pabansheematt Posted April 13, 2008 Report Share Posted April 13, 2008 I have a 492 cheetah power valve motor. Bikes got cpi small bore pipes. Pj 34 carbs. jetting 62 pilot and a 150 main, that seems to be fine. Problem is at WOT it sounds like its breaking up, just quits pulling. If I lay of the throotle just a little it clears up. The only other idea I came up with is maybe the power valves are'nt opening all the way, but its a new motor so I kinda dought it, or do I need big bore pipes? Any help would be great. Quote Link to comment Share on other sites More sharing options...
pabansheematt Posted April 13, 2008 Author Report Share Posted April 13, 2008 I have a 492 cheetah power valve motor. Bikes got cpi small bore pipes. Pj 34 carbs. jetting 62 pilot and a 150 main, that seems to be fine. Problem is at WOT it sounds like its breaking up, just quits pulling. If I lay of the throotle just a little it clears up. The only other idea I came up with is maybe the power valves are'nt opening all the way, but its a new motor so I kinda dought it, or do I need big bore pipes? Any help would be great. up Quote Link to comment Share on other sites More sharing options...
trex banshee Posted April 14, 2008 Report Share Posted April 14, 2008 try going up on your main..you say its fine but sounds like to me it wants more fuel. Quote Link to comment Share on other sites More sharing options...
xXBlessedWithDeathXx Posted April 14, 2008 Report Share Posted April 14, 2008 try going up on your main..you say its fine but sounds like to me it wants more fuel. i believe he went up to 172 on the mains and it got worse so he went back down to 150 where it wasnt so bad. he even drilled out a set of 145 to about 230 and it was the still acting up. Quote Link to comment Share on other sites More sharing options...
trex banshee Posted April 14, 2008 Report Share Posted April 14, 2008 well if mine were to do that and you making it rich makes it worse then i would put a smaller main jet in it than the 150..just keep in eye on your plugs but i have experienced and engine way too rich will also cause a sort of a pop cause it just can't burn it all guess thats the symptoms of a fouled plug but Id go leaner until the miss goes away while keeping an eye on your plugs like already stated. Im guessin you already replaced the plugs? Quote Link to comment Share on other sites More sharing options...
pabansheematt Posted April 14, 2008 Author Report Share Posted April 14, 2008 well if mine were to do that and you making it rich makes it worse then i would put a smaller main jet in it than the 150..just keep in eye on your plugs but i have experienced and engine way too rich will also cause a sort of a pop cause it just can't burn it all guess thats the symptoms of a fouled plug but Id go leaner until the miss goes away while keeping an eye on your plugs like already stated. Im guessin you already replaced the plugs? I seem to have got it fixed. The power valves were stuck closed. Must have been due to my way to rich jetting, I cleaned them out & put smaller jets in and its running way better. I think I need to go smaller yet. Maybe a 145 main. Quote Link to comment Share on other sites More sharing options...
bonbon Posted April 14, 2008 Report Share Posted April 14, 2008 I seem to have got it fixed. The power valves were stuck closed. Must have been due to my way to rich jetting, I cleaned them out & put smaller jets in and its running way better. I think I need to go smaller yet. Maybe a 145 main. Glad you found your problem. Just curious, what is the bore and stroke for your motor? Quote Link to comment Share on other sites More sharing options...
trex banshee Posted April 14, 2008 Report Share Posted April 14, 2008 I seem to have got it fixed. The power valves were stuck closed. Must have been due to my way to rich jetting, I cleaned them out & put smaller jets in and its running way better. I think I need to go smaller yet. Maybe a 145 main. glad to hear you got it fixed...stupid powervalves :biggrin: Quote Link to comment Share on other sites More sharing options...
pabansheematt Posted April 14, 2008 Author Report Share Posted April 14, 2008 Glad you found your problem. Just curious, what is the bore and stroke for your motor? It has a 73.5 mill bore, and 4mill stroke & 5 mill rods. Quote Link to comment Share on other sites More sharing options...
dajogejr Posted April 15, 2008 Report Share Posted April 15, 2008 Main isn't your problem, or not the majority of it...your pilots are HUGE... Take them down to a 52 or 50.... With 62 pilots, it's probably getting loaded up before you even wick the throttle.... Quote Link to comment Share on other sites More sharing options...
trex banshee Posted April 15, 2008 Report Share Posted April 15, 2008 Main isn't your problem, or not the majority of it...your pilots are HUGE...Take them down to a 52 or 50.... With 62 pilots, it's probably getting loaded up before you even wick the throttle.... my cousins bike has 28pwk's and we had to put 62 pilots in it to make it run right, after i ported it it would not even run with a 52. It also has a 162 main. I thought it was crazy shit but that is where it runs :biggrin: Quote Link to comment Share on other sites More sharing options...
chris c Posted April 15, 2008 Report Share Posted April 15, 2008 u need the big bore pipes to work well. the big bore cpi pipes goes from 440cc n above the 1 u have goes from 350cc to about 430cc. check on cpiracing.com n it tells u there Quote Link to comment Share on other sites More sharing options...
dajogejr Posted April 15, 2008 Report Share Posted April 15, 2008 my cousins bike has 28pwk's and we had to put 62 pilots in it to make it run right, after i ported it it would not even run with a 52. It also has a 162 main. I thought it was crazy shit but that is where it runs :biggrin: True...but these are 34PJs.... u need the big bore pipes to work well. the big bore cpi pipes goes from 440cc n above the 1 u have goes from 350cc to about 430cc. check on cpiracing.com n it tells u there There are plenty of people that run SB pipes on these motors.... For all out drag, I'm thinking BB would be a better choice...but if it's all out drag, he should have the power valved blocked off like the rest of the Cheetah guys do.... Quote Link to comment Share on other sites More sharing options...
trex banshee Posted April 15, 2008 Report Share Posted April 15, 2008 True...but these are 34PJs.... True.. :biggrin: I just thought it was crazy how big we had to go even on the smaller carbs compared to the 34's. Quote Link to comment Share on other sites More sharing options...
pabansheematt Posted April 15, 2008 Author Report Share Posted April 15, 2008 Main isn't your problem, or not the majority of it...your pilots are HUGE...Take them down to a 52 or 50.... With 62 pilots, it's probably getting loaded up before you even wick the throttle.... Thats what I thought to. But i tried 45's 50's 52's 58's 62's and 68's. I found it runs preety smooth with the 62's. I'm thinking my problem stems from the 162 mains I was running, I now rejetted to 150's thinking of going to 145. Bike is running alot better with smaller mains. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.