Club pistons for G9/Mod 20

[Groily]

Although there are loads of threads on twin pistons, can't see anything on here specifically on the performance and quality of the club ones. Is anyone who's been running a pre-'59 500 twin with a pair for a decent period of time/mileage prepared to share their experience to date? Fit, vibes/affect on balance factor, oil consumption etc? Be very grateful for any practical feedback before deciding whether to continue the hunt for decent old stock or just take the easy route.

[GSAX1]

I've done aboout 10000 miles on the JP pistons. Not sure if they are supplied by the club now.

They are stone-heavy, weigh 50% more than the original wire-wound. I had to rebalance the crank. They slap around merrily when cold, but are OK when hot. I have a very reasonable oil consumption of about 0,7 liters per 1000 km.

Mine is a '55 twin.

Hope this helps,
Michael

[CAB]

Hello
A friend of mine has just had his 650SS "restored" but he is having a lot of problems with it (charging, starting and it's now running on 1 cylinder). When he got the bike back he was told to put a capful of 2 stroke oil into each tank full of fuel whilst running it in.... Anyway today we visited another classic bike restorer as my friend is thinking about getting him to sort the bike out. He mentioned the capful of 2 stroke oil to the restorer and he was very surprised (I was as well when I first found out). He asked my friend what type of pistons had been fitted and he said JP to which the restorer replied that he doesn't like using them due to thermal expansion problems....
Now my friend is even more worried about the standard of the first restoration. Has anyone else heard of this problem?
CAB

[paul knapp]

I too have JP pistons, quite rattly when cold as I had an extra tho bore clearance honed to compensate for the very hot riding days here. Oil consumption is an infrequent top up.
Weight is another story! When I compared them with the originals, they were a lot heavier, so I sent them back to the factory and had JP machine out the skirt I.D. and part of the pin boss. I then used a rotary burr to further remove more metal from around the sides of the pin boss. This brought them to within 6 grams heavier than originals.
Vibration is more noticable over 50 M.P.H., but since I don't use the machine for fast runs, isn't a problem for me.
I never have had any signs of 'nipping up', even when pulling hard up long hills on a 38plus Deg. C day. I always use straight SAE50 in the tank.

Paul.

[RogerNorman]

The set in my '54 G9 were fitted in about 2005 and have done around 10000 miles since ( I have a few bikes to chose hence the low mileage relatively). I tend not to hang around -as anyone who rides with me will support and I haven't suffered a problem. Oil consumption is not brilliant but then that may be oil leaks as well and frankly I don't bother to check how much it uses - just top it up or change it.
The originals suffered from being a bit too enthusiastic coming back from East London and Essex Section one night on the climb up from the Dartford Tunnel on the M25. Won't mention the speed in case an officer of the Law reads this! But its probably no wonder it seized.
(The fact that I am closely associated with JSL has no bearing on the above). At the end of the day if you need pistons unless you are prepared to spend a fortune with a set of specials from say Omega (as I am contemplating with my Typhoon) use what's available.

[smsxr05]

I had some club pistons fitted in my 500 twin and it kept nipping up. I had the rebore done out another thou and all seems well after about 3000miles. Can't say if it was the pistons or the rebore at fault though.

[Groily]

Thanks very much to one and all.
Might go the modern route, but I'll keep hunting for serviceable originals, as the omens are looking good subject to the inevitable rings issue. Very good to hear Paul's and Roger's and smsxr's experience. I guess we're talking, what, 3.5-4 thou bore to piston clearance - or maybe a bit more even?

Frankly, I'm inclined to rebore, sleeve (or even get extra cylinders to save those I have from unnecesary enlargement) if I can find usable BHBs or Hepolites, but that's nothing to do with criticising the Spares Scheme Roger - it's good that there's anything available and I might yet go there.
That said, my Mod 20 has never run as sweetly since the wire-wounds I had in it died about 25 years ago. Of course I was young and even more stupid then, so didn't think it could possibly matter - but the difference was immediately noticeable and I've missed them ever since.

[moley]

What size pistons do you require and i will have a look in my spares? cheers andy

[OLD SHEP]

I've just fitted new pistons from the Club to my 1956 Model 30 600cc. Now running them in. Done about 500 miles, so far, so good. Not smoking like before. Rebored by Dave Massam (see ad in OBM) and sounds good. Chris

[Groily]

Thanks again folks.

Thanks Andy - first choice is a pair +40 pre-59s, Hepolite or BHB, wire-wound or not, which would go into an available good set of barrels. Otherwise, I'm into re-sleeving etc as mentioned (which I don't mind having done).
Steve Surbey has some good +40 pistons (can't remember which type, Heps I think), but no good rings in that size, and nor do I. He's also got some +20s with NOS rings which I'll be buying anyway, and I may just be in luck courtesy of one of our gracious number here for a set of std wire-wounds, which would be the best of all possible and joyous solutions (with a pair of resleeved barrels).
Simplest solution is new club slugs, but I don't think it's my favourite option.
Many thanks for offering to look, really appreciated.
Bill