The BSA A7-A10 Forum

Technical => A7 & A10 Engine => Topic started by: BSA500 on 03.11. 2014 16:35

Title: Time for a rebuild
Post by: BSA500 on 03.11. 2014 16:35
I was thinking of taking the A7 off the road this winter for a little overhaul(big one really, shes done 15,000 miles in the last three years). She took things into her own hands and stripped the magneto gear, hopefully some pics follow showing the damage. As a background it has been using a little-lot-of oil and rattling....

(http://i11.photobucket.com/albums/a170/bsa500/DSC03936_zpsde6ef34e.jpg) (http://s11.photobucket.com/user/bsa500/media/DSC03936_zpsde6ef34e.jpg.html)

When she broke down I dropped this into the plug hole duh

(http://i11.photobucket.com/albums/a170/bsa500/DSC03942_zps16ad76e0.jpg) (http://s11.photobucket.com/user/bsa500/media/DSC03942_zps16ad76e0.jpg.html)

(http://i11.photobucket.com/albums/a170/bsa500/DSC03943_zps885d69c7.jpg) (http://s11.photobucket.com/user/bsa500/media/DSC03943_zps885d69c7.jpg.html)

(http://i11.photobucket.com/albums/a170/bsa500/DSC03950_zps24dbaf73.jpg) (http://s11.photobucket.com/user/bsa500/media/DSC03950_zps24dbaf73.jpg.html)

(http://i11.photobucket.com/albums/a170/bsa500/DSC03952_zps45479235.jpg) (http://s11.photobucket.com/user/bsa500/media/DSC03952_zps45479235.jpg.html)


And there goes my hope that the bottom end didn't need to much attention

[imghttp://(http://i11.photobucket.com/albums/a170/bsa500/DSC03954_zps7889e052.jpg) (http://s11.photobucket.com/user/bsa500/media/DSC03954_zps7889e052.jpg.html)][/img]
Title: Re: Time for a rebuild
Post by: muskrat on 03.11. 2014 18:51
G'day BSA500.
She looks like she could do with a freshen up.
Going by the amount of blow by on the piston, I'd check the little end bush and the rods for straightness. What does the bore look like (any scuffing on the sides)?
Cheers
Title: Re: Time for a rebuild
Post by: BSA500 on 03.11. 2014 19:41
No real scuffing but I can feel a little rock on the small ends. This barrel was relined to standard approx 15 years ago and about 5-6 years ago re ringed as there was only 1-2 thou wear. She has done well but I suspect a rebore is on the cards. Also found the ider pinion has some movement in the bush. Of course the bottom end has to come down but there is no twist/up down movement on the big ends but I will measure up everything that can wear.
Title: Re: Time for a rebuild
Post by: BSA500 on 05.11. 2014 10:02
Took another piece or two off the engine yesterday, mainly the dynamo. It had been on so long it had 'glued' itself on with a combination of rust and road grime. I had to free it off with a rubber mallet!!
Title: Re: Time for a rebuild
Post by: BSA500 on 10.11. 2014 09:57
More pics of the strip down.....

(http://i11.photobucket.com/albums/a170/bsa500/DSC03962_zps4552fb07.jpg) (http://s11.photobucket.com/user/bsa500/media/DSC03962_zps4552fb07.jpg.html)

Valve measuring 0.31 inch so spot on, one less thing to buy

(http://i11.photobucket.com/albums/a170/bsa500/DSC03964_zpscff44cf1.jpg) (http://s11.photobucket.com/user/bsa500/media/DSC03964_zpscff44cf1.jpg.html)

A look inside the timing side conrod has a bit too much movement compared to the drive side :(

(http://i11.photobucket.com/albums/a170/bsa500/DSC03967_zps9ced5576.jpg) (http://s11.photobucket.com/user/bsa500/media/DSC03967_zps9ced5576.jpg.html)

I think the valve springs need replacing initial measurement was 1.81 inches(outer)


Title: Re: Time for a rebuild
Post by: muskrat on 10.11. 2014 19:20
G'day BSA500.
I know where you'll be over winter. Looks like a full rebuild, but it's not that bad compared to modern stuff. We're all here to help.
Cheers
Title: Re: Time for a rebuild
Post by: bsa-bill on 10.11. 2014 19:36
hi BSA500
What is the mark arrowed
Title: Re: Time for a rebuild
Post by: BSA500 on 10.11. 2014 20:56
BSA bill That mark is just a lump of carbon. Muskrat-yep looks like a winter project but I have rebuilt her before kind of looking forward to it. Pity it has to cost money. More piccys as I go
Title: Re: Time for a rebuild
Post by: muskrat on 10.11. 2014 21:18
Ahh, that dreaded cost thing. I bank on a full rebuild costing about $1000AU (one weeks gross pay). If I do 5000 miles in a year that's only 20 cents a mile. Or If I do 50,000 miles between rebuilds it's only 2 cents a mile. Less painful that way.
Cheers
Title: Re: Time for a rebuild
Post by: BSA500 on 11.11. 2014 11:54
Just had a duh moment. I have said about micing the crank etc to see if it needs a regrind as I have a micrometer. It dawned on me today I have a 0-1 inch mic, not quite big enough I think :(
Title: Re: Time for a rebuild
Post by: BSA500 on 13.11. 2014 13:17
As I move forward with the strip down the issue of rebore etc comes to mind. Down Sarf we lack many engineering firms. I was wondering if anyone has any recommendations for firms based in and around Kent. I have contacted Modus Langton Green and the quote for £420 for rebores, possible regrinds and possible line reaming of the timing bush made my eyes water  *eek* *eek*.
I have yet to talk to Hodson engineering at Gaza Barracks near hildenborough and I am awaiting a reply from Dartford rebores.
Thanks Andy
Title: Re: Time for a rebuild
Post by: RichardL on 13.11. 2014 15:50
You're in the UK, shipping to Wales should be cheap. For the work you've described, SRM shows about £231 on their website, including a  new timing-side bush. Now, you may need other work, but this is for what you've described and you are fairly assured of the highest quality results.

Richard L.
Title: Re: Time for a rebuild
Post by: Topdad on 13.11. 2014 15:55
Andy, I'd wait to get some companies used by other members ,could save alot of greif down the line. Also why not at least get a quote from SRM and there is also a member who has done quite alot of work for members with good feed back, can't for the life of me think who he is ( apologises if he reads this ) but sure someone else will provide it ,best of luck BobH.
Title: Re: Time for a rebuild
Post by: Topdad on 13.11. 2014 15:58
I was typing when Richard posted this so theres one confirmation from across the pond and also I agree with what was posted ,mine was done by them 10yrs plus ago and still going well, BobH.
Title: Re: Time for a rebuild
Post by: BSA500 on 13.11. 2014 16:35
I am still in the process of strip down so it will be a little while before I am ready for the machining. I was hoping for a local firm as I also need an accurate measurement of the bores before I can order the pistons. I will get a quote from SRM but even though I am in the UK the postage costs there and back will still be steep. Them old crankshafts and barrels are bloody heavy old things :)
Things like sludge trap cleaning, small end bushes and shimming the crank are not an issue and easy to do.
Title: Re: Time for a rebuild
Post by: RichardL on 13.11. 2014 17:20
Sorry, I couldn't resist the challenge. You can ship 45 kilo (edit: probably more than you have)  from Tonbridge to Aberystwyth for about 60 GBP, round trip (myHermes). Seems you would still be better off by about 120 GBP. Otherwise, look up Andy at Leigh Classics in Leigh-On-Sea. Minimally, he can mic your bores, but could do the work, as well (he might farm out machining). Tell him Richard from Chicago said hello. I'm still waiting for my free RGS replica for recommending his shop.

Richard L.
Title: Re: Time for a rebuild
Post by: BSA500 on 13.11. 2014 19:27
Sorry, I couldn't resist the challenge. You can ship 45 kilo (edit: probably more than you have)  from Tonbridge to Aberystwyth for about 60 GBP, round trip (myHermes). Seems you would still be better off by about 120 GBP. Otherwise, look up Andy at Leigh Classics in Leigh-On-Sea. Minimally, he can mic your bores, but could do the work, as well (he might farm out machining). Tell him Richard from Chicago said hello. I'm still waiting for my free RGS replica for recommending his shop.

Richard L.
Richard if I use Andy I will be sure to tell him to ship your RGS directly. *smile*
Title: Re: Time for a rebuild
Post by: morris on 13.11. 2014 21:50
I will get a quote from SRM but even though I am in the UK the postage costs there and back will still be steep. Them old crankshafts and barrels are bloody heavy old things :)

 *bright idea* This is how I do it; take the wife on a trip to the (Welsh) coast, and when arriving, well I'll be damned, by accident you have the engine in the back of the car... bit stupid then not to have a quick drop by at SRM, no?
Title: Re: Time for a rebuild
Post by: BSA500 on 14.11. 2014 09:34
Hmmm nice idea, but my chances of survival would not be good I think  :!
Title: Re: Time for a rebuild
Post by: Topdad on 14.11. 2014 10:44
Do it over a weekend , get there friday have alook round the workshops (and be impressed ) even your better half will be surprised and then you're free to look at the wonderful countryside around there combined with great pubs and restaurants so I'm told . Also have you considered the end feed conversion for the bike , well worth thinking regards Bob
Title: Re: Time for a rebuild
Post by: Duncan R on 14.11. 2014 18:28
Not sure if you have 4 wheeled transport but I got all my work done at T&L Engineering in Bedford,only a 90 min trip from North Kent. The work was excellent ,on time and a fair price.
Title: Re: Time for a rebuild
Post by: BSA500 on 14.11. 2014 20:35
I have a few irons in the fire so to speak. I remembered that where I first had her rebuilt is still open in a roundabout way. I first used Vic Millers in Hastings to have the bottom end rebuilt and a little later the cylinders were resleeved(20 years and 50,000 miles ago). The shop is still there doing classic bike rebuilds they are called Cosmo Motorcycles.
More investigation of the big ends shows more wear/movement in the timing side which is a little strange seeing it gets the oil first hey ho
Title: Re: Time for a rebuild
Post by: terryg on 15.11. 2014 07:08
Another satisfied customer of T&L (Elstow, nr Bedford) here. Good communication and they did what they said they would at the price quoted. They also pointed out what did NOT need doing.
Title: Re: Time for a rebuild
Post by: BSA500 on 16.11. 2014 19:54
So took the crank out so more pics...

(http://i11.photobucket.com/albums/a170/bsa500/DSC03976_zpsf6de4958.jpg) (http://s11.photobucket.com/user/bsa500/media/DSC03976_zpsf6de4958.jpg.html)

Damaged shims

(http://i11.photobucket.com/albums/a170/bsa500/DSC03972_zpsebc60799.jpg) (http://s11.photobucket.com/user/bsa500/media/DSC03972_zpsebc60799.jpg.html)

Timing bush

(http://i11.photobucket.com/albums/a170/bsa500/DSC03973_zpsb3a5c4d7.jpg) (http://s11.photobucket.com/user/bsa500/media/DSC03973_zpsb3a5c4d7.jpg.html)

Big end shells note hardly any wear so good news and from rough measurement no wear to the crank

(http://i11.photobucket.com/albums/a170/bsa500/DSC03979_zps0a698fa4.jpg) (http://s11.photobucket.com/user/bsa500/media/DSC03979_zps0a698fa4.jpg.html)

(http://i11.photobucket.com/albums/a170/bsa500/DSC03977_zps7f0f1710.jpg) (http://s11.photobucket.com/user/bsa500/media/DSC03977_zps7f0f1710.jpg.html)

But the timing side of the crank looks like it may need attention. That looks to be some timing bush shavings

(http://i11.photobucket.com/albums/a170/bsa500/DSC03974_zps16e6872d.jpg) (http://s11.photobucket.com/user/bsa500/media/DSC03974_zps16e6872d.jpg.html)

Title: Re: Time for a rebuild
Post by: BSA500 on 01.01. 2015 21:30
Ok did some measuring,big ends are fine. Checked the timing side journal and it measures 1.366 inch so what timing bush size would be suitable -10?
Title: Re: Time for a rebuild
Post by: beezermacc on 01.01. 2015 22:04
Standard size is 1.375 so logically -010 is 1.365. If yours measures 1.366 that suggests it has been ground down once and there is little or no wear. You need to check for ovality i.e. that the up/down measurement is the same as the front / back measurement. Also make sure there isn't a lip on the outside of the journal. If everything meausures OK a -010 bush should do the trick. Obviously it will need reaming to ensure roundness and fit. As an aside I usually have the timing side journal ground round, regardless of size and have a bush made to suit; this prolongs the life of the crankshaft because each cut is usually about 3 or 4 thou rather than the 10 thou required to suit a commercially produced bush.
Title: Re: Time for a rebuild
Post by: RichardL on 01.01. 2015 22:21
Well, Beezermacc was typing at the same time with some good advice beyond what I have here, but since I'm not contradicting in any significant way, I'll go ahead and post (having completed the thumb typing).


Since it costs no more, I would go with a -0.020" new bushing. I think this will put less stress on the machinist rather than starting with a sparce 0.007" to work with. This is how I see the numbers:

1.366" (timing-side OD) + .001" (bearing clearance)= 1.367"

If -0.010" bearing: 1.367" - 1.36" = 0.007" (to remove to match the crank journal)

If -0.020" bearing, then 0.017" to machine down. Of course, the machinist should know or be told to clean-up the journal (it seems grinding may not be needed, or, at least, not much), then ream the bushing for 0.001" clearance with respect to the journal, not according to the bearing's undersize rating (with no more than 0.0015" clearance, but you know that).

As always, and for good reason, I stand to be corrected and wear the dunce hat if this is proved to be spurious advice.

Richard L.
 
(I made a small edit, in light of Beezermac's advice.)

Title: Re: Time for a rebuild
Post by: beezermacc on 01.01. 2015 23:11
The journal measures 1.366, not the bush, so the journal is oversize which is good. If the journal does not need machining, as the initial measurements suggest a new bush at 1.365 will be 0.001" too tight, again which is good. If the journal is round (i.e. less than 0.001" oval - some people might expect it to be even better than that but I reckon 0.001" is the limit) there is no need to have it machined which would shorten the life of the crank. When the bush is fitted it will shrink a bit more so, after reaming about 0.002" the crank can go straight back in. No point in taking another 010 off the crank if it is not required. All this assumes further measurements confirm the journal is OK.
Title: Re: Time for a rebuild
Post by: RichardL on 01.01. 2015 23:36
I'm certainly not debating with you, Andrew, but just to be certain I was not misunderstood, I would like to expand on what I said. I noted that the timing side (journal) OD is 1.366". The specs I was reading gave the standard bush ID as 1.375" in some models, then, 1.37" for others. I just quoted the latter, figuring it didn't much matter based on my logic of removing more material. In my own awkward way, I was trying to say that the crank should not be reduced in diameter beyond establishing roundness and smoothness, after which the new undersized bush would be machined (reamed or bored, I'm not positive which). The last time I had a new bush fit I handed the machinist the new one that I had on hand, which was maximum undersized. I forget how much he had to remove, but it wasn't billed by the thousandth, so I figure why bother cutting it close with meat to remove.

Much respect,

Richard L.

(Man I make a lot of typos!)
Title: Re: Time for a rebuild
Post by: Triton Thrasher on 02.01. 2015 10:18
(http://i11.photobucket.com/albums/a170/bsa500/DSC03967_zps9ced5576.jpg) (http://s11.photobucket.com/user/bsa500/media/DSC03967_zps9ced5576.jpg.html)


The straight scratches on the pistons look like what you get when the honing grit isn't all removed from the bores.

Use soap, hot water and a sponge, until the bores no loger put a black mark on a paper tissue.

Your rings may never have bedded in properly. Is it safe to say "dry assembly" and "cheapest oil" and "make the engine pull hard" for running in, around this forum?
Title: Re: Time for a rebuild
Post by: BSA500 on 02.01. 2015 13:31
Re the crank the journal measures up nice and 'round' no hint of being oval. I shall prob get the -20 timing bush to give him plenty of metal to bore out  *smiley4*
Re the pistons. Those have been in these STD bores for the last 15 years with one ring change 5 years ago due to the lack of wear. The scratches have only occurred in the last 5 years. I suspect it could be down to lack of air filter *dunno*. No dry assembly always plenty of oil used, proper running in but after that plenty of revs and snappy get aways at the traffic light Grand Prix  ;). I put the lack of wear on the crank etc down to the fact I changed the oil pump(after the original pump failed) to a cast iron bodied SRM pump. She has done circa 50,000 in the last 15 years so not so bad(have to admit this is the second crank after I cracked the big end journal when the timing slipped and the oil boiled ooopps)
Title: Re: Time for a rebuild
Post by: BSA500 on 14.01. 2015 09:18
I have located some pistons at a good price but was wondering if anyone has used this shop/store and how was their experience. Its www.classicbikeshop.co.uk
Title: Re: Time for a rebuild
Post by: chaterlea25 on 14.01. 2015 16:18
Hi,
I cannot see any A7 pistons on their website ??
(or am I missing something??)

John
Title: Re: Time for a rebuild
Post by: BSA500 on 14.01. 2015 20:51
No your right, but when I inquired about the price etc they came back with a quote for a set of A7 pistons +20 of £100 incl vat(£3 p&p)
Title: Re: Time for a rebuild
Post by: BSA500 on 02.02. 2015 13:51
Piston update they do not stock A7 pistons( http://www.classicbikeshop.co.uk/). I have ordered mine from Draganfly(on back order) seems nobody stocks A7 pistons these days. A10 on the other hand how many do you want sir :(
Title: Re: Time for a rebuild
Post by: muskrat on 03.02. 2015 11:24
G'day BSA500.
I just had a quick look at this list (download) www.britcycle.com/products/Pistons_Rings.pdf
The C15, C25 and B25 are 1mm bigger,Notrun 500 twin pistons are the same bore size. You'd have to check the pin size and crown height.
I used to run std A75 pistons (67mm) but had to use A10 rods shortened by 2.5mm in my A7SS racer (crown height was shorter).  *eek*
Cheers
Title: Re: Time for a rebuild
Post by: edboy on 03.02. 2015 19:31
norton pistons would be difficult as the valve recesses are offset compared to bsa pistons. i m after +80 pistons for an a7 and in the same boat. t150 pistons are close but have a higher dome so what about a spacer at the cylinder head muskrat? have you looked at wiseco pistons?
Title: Re: Time for a rebuild
Post by: muskrat on 04.02. 2015 08:27
To use T150/A75 pistons you'd need to space the barrels 10mm *ex*. Don't know of a Wiseco that fits.
Try your local engine re conditioner. They have books of piston sizes.
Cheers
Title: Re: Time for a rebuild
Post by: Rocket Racer on 05.02. 2015 00:28
Not wishing to turn this into another some pistons are crap thread, I would say take your time with getting pistons that suit. There are brands I won't touch with a barge pole, I think they are made from recycled aluminum windows.
Try and find some NOS ones, tricky I know but worth the effort of a big seize
Title: Re: Time for a rebuild
Post by: Rocket Racer on 05.02. 2015 00:42
http://www.vintage-motorcycle.com/index.php?language=en&site=4&pid=113&id=21072&limit=0 (http://www.vintage-motorcycle.com/index.php?language=en&site=4&pid=113&id=21072&limit=0)

I'd be thinking about these if I were you, NOS is always my preference, or are these the wrong A7... *eek* doh always forgetting the mk1/mk2 thing. Anyway good luck
Title: Re: Time for a rebuild
Post by: terryk on 05.02. 2015 07:05
Hi BSA500 I have a number of NOS BSA A7 piston sets both long and short stroke what compression ratio were you chasing?
I'm in Australia so post cost need to be taken into consideration.
cheers Terry K
Title: Re: Time for a rebuild
Post by: BSA500 on 05.02. 2015 08:44
Thanks for the replies and offers. I currently have a pair on order from Draganfly so fingers crossed they come soon. They reckon they will  :!
Title: Re: Time for a rebuild
Post by: BSA500 on 05.02. 2015 08:46
Oh the engine is a 1957(in a 1960 frame) alloy head currently sporting 8.5:1 in worn out standard bores. I have plenty other things to do to it so a little extra time won't hurt(and its effing cold out I normally ride the winter so a winter in the car is quite new to me  *smile* )
Title: Re: Time for a rebuild
Post by: edboy on 05.02. 2015 19:29
its a shame otj are no longer around in kent. a set of cord piston rings would have kept you going through the winter. do you remember those? steel rings for worn out barrels and i believe otj were a main supplier.
Title: Re: Time for a rebuild
Post by: BSA500 on 08.02. 2015 20:11
OTJ was just up the road for me so yes its a shame they went  *sad2*
Title: Re: Time for a rebuild
Post by: rocker21 on 12.02. 2015 12:17
I have used Rob walker Engineering Nr Witney  in Oxfordshire, superb workmanship, not the quickest but definitely good and reasonable prices.
have a look at his web site.
Title: Re: Time for a rebuild
Post by: BSA500 on 12.06. 2015 13:05
Right update. Yeah I know its been ages and I am useless. I shall post some of the rebuild pics. But she is now back on the road being run in. I tend to ride as normal but don't over stress on the hills and no fast getaways from the lights *smile*

(http://i11.photobucket.com/albums/a170/bsa500/DSC04138_zpsoj6pnak0.jpg) (http://s11.photobucket.com/user/bsa500/media/DSC04138_zpsoj6pnak0.jpg.html)
ready for the engine machine work to be done

(http://i11.photobucket.com/albums/a170/bsa500/DSC04268_zpsuzbazhpr.jpg) (http://s11.photobucket.com/user/bsa500/media/DSC04268_zpsuzbazhpr.jpg.html)
sad without the engine

(http://i11.photobucket.com/albums/a170/bsa500/DSC04272_zpsg0ghsgff.jpg) (http://s11.photobucket.com/user/bsa500/media/DSC04272_zpsg0ghsgff.jpg.html)
back from the shop

(http://i11.photobucket.com/albums/a170/bsa500/DSC04274_zps5mfplnvt.jpg) (http://s11.photobucket.com/user/bsa500/media/DSC04274_zps5mfplnvt.jpg.html)
clean bit and rebored cylinders

(http://i11.photobucket.com/albums/a170/bsa500/DSC04284_zpsi4ncak06.jpg) (http://s11.photobucket.com/user/bsa500/media/DSC04284_zpsi4ncak06.jpg.html)
setting endfloat

(http://i11.photobucket.com/albums/a170/bsa500/DSC04288_zps6ptfltei.jpg) (http://s11.photobucket.com/user/bsa500/media/DSC04288_zps6ptfltei.jpg.html)
going back together

I will post a picture of the finished beasty soon

Title: Re: Time for a rebuild
Post by: BSA500 on 08.07. 2015 13:15
Well she has reached the magical 500 mile mark so is run in  *smile*. A couple of leaks of course the gearbox while on the side stand and a small leak from the head joint which might explain some oil burning. I forgot to aneal the gasket thinking a new one would be fine-wrong. This is the first time I have forgotten and the first time I have had a leaky headgasket. Still got stuttering on acceleration getting worse as it gets hotter which points to Magneto(if its chilly I hardly notice it).
The thing is ,normally when a mag starts to fail, it goes downhill quite rapid, but this issue has been plaguing my bike for 2-3 years of constant riding 25 miles a day ????
Title: Re: Time for a rebuild
Post by: Topdad on 08.07. 2015 13:22
Wheres  Beezergezzer when you need him
Title: Re: Time for a rebuild
Post by: BSA500 on 08.07. 2015 13:35
I know. With that in mind I have a mag rebuilder close to where I work called Paul Bruschan in Aylesford Kent. Has anybody used him for work etc