Any harm in starting the bike with no exhaust installed?

Besides hearing damage?

Not really sure, but along with the ear-plugs you might want to keep a extinguisher close by also....

Damaged exhaust valves. Ed

Damaged valves? Even with 85 degree ambient temp?

I believe the problem is related to the exhaust gas temperature rather than ambient temperature. Ed

We've done it once, out of curiosity. A 15 ~ 20 second idling run won't hurt valves based on that experiment.

The motor was stock & in a good state of tune. We were only changing exhaust systems.

Unique burbling sound. 4" flame out of the exhaust ports for interesting visuals. Smoked the frame paint a little but we didn't let it idle long enough to do permanent damage & the residue cleaned right off. Didn't rev it; brought it up just off idle to about 1,500 RPM for a second or two. Sounded "better" at idle 'cause each individual exhaust pulse was more defined.

If you choose to try it, wrap aluminum foil around the frame tubes in the immediate vicinity of the exhaust ports so you don't have to clean. Don't rev it and limit run time to a very short period.

Good Ridin'
slmjim & Z1BEBE

Your neighbors will totally love you. :laugh:

I've done it many times on various cars and bikes while assembling them. Never had a problem. Sometimes you want to know it doesn't have any serious problems before going through the trouble of mounting an exhaust, in case you have to yank the motor back out.

Be ready for it to sound weird. It will have a "liquid being poured into a metal bottle" sound, which makes sense since you are hearing the cylinder resonating as its volume changes. Its a similar sound but sped up.

Last fall I'd rolled off a smaller sized curb (done this many times prior) with very little air in the shocks, didn't notice it until I tore it down, but one of my pipes down in the 4 into 1 collector got dented in pretty good. My buddy has a way with metal and while he's fixing up my pipes, been tinkering here and there, new wires, plugs etc. Figured I'd fire it up, just didn't wanna have another one of my not so bright moments. Costs a lot more when you have a lot of not so bright moments LOL.