bizanchee Posted January 2, 2004 Report Posted January 2, 2004 help! i always thought compression is higher on warm cylinders....i mean thats how we test the compression on aircraft. ok heres the deal i am running 21cc domes at sea level on a motor that has never been rebuilt i checked cold first and then hot and here is what i found: Cold left- 145 Right-150 Hot Left-137 Right- 135 ?? stumped but ok i never checked the compression prior to installing the 21cc domes. i Know that the 21cc domes should (on a fresh motor) give 157 psi at sea level. basically i dont know where i stand.....do i need to do a top end?? if not then when? what are the compression limits? thanks for all your help guys Quote
banshee04le Posted January 2, 2004 Report Posted January 2, 2004 i would recommend a cylinder leak down test in an attempt to pinpoint the cause of the discrepency. not sure on the specs you requested. Quote
dlnoss Posted January 2, 2004 Report Posted January 2, 2004 It's a little strange. I'm sure it was lower with the stock head but I don't know why it's lower when warm. Quote
bizanchee Posted January 3, 2004 Author Report Posted January 3, 2004 where can i get a cylinder leakdown tester and how much? and i just have no idea when to do my top end now well thanks for the input guys.....i dont know where my banshee would be without this forum Quote
SHEEGUY SMOKEDYAA Posted January 3, 2004 Report Posted January 3, 2004 Hey dude I am new here and probably going to get bashed but your compression should not be lower when warm than cold. Should be higher warm than cold or no differance. Higher warm would tell me warn rings or topend Quote
banshee04le Posted January 3, 2004 Report Posted January 3, 2004 $54.95 from harbor freight. you need a compressed air supply to use it. screws into the spark plug port and guage measures air leaking past rings and or reeds. could probably be adapted to pressure test crankcase as well i would think. i dont know off hand why your compression is lower when hot...but i think the cold numbers are a better guage for determining top end condition. the leak down test cant be beat though . Quote
SHEEGUY SMOKEDYAA Posted January 3, 2004 Report Posted January 3, 2004 Also just a thought. leak down on a two stroke ??? its only going to come out though the crank seals and if it bleeds by the rings??? Out the crank seals so I do not know where people are going with that???? rings or seals and if it needs one it probably needs the other Quote
banshee04le Posted January 3, 2004 Report Posted January 3, 2004 how come my link did't post oh well...you can type it in if you want... www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=4317 p/n: 4317-0vga Quote
SHEEGUY SMOKEDYAA Posted January 3, 2004 Report Posted January 3, 2004 Sorry Bro but I guess I am a little slow that compression chart you are going off of where did you get it. If it is pro-designs it is not completely correct it will vary. You should also make sure your gauge is correct. Maybe check it with another one. Quote
banshee04le Posted January 3, 2004 Report Posted January 3, 2004 Also just a thought. leak down on a two stroke ??? its only going to come out though the crank seals and if it bleeds by the rings??? Out the crank seals so I do not know where people are going with that???? rings or seals and if it needs one it probably needs the other huh? Quote
SHEEGUY SMOKEDYAA Posted January 3, 2004 Report Posted January 3, 2004 Have better advice my fellow shee rider???? Or is your shee riding you???? Quote
banshee04le Posted January 3, 2004 Report Posted January 3, 2004 i think my advice was already better...and i like it when shees ridin me Quote
SHEEGUY SMOKEDYAA Posted January 3, 2004 Report Posted January 3, 2004 Harber Frieght??? Real quality my fellow shee rider I would guess by that you probably buy auto parts from autozone? Like changing parts? Oh yea !!!!! Last time you did a leak down on a two stroke what did it tell you??? Quote
banshee04le Posted January 3, 2004 Report Posted January 3, 2004 i do them at work all the time moron...not on banshee motors...mostly on four strokes...but also on 2 strokes. i am a factory authorized service tech for lincoln electric...and engine driven welders are 4cycles (burco makes a cool 2stroke powered welder though) but my shop also does warranty service for stihl and homelite. i have done leak down tests, as ive said, and found problems in the past w/rings and reeds. i have different provisions for pressure testing the crankcase but same theory applies. a 2 stroke is a 2 stroke and your obviously an uneducated, babbling fool Quote
SHEEGUY SMOKEDYAA Posted January 3, 2004 Report Posted January 3, 2004 Geee four stroke and lincoln electric not a banshee!!! Not a two stroke like I said last time you did a leak down on a two stroke what did it tell you???? Did not answer just talking smack!!! Anyway certified is only book smart no real world problem solving skills!!! Quote
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