edge076 Posted May 4, 2005 Report Share Posted May 4, 2005 I have recently purchased a used pro design cool head. I replaced the stock head w/ the cool head and installed 20cc domes, I started it up, and drove down the road and back about 1 mile and pulled it into the shop, i had replaced the plugs with new ones when i put on the head, well when i took out the plug to check jetting, the plug was still bright white and the tip of the plug was starting to blister. I orginally thought that it was the octane of fuel i was using, i was running 87 in it before the change over and i was going to get some 91 to run in it, anyways, i thought i would check the compression and it was only 100psi, then i thought that i would warm it up to see if it would seal up better, but when i ran it down the road again and came back the plug was really dark and the compression was still 100psi, and all i did was move it in and out of the shop, I know i was a little rich before i swapped heads and i was going to change the jetting but now i don't know what to do. I am at 3200ft and i have 20cc domes, i think the compression is suppose to be around 147psi. When i was running it around it ran perfect. It had great throttle response and it had ran better than it ever has. I can't imagine it is time for a rebuild. What does anyone else think. Quote Link to comment Share on other sites More sharing options...
banshee boy 98 Posted May 4, 2005 Report Share Posted May 4, 2005 I have recently purchased a used pro design cool head. I replaced the stock head w/ the cool head and installed 20cc domes, I started it up, and drove down the road and back about 1 mile and pulled it into the shop, i had replaced the plugs with new ones when i put on the head, well when i took out the plug to check jetting, the plug was still bright white and the tip of the plug was starting to blister. I orginally thought that it was the octane of fuel i was using, i was running 87 in it before the change over and i was going to get some 91 to run in it, anyways, i thought i would check the compression and it was only 100psi, then i thought that i would warm it up to see if it would seal up better, but when i ran it down the road again and came back the plug was really dark and the compression was still 100psi, and all i did was move it in and out of the shop, I know i was a little rich before i swapped heads and i was going to change the jetting but now i don't know what to do. I am at 3200ft and i have 20cc domes, i think the compression is suppose to be around 147psi. When i was running it around it ran perfect. It had great throttle response and it had ran better than it ever has. I can't imagine it is time for a rebuild. What does anyone else think. 364356[/snapback] 100psi is VERY LOW sounds like a rebuild is in order Quote Link to comment Share on other sites More sharing options...
bigboybanshee Posted May 4, 2005 Report Share Posted May 4, 2005 I would definitely drain that 87 octane first and put you some premium in there before running it anymore...100psi does sound low, was it like that in both cylinders? Is it possible that the gauge may be inaccurate? I would imagine if your top end was going you would be having trouble starting it up, etc...how many hours do you have on the top end now? We'll get this figured out Quote Link to comment Share on other sites More sharing options...
holeshotkid Posted May 4, 2005 Report Share Posted May 4, 2005 Do you have access to another compression tester? I would try to double check the gauge somehow to eleminate the possibility of it being off. Definately run at least 91 octane with those domes. Quote Link to comment Share on other sites More sharing options...
holeshotkid Posted May 4, 2005 Report Share Posted May 4, 2005 Ya snuck that one in on my BigBoy... Quote Link to comment Share on other sites More sharing options...
JeremyKS Posted May 4, 2005 Report Share Posted May 4, 2005 i believe this bike is a 2005 or 04 model bike Quote Link to comment Share on other sites More sharing options...
bigboybanshee Posted May 4, 2005 Report Share Posted May 4, 2005 Ya snuck that one in on my BigBoy... 364385[/snapback] As far as it being an 04 or 05 bike that doesn't matter too terribly much. I put well over 60/70 hours of riding on my banshee the first year I had it, and was rebuilding the top end mid way through year two. There are a number of reasons the top end can wear out in a year or two; if that's even the case here. I'm hoping the gauge is giving inaccurate results. Quote Link to comment Share on other sites More sharing options...
edge076 Posted May 4, 2005 Author Report Share Posted May 4, 2005 Yea i am definetly going to run 91 in it. It is an 04 model, has around 50-70 hrs on it. When i had my head off of it the cylinders and everything looked in excelent condition, I am a cerified diesel tech so i now how to tell good from bad. I will try and find another compression tester b/c that would make since on how it didn't change from cold compression to heated compression. I just thought this was strange but if someone sees that i am doing something wrong, let me know. It just runs too bad ass now to think itwill need a rebuild. Thanks Quote Link to comment Share on other sites More sharing options...
edge076 Posted May 4, 2005 Author Report Share Posted May 4, 2005 Yea i didn't check both cylinders, i will do that tonight. Also i have never kicked this thing over 3 times in a row to get started, warm or cold. Usually i don't even stand up to start it. Thanks Quote Link to comment Share on other sites More sharing options...
superchicken Posted May 4, 2005 Report Share Posted May 4, 2005 when you checked the compression did you hold the throttle wide open?also did the testor you used have the same length threads on it as you spark plugs? Quote Link to comment Share on other sites More sharing options...
dajogejr Posted May 4, 2005 Report Share Posted May 4, 2005 Yea i didn't check both cylinders, i will do that tonight. Also i have never kicked this thing over 3 times in a row to get started, warm or cold. Usually i don't even stand up to start it. Thanks 364428[/snapback] That being said...sounds like a bad tester as mentioned. If it was @ 100PSI at that elevation, it'd be a mutha to start... 87 Octane in a shee..c'mon. I put better than that in my lawnmower... Quote Link to comment Share on other sites More sharing options...
bigboybanshee Posted May 4, 2005 Report Share Posted May 4, 2005 Aside from the compression part of this issue, you did say your plugs looked really lean. What mods (other than the cool head) are you running with what jets and carb size? When you ran those new plugs, did you run it WOT through 6th gear? It's always good to warm your banshee up on old plugs, slap the new ones in there, fire it up and rip it through 6th gear...pull the clutch, kill the engine, and keep the throttle pinned until you come to a stop. (You may already know this but figured I'd explain in case you didn't ) Keep us posted! Quote Link to comment Share on other sites More sharing options...
NEVER SATISFIED Posted May 4, 2005 Report Share Posted May 4, 2005 87 Octane in a shee..c'mon. I put better than that in my lawnmower... 364448[/snapback] Quote Link to comment Share on other sites More sharing options...
edge076 Posted May 5, 2005 Author Report Share Posted May 5, 2005 Checked compression last night with a new tester. I got 120psi with throttle wide open. I am going to buy a new tester today and try another test before i do any thing else. Any other suggestions would be nice. Has anyone ever heard of checking crank case pressure on a banshee. We do that on diesel engines to check for blowby and/or leaks. Curious if anyone has a fancy setup to do this. Thanks Quote Link to comment Share on other sites More sharing options...
NEVER SATISFIED Posted May 5, 2005 Report Share Posted May 5, 2005 Has anyone ever heard of checking crank case pressure on a banshee. 364884[/snapback] this is possible.. run a search and it will pop up... as for the 120psi... eeeeek still low im not sure on a pro design head.. how are the gasket seals on those.. are they just gaskets or do they run rubber o-ring seals? i have anoss head and my rubber seal wasnt seated right and i had low comp.. did it lack power or does it feel like it lacks power? Quote Link to comment Share on other sites More sharing options...
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