rideblue_05 Posted February 5, 2005 Report Posted February 5, 2005 Me and my buddy checked our copresstion yesterday. We warmed our bikes up then checked them. I have 135 in each cylinder and he only has 110. My bike has a coolhead and his dosent. We are at sea level I think he needs a rebuild on his and I am ok but I wont to ask a few questions first. 1) How low comp. before a new top end? 2)What is better for just power, milled head or aftermarket? 3)How much compression before u need to weld crank and race gas? 4)If adding a timing plate and advance +4, do u need race gas? Any suggestions apreciated! Quote
. Posted February 5, 2005 Report Posted February 5, 2005 depending what size domes your running will depend what compression you'll need to rebuild standard is at like 100-105 or difference of 10 psi between cylinders. do a search on here, these questions have been asked a million times, there should be something. If you cant find it, report back and we'll go into it further Quote
RBD Posted February 5, 2005 Report Posted February 5, 2005 A word about compressing gauges, they are not all that accurate and are best used as a comparison between cylinders. Only a good compression gauge such as a Snap-on will give good results. The ones you buy from auto parts stores and discount places tend to be of and not work that well. Even the best gauges need to be maintained and treated with respect. One thing that happens to compression gauges is the Schrader valve will get dirty from use and then they leak giving low readings. The needle should jump up and stay with every kick and not fall backwards between pluses. When checking compression, hold the throttle wide open and then kick until your leg is ready to fall off or when the gauge no longer moves. Note it will take vigorous kicks several times. Always check the same cylinder two to four times to get a consistent reading. Ron Quote
rideblue_05 Posted February 5, 2005 Author Report Posted February 5, 2005 What about my crank and race gas with +4 timing? Quote
FIRST BANSHEE Posted February 7, 2005 Report Posted February 7, 2005 stock comp... 110-130 milling a stock head is fine for power +4 degrees is fine on pump gas if your below 160 psi theres alot of opinions about welding the crank,thats up to you. Quote
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