I'm building a 400ex hybrid ith a yz400f motor, +2 a-arms with elka shocks, +1.25 swing arm with elka rear shock and linkage, +4 extended axle, +2 anti-vibe steering stem, laker custom plastics, nerf bars with aftermarket foot pegs, do you guys think it will be as good a my friends new stock LTR450 on a MX track?

 

The yzf 400, lacks good torque, to pull the quad frame. The 450 quads, will probably out do your engine. You might out ride the other guy, and I think your engine is a little lighter, so that will help.

 

The YZ400F engine doesnt lack torque it has the same hp as the LTR450, so it wouldnt lack torque.

 

Ummmm, HP & torque are two different things. Just because one engine has the same amount of horsepower as another engine does not mean they share torque curves.

A 4 cyl. car engine may have 260 HP, same as a V-8...... BUT the torque numbers wouldn't even be close. Same goes for a single cyl. engine.

I don't think anyone is saying that the 400 Yamaha is a turd, no. But it lacks the torque numbers of a 450. Remember the old saying..... " There is no replacement for displacement !! "

 

I think if you are spending all that money on a ex....maybe you should consider a different machine? Unless you want something completely different and i can see why you would. The chasis mods sound good and it should go around a track nice but why are you using a 400 motor?

 

I'm using a YZ400F motor because i all ready own the motor, and it is lighter than a 450, and it is a dry sump like the 400ex motor was, it will fit in the frame better because of no oil pan to worry about getting in the way, I want to build something that not many people have a 400ex HYBRID, and it will be all built by me and my buddy right from a bare frame.

 

sounds pretty cool....the stock zuki doesnt have the greatest power i been hearing...that is untill its modded....i think they will have a tad bit more power then you will but im not positive. By the way where the you live in Alberta?

 

I'm wasn't trying to slam, by any means. I have ridden a hybrid lonestar frame with a yzf400 engine. It lacked torque. If you could keep it at 9,000 rpm,it was scary. On a mx track that rpm range is hard to keep. Good luck, with your build.[img]i/expressions/face-icon-small-smile.gif[/img]

 

If the quad lacks tourqe like you say it will, then i will send the engine to a yamaha shop or a engine builder and get it made in to a 426 or a 440 stroker.

 

The stroker would help alot.