400ex re-ring

[markk]

Alright, about this time last year i built my 416, And by the end of this race season/ride season it was smoking pretty bad. I was wondering how many people just re-ring the pistion, or replace piston and rings. The piston and the cylinder both look pretty good. The cylinder does have a very slight ridge, but nothing bad.
Im just curious if i really need to buy a new piston?

[jhr400EX]

It probably wouldn't hurt to just hone the cylinder and re-ring the piston.

[TC426EX]

You shouldnt need to replace the piston...

Just do a typical top end rebuild, and that means simply hone the cylinder and replace the rings... You may want to check your valve seals while you got it apart to make sure they are kosher as well...

[ckasper18]

I myself would replace the piston as well and check the cyclinder clearance to make sure the jug is not out of round you got it a part just replace it and be done.

[markk]

Originally posted by ckasper18
I myself would replace the piston as well and check the cyclinder clearance to make sure the jug is not out of round you got it a part just replace it and be done.





It's kinda more about the money/time issue. If i dont have to replace the piston that mean i have a chance at racing Texas GNCC.

Thanks for the valve seals tip TC426ex, Ill check those out now!

[Colby@C&DRacing]

I wouldn't do anything until you have the piston to cylinder clearance measured. if it is over 3 thousands of an inch you will need to bore to the next size piston. If you machine shop bored it to big in the first place that will explain way your motor only lasted a season. if it is still within tolerance then you can just hone it and put new rings in.

[markk]

Originally posted by Colby@C&DRacing
I wouldn't do anything until you have the piston to cylinder clearance measured. if it is over 3 thousands of an inch you will need to bore to the next size piston. If you machine shop bored it to big in the first place that will explain way your motor only lasted a season. if it is still within tolerance then you can just hone it and put new rings in.


Actully i feel that it was my fault it only lasted one season. I was running a K&N filter for 1/2 this year, And my motor had a CHIT load of hours on it. I dont really know how many, But i would at least say over 450hours, probley more. I rode it hard every week day that i didnt work, and every weekend that there wasnt a race. I just checked it, and i can get 2 thousands in between the piston and cylinder wall, But not 3 thousands.

Thanks for the info