Used 400ex, with 426 bore???'s

[JD3500]

Looking at used 2001 400ex, has Wiseco 426 kit, hot cam, sparks pipe, jet kit, K&N air filter, ignition box, sand paddles & dirt tires

My first quad but ive had a ton of motorcycles. My questions is. What are my options if this motor does need rebuilt. can i redo it to 426 again or does it have to be bored out to 440, cause i dont wanna do that.

Also, in my hunt for a 400 what should i specifically look for? Any years better than others? specific problem areas.

Im lurking the forum and learning alot.

this will be a rec quad. 90% dunes. rest trails.

Edit: Can i run pump gas with this motor?

[bkelley]

First off, welcome to the site. Always nice to see new EX owners.

Originally posted by JD3500
Looking at used 2001 400ex, has Wiseco 426 kit, hot cam, sparks pipe, jet kit, K&N air filter, ignition box, sand paddles & dirt tires

My first quad but ive had a ton of motorcycles. My questions is. What are my options if this motor does need rebuilt. can i redo it to 426 again or does it have to be bored out to 440, cause i dont wanna do that.If something does happen with the 426 you'll have two options. Bore it out to a 440, or buy a new cylinder. Generally speaking, if a 426 kit is done correctly you'll have very little to worry about, it's considered as reliable as stock. It's only when you get to 440+ when reliability becomes an issue. Of course, every situation is different and anything can happen. I'm just speaking generally.

Originally posted by JD3500
Also, in my hunt for a 400 what should i specifically look for? Any years better than others? specific problem areas.

Im lurking the forum and learning alot.

this will be a rec quad. 90% dunes. rest trails.

Edit: Can i run pump gas with this motor? The 400EXs are mechanically the same from '99 until now. In '05 the gearing changed from 15/38 to 14/39 and the plastics changed. Plastics changed again in '08 and it was renamed to the 400X for whatever reason. You're gonna want to ask if it's ever been in a major wreck or has had any major work done. Look for bends in the frame and if it's had any motor work done ask who did it and what exactly was done. Compression ratio, size of the piston, et cetera. Anything over 11:1 compression will need race fuel to run safely. 10:1 to 11:1 is pump premium safe.

[JD3500]

Thank you.

426 is for sure as large as i want to go. I will post pics if checks out and i bring her home.

[PaRedneckRiders]

Ya 426 imo is the best bore for the 400, it still has alot of power and a descent amount of speed, but a well built 426 will run with 440s all day
imo a good 426 would b one with a wesico or je 426 with 11:1 compression
stage 2 hotcam
k&n air filter
and a full pipe (i would go with lrd or curtis sparks) but any pipe is ok even the lexx pipes u can get off ebay for like 170 are not bad pipes just not as good as some of the well know brands

[PaRedneckRiders]

and btw if there is anything done to it
Big bore, pipe, cam, etc
Ask what the jets are set at because it may b running lean