Forum

[Norm]

Tim I have watched with interest on here over the years and considering the number of 500's they have, the piston crown failure percentage per bike numbers was much lower than in Aus or NZ.Originally they believed I was scaremongering but we had the numbers on the board. Obviously it has something to do with our temps,roads and distances we ride. Good thing now is it is a long time since I have heard of a piston failure. Either people have stopped riding them or most of them have had a better piston fitted

[Tim NZ]

Most down here have had better pistons fitted by now, but I still see and hear of them disintegrating.

[slowmo]

Thanks guys, I'm convinced, a better piston is the the way to go. Does that mean a rebore as well, or can I put the new piston and rings into my present barrel? (assuming the omega piston rings are cast iron).


My old iron barrel shows little obvious sign of wear, no lips or scores and the ghosts of the original hone are still visible all around the circumference.

[Bullet Whisperer]

Hi Slowmo, by your description of the bore, I would deglaze it and re use it with a new piston and rings. There would probably be less running in time needed and lower odds of seiziure if you gave it some stick. as well. Cheers, Paul.

[Ivor]

Ok, I`m convinced that it would be sensible to replace the piston and rings with a forged one. The bore in my barrel shows lots of criss cross marks and a few vertical marks that you can see but cant feel with finger or nail. So can I just fit new piston as is or do I need to get a rebore done. Going back to the valve guides, how do you check for this 0.10 tolerance?

I have just removed the piston and the gudgeon pin came out with finger pressure, no heat required. Should I be worried?

Thanks in advance for any advise on this, it`s a long time since I`ve done this kind of engine work but at least I`m enjoying it!..

[mauri]

you will minimally need a micrometer, otherwise bring it to mechanics shop to get it measured.



clearance between gudgeon pin and small end is 0,00 to 0,01 MM



measurements like these should be done in a temperature controlled room of 20°C or as close to this as possible.

part should be place in there at least 24h before.

[mauri]

i almost forgot again, this is for the inlet valve.