PDA

View Full Version : '78 Yamaha DT400-how much compression?


Brad200X
03-09-2009, 06:47 PM
Alright guys, I have a DT400 and it feels a little gutless for a 400CC 2-stroke. Can the decompression valve go bad? Is it adjustable? What kind of comp. should this bike have?
dirtface
03-09-2009, 08:29 PM
I had one of those bikes and it was a 2-stroke, so it wouldn't have valves. It sounds to me like it needs a topend rebuild.
Brad200X
03-09-2009, 09:07 PM
It is a 2-stroke. The decompression valve is supposed to make it easier to kick.
bandito90
03-10-2009, 02:54 PM
I new a guy that had one of these years ago.I never rode the it,But if it is like the smaller dt/mx bikes it would have a broad power band .Not peaky like a yz or other similar motorcrosser.
Brad200X
03-10-2009, 04:58 PM
Yeah its power definitely comes on more like a street bike, as it is street legal, but it feels like should be faster. That's why I'm kinda thinking the decomp. is stuck open or something.