alexmarq1986 Posted December 6, 2008 Report Posted December 6, 2008 Ok so i read a lot about compression being a big deal so i went out and bought a compression tester and tested my 01 banshee and the results were 100 on one cylinder and 102 on the other, tested 3 times and got same results all the time. The quad runs good and starts in less than 5 kicks when cold. I was just wondering if the results are good for these mods and elevation: FMF Fatties gold Boyesen reeds Reed spacers No lid air box with k&n air filter elevation is 4000 ft. Thanks in advance Quote
kodie Posted December 6, 2008 Report Posted December 6, 2008 I don't know but the people who do will need to know if you have stock head or aftermarket and if its aftermarket what size domes. Quote
alexmarq1986 Posted December 6, 2008 Author Report Posted December 6, 2008 I don't know but the people who do will need to know if you have stock head or aftermarket and if its aftermarket what size domes. Its a stock head Quote
Meat Posted December 7, 2008 Report Posted December 7, 2008 explain how you performed the compression test pls Quote
alexmarq1986 Posted December 7, 2008 Author Report Posted December 7, 2008 (edited) Got it to operating temp for 5 minutes, turned off ignition, fuel and key. kicked it like 5 times at WOT till gauge stopped going up. I searched the forums and thats what it said to do in a lot of the old threads i saw. Did i do it right? Edited December 7, 2008 by alexmarq1986 Quote
98_shee Posted December 7, 2008 Report Posted December 7, 2008 (edited) normally it takes around 10-15 kicks, did you have the other plug in? the piece that screws into the head should have the same thread length as the plug. Edited December 7, 2008 by 98_shee Quote
Meat Posted December 7, 2008 Report Posted December 7, 2008 some guys say do it hot some say cold. I was taught to do it on a cold engine and 120psi is the cold compression number. I dunno what it should be on a hot engine. sorry. But hot or cold, your cylinders are close to having the same psi and thats a good thing. Your elevation is a factor. There used to be compression charts for this kinda stuff. search for a "compression chart" and the chart can tell you what your comp should be at various elevations. As long as the quad is still running good and not smoking a lot, I'd be confident in that engine with 100 psi. When it gets hard to start, thats a good sign the motor is getting tired and needs freshened up. Quote
alexmarq1986 Posted December 7, 2008 Author Report Posted December 7, 2008 normally it takes around 10-15 kicks, did you have the other plug in? the piece that screws into the head should have the same thread length as the plug. Yes I did one plug at a time ( took one off tested and did the same with the other) the testers thread was just a little shorter than the spark plug Quote
alexmarq1986 Posted December 7, 2008 Author Report Posted December 7, 2008 some guys say do it hot some say cold. I was taught to do it on a cold engine and 120psi is the cold compression number. I dunno what it should be on a hot engine. sorry. But hot or cold, your cylinders are close to having the same psi and thats a good thing. Your elevation is a factor. There used to be compression charts for this kinda stuff. search for a "compression chart" and the chart can tell you what your comp should be at various elevations. As long as the quad is still running good and not smoking a lot, I'd be confident in that engine with 100 psi. When it gets hard to start, thats a good sign the motor is getting tired and needs freshened up. Thanks for your help I will look for the chart. Quote
jamebo Posted December 7, 2008 Report Posted December 7, 2008 According to Noss Machine's website, stock compression at 4000' is estimated to be 106. Your probably close to where you should be on compression. Quote
alexmarq1986 Posted December 7, 2008 Author Report Posted December 7, 2008 With the mods I hvae it's pretty close to stock right? Or should my compression be higher because of them? Quote
jamebo Posted December 7, 2008 Report Posted December 7, 2008 With the mods I hvae it's pretty close to stock right? Or should my compression be higher because of them? Compression is changed with aftermarket heads with different sized domes, or shaved stock heads. The smaller the domes, the higher the compression. A motor with no internal mods done or headwork would be considered stock compression readings. Quote
GrMeyer Posted December 7, 2008 Report Posted December 7, 2008 Well if you have read from my other post, i put a noss head on with a 20cc and only got around 115psi. But I have started to see that it smokes alot on start up but when it is warm it is fine. As of the Hot and Cold test... School said that you should do it on a warmed up motor. Due to that fact that metal expands when it is hot. So i have always done mine on a warmed up motor unless you cant get it started and want to see where your at. Quote
Meat Posted December 7, 2008 Report Posted December 7, 2008 According to Noss Machine's website, stock compression at 4000' is estimated to be 106. Your probably close to where you should be on compression. :thumbsup: Quote
alexmarq1986 Posted December 7, 2008 Author Report Posted December 7, 2008 Well if you have read from my other post, i put a noss head on with a 20cc and only got around 115psi. But I have started to see that it smokes alot on start up but when it is warm it is fine. As of the Hot and Cold test... School said that you should do it on a warmed up motor. Due to that fact that metal expands when it is hot. So i have always done mine on a warmed up motor unless you cant get it started and want to see where your at. Allright so I guess my compression is good, thanks to all you guys for your help. What a great forum. Quote
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