Short version: High idle after WOT that sometimes returns to normal, others just stays high with SBP HD air filter on a 66cc HT with NT carb. When switching to my stock filter with a couple holes drilled in the housing, no high idle after multiple WOT runs, but with some 4 stroking and loss of top end.
Long version:
Been struggling with a high idle after a WOT run on my 66cc HT lately. Assuming it was an air leak, I RTVed my carb/intake join and I already had an O-ring on it (NT carb, BTW).
And I have a weeping clutch side crank seal, so just assumed that might be the source of the leak too (have a new one in the mail).
BUT, on a whim today when pulling into the garage with my idle sky high, I start spraying brake cleaner all over, crank seal, no idle change. Carb/intake joint, nada. Exhaust flange? Nothing.
Hmmm... For giggles, I took off my SBP HD air filter which I have been running since installing the motor, and replaced it with the stock air filter with some holes drilled in the cover. I got a little 4 stroking on the top end and lost a couple MPH, but even after several WOT runs, she still idled great!
Then put the SBP air filter back on and the 4 stroking at WOT is gone and got my speed back, but sure enough, as soon as I finish a top speed WOT run, the high idle is back! Sometimes it returns to normal after a few seconds, sometimes is just stays high. If I shut the bike off and start her again, she starts with a regular low idle until I go WOT again.
My father-in-law suggested that maybe the bike just takes a long time to warm up and that is where the idle is supposed to be with this setup, and she is not actually running lean? Sounds fishy since the idle is sooooo high.
BTW, I did recently go from a 72 jet to a 68 to get rid of high speed 4 stroking. The needle is at the leanest position since any richer and she runs terribly at mid throttle. Maybe I just need to try running with the needle clip in the second to top for a longer amount of time? I usually just give up after about 5 minutes of riding around with the needle in that position since she runs so poorly!
Hmmm, I guess I could let the bike high idle for a minute then cut the power and check the plug, to get a reading to see if it is a lean condition causing the high idle?
Anyways, could this be caused by an improperly sealing air filter? Maybe just deal with crappy mid-throttle response when cold and try the needle one notch richer?
Long version:
Been struggling with a high idle after a WOT run on my 66cc HT lately. Assuming it was an air leak, I RTVed my carb/intake join and I already had an O-ring on it (NT carb, BTW).
And I have a weeping clutch side crank seal, so just assumed that might be the source of the leak too (have a new one in the mail).
BUT, on a whim today when pulling into the garage with my idle sky high, I start spraying brake cleaner all over, crank seal, no idle change. Carb/intake joint, nada. Exhaust flange? Nothing.
Hmmm... For giggles, I took off my SBP HD air filter which I have been running since installing the motor, and replaced it with the stock air filter with some holes drilled in the cover. I got a little 4 stroking on the top end and lost a couple MPH, but even after several WOT runs, she still idled great!
Then put the SBP air filter back on and the 4 stroking at WOT is gone and got my speed back, but sure enough, as soon as I finish a top speed WOT run, the high idle is back! Sometimes it returns to normal after a few seconds, sometimes is just stays high. If I shut the bike off and start her again, she starts with a regular low idle until I go WOT again.
My father-in-law suggested that maybe the bike just takes a long time to warm up and that is where the idle is supposed to be with this setup, and she is not actually running lean? Sounds fishy since the idle is sooooo high.
BTW, I did recently go from a 72 jet to a 68 to get rid of high speed 4 stroking. The needle is at the leanest position since any richer and she runs terribly at mid throttle. Maybe I just need to try running with the needle clip in the second to top for a longer amount of time? I usually just give up after about 5 minutes of riding around with the needle in that position since she runs so poorly!
Hmmm, I guess I could let the bike high idle for a minute then cut the power and check the plug, to get a reading to see if it is a lean condition causing the high idle?
Anyways, could this be caused by an improperly sealing air filter? Maybe just deal with crappy mid-throttle response when cold and try the needle one notch richer?
