My local dealer has a 400ex frame at a very reasonable price, and I'm thinking I might buy it for my 300ex. I've done many engine mods, so the power is quite substantial compared to stock, however now I would like a better frame/chassis.

What I would like to know is if the engine would be a direct bolt in. And second, how many parts would be interchangeable from my 300ex with the 400ex frame. I am hoping I would be able to use the swingarm, a-arms, handlebars, axle, rear shock, etc...

The only areas where I think I may run into problems would be the exhaust, front shocks, and possibly gas tank. The exhaust probably would not mount up because of different mounting locations, so if I got an aftermarket exhaust for the 400ex, would it connect to the stock 300ex head pipe? Also, the front shocks on a 400ex are longer than the 300ex, correct?

Any help and insights would be appreciated. I'm hoping by upgrading to the 400ex frame, over time as my budget allows, I would be able to upgrade to higher performance chassis accessories compared to what is currently available for the 300ex.

Thanks in advance.

 

My advice, for what it is worth, is to get 400EX a-arms and shocks if you get the frame. They are cheap enough ( 220.85 for a-arms and shocks 129.00). You could run 300EX shocks, but you will have to lower the mounts about 3 inches. You can run 400EX a-arms on a 300EX with 400EX shocks with a shock relocation kit from ATV Racing.
The 400EX fuel tank is also cheap (66.95).

The swingarms measure the same width, but I don't know if they can be swapped. Also, difference in length of rear shock.

Hope this was at least a little bit helpful.

See Ya,

Darrin Talbott

 

I was reading this and I have a question..... Does the 400EX swingarm fit the 300EX chassis?