Bringing a YZ400F Back From the Dead

So they split the crank and just replaced the half...??? What did that run you..?? I have some wear on my 426 crank sprocket...may have to do the same thing...

Lapping them didn't really take time at all. I don't know the proper way of doing TI valves, but these stainless ones lapped in just fine.

I paid $400 in labor to have the bottom end opened up and things replaced. I don't know if that's too much, but I don't feel like I got jacked. I know it's something I could have done myself If I took some time, but I really didn't want to. It didn't need the sprocket, but it would have a year or two down the road and I didn't want to do this again.

Lapping them didn't really take time at all. I don't know the proper way of doing TI valves, but these stainless ones lapped in just fine.
The proper way to lap Ti valves is NEVER, not under any circumstance whatsoever. The hard coating is much less than .001" thick, and any damage done to it by the abrasive paste means a dead valve.

Steel valves are a different matter, but even then, lapping is only useful as a touch up on valves and seats that have very little wear on them, and it can never be a substitute for grinding (or replacing, obviously Ti valves can't be ground) the valves, and refinishing the seats correctly.

Steel valves are a different matter, but even then, lapping is only useful as a touch up on valves and seats that have very little wear on them...

Good to hear. The had very minimal wear, so we didn't do much. My hold up now is that the valves and valve shims came from a different head, so the clearances are all off. Nothing that some new shims can't help though.

I really can't recommend using used valves from one head in another used head. As little wear as YZF's put on their guides, it may work OK, but it isn't ideal, by any means.

bikes lookin good, how much is it costin ya

I spent $1000 for the boxes of parts. Considering that the Previous owner had already powder coated the frame and the boxes had about another $700 worth of new wear parts (gaskets, seals, bearings, chain sliders etc.), I feel like it was a good deal. All said and Done, I'm about $1,800 into.

A bit much for a '98 YZ400, but the license plate (plated before the Feb 2004 cutoff) is pretty cool. :cool:

cool bike. if any one in michigan needs work i got a great guy who knows his stuff and works out of his place, so the price is right. i just paid 125 for a valve adj, and a carb over haul. parts and all. and where did you get that kik stand?

Any update?

Have fun... :thumbsup:

amazing project man.

keep it poseted

Updates???

I spent $1000 for the boxes of parts. Considering that the Previous owner had already powder coated the frame and the boxes had about another $700 worth of new wear parts (gaskets, seals, bearings, chain sliders etc.), I feel like it was a good deal. All said and Done, I'm about $1,800 into.

A bit much for a '98 YZ400, but the license plate (plated before the Feb 2004 cutoff) is pretty cool. :ride:

another thread back from the dead --- normally i'd say you were throwing cash away at an alarming rate doing all this to an 11 year old scoot , but you're right --- the license plate makes it all worth it

I vote for motard wheels if you are still around and working on this thing !

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