2001 WR426 - blown engine... what now ?

A friend of mine just sold his YZ250 2 stroke to buy a 2001 WR426F.

We found a bike that he bought for $1500, but the engine was seized. We had hoped just the cylinder and piston were messed up and we could fix that by replacing them with a big bore kit.

After getting the bike and tearing it down, the piston was really messed up with part of the skirt broken off and probably dropped into the bottom end.

The worst part was that the cams and the journals in the top end were also scored pretty bad. The center intake valve also appears to be stuck.

The big question is, how best to get this bike up and running without spending a whole lot of money on it.

If we could find a replacement head and cams, we could still go the big bore route and just clean out the bottom end and hope it is ok.

The other option is to just look for another engine on ebay that someone might be parting out.

Anyone know if you can buy just the head for one of these without spending too much ?

Any input you guys have would be appreciated.


Anyone know if you can buy just the head for one of these without spending too much ?

Check Eric Gorr's website inthe "garage sale" section...he had a couple of rebuilt heads going for about 750 with Kibblewhite valves. You might also contact Engine Dynamics and ask them about the cost of rebuilding. While I have not personnaly used them, they come highly recommended, and from what I read on this board, they are able to salvage some pretty badly damaged heads.

We were hoping to keep the cost down to a minimum but still get a bike that runs.

I've seen some YZ426 engines on Ebay for about $700. I assume we could take the top end, cylinder, and piston from the YZ and then either use the existing WR lower end or swap parts back and forth between the transmissions to get one that works.

any other ideas ?

Thanks for the suggestions so far.

The WR400 engine would seem like a downgrade instead of an upgrade.

It would really be nice if I could just find a head and then get a big bore kit for the cylinder and piston.

Still need to check with Engine Dynamics on what their cost would be to rebuild the journals on the existing head.

If anyone has any ideas on head rebuild cost, or someone or someplace where I can get a replacement head, that would be great.

Engine dymanics does great work. I'd figure he'd charge about $700 for what you want done to the head.

The 400 motor is almost the same power as the 426 but they aint cheap either.

$700? You can buy a whole new head from the TT store for $500.

By the time you replace valves, seats, cams and get somebody to grind the valves and assemble it you'll be into it for $1000.

If you buy a complete motor off ebay, make sure it doesn't have any cam / head / valve problems either.

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