Bike wont start after piston install?

[07ERider]

I just put a new 14:1 Rossier piston in my bike, I also had Rossier port the head. I just tried to start it for the first time since the install and it wont fire. It turns over just fine and nothing sounds weird but it just wont fire.

I checked all the valve clearances as well as the decomp also and they were fine.

What could I be overlooking? I guess I should check the valve clearances again to be safe.

Would the decomp gap being too tight cause it to not start? or would it be if it were too loose?

[quadgod440ex]

Are you sure u staggard the rings correctly ? Each ring should be 180 degrees of each other . If everything you feel is correct , i would check your timing. If your timing is on for a fact. Then try bump starting it. Sometimes bikes that works. I personally never had to bump start a bike after a rebuild but ive read of people doing it. Good luck man let us know.

[pro-rider46]

check to see if you are getting spark

[07ERider]

I am getting spark, I shocked myself in the process of checking.

As far as timing goes, with the piston at TDC on the compression stroke the cam gear marks were inline with the cam tower marks so it should be in time?


I staggered the compression ring 180* from the oil rings.

[Chino886]

check cam timing marks again, rotate crank through cycle and make sure you are at TDC.

Check clearances again!

it will start, just check and recheck.

[Colby@C&DRacing]

If you installed a high comp piston along with a new cam the factory recommended decomp clearance will not work on the ER. You will need to use a compression gauge and set cranking pressure to get it to start properly.I have see this time and time again each piston and cam combo requires a different setting.

[07ERider]

Well I just went back out to the garage and tried to start it and it fired right up after a few seconds. So I dont know, im sure that the decomp setting is not optimal but at least I know it runs and thats good for now. If it continues to give me fits I will just have to fine tune the decomp.

Thanks for all the help and input guys.