Topic: Start engine w/out exhaust?!

[brentnclemson]

I recently took the exhaust off to give it a new coat of 1200 degree semi-gloss.  While I was painting a buddy started the bike w/out the exhaust to "see how loud it is."  Well, anyone who has done this probably knows it's not that much louder...in fact, it sounded pretty strange.

Question...could this hurt the engine at all?  I can't think of any way it would, but after putting the exhaust back on the #3 pipe barely gets warm.  Took the plug out, the spark looks OK.  I did take the float bowls off the other day to clean them, but besides that and the exhaust I've done nothing to the bike.  All pipes were the same temp previously.

Any idea what might be causing this?  Thanks guys!

[mattcb350f]

Running an engine without exhaust for a short period will not hurt the engine at all. The danger in running without exhaust is that there is no back pressure on the valves which helps cool them. The only time the valves would be hurt is if you took the bike out and ran it under full load at wide open (i.e. drag racing, high speed). But a few blips in the driveway to wake the neighbours won't hurt.

To answer your other question, I don't know why the #3 pipe would be cool now. Is this compared to the other three? This would'nt likely be caused by the no exhaust run. If anything, I would guess that if you suspect the cylinder is firing, and the plug is clean than maybe the float needle is stuck on that cyl. from cleaning the bowels.
 Matt.

[goon 1492]

+1 its gotta be either no spark or no fuel for the fire

[brentnclemson]

Sounds good, thanks guys!  I couldn't come up w/ any reason why running it w/out the exhaust could hurt anything, but it showed up right after I did this!  Pretty crazy sound if you haven't heard it on these bikes...at idle it sounds like bubbles popping...

Anyway, I'll check the float valve, that definitely could be the culprit.