Lost mid-range power

I went for a ride this afternoon - about 40 degree weather, and on the way home (after the sun went down), the bike started to feel really weak between about 4500 and 6500 rpm. The bike had been running at around 60-65mph for a couple of hours, so was nice and warm, and probably expanded a bit.

I'm thinking that this could be attributed to a poor connection on the exhaust side at the manifold? I think I may need to replace the crush washers (or whatever they're called), cause the exhaust is nice and rusted, so probably hasn't been touched in a while..I know I haven't done anything to it since taking possession of the bike.

Could a leak cause this loss of power? The bike runs fine when its only moderately warm - no power loss at all. I checked to make sure it wasn't low on gas - that was definitely not the problem since I filled up with about 5 litres of gas.

Doesn't seem like it would be exhaust related, at least not how you are thinking. The reason I say that is that if things are hot and expanding, those washers are more likely to close up a hole, not create one.

More likely a problem on the intake side. Could be less related to the heat and more to the cold air. Cold air is denser so might be leaning the mixture out a bit. Of course the flaw in that thinking is that the air was always cold. Long way of saying I think it's on the intake side, not the exhaust side.

sounds like it may have been running hot. Possible lean condition. If the plugs are white in warm weather, cold air will cause a lean condition.

Post edited by: nads.com, at: 2006/10/27 23:56

So whats the fix for this then?

It isn't a new main jet, right? - should I look at the needles?

I don't think my needles are adjustable.

Btw - I have a Supertrapp 4-into-1 exhaust on it.

Post edited by: pyxen, at: 2006/10/28 22:10