What models (if any) have the same engine?

[Myke Nytemare]

Hello all,

Ready to pull the trigger on an Xs400 that is not complete (lots of redone and new parts), but the engine is original and hasn't run in a while and when it didn't leaked and has physical (laydown) damage.

Since I'm going to have some time putting the bike together I figured I could get a used engine and do a fresh rebuild. I'd like to know if SR or other 400s can bolt right up...or even a xs500. Hopefully someone here can direct me to resources for engine internals as well.

 

[BBS360]

I believe anything in the same family would probably fit, by that I mean xs250,360, & 400 sohc only.
Anything else is probably a no-go. The engines are different physical shapes with different mounting points, especially dohc bikes.
A quick look at the SR motors also shows very different mounting points.
You wouldn't want an xs500 motor. Prone to cracked heads and even harder to get parts than our bikes.

Is the motor beyond repair? If not you're probably looking at similar amounts of work to get it going vs any other used motor.

What do you mean by engine internal resources? You're posting to probably the biggest resource on these bikes in the world. Hundreds of old threads on all subjects.
The OEM and Haynes manuals are available on the board.
There are threads on where to buy parts but your best bets will be your Yamaha dealer, eBay, Google, and the classifieds section here.

Edit: Is this the same bike you were going to go look at?

 

[Myke Nytemare]

By internal I meant parts like oversized pistons and rings, etc. If I'm gonna rebuild it, I'd like to go as performance oriented as possible without forced induction like that one awesome bike on here... I think it's Drewpys. That's part of the reason i was wondering if a slightly larger engine would "bolt right up".

What engine component/Performance options are there if I'm gonna have machining/light porting done before reassembly?

No, this is a different bike...the other one was sold the next day before i could even go look. Not too many other bikes to see that are XS400s....some XS triples and some CX500 Hondas in my area, but not many smaller bikes :-(

 

[BBS360]

Other than OEM oversize pistons (max 70mm if you can find them) there aren't really any drop-in performance upgrades for the engine internals. The sky's the limit if you want to spend tons of money on non-OEM parts and machining.

Check out the big bore thread to see what's involved in running bigger pistons: http://www.xs400.com/threads/holy-grail-of-xs400-big-bore-pistons.9388/
There's another "replacement piston" thread, should still be on the first or second page. Didn't really reach any conclusions there beyond "it's a lot of work".

 

[Myke Nytemare]

Thanks for the info... I'll definitely look into getting a a sleeve/piston/rod combo if someone knows it'll work as I have a friend I could send the engine to for machining. I'm willing to spend the cash if someone knows it'll work....guess that's everyone's issue, knowing what will work in the 400 block.