Topic: Piston width and combustion chamber mods

[Ace]

Hi all, do any of you who have 900cc engines and then some make the standard combustion chambers wider to ensure the bigger dome and width pistons don't hit the bottom of the head?

[mick7504]

That shouldn't be a requirement mate.
If you are using pistons from a different motor, you'll have to check the compression height which should be 25mm.



If the piston deck is coming right to the top and level or above the top of the sleeve @TDC, you will need to pack the cylinder base with a thicker gasket.
Piston/valve intersection is something else to be aware of as well.
Have you got any photos that you can post?
It will help to see what's going on.
Mick

[kos]

Don't forget the head gasket (composite) , normally this is .040" crushed after torquing...you can run these plain bearing engines at  a min of .035" and have no problems.

KOS

[Big Jay]

Some of the older RC kits and the current JE high compression 836s had/have a full dome with no squish band area. Those require the combustion chambers to be opened to the bore size.

[Ace]

Thanks guys.  I did pack another gasket under neath and also I have some big domes pistons as Big Jay mention.

Hey Big Jay, need some parts so any discount for forum members?  I seem to be in need of one HD cylinder stud so while I'm there I might as well do some early xmas shopping