Satsol67 Posted November 10, 2006 Report Posted November 10, 2006 I just put my topend back together and one of my jugs dont have the same compression as the other. My domes have some grooves from the piston before coming apart. Would this be the reason for the uneven compression? I know I need to replace it funds are low right now. Thanks Ron Quote
dajogejr Posted November 10, 2006 Report Posted November 10, 2006 What are the actual readings, and....did you use a quality tester? Quote
Satsol67 Posted November 10, 2006 Author Report Posted November 10, 2006 Yes i used a tester. the left side pumps right up to 115 and the right side i have to kick the shit out of it to get to 100. Quote
David Keith Posted November 10, 2006 Report Posted November 10, 2006 Yes i used a tester. the left side pumps right up to 115 and the right side i have to kick the shit out of it to get to 100. Anytime there is more than a ten percent difference in compression between cylinders, you should find the problem & correct it. Just my opinion after working on all kinds of Japanese bikes for more that thirty years. :cool: Quote
Satsol67 Posted November 10, 2006 Author Report Posted November 10, 2006 I pulled it all apart angain this morning to be sure the rings are in there right and they are. I also tried switching side for the domes to see if the compression would change sides but it didnt. My readings are 105 on the right and 120 on the left. I have tried spaying wd40 around the base and the reeds to see if it is sucking air but that seems right. I am lost. Once the rings seat do you think the compression will even out? Ron Quote
dajogejr Posted November 10, 2006 Report Posted November 10, 2006 They're not going to even out that much, if they do....and that's more than 10%. Base gasket leaking won't effect the static compression reading, only the leak down test. You have another problem, could be improper clearances, bad seal on the head, or that bad dome... Quote
sheefreak Posted November 10, 2006 Report Posted November 10, 2006 Check your squish on both cyls to see if they are way off. Quote
Satsol67 Posted November 10, 2006 Author Report Posted November 10, 2006 I'm just going to replace that dome. The things runs like a bat out of hell! It has never gotten to 6th gear this quick before. The way it used to be was when i would mess around i would have to go back into 5th in order for 6th to wind out. Shit now it winds 6th out like it isnt nothing. I cant wait to see what its going to be like once i get the timming plate. Ron Quote
Satsol67 Posted November 11, 2006 Author Report Posted November 11, 2006 Ok this is what i have. When I do 15 kicks on each side the left reads 115 and the right is 95. What I did was order 64.50 thinking I would do a bore to that size and all would be good. When the new pro lite came I noticed that they looked like they would fit without a bore so I just honed the cylinders out. Like a dumdass I didnt go buy a feeler gauge to check ring gap. My question is where do i go from here? Do I just eat the pistons and go with it for now until i have the funds to do a bore? Also what is the clearance suppose to be between the piston and walls? I ask this because it is easyer to check that then pull the jugs off and check ring gap. I know i am an ediot! It runs good over all I just dont have the funds to redo it right now. I dont do any dune riding or anything like that. So i dont do WOT that much if that even really matters. What should i do for now being on a real limited budget? I still want to get new domes being that my old ones have grooves from when the piston came a part last time. Part of me thinks thats why it has so uneven compression. Please help. So for the book. Ron Quote
dajogejr Posted November 11, 2006 Report Posted November 11, 2006 Ok this is what i have. When I do 15 kicks on each side the left reads 115 and the right is 95. What I did was order 64.50 thinking I would do a bore to that size and all would be good. When the new pro lite came I noticed that they looked like they would fit without a bore so I just honed the cylinders out. Like a dumdass I didnt go buy a feeler gauge to check ring gap. My question is where do i go from here? Do I just eat the pistons and go with it for now until i have the funds to do a bore? Also what is the clearance suppose to be between the piston and walls? I ask this because it is easyer to check that then pull the jugs off and check ring gap. I know i am an ediot! It runs good over all I just dont have the funds to redo it right now. I dont do any dune riding or anything like that. So i dont do WOT that much if that even really matters. What should i do for now being on a real limited budget? I still want to get new domes being that my old ones have grooves from when the piston came a part last time. Part of me thinks thats why it has so uneven compression. Please help. So for the book. Ron So you didn't measure a thing, just honed 'em and guessed? Ballzy my friend, very ballzy. You can spend a little now or a lot more later. Sorry to say it, but I would take the cylinders to a machine shop, have them measured properly. New Piston/Bore clearance should be .060 to .065 Ring End Gap Clearance: .012 to .018 and if they're at or more than .020, trash them. You really need to get a clymers manual, new pistons, and take the jugs and pistons to the machine shop. If you think you're on a tight budget now, wait till you lock up a crank... Quote
dajogejr Posted November 11, 2006 Report Posted November 11, 2006 Sorry...David Keith pointed out a good point. Let me reiterate the clearance numbers. Piston to wall clearance Metric (mm) .060 to .065 American .0024 to .0026 Ring End Gap Metric (mm) .30 to .45 American .012 to .018. Ring Service Limit (replacement) Metric (mm) .5 American .020 Sorry for any confusion. Quote
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