I have just installed a 12:1 piston in my Warrior. I ran a cylinder hone (bottle brush type) down the cylinder to break the glaze and allow a good ring seal. When I first checked compression it was at 150 psi. It smoked a bit for the first hour of operation as I figured it would until the rings seat. Now it doesnt smoke but my compression dropped,(120psi) I expected it to go up as the rings were broken in. My question is should it go up a bit with more break in time? What else could cause this? I suspected I may need a valve job as the quad is 3 years old. I am using the stock bore but it was in acceptable condition. Any words of wisdom? Also will raising compression ratios effect jetting? Thanks.

 

Did you not bother to check piston-to-cyl clearance? My warrior bore was so egg-shaped they had to overbore it twice to bring it back in spec. And that was with not too many hours on it and with meticulous maintenance too. I bet you dont have a real good fit there. Your future oil consumption should bear this out. 120 psi with a 12:1 piston is really low. It doesnt pay to skimp on this type of a modification! Good luck, because you may be ending up doing the job all over again.

 

Although not measured I did slide the ringless piston down the bore and it didnt have any play in the bore, this is not to say that it's impossible but I hope that isnt the case. If so, I tossed a bit of cash on the piston!

 

scott,
i have a 96 warrior that needs a head and valve job. i am thinking of replacing all of it with aftermarket items. and possibly boring it out if it wouldnt cost much more, if you have any info please email me or post it . thanks

 

Call Lenny at Duncan Racing 619-258-6306 (Tell him I want a discount on my next order for your referral!) He will hook you up with some great options for your warrior performance mods. Couldn't be happier with mine...it's done right, and it rocks for a warrior. Hint: don't skimp, it doesn't pay in the long run!