putting a 400ex motor on a 300ex?

i personally think it can be done


i mean in my car i took out the honda accord motor and put a prelude motor in it so its got to be easier than that was

 

you probly can do this but ur going to hav to put on a longer swingarm. im not sure ur frame can handle the 400's power

 

The frame def. won't handle the extra power, you'll need to gusset and reinforce it. If you don't you WILL get cracks. If you think your a good enough rider to keep the front end down then you could get away with the stock swingarm but you have to strengthen it especially on the chain side. They tend to crack near the pivot point if you have a 300 ex with a modded motor and ride it very hard and very often. You won't need to do much, i just welded a small piece of steel alond the top surface of the swing arm on both sides.

 

don't do it. What would be the advantage anyway, a couple pounds? The frame won't be able to handle it either. I was riding with 2 friends of mine last summer. One was on a 300 and the other on a 400. They came up over a hill from each direction and hit each other head on. Their front left tires hit so the impact was about the same for both. The 300 was toast. the whole frame was bent to the left badly and 3 or 4 welds were torn apart. The 400 only had a bent tie rod. Much weaker frame on the 300.