steady Posted February 4, 2012 Report Posted February 4, 2012 I just finished my first build and did a 4mil dune ported. Once i got it all together, I did a leak down with no loss at all even after 20 minutes. Bolted up carbs 34mm pj, exhaust and other items...and it started on the third kick. It would only run while i was on the throttle, would left off occasionally to try to set the idle. When I would idle down the motor made some noise. Idle up it go away. When then all of a sudden it died and wouldn't start back up. First thing i noticed the fuel was coming out of one of the carbs, which made me believe the float was stuck. Then i went ahead and did a compression check. I got 170 on one, and 160 in the other. The spark plug on the 170 side was a little lighter tan, and the 160 side was pretty brown. Does anybody have any idea, why it wont crank and how much issue is having different compression numbers. Thanks ahead of time for the help, here is some spec i am running, 19 cc domes, 32:1 race gas/klotz, stock reeds, 34 pj (160main, 48 pilot, 1-1/2 air screw) 1400 altitude, cpi, Quote
sleeper06 Posted February 4, 2012 Report Posted February 4, 2012 numb 1 pj are an old design and have a few inherent problems in the idle /choke tube assembly,second if your port heights are not identical compression will be diffrent or a problem with assembly occured Quote
Burt Reynolds Posted February 4, 2012 Report Posted February 4, 2012 DId you kick both sides at WOT until the needle wouldnt go up any further? If your cylinders were within 5 or less of eachother i would say clean and adjust your carbs,and rebuild them if necessary,but if there really is 10 psi difference you might have a problem. I was thinking though,if its a new top end,if one side ran really rich for a few minutes the two sides might have starting breaking in differently,like one side sealing up the rings faster. If you get your carb deal straightened out,run it for a for a little while and see if it evens up Quote
steady Posted February 4, 2012 Author Report Posted February 4, 2012 i didn't do wot compression check. So i did this morning and i got 170 on both cylinders but the motor was cold. I still couldnt get it to crank. So i took the carbs off and there was trash in the carbs. So i have them soaking again. Hopefully I can get them cleaned and try again. If i have compression is that a good sign motor is right, just maybe having some major carb issues? Quote
Burt Reynolds Posted February 5, 2012 Report Posted February 5, 2012 (edited) Yeah having even psi is a good sign,sounds like your carbs may be the issue. ALways do a compression check with the throttle wot. ARe you taking the bowls off and the jets out and blowing compressed air through the passages. Whenever i clean i carb i completely take it apart. Choke,air screw,jets,ect. Make sure your getting spark too Edited February 5, 2012 by Burt Reynolds Quote
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