750 pistons..

Sorry if this topic has been covered before but i cant find it in the archives......
I am in the middle of a complete engine rebuild after a crankshaft nut went walkabout in the crankcase.. The only items i managed to salvage were the camshaft and the cylinder head.. I purchased a pair of ''Hepolite'' plus 20o/s from flee bay.. When they arrived they turned out to have different cut outs in the crown for the inlet valves, this was about 3mm difference. Also i was not happy with the general look, or feel of them. Compared to the originals they felt very light and looked as though the walls were very thin.. Anyway, cut a long story short, I am looking for the best set of pistons i can purchase.. I dont want to go down the road of modifying the rods.. Just standard, +20thou o/s, combat spec pistons... Any help gratefully appreciated...

The new "Heploites are not made by the same people who made the old "Hepolites" although I have not seen any problems with using them.
I have also had very good luck with the Taiwanese JCC pistons sold under several different labels. I install these 10-1 over the Hepolites. [customers choice] Jim

Fitting lighter pistons is a good move. It could be that the new Hepolites are spun cast then forged - as the Japanese have made pistons that way for years .

........"I am looking for the best set of pistons i can purchase".........check JSmotorsports.com for their longer rods and lighter pistons set up. lots of good stuff for our engines there.

Hi,

I have just rebuilt a 750 top end using Aussie made JP pistons. These are available from FEKED.COM. They are nicely made and weigh within a few grams of AE made Hepolites. They are stadard crown height i.e 9 to 1 cr. This should give 10 to 1 cr with your Combat head. You will need to check valve to piston clearance to be on the safe side.
FEKED are good to deal with over the telephone.
Hope this helps.

Martyn.

JP pistons are cast not forged but they are notorious for seizing when using the "normal" clearances for cast pistons. Better use the recommended clearances for forged pistons and put up with the rattling when the engine is still cold.

I have just done my 750 & used the JP pistons, bought from Mick Hemmings.
He also does forged pistons but are more expensive. I did have to file the bottom of the skirts away as they were smacking the crankshaft. They actually seem fine now, rides lovely. Bought the high compression ones as my head is a low compression RH5.
Could also look on Mr. Maney's sight.
Hope it warms up soon, must pop down near the Piddle for a Dorset cream tea.