Ieat4strokes Posted March 13, 2012 Report Share Posted March 13, 2012 Did compression test on new 421 motor and it's pumping 175/180 on each cylinder? Race gas only? Quote Link to comment Share on other sites More sharing options...
sheerider11 Posted March 13, 2012 Report Share Posted March 13, 2012 That's very border line. What's you highest pump octane? Quote Link to comment Share on other sites More sharing options...
wacko2000 Posted March 13, 2012 Report Share Posted March 13, 2012 That's not borderline-ytou need to run race fuel The cut off is 155-160ish Joe Quote Link to comment Share on other sites More sharing options...
EvilBanshee Posted March 13, 2012 Report Share Posted March 13, 2012 Minimum i would use 100LL. Quote Link to comment Share on other sites More sharing options...
sheerider11 Posted March 13, 2012 Report Share Posted March 13, 2012 That's not borderline-ytou need to run race fuel The cut off is 155-160ish Joe Well there you go, I've been told where you were at is the cut off point. But weren't you saying this motor is running like shit?? This might be the problem Quote Link to comment Share on other sites More sharing options...
Ieat4strokes Posted March 13, 2012 Author Report Share Posted March 13, 2012 That's not borderline-ytou need to run race fuel The cut off is 155-160ish Joe Thats what i thought, 160 ish...... but ive been out of the banshee groove for a couple years, all my friends sold thiers off, now everyones riding again and ive built a few motors and couldnt rememeber the exact number.... Thanks again Quote Link to comment Share on other sites More sharing options...
Ieat4strokes Posted March 13, 2012 Author Report Share Posted March 13, 2012 Well there you go, I've been told where you were at is the cut off point. But weren't you saying this motor is running like shit?? This might be the problem agreed...... yea its a dog up top, spits and sputters at powerband point, will just not rev out..... we put motor together and fired it up, started on 2nd kick, idled and reved out clean and crisp.... he ran it down the street one time and came back (on 93 pump) and thats when I questioned the compression etc, so this morning did a compression test and it hit 180/178 ish on each side.... we drained the gas out and went and got some 110 from our local airport still does the same thing..... would the T5's keep it from running on out?...... also timing is at +4 on 110 octane @ 180lbs should I bump it up to around +6-+7 ish...... Quote Link to comment Share on other sites More sharing options...
Smokestack Posted March 13, 2012 Report Share Posted March 13, 2012 Almost sounds like too much timing.. Quote Link to comment Share on other sites More sharing options...
Ieat4strokes Posted March 13, 2012 Author Report Share Posted March 13, 2012 +4 on 110 pump at 180lbs is too much? When Jeff built my fast drag port @ 180/190 ish he recommended +7 on race fuel........ Quote Link to comment Share on other sites More sharing options...
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