The BSA A7-A10 Forum
Technical (Descriptive Topic Titles - Stay on Topic) => A7 & A10 Engine => Topic started by: PatM20 on 09.04. 2018 08:31
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Has anyone tired the cheap piston kits (pistons, rings, clips and pin) you can get off ebay?
The ones that have the Wellworthy type oil ring.
Regards
Pat
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Has anyone tired the cheap piston kits (pistons, rings, clips and pin) you can get off ebay?
The ones that have the Wellworthy type oil ring.
Regards
Pat
I haven’t but are they much cheaper than (say) JP (from Aussie) or the Wassel “hepolites” ?
I bought JP from Draganfly which is odd given they are made in Aus and I’m in nz, but they were cheaper buying from DF than buying direct from JP. Not all think JP are good but I’ve not had problems with flat tops for 8000 Miles now.
British Only were selling some decent Taiwanese pistons a while back, not sure if they still do, very light but rings were said to be not much good.
Edit. British Only seem to have 25% off pistons at the moment
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i fitted Taiwan pistons but also put gandini rings on them no problems so far
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No personal experience but a friend with a vintage shop who restores Italian and Brit bikes tells me the pistons are fine, but uses Hastings rings.
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Had a look on ebay at the Hepolite/wassell pistons with English made rings which seemed good value.
Ebay also had some slightly cheaper pistons, but they didn't have the split horizontally either side in the oil ring groove. Maybe because they are using the three piece oil ring, but wasn't sure why.
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I have used what USED to be called "Cycle Craft" pistons in a lot of bikes and now called JCC or EMGO and are Asian made cast pistons and they tend to be excellent and * *fight* * makes some of the purists angry but IMHO they are vastly superior to the original hepolites. Digital weight scales and calipers/Mics dont lie. The specs are very consistent to the point of on many Triumphs, Nortons and Unit A65s I would only order one set for each size and then have the machine shop bore and fit those pistons to multiple cyls back when I did a lot of engine rebuilds.
I did not worry about as they were spot on size wise. (And weights) But still good to check. After 25 years though I found one set mismatched.
Check ANY set of pistons and they are "graded", New out of the box they will typically have small paint dots typically on the pin bosses. Red, Yellow, green or sometimes 2 dots side by side.
Depending on QA or the inspectors they grade and sort the pistons to ensure consistent pairs. In my one exception they were mismatched and off by 1.5-2 grams IIRC. ( common and expected deviation with Original Hepolites & Wellworthy)
However the pins supplied tend to be weighted wildly different so best to check them. The circlips also reportedly have issues with some sets but I never experienced any issues but on some builds I use my own sourced specialty clips.
Rings tend to be cheap and so-so quality. Okay for a penny pincher and budget build but not up to mosts standards so I avoid the supplied rings and use a mix of US supplied as well as Hepolite and Hastings rings depending on availability and the builds specs.
One bit of a footnote, Maybe one day I will compile a ORG Chart or family tree of the companies but in the 40s thru 1960s most parts supplied were a select group of manufacturers, But some of these names live on but NOT the same company. IIRC Hepolite was bought out circa late 1990s but US Federal Mogul who promptly did a partial shut down, farmed out most production to a sub-par Spanish or Italian company,(GPM?) and then folded the Hepolite name entirely. The name has been revived but NOT the same company & think some sort of repops and merely branded with the Hepolite name.
So, flame suit on, * *dunno* * but model and brand specific enthusiasts tend to have limited fields of view and blinders on. At the end of the day its JUST a cast piston. British bike owners tend to reverently think a OEM Hepolite or WellWorthy are the be-all and end all of what the world revolves around. But in any other form of motorsports or performance a cast piston is the lowest echelon of quality. Something you might use in a air compressor or yard & Garden equipment but certainly not in a road going vehicle. Auto folks have some options for those on a budget and there is some quality mid point pistons out there but otherwise forged pistons are de rigueur and only a true Bodger would stoop to a cast piston.
So, I used to deal with people in my shop who would haughtily turn up their nose at a Cycle craft-JCC-EMGO piston ( on average $40-60 dollars a pair vs $180-200 USD for a Hepolite made in UK set) as if in the comparison of cast pistons was much more than a few minute degrees of separation in reality.
I still tell people if you want to reuse your rods, and run cast pistons then ride the bike accordingly. But if you want performance then step up and upgrade your crank, rods, pistons & valves to modern materials.
One final note: I have wondered about the BSA pistons with large slots in them, expansion joints certainly but in Nortons they are considered little more than a ornamental paper weights and most will warn you to NEVER run those slotted pistons. (Always a Alfred E Newman-What me worry types who relate years of service as an exception) But I have not heard the same tales of woe with BSA pistons of that type. Is it because better made or more agricultural usage? So, I do have some very ancient dealer stock Wellworthys with such slots and always wondered about them.
More relevant when asking about experiences of such is a summary of type of expected use, Parade, display and Sunday best rider? Or flogged in the Alps or Nurburgring?
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Used to love Mad magazine with Alfred E Newman!
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According to some one in the trade , John Healey I think it was, there is only one factory that makes BSA pistons for wholesale trade.
So unless you are buying a custom made forged piston thye all come from the same factory in Tiawan.
Apparently they have been making pistons for British motorcycles from the get go and were supplying pattern pistons when BSA's were new.
There were a few others but they all stopped when volumes dropped.
Now this exclude the specialty people like JP but their pistons are basically hand made to order.
So the only real difference was the rings.
The new "hepolites" come from the same factory as the unbranded Tiawan pistons.
This to me sounds about right because to get reasonable volume efficiencies you need to cast thousands and the world demand is apparently only a few hundred a year.
However with the rise of China, I have no doubt that some Shylock will send some pistons to Wee Fool Woo pistons with a note, make me 1000 that look line this real cheap and sell them on ebay where he can not be held accountable for any damage or injury they might cause.
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i have to go back to my recommendation of IMD pistons, made and supplied retail for A7/A10 (up to +40 thou") - from the UK. You would choose these for quality rather than price. The pins, circlips, rings are perfect out of the box. The pistons are light, rings are a special design, with a 3-piece oil, they bedded in quickly and thoroughly. I was told "you don't gap them" and I didn't (couldn't get them out easily because they're "modern" - deeper, thinner). I've done about 1.5k miles on since. It never burnt any more oil, since this upgrade and runs beaut. Adrian the proprietor source the flanged liners - to go back to standard bore.
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IMD seem to be the cheapest in the UK at £72.00 for pistons, rings, pin and clips (UK ebay number 152961015133). Even cheaper than a Heoplite/Wassell equivalent.
I am assuming it is the same "IMD".
Their pistons don't appear to have the horizontal split either side of the oil ring groove.
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I always go Wiseco or GPM and have had no issues on any of my bikes "you get what you pay for"!
Regards,
Kim
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Pat,
These are the IMD pistons: https://www.ebay.com/itm/BSA-A10-PISTON-KITS-2-Standard-GOLD-FLASH-1950-1962-NEW-70mm-/152961015133?hash=item239d2fdd5d
Like Magicflem, our immensely-respected engineer in this region - used to rate the Wiseco the best. He is very hot on piston quality. The Wiseco's were a performance item (forged piston): at +80 thou", 9.75:1 comp - as far as I can gather. You could only get them from Cake Street Classics. I talked to Roger Sharman and he ran out of these long ago. There are no known alternative sources. When our engineer examined these IMD sets - he saw them as being the closest to that Wiseco quality.
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I used to be a tree surgeon, now retired and ran mostly Stihl saws.
As an experiment we put a couple of cheap pots and pistons in two of the saws we used for logging. They lasted five years and were around 30% of the cost of genuine Stihl equivalents. I still have one of the saws, the other got run over by a JCB.
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I was impressed with the quality of the Taiwanese pistons and rings I fitted to the Star Twin donkey's years ago. 20,000 hard miles and performing admirably until I did a complete barrel and piston swap. I am no fan of original Hepolites. There is one member of the NOC forum who insists that ONLY NOS Hepolites should be used. Hmm. I have a box of failed pistons, mostly Norton twins plus A10. In fact all the piston failures I have had over the years as original Hepolite. I have a set of NOS Hepolite A7 pistons in a box. Much heavier than the original pistons used by BSA. Oddly, the slotted pistons seem to be fine in BSAs but not in Nortons. I wonder why.
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Have to say I’m curious as to the knocking of original Hepolite / Wellworthy pistons. During my engine rebuilding years (60’s – 90’s) I rebuilt hundreds of engines, from a lawnmower to single seater race cars and most everything in between. I used a thousand or more pistons, with virtually all being Hepolite. I’d use them in preference to OEM (in many cases OEM were Hepolite anyway; Ford was an exception). Ford quality wasn’t bad, but they often used odd sizes, such as +.005” and + .025”. Like Sluggo, I had no time for split skirt pistons. The purpose of the split was for expansion, enabling a quieter motor through decreased bore clearance - at the expense of strength. Naturally, I always used ‘powermax’ forged pistons for competition or an engine likely to be frequently ‘hammered’. Otherwise cast pistons were / are perfectly satisfactory and most vehicles were fitted with them. Of course I have seen damaged pistons, but they were all caused by external factors - overheating, seizure etc. except one – a Ford piston where the gudgeon pin bosses had detached from the piston crown. I cannot recall a single Hepolite failure caused by piston quality issues.
Likewise I don’t understand people worrying that this gudgeon pin or piston is a gram or three heavier than the other. We’re not building a F1 engine, folks. These are ‘cooking’ engines and, with 28 grams to the ounce, a couple of grams off perfection is essentially irrelevant. These engines vibrate anyway, so trying to achieve perfect parts balance is a waste of effort. I sometimes think we are in danger of trying to make a diamond-encrusted silk purse out of a sow’s ear.
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Just a comment. It doesn't matter if a piston is cast or forged within common man road bike rpm's. For the same geometries the engine performance will be the same. The big difference is when it all goes wrong. Cast pistons break up and stick a rod anywhere. Forged pistons stay in one piece and leave something re-buildable.
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Not sure about the last sentence. Pistons are usually the victims of engine damage - usually overheating but occasionally over-revving. Have seen rods that snapped at the little end (mainly), bent rods, lots of seized pistons but only ever one engine damage attributable to piston failure (and that wasn't too bad) so whether an engine is rebuildable or not really rests on other factors. Playing devil's advocate, one could say the fitting of forged pistons is more likely to result in engine damage (because of the reason they were fitted in the first place - ie the engine is going to be hammered).
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Good logic RD, I think we sometimes get carried away with stuff from the good ol days vs modern hi tech manufacturing methods and materials. The problems come when you mix them up and dont understand the differences and why things were done a certain way in the past. Using forged pistons and crankshafts and billet conrods are all admirable advances in technology over what was originally used in these machines, but seriously, unless you plan to ride it hard and long, why?? even then, using those "upgrades" is pointless unless you also upgrade the parts that interface with them - I'm sure Musky and Kiwi Racer have lots of good stories to tell about doing such things and the resulting outcomes.... ::hh::
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Good logic RD, I think we sometimes get carried away with stuff from the good ol days vs modern hi tech manufacturing methods and materials. The problems come when you mix them up and dont understand the differences and why things were done a certain way in the past. Using forged pistons and crankshafts and billet conrods are all admirable advances in technology over what was originally used in these machines, but seriously, unless you plan to ride it hard and long, why?? even then, using those "upgrades" is pointless unless you also upgrade the parts that interface with them - I'm sure Musky and Kiwi Racer have lots of good stories to tell about doing such things and the resulting outcomes.... ::hh::
Spot on Jules, horses for courses really.
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Good logic RD, I think we sometimes get carried away with stuff from the good ol days vs modern hi tech manufacturing methods and materials. The problems come when you mix them up and dont understand the differences and why things were done a certain way in the past. Using forged pistons and crankshafts and billet conrods are all admirable advances in technology over what was originally used in these machines, but seriously, unless you plan to ride it hard and long, why?? even then, using those "upgrades" is pointless unless you also upgrade the parts that interface with them - I'm sure Musky and Kiwi Racer have lots of good stories to tell about doing such things and the resulting outcomes.... ::hh::
Actually I never fit any product that says "machined from billet " as it is totally meaningless .
If the vendor is trying to infer it is superiour to either a casting or forging then they are playing with themselves and you .
The first questions is
" machined from what kind of a billet ? "
Forged ?
Cast ?
Hot Rolled ?
Cold Rolled ?
Extruded ?
Even worse is most parts I see that are " machined from billet " are dimensionally identical to the original casting / forging which is so wrong in engineering principles I can not even think about where to start.
And the next question is Billet of what ? , butter, cheese pure aluminium .
There are a lot of automatic copying machines out there that will allow any old idiot to pot an object on a plinth, then scan it then machine an exact copy of it from whatever was clamped into the work place, a block of wood a block of steel a block of cast iron.
However it does not have any mans of compensating for GRAIN SIZE & ORIENTATION and these are vital engineering parameters for engineered parts.
Now if they are just gee gaws for a HD the fine cause the bike will never be ridden .
But if they are parts for your BSA have a real serious think about fitting one , or better still don't fit it .
A silly example of how a change can have drastic effects
Kohler introduced 2 new engines , the Command & the lower priced Courage
The Command was designed, the courage was a modified Command
Some one decided to swap the expensive forged crank with a cheaper Cast malleable iron one on the Courages.
The result was over 20,000 warranty repairs because the extra weight & different vibrations charasterics caused the closure plate bolts to back out & the crank case to split ring down the barrel crankcase base.
Or to use a BSA example, the "Titanium Tragedy " when BSA copied the Victor frame used on the works bikes that was made from 531 high ensile steel tubing with titanium tubing to gain strength & loose weight.
Not a single one finished a race as the "stronger " frames cracked up & fell apart on the starting lines .
To get the same strength around the little end a "billet machined " con rod would need to be near 3 times the cross sectional area as a cast one and around 5 times the size of a forged one if it is cut from a billet with the grain running top to bottom ( which it should be ) because that orientation has planes of weakness in the grain direction so the little end is highly likely to let go a either edge of the little end bush hole .
To overcome this you have to increase the section size in this region so you have just added weight to the very place where you don't want it .
So don't take the description "machined from solid billet" to mean any sort of improvement in quality because alone it is nothing like it.
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Totally agree. Never been able to understand how a machined item (eg con-rod) can be as strong and endure the stresses invoklved, as a forging. Likewise I could never see the advantage of machining rods by making then into an H section.