PlaynSand Posted December 22, 2003 Report Share Posted December 22, 2003 Results on new machine with aprox. 10 hrs. on engine. Left side 106 psi. Right side 106 psi. Elevation 3105 feet Ambient temp 60 degrees F Engine cold Used known good gauge, throttle wide open and kicked until gauge stopped. This is a little lower than the comp. charts show but is this about normal? Also would like to get this up to about 150 psi for my elevation , what dome size is recommended for pump gas? The compression charts I have looked at vary a lot , who's is accurate? Quote Link to comment Share on other sites More sharing options...
spoin39 Posted December 22, 2003 Report Share Posted December 22, 2003 I would have the cylinder heads shaved (.0030) add a coolhead w/20cc domes, and maybe replace pistons w/wiseco, vitos, or pro-x. I don't know which comp. chart is accurate but this would get you at your goal of about 150psi. Quote Link to comment Share on other sites More sharing options...
reas11 Posted December 22, 2003 Report Share Posted December 22, 2003 Results on new machine with aprox. 10 hrs. on engine. Left side 106 psi. Right side 106 psi. Elevation 3105 feet Ambient temp 60 degrees F Engine cold Used known good gauge, throttle wide open and kicked until gauge stopped. This is a little lower than the comp. charts show but is this about normal? Also would like to get this up to about 150 psi for my elevation , what dome size is recommended for pump gas? The compression charts I have looked at vary a lot , who's is accurate? 106 sounds low to me , i would think something is seriously wrong Quote Link to comment Share on other sites More sharing options...
sandfool Posted December 22, 2003 Report Share Posted December 22, 2003 i did the exact same thing on my bike w/ about the same hrs on it.i read 110 lbs the first time and used 2 gauges(they read the same). i repeated the drill again the next day and kicked the bike over w/shoes on this time and as fast and as hard as i could and got 115 lbs with throttle wided open. i am at 1200 ft here so we are probably the same. i plan on shaving my head .020 -.030 to get closer to 150 lbs in the future.compression helps more w/ the low end than the topend so dont think you need 200lbs compression. someone has a 10 things to do to a shee list somewhere on here and its very good to enhance the performance,you might want to check it out.its all good advice. Quote Link to comment Share on other sites More sharing options...
PlaynSand Posted December 22, 2003 Author Report Share Posted December 22, 2003 I really think my topend is in good shape and I think all test will vary some. I just got my pipes jetted in real close before the weather turned cooler ,so now I am waiting on spring. I am just wanting to up the compression to help the bottom end power but not get crazy . I am very happy with mid range and top end power is great ,just a little soft on the bottom. I am leaning towards 21cc domes because I do a lot of riding where the elevation is about 1500. I am interested in some other's test with 21cc domes at a simialar elevation. Quote Link to comment Share on other sites More sharing options...
bizanchee Posted December 22, 2003 Report Share Posted December 22, 2003 You will not receive an accurate compression reading on cold cylinders. The reaon for this is heat=expansion. On a cold cylinder you are getting more"blowby" the rings. Warm your machine up good, and then immediately take the reading......i assure you it will be alot higher, just becareful you dont burn yourself Quote Link to comment Share on other sites More sharing options...
Leadfoot350 Posted December 22, 2003 Report Share Posted December 22, 2003 21's are safe for pump gas of 91 or higher in 1500 and higher altitude. Quote Link to comment Share on other sites More sharing options...
dlnoss Posted December 22, 2003 Report Share Posted December 22, 2003 I think your compression is fine for your elevation and being checked cold. Using premium pump gas, I'd consider running 20cc unless you will be riding much below 1500'. Quote Link to comment Share on other sites More sharing options...
Banchetta Posted December 23, 2003 Report Share Posted December 23, 2003 106 isn't bad for that elevation and remember.....you only have 10 hours on it!! Its still breaking in....I rebuilt my shee and only had 142psi w/ head mods and about 4 hours on it...Checked it 2 months later and had 165psi......Let it break in.....you'll see a difference.. Quote Link to comment Share on other sites More sharing options...
q8bizkit78 Posted December 27, 2003 Report Share Posted December 27, 2003 try changing ur pistons rings Quote Link to comment Share on other sites More sharing options...
98bonerSTOCKshee Posted December 27, 2003 Report Share Posted December 27, 2003 try changing ur pistons rings I don't think he should just into a ring change... ....fresh motor needs break in ....test need to be on warm engine if it's below 110 on a broke in motor that's warmed up then maybe look @ the rings but I think it's to early.. He's getting same reading on both cylinders that's great!! .... Quote Link to comment Share on other sites More sharing options...
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