NN2 Posted April 2, 2008 Report Posted April 2, 2008 Here's the history of the bike. Bought it a couple months ago. Rode it a couple times before taking it completely apart for a frame up rebuild. I was told it had a trail port and a new top end and new crank with only a few hours on it. I confirmed this when I took the top end apart and could still see the hatch marks in the cylinder walls and the hot rodz crank in the bottom. Piston to wall clearance was well with in spec. I pulled off the cylinders to powder coat. Put it back together with a coolhead instead of the stocker. I put in 19cc domes and was expecting 160psi + (roughly 800ft elevation). I kicked it over 20 times and had about 135psi in the cylinders. Didn't seem right so I put in a new o-ring kit. Kicked it over and same reading. Started it up and let it run for a few minutes. Compression tested again and it was 130psi. I've checked the squish and it is .058" and .062". My next step was going to try a leak down test but I didn't see any leaks around the o-rings after running it the first time so thought there would be no point. Thought about trying another compression test gage also but it doesn't feel like I'm kicking over 160 psi either. Shouldn't the squish be more?? How much of a difference in power is there with 130psi vs. 160psi? Thanks for the help guys. Quote
2001Stroker Posted April 2, 2008 Report Posted April 2, 2008 Yea, I would definiteyl try a different guage and a leak test. I have 19cc domes at sea level, and I'm getting 185psi on both sides. If you take it back apart, have the cylinders and pistons mic'd, just to make sure they are the correct size for each other. You ARE testing it correctly, right? Holding the throttle wide open, kicking it an ass load of times.......I also read on here somewhere, to make sure that the compression tester is the same depth as your spark plugs. If it takes up more cc's than your plugs, it will read higher, and vice versa. Quote
wesw Posted April 2, 2008 Report Posted April 2, 2008 your squish is to loose get one around 45 thousands it will help a lot. what brand of domes were they. Quote
NN2 Posted April 2, 2008 Author Report Posted April 2, 2008 Yup, kicking it over with throttle wide open about 25 times. After 10 kicks it pretty much tops out. The I got the domes with the Pro Design head. How do you change the squish with a cool head? I can see how you do it with a stock head and different gasket thickness but not with a coolhead. I'll be trying a different gauge tonight. Quote
dajogejr Posted April 2, 2008 Report Posted April 2, 2008 your squish is to loose get one around 45 thousands it will help a lot. what brand of domes were they. Exactly what I was thinking. Mid .040's will get you where you need to be. Get a thinner base gasket...you probably have a .020 base gasket. Get a .011 and you should be just about perfect. Quote
lincster Posted April 2, 2008 Report Posted April 2, 2008 Exactly what I was thinking. Mid .040's will get you where you need to be. Get a thinner base gasket...you probably have a .020 base gasket. Get a .011 and you should be just about perfect. Cool heads don't have base gaskets, they use O rings to seal. NEXT!!!!! Quote
dajogejr Posted April 2, 2008 Report Posted April 2, 2008 Cool heads don't have base gaskets, they use O rings to seal.NEXT!!!!! Not to sound like a smart ass...but... That's why I said base gasket. As in the gasket at the base of the cylinder...or..the BOTTOM. Thanks for the tip on the Cool Head and Orings...never seen one before... :whistling: Next. Quote
NN2 Posted April 2, 2008 Author Report Posted April 2, 2008 (edited) Exactly what I was thinking. Mid .040's will get you where you need to be. Get a thinner base gasket...you probably have a .020 base gasket. Get a .011 and you should be just about perfect. I just got an engine gasket kit with all the needed gaskets. Is there a typical gasket thickness that comes in those kits? Such as .020". Where can I get the thinner base gasket? What's the difference in power between 130 psi and say 170psi? Edited April 2, 2008 by NN2 Quote
dajogejr Posted April 2, 2008 Report Posted April 2, 2008 You'll get back a lot more low end and midrange punch at the sacrifice of a little top end. You will need at least a mix of race/pump fuel if you get to 160s and 170s...too. Call Jeff @ FAST...he'll have what you need. Quote
lincster Posted April 2, 2008 Report Posted April 2, 2008 Not to sound like a smart ass...but... That's why I said base gasket. As in the gasket at the base of the cylinder...or..the BOTTOM. Thanks for the tip on the Cool Head and Orings...never seen one before... :whistling: Next. Well I was being a smart ass so I deserved that one.... It's all good.... NEXT!!!!! Quote
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