Question about cylinder and piston.

[short4stuff]

Ok well I took the topend of my tri-moto 175 apart and I took the rings off the piston and put the piston in the cylinder like that.
My Q is how much space should be between the piston and cylinder??

Thanks, Chris
BTW I am doing a total restore on my 175.

[rob0781]

should fit snug i'd think

[smokinwrench]

New Wiseco pistons have a tollerance of 0.003. It will be able to run with more clearance than that.

[KASEY]

stock cast pistons usually run .001 to .002 less clearance than a forged piston ,, anything over .005 clearance should be looked at real close that is where piston skirts start to slap and can break off ,,, :D :D

[smokinwrench]

anything over .005 clearance should be looked at real close that is where piston skirts start to slap and can break off ,,, :D :D

I had a piston that broke this spring. I would say it had about 0.035 of piston slap. I got lucky that it didn't break the case.

[short4stuff]

ok well whats .035 in mm ?? ... is that like 0.035 of a mm ?

[smokinwrench]

inches as in bigger then you spark plug gap. It was totally wore out.

[hondaATCman]

I guess you could run a feeler gauge between the piston and cylinder with the rings off, but I have always taken the piston out, measured the cylinder in the middle and then the piston with a micrometer, then subtracted the piston measurement from the cylinder measurement. Keep in mind that the cylinder gets kind of egg shaped after a period of time and there will be a difference in the size in the middle than there is at the top.

[short4stuff]

alright well i took a piece of paper and folded it in half and then in half again and that fits in there tight.... now I dont know what that width on that would be but does anyone know if that would be too much?

[hondaATCman]

You can't really measure something as critical as the engine with a peice of paper. It does sound like there is too much clearance, but you need to get a good set of feeler gauges; they're only a few bucks.

[short4stuff]

ok well according to F7firecat the thickness of a piece of paper is about .0035 so I have about .014 of room between my cylinder and piston. My Q is will I be able to run it like this or will I loose alot of power?