400ex exhaust

[jeenyus]

my friend has a 400ex, he was riddin yesterday and lost the end of his pipe,

is it dangerous to ride again without that piece?

[Banchetta]

no

[05bansh]

when you say the end of the pipe are you reffering to the cap?

[Flyin_Shee]

If it's the end cap, then he should at least rejet if not replace it..I've heard about the valves eventually being ruined because of no back pressure?

 

If it's part of the pipe, I'd definately just replace it instead of risking damage to the engine.

[Banchetta]

If it's the end cap, then he should at least rejet if not replace it..I've heard about the valves eventually being ruined because of no back pressure?

 

that is just a myth. You can't ruin valves by not having backpressure. You can however get a slight hp gain w/ the correct backpressure. A 4-stroke motor will work like a 2-stroke, just no wheres near the amount of effect since the valves are mechanical and the 2-strokes reed valves are controlled by the exhaust...I know of a couple of duncan exhaust on 4-strokes and know of several other brands on various 4-strokes, so far the Duncan is the greatest gains and very noticeable w/ seat of the pants feel...Even rejetting, he'll get more performance w/ the stock exhaust on then taking it off...this is where the back pressure thing comes in..