KarTek Posted August 2, 2014 Report Share Posted August 2, 2014 So I've been chasing this for a while. Backfires out the left side, won't rev past 5500 RPM. What I've determined it's NOT: Stator (traded with another one) Carb adjustment (swapped carbs) TORS (removed) Parking brake sensor (removed) Ignition is OK (traded CDI boxes Weird stuff it's doing: Bubbles in the coolant Pops out the left carb and exhaust 135 PSI on the left, 175 PSI compression on the right. Flywheel almost looks like it's vibrating fore/aft when the engine is revved up but this may be an optical illusion because of the engine vibration due to poor running. The left exhaust pipe ACTUALLY TWISTS when the engine is revved, despite the fact that the pipe is secured and all the mounts are good. The right side is solid. So, I need a plan of action. Where else to check? The condition developed over time. Thanks for the assistance! Quote Link to comment Share on other sites More sharing options...
WINDYCITYJOHN400 Posted August 2, 2014 Report Share Posted August 2, 2014 Gotta cover more basics. Reeds broken? Blown O-ring/head gasket Leakdown check Quote Link to comment Share on other sites More sharing options...
KarTek Posted August 3, 2014 Author Report Share Posted August 3, 2014 OK, I'll get on that, thanks! Quote Link to comment Share on other sites More sharing options...
possum Posted August 3, 2014 Report Share Posted August 3, 2014 change flywheel. check back Quote Link to comment Share on other sites More sharing options...
KarTek Posted August 3, 2014 Author Report Share Posted August 3, 2014 OK, just got back from tearing the engine down to some degree. Reeds in perfect condition. Will check o-rings tomorrow if I have time. I also have to look and see if I have a spare flywheel. I have a whole extra engine in parts but not sure of the FW. Thanks. Quote Link to comment Share on other sites More sharing options...
trickedcarbine Posted August 3, 2014 Report Share Posted August 3, 2014 Definitely the head... Quote Link to comment Share on other sites More sharing options...
KarTek Posted August 4, 2014 Author Report Share Posted August 4, 2014 (edited) Took the head off today and found this: Left side (the misfiring side) is much cleaner than the right side. Piston cleaner too: The head looks OK: Found a crushed O-ring on the left side. Is it possible for them to blow out like this? I figure this is causing the compression leak and bubbles in the coolant. Edited August 4, 2014 by KarTek Quote Link to comment Share on other sites More sharing options...
trickedcarbine Posted August 4, 2014 Report Share Posted August 4, 2014 Might have just been o rings. Super common. Might get lucky and be able to change the o rings and be good to go. But I would bet if that crank has been drinking coolant, there might need to be a little attention paid to the lower end. Quote Link to comment Share on other sites More sharing options...
KarTek Posted August 4, 2014 Author Report Share Posted August 4, 2014 OK, I'll start with the obvious and replace the o rings, clean all the mating surfaces and put it back together. Run another compression check and see how that goes. I guess Chariot would be a logical source for parts since they sponser the forum? Quote Link to comment Share on other sites More sharing options...
trickedcarbine Posted August 4, 2014 Report Share Posted August 4, 2014 (edited) No, those little o rings don't come with chariot stuff. Edited August 4, 2014 by trickedcarbine Quote Link to comment Share on other sites More sharing options...
KarTek Posted August 4, 2014 Author Report Share Posted August 4, 2014 OK, I'll figure out a source. So, next steps: Once I get the head cleaned up and back on, if the compression is still down, do I need to be looking at rings? Would case leak down effect compression? Thanks Quote Link to comment Share on other sites More sharing options...
trickedcarbine Posted August 4, 2014 Report Share Posted August 4, 2014 Really inspect the whole thing thoroughly. Look to see if you see glazing in the cylinder walls or any silver streaking, both very common in a motor that ate coolant. You will have to hone the cylinders if that is the case. Also, get the motor out and tipped forward to make sure there is no coolant in the bottom end. You can TRY dumping some fuel down the holes where the crank is and use it to flush any coolant/fuel goo out. Ultimately there is still no garuntee. I just sourced a good O ring kit from ATV galaxy on the last build I just did for a buddy. When you install it all. Don't try to assemble the whole head and just slide it on. You will decimate those little o rings on each stud. Best way, is to ring up the domes, set them on with the notch facing forward. Then the main shell. Now drop the little o rings on each stud. Top plate is last, don't forget the two thin rings over the spark plugs. Viola! Pro Design Sammich! Quote Link to comment Share on other sites More sharing options...
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