Rebuild question

[legacy400ex]

I am at the point of rebuilding my 400ex. It started smoking constantly and decided to stop riding it before something bad happend. I am wanting to go with a high comp piston and a stage 2 hot cam. What is a good size piston to go with 416,426, or just stay stock bore. Also is there anything else that i should get while it is apart. The quad already has a white bros e-series exhaust, edelbrock carb, and tci rev box. It just needs more power.

[Dill]

I would stay stock bore if its currently not worn out. While you have the head off, you might as well have it ported while you're at it.

[Sparky_20]

I would replace the cam chain with a heavy duty chain as well as a tensioner and guides while your in there. Like dill said if the cylinder isnt worn out you might as well stay with a stock bore. If it is showing some wear then I would go up to a 426

[j450rking]

i don't think you should't bore it just b/c it's not worn out if you want more power thats the way to go. a 416 with a port and polish and a cam is one of the best things you can do. and you allreddy have the carb so thats what i would do.

i say go for it if you want mor epower don't think twice to bore it out and get a nice 11-1 piston

[legacy400ex]

I was also thinking of the 416, i have heard alot about them. I think that is the way i am going to go. Also how hard is it to rebuild the motor, considering i will have someone do the machine work to the cylinder. I mess with 4 cylinder cars alot, just wondering if it is possible to do it my self.

[flauge]

I come from working on 4 bangers too and i'll say that my 400 is a lot easier to work on. Everything is just right there and easy to get to:cool:

[Sparky_20]

I would leave the internals to an experienced machine shop. just my opinion tho

[400exrider720]

Im 16 and was scared to death of doing the work myself. With help from everyone on here I did it and once you open it up you will see how easy it is. All you need is a good torque wrench and thats all the special tools you need. Use a good manual and take your time. Its pretty simple.

[j450rking]

Originally posted by 400exrider720
Im 16 and was scared to death of doing the work myself. With help from everyone on here I did it and once you open it up you will see how easy it is. All you need is a good torque wrench and thats all the special tools you need. Use a good manual and take your time. Its pretty simple.

i did the same thing and now i'm about to finish a full rebuild

[legacy400ex]

Thanks for the help guy's. I think i will try it my selft, i have a service manual and it goes very in depth about the engine. If i have any more questions i will ask.