Picked up a '99 WR400

I just bought a WR400, and I don't think the motor has ever been touched (as far as I know). I was planning on getting a new piston for it this winter, and possibly get a new cam chain. Im not planning on doing anything with the valves, unless I see a problem when I do the piston.

I would like to know what other things I should do/replace for peace of mind? Ive read about how the 426 rod end was 2mm bigger and it is possible to switch my crank out for it, but what parts would I need for such a conversion?

Why fix it if it ain't broke?

I don't want it to grenade! 9 years on the same piston/cam chain seems like a long time for such a bike, maybe im worrying about nothing?

My 2000 STILL has the valves in spec after all this time and runs perfect.

Tuff bikes. (I joined TT 6 years ago how am I a newbie? And where did my posts go? )

Could anyone recommend a quiet muffler for this bike? It doesn't run right with the stock muffler with the baffle, and its way too loud without the baffle.

My 98 WR400 is still going strong with a zillon miles on it. Very strong motor unless abused. Try a PMB insert in the stock pipe (baffel removed) Quiet and pretty strong - also cheap!

I put the GYTR insert in mine and it is great. No jetting issues and gives it a bit more response. The good thing if you need to quiet it up then pop the GYTR out and put the stock in. 2 min job. KJR

As far as the piston replacement...check the compression. If it is good It is fine. I have a 99 and it runs strong. This is the XR of the hi perf bikes. Very durable internal motor parts. KJR

I put the GYTR insert in mine and it is great. No jetting issues and gives it a bit more response. The good thing if you need to quiet it up then pop the GYTR out and put the stock in. 2 min job. KJR

I see no reason why you cant just run the gytr unit 100%, mine is quieter than a stock 150R.......

Took it out for a real ride on Friday, its not a bad bike, although I found a few things that will need attention. The fork seals are leaking, the chain guard for the swing arm will need replacement, and a few other little stuff. The shock will need to be rebuilt as it will travel to a certain spot and then stick, something I didn't notice on the test ride. And it is leaking coolant out of the left radiator area, but only half of the time, again I didn't notice it on the test ride. I wish I had noticed all of this before I had gotten it, cause I would have held out for a 450 but oh well.

On the plus side, it starts up the first or second kick, and it has an over sized after market YZ tank and a YZ seat. I have no idea what brand or what gallon the tank is, but it does have to petcocks, one for each side. Once I get the bugs worked out I think it will be a decent bike. Anyway, heres a crappy pick of me on the bike, its nothing special-

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