy rods usually need the barrel slots made wider, not hard but it takes some courage to get to work on them with an angle grinder *eek*
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Sorry for the late replies, everyone. I have been working a lot this week.
KiwiGF, I measured (albeit quickly) the old con rod length and got 6.5, but if the discrepancy is that close, I could have easily been wrong. I will measure them tomorrow. Hopefully they're the same. I have gone for the lower compression 8.25:1 pistons, down from 9:1. Do you suppose I could measure the barrel slot and con rod big end and as long as the barrel gap is larger, I'll be OK?
Thanks for all the help, guys. I'm going to get back to work on it this weekend.
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The easy way to check the rod length is to directly compare them with the pin through the small ends.
About 10 years ago I bought R and R rods for my A10 and the centers were 6.5 inches (BSA figures 6.469 - 6.467 inches) about 1mm longer than the original rods, which could be a problem with high comp pistons, 357 cam, large valves, skimmed head etc, as was my experience. I then changed for Thunder engineering rods which were excatly the right centres.
So check valve to piston clearance if using longer rods.
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G'day Andrew.
I have R&R rods with 10:1 pistons in the Cafe. I can leave it in a pub car park without anyone under 16 stone being able to start her *ex*. I'm only 10 stone but know how to do it *smiley4* Gotta start 1st or 2nd go otherwise I'll need another beer *pull hair out*
Cheers
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I used MAP rods in my rebuild.
Yes, measure the stretch of the bolt, as you torque the bolt will get longer and longer.
The rods are a good working length, but my head has not been glassed or decked by an over exuberant handy man 20 times.
You have Baxter cycle in Iowa, Morries place in Illinois, and worst comes to worse a place that has a shop in the US and Canada if you feel the need to spend 50% more and wait an extra month.
The quality of the parts you source from just those two suggestions is going to far exceed anything you get from across the pond. More than likely you can find NOS over here, as everywhere else NOS has been gone for 35 years.
Lean much more toward buying engine parts from a place called SRM, and lean as far away from buying motor parts as you can from places like Draganfly or Fekked.
Dont skimp on your engine or gearbox if this is not for "shows".
Hands on help is hard to find in America, there is not a "guy" in every village with a set of Whitworth tools in his box. You re basically on your own, and if you find yourself broken down 50 miles from home because you bought the cheapest repop parts you could find....there is only one person to blame. The closest riding partner I know of would be Richard L. on this forum, and he must be 200 miles away. That is a long ride on a trailer to get friendly help.
I would hold off on a shiny paint job or new chrome and spend the money on the motor and gearbox at this point if money needs to be saved.
Lee
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Oh yeah, forgot. *smile*
My advice is to put in the camshaft and its timing gear before you install the crankshaft.
Also install the pistons and rings into the cylinders, than lower the cylinders down onto the rods. Way fewer broken rings I would think.
Lee
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and worst comes to worse a place that has a shop in the US and Canada if you feel the need to spend 50% more and wait an extra month.
And which one is that?! Just kidding. That's usually how I feel when I order just about anything. Why does it have to be SO expensive?!
muskrat, that sounds like it would be a real challenge for anyone without some... let's say, insider knowledge!
I'll check the conrods tomorrow versus the old ones and see how they compare. Really hoping they're the same, but I don't believe any work has been done on the head so a few checks should tell the story. I do have the 357 cam.
coater, I bought some what I thought were new crank bolts from Draganfly and they arrived pretty rusty. It looks mostly like surface rust, but it turned me off a bit. I have bought plenty of other parts from them and been satisfied; no engine parts though. I think I've only bought a couple of bits from Fekked; maybe a cable and some crank shims.
I'll be fine on the rebuild. My Dad and I have been rebuilding bikes for the last 13 years or so. Many japanese bikes, several BSA's, and the Moto Guzzi shown earlier here. As I'm sure you, and everyone else know, it's all the little things that matter and I'm learning all the time about how to do things properly. I've got a slightly beat up set of the valanced fenders to put on the bike eventually, but that can wait until its had its break in miles completed, etc. And yes, the pistons into the barrels before the rods is much easier... unless you're the one holding the cylinders up! A wood block can solve that, though.
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Unrelated to the title of this post, but we managed to get some work done on the BSA this afternoon.
I bought the front end upgrade from Paul Goff with progressive springs, new upper/lower bushes, new fork seals, and the Eddie Dow type damping rods. I had those parts laying on the bike lift for a couple of weeks and thought, "I could probably knock that job out in a day" so decided to give it a shot.
It took a few hours, but we managed the job (mostly.) I'm having some issues where the RH fork leg is slightly higher than the LH side, causing the axle to not go in. Not sure what has happened yet.
(https://i.imgur.com/yPVbQLt.jpg)
(https://i.imgur.com/kjMZMHC.jpg)
Here are the old caps.
(https://i.imgur.com/c8YS7Sd.jpg)
And the new ones.
(https://i.imgur.com/qxT9609.jpg)
(https://i.imgur.com/DAmVntS.jpg)
(https://i.imgur.com/0z4zIOj.jpg)
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A little more information for anyone thinking about the GPM (Gandini) branded pistons. These are all +.040"
- Each piston weighed 281.5 grams WITH the rings installed
- Gudgeon pins weigh 67 grams
- Clips (2) weigh less than 1 gram.
For a total of approximately 349-350 grams per side.
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A little more information for anyone thinking about the GPM (Gandini) branded pistons. These are all +.040"
- Each piston weighed 281.5 grams WITH the rings installed
- Gudgeon pins weigh 67 grams
- Clips (2) weigh less than 1 gram.
For a total of approximately 349-350 grams per side.
Thanks, all info like this is good, regarding a comment you made earlier, if the steel rods are “thinner” than the OEM (and they look like they are) then no mod to the barrel slots should be necessary, the extra length (if they are longer) should not make a significant difference to the clearance between rod and barrel.
The gudgeon pins are quite light compared to those I weighed, and will help offset any extra piston weight.