Yamha DT400 Tuning Issues

[Rogue6]

Hey everyone. I just picked up a 1977 Yamaha DT400 as a budget dirt ride. This is my first two stroke and I was hoping someone might be able to offer some help. I am having just one big issue with it.

The biggest problem is throttle response of the engine itself. It will rev up just fine, doesn't feel like any flat spots, but it revs down very slowly. It almost seems like the slide doesn't close fast enough. The cable isn't catching and the throttle snaps back just fine. I went through the entire bike, the reeds look just fine, the carb was cleaned out and the slide movement was smooth.

So does anyone have any idea why my bike won't rev down quickly?

Thanks in advance. The site has already answered a lot of questions with a few searches.

 

[tuckers20]

Hi rogue6, i own a 1978 dt400. Mine does the same thing when its standing still in neutral. I think thats just what they do. When im on the trail the bike rides fine i dont have any issues with the revs not goin down fast enough. But thats jst what i think.

 

[Rogue6]

Hey thanks a lot for the response. I was starting to wonder with it being a large 2 stroke if that's just how it was. Glad to hear it's not just my bike.

 

[SFO]

crank seals, air leak.