1926 EW 350 Piston-Bore Clerance

[916nik]

Hi,
I am in the process of rebuilding my 1926 EW 350 and I am about to order a new set of pistons from JP Pistons in Adelaide, does anybody out there have any experience what piston-bore clearance I should aim for?
Thanks
Nik

[oily bloke]

Hi Nik,
I have just completed the rebuild on my EW. At the time I was warned against JP pistons as they were found to be round and not cam ground oval  (which allows expansion to round when hot). This and an alledged poor quality aluminium alloy which had a high expansion rate was leading to seizures. With this in mind I fitted Honda CB750F pistons. A couple of thou off the top and larger thin wall small end bushes to accomodate the larger gudgeon pin. I have a slightly higher compression EW which goes really well. I have yet to finish running it in but I hope this mod will prove to be worthwhile. The clearances were 4 thou front and 6 thou rear. I used all the rings but some prefer not. That one is your choice.
Hope that helps but I suspect it might have clouded the issue for you. I dare say some of the other contributors on here will have a different but no less valid view.
Cheers
Andy

[Clive]

Hi Nik,
Yes i agree with Andy my EW has been running with CB750 pistons for several years now and no problems . Well may be one , i fitted the pistons complete with oil rings and have recently had to replace the back cylinder EX valve guide ,i do use lead replacement in the fuel , next strip  i may  take the oil rings off and see if that stops the valve guide wear rate!!!! nice to have a clean exhaust though.
Regards
Clive

[916nik]

Thanks for the replies, I will do a bit more research before I progress.
Regards
Nik

[Ian]

I have used JP pistons for years with no issues