oldskool Posted March 31, 2013 Report Share Posted March 31, 2013 I've read here that detonation can cause plugs to back out. Timing is at +4, running 93 octane 40:1 Any suggestions appreciated Quote Link to comment Share on other sites More sharing options...
Paul M Posted March 31, 2013 Report Share Posted March 31, 2013 yep deto more then likely , whats your compression ? is your fuel old ? Quote Link to comment Share on other sites More sharing options...
Paul M Posted March 31, 2013 Report Share Posted March 31, 2013 what people dont relize is that the more advance timing you run , you will need a higher octain fuel especially is you have a high compression motor ! Quote Link to comment Share on other sites More sharing options...
oldskool Posted March 31, 2013 Author Report Share Posted March 31, 2013 Last time I checked comp was at 142 psi. I'm gonna go check it again. IF its around 140psi which should be fine on 93 octane, would you retard the timing to +2 or 0? Thanks Quote Link to comment Share on other sites More sharing options...
WINDYCITYJOHN400 Posted March 31, 2013 Report Share Posted March 31, 2013 How long has this motor been in use? Is this a fresh build or a motor that was been together for a while? What mods? Any recent changes? Quote Link to comment Share on other sites More sharing options...
sleeper06 Posted March 31, 2013 Report Share Posted March 31, 2013 Static compression,kicking compression can not be the ultimate deciding factor in fuel used,is the motor ported,do you have an air leak,did it just start doing this and ran fine before or have you never ran engine.dont bandade it find real problem Quote Link to comment Share on other sites More sharing options...
Surfrjag Posted March 31, 2013 Report Share Posted March 31, 2013 I would look into fuel availability. Like vent cap and float height. Even petcock.. Quote Link to comment Share on other sites More sharing options...
n2otoofast4u Posted March 31, 2013 Report Share Posted March 31, 2013 If the motor has been operational for some time with no issues then all the sudden you are pushing plugs out and there is no major changes in the environment you are running it in then you have an issue that has come up on the motor like an air leak, water leak, etc... If you could give some more of your situation about how long the motor has been together, elevation, temperature, etc. there are many here who can probably get you lined up with your problem in a short time! Quote Link to comment Share on other sites More sharing options...
oldskool Posted March 31, 2013 Author Report Share Posted March 31, 2013 First off, I'm not an engine builder, but with the help of a credit card and this forum I put together a +4mil, stock cylinder. The cylinders are not a fresh bore. I bought them with what looks to me like an aggressive drag port and was told for a 4mil. I put new crank with new piston/rings. Checked comp again today with warm engine and got 150/151 psi. Running coolhead with 20cc domes. 34mm mikuni TM's no crossover. Timing plate at +4 Including this weekend, The engine prolly has two tanks of fuel run thru it. 75% drag. It has absolutley no bottom end, but thats prolly the port job and 34mm carbs(I think). It runs very strong at the track. We run about 500ft. After 3 runs, the plugs are loose This is a totally different bike than what I had with stock crank, so I know I'm making power, plus I'm kicking asses that I couldn't before. When the guy with the can am 1000 got his ass handed to him, I was a happy ole man! Thanks fellows Quote Link to comment Share on other sites More sharing options...
WINDYCITYJOHN400 Posted March 31, 2013 Report Share Posted March 31, 2013 Add fuel, Switch to race gas, get some measurements of your clearances on your domes........Much more to come, but it's a starting point. Remember.........they all run like a raped ape just before they ventilate the pistons. If your backing plugs....STOP RIDING TILL YOU FIGURE IT OUT! Quote Link to comment Share on other sites More sharing options...
shanYE west Posted March 31, 2013 Report Share Posted March 31, 2013 why not start with a leak down..... If your adding fuel to a leaking motor... it wont fix anything . Start with a leak down.. if it passes then add fuel. Quote Link to comment Share on other sites More sharing options...
oldskool Posted April 1, 2013 Author Report Share Posted April 1, 2013 Sorry, I forgot. leakdown test was done a few times. Its good. Windy, are you asking for squish, if so it was .045 1 Quote Link to comment Share on other sites More sharing options...
Finch Posted April 1, 2013 Report Share Posted April 1, 2013 Add fuel, Switch to race gas, get some measurements of your clearances on your domes........Much more to come, but it's a starting point. Remember.........they all run like a raped ape just before they ventilate the pistons. If your backing plugs....STOP RIDING TILL YOU FIGURE IT OUT! Doh! i just kept putting them in tighter! Whats your jetting? Quote Link to comment Share on other sites More sharing options...
possum Posted April 1, 2013 Report Share Posted April 1, 2013 like windy says switch to race gas. And see what that does. if you know jetting is good. Quote Link to comment Share on other sites More sharing options...
WINDYCITYJOHN400 Posted April 1, 2013 Report Share Posted April 1, 2013 Sorry, I forgot. leakdown test was done a few times. Its good. Windy, are you asking for squish, if so it was .045 With your compression and squish, I wouldn't feed that motor pump fuel. Quote Link to comment Share on other sites More sharing options...
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