2000 426 granaded engine

[brent426]

I just purchased a 2000 426 for 800 bucks with a blown motor. The crank is brand new as the previous owner installed it and on the next ride it blew the top end. One of the chain guides broke and let loose and the cam chain derailed. Needless to say it went off like a bomb. The crank checked out perfect and looks perfect too. I have orded a crapload of new parts for this bike, new crank bearings, last owner skippd this on new crank install, new cylinder, piston, pin, cilps, head, valves, all buckets and cams are in great condition and I will shim them into the new head, and I ordered a new cam chain, both cam chain guides, and a new oil pump. This was a lot of money. The question I had is about the tennsioner. It looks good and still retracts and auto extends, have there been any issues with these tensioners? Just dont want to loose tension on the chain on this new motor. If anybody knows any problems or the lack of problems, please let me know. Thanks

[grayracer513]

The YZF tensioners are as nearly foolproof as a thing can get. If you had a bolt threaded through the back of the cylinder with a knob on it that you could put a twist on and hold, you could easily take up any slack that appeared in the chain by simply maintaining a light twist on the knob, and the chain would be unable to push back the tensioner as long as you held the small amount to force on the knob necessary to prevent it from unscrewing.

Substitute a nice little housing, some hardened, extremely finehh threads, and a spring in place of your fingertips, and you have a YZF chain tensioner. They're almost too simple not to work. But they can wear over time, and they don't cost that much.

The tensioner should retract and extend smoothly, and it should be impossible to cause it to skip back by pushing against the plunger at any point in its extension.

[dejavudarrell]

How much to rebuild my I ask?

[426 NOOB]

If it were my motor, I would just replace it just to be safe, especially since you already have the motor apart and are putting tons of $ in it. Extra expense now might save you pain and frustration later.

[Ga426owner]

Whats another 30.00 bucks for all the new stuff you invested in....?

[BeauGt]

Get a 450 cam you will love me for that later trust me.

[brent426]

thanks for the infromation, sounds like good advice. One other question I had for reasembly of this new head. Do I need to lap in new valve to new valve seats or can I just run em?

[brent426]

For thoes wondering what I am putting into this build it is 1250 and some loose change hear and there. I know I could have purchased this bike running cheaper, but It gives me fun project and in the end I will have a new motor. I have build pleanty of motors before, just not a 426 or of its family.