Pistons

[RDfella]

Be aware also that boring past .060 (which will be necessary to accommodate liners) weakens the block / flange area. Could find your block going up and down with the pistons! How Musky gets away with his set-up I've no idea ........

[muskrat]

G'day RD.
The liners in the Cafe have about 1mm wall thickness bored for 72mm pistons. There is a light spigot in the barrel skirts to stop the sleeves "falling" out. That plus the through bolting (4 outside head bolts go through to the crankcase) hold it all together.
Cheers

[mikeb]

What do we reckon about the other makes hepolite, IMD, Jp etc

no one has yet commented on IMDs. i've fitted them to the a10 and think they are great, especially with the 3-piece oil ring. i've noticed the oil stays cleaner for much longer and none gets burnt. when getting the liners fitted the engineer involved commented positively on their design (exactly why went over my head). the down side is they are only available at lower compression and i can certainly notice the difference on the a10. strangely, the other possible down side is they are light so you may want to rebalance the crank (hence its not just a top end job).
i don't quite share trevors enthusiasm for JPs but only have had a couple of attempts with them. from memory they need to have wide clearances and so before long slap around a bit when cold. fully agree the rings don't suit our bikes. there are better options (tho few in +080, which JPs will do)

[muskrat]

G'day BSA500.
Going back to your original 
Have you had the barrels and pistons accurately measured for size/ovality/tapper  If all measure within tolerance just a new set o rings and a light hone may suffice.
If your looking at new pistons I would go the next oversize.
Cheers   

[BSA500]

G'day BSA500.
Going back to your original 
Have you had the barrels and pistons accurately measured for size/ovality/tapper  If all measure within tolerance just a new set o rings and a light hone may suffice.
If your looking at new pistons I would go the next oversize.
Cheers

No not yet but the main reason for tearing her down was the oil burning and new vibration/rattle (everyone said its not making a noise but I know my bike). Turned out  the oil burning was down to the headgasket leaking between cylinders(no visible leak or blowing found by leakdown tester) and the rattle was the horribily worn small end bearings. There is no ridge on the bore and no scoring. I had got a new set of rings,nos bsa, and was going to swop them over. I then went and broke the piston skirt. There is some scuffing I guess from the wobbling small ends etc.

[BSA500]

BTW I like the look of the IMD pistons

[groily]

BTW I like the look of the IMD pistons

I think they are top notch and I put some +40s in my A just before passing it to its new close-mate owner. Going v strong. (Circlips are rather hard to fit, note.)
But, availability for A7?? Couldn't see any when I looked, but it's an ever-changing area and I may need to go to Specsavers . . .

[BSA500]

Yeah the only ones I could see were the A10s

[chaterlea25]

Hi All
There are some on ebay including a NOS original Hepolite +030 set
also a secondhand +020 piston

https://www.ebay.co.uk/sch/i.html?_from=R40&_trksid=m570.l1313&_nkw=BSA+A7+pistons&_sacat=0


John

[BSA500]

Sort of an update I checked bore wear with the old rings and a nos of bsa rings. The old rigs were plus 20 thou gaps the new rings visibly smaller

[rocker21]

i have a pair of new +.020 pistons, i think they are 8:1 or possibly 8.5:1  made by JCC dated 06/31/1996 if any one wants them.
pistons are complete with rings, pins and circlips

[sean]

I have fitted the IMD liners and pistons to my A10   .....the lower compression pistons seem to run fine on todays gasoline ...the circlips are a pain to install       on the plus side motor is easier for me to kick over with the lower compression my knees are grateful .

[olev]

There is a gentleman in our local club who runs a 498cc ohv H8 AJS with a yamaha piston.
It has a locally made cam and goes very well.
There must be pistons from other engines that would fit our machines even if they needed modifying a bit.
I vaguely remember something from a mini was supposed to fit.??  not sure it was a piston though.

cheers

[rocker21]

just for your info a +.060 A10 piston will fit a B31 with a spacer under the barrel of approx 1mm , rode it to Holland a few years back, ran fine.

[muskrat]

There must be pistons from other engines that would fit our machines even if they needed modifying a bit.
cheers

Depends on how much modifying. I ran std T150 pistons (=to+20) in my A7SS racer  . BUT I had to use A10 rods shortened by 2mm  . Gave it 14:1 compression on methanol.
A friend had a Daihatsu diesel piston in an XT600.
Cheers
ps: Trihard 6T pistons are 71mm https://draganfly.co.uk/triumph-pistons-rings/