... might sound like a COMPLETE dumbass, but what happens when you burn out your valves?Example; when you run without a pipe and your mixture's too rich? What all is happening during the process and how are they being burned?

 

I think it’s when your engine runs too hot for extended periods of time. The heat will deteriorate the metal of the values, causing them to not seat properly. That in turn will cause a loss of compression.

 

Most later bikes like yours may have burnt (exhaust) valves mostly from high mileage. Then the poor motor loses
compression which causes hard starting and a cronic bad idle.
Other than that, exhaust valves can go bad from overheating (running lean, bad timing, low coolant).
High mileage causes usually means new valve guides, valve seat work,shimming etc. Maybe a engine overhaul.
ps. running rich has a cooling effect on the cylinders and a fouling effect on the plugs.

 

Burnt valves also appear more readily if your seats are worn to the point where the is significant "Blow-By" past your valves and seats upon compression. Unfortunately the definitive way to check this requires you to remove the head but you can still do a leak down test.

As Pugetpower stated - it's a lean mixture that will burn valves and/or melt pistons.

 

thanks for the explanation... [sm=tongue.gif]

 

oh yeah, is there a way to tell by the way yourexhaust looks or smellsif you're running rich or lean?

 

Running rich: Poor gas milage, excess gasoline odor in the exhaust gas
Running lean: harder to tell, but the engine will run hotter than normal

 

cool... thanks again

 

Whats normal running temp? I will check the manual now.

The other night i was at 220 ish ...

 

Normal running temp depends on outside air tempreature and will fluctuate if colder or hoter outside. My bike runs about 210 on a moderately warm day approx 70 F +1 on what Winchester said about the leak down test. This is the easiest way to see if your losing compression due to a burnt valve (intake or exhaust), rings are leaking compression, or headgasket issue. Its fairly easy to do if you have a leak down tester and compressed air. If your running rich you might see carbon build up on muffler tip (more than usual) Lean is tough to tell. hope this helps.