Originally Posted by
vnmsgt
Well ran my 7-port at the race this sunday and had some tuning problems with it. First I could not get it to stay running till the temp hit over 175 degrees, had to keep the glow ignitor on it or it would stall, yes I did try and new glow plug (OS P3) and it did the same thing, kept doing it. Then it would want to heat up after about 3 minutes. Got up to 305 degrees and would lose bottom end. Tried richening the HSN up the next heat race and it ran at 256 at the end of the heat but again after 3 minutes, it lost its bottom end and also was BONE DRY OF FUEL in a 5 minute main! During the B-Main it was running the same and again had to let the motor warm up to keep it running. Only thing I could see when I got home was the exhaust gasket on the case was all tore up and leaking. Could that have caused this problem? The first 2 minutes of each heat and main it ran awesome. Pinch is still great too.
It is amazing how many times I read the same identical symtoms on the 7 port from different people. I have/had the same problem too. I say have/had because I just recently changed my carb to a Nova but haven't been able to race it yet. I will be running it tomorrow if it doesn't rain for a test and tune session at the track. However, I did start the engine and it definitely seems to tune much better so I am hoping the problem is solved but won't know until tomorrow for sure.
I am with you, for the few minutes that the engine runs great it really screams. If it could only run like that the entire race instead of 3 minutes.