Timing/Cam Chain WR 400 replacement

Can anyone tell me how hard this procedure is and what needs to come apart to accomplish it. I did read all the threads I could find. Would I need to pull the fly wheel off, the head off ect. ?? The bike is a 99 with about 6 races on it, should I even change it?

Thanks everyone.

6 races - so you're saying 1.5 to 2 hours actual motor time on a 99???

Don't bother until you're at 50 maybe more...

If you need to know though:

yes to the flywheel, remove valve cover and you'll have to remove cams - mark the chain/gears on both cams AND at the crank, transfer marks to new chain - install new chain crank first lining up mark - when putting in cams hook under new chain while pointing both down and inwards - line up your marks and tilt/move/roll them into the seats simultaneously and all should be good. Tighten in star pattern NO MORE than specified torque.

Check your clearance while you've got the lid off

Hare scrambles and a couple enduros. But it also has regular weekend time. I bought used so I can't be sure on total hours. I am a little confused about marking the chain/gears. I can see marking the cams but why would you mark the old chain?


Well, let's see - if you mark the old chain along with the gears (I do a double Line on one cam gear/chain spot as my reference), you can transfer the marks to the new chain (counting the links in between) then you can be 100% certain your cams are set exactly as they were once assembled - most of the guys on here who ask about doing any cam work come back asking if there's a sure fire way that they can verify that their cams and everything are set right - I just wanted to save you having to even think about it - worked for my rebuild, thought I'd pass it along. It's easy to install something one tooth off without noticing because the crank may have turned a slight bit etc.

Oh, and it also helps because when you point the cam gears down/inwards to install them, it's really hard to figure out which cam gear will end up where, it's easier to see when you have a line on each whether they will meet up or not before they are lifted/rotated in place.

Yes its true if thats all the time on the bike its just broken in many say they have 11000 miles on theres but they maintain the bike religiously. Unless the races were paris to dakar then we might have an issue then. They are well built bikes and not too fragile unless just plain abused and neglected

I put my hot cams in the bike. I just here horror stories. I guess I will just give it a good visual inspection before I change it. Thanks for your helpful reply!

Just so you know, visually - it will most likely look perfect, the only way to tell for sure is to measure the stretch which is pretty hard to do unless you remove it because of the little chain available in the head, mine looked perfect until I layed it side by side with the new one and noticed the stretch.

You can tell a lot more from your valve clearances - check the clearance, if it's on the tight side, remove the cams to see your shim size, ~184's are usually factory - if your bike has smaller values then they have been adjusted at least once before, at which point I would guess that a piston, rings, bore inspection/overhaul and valves/chain wouldn't be a bad idea in order to save yourself the possibility of a much more costly repair in the near future.

If a valve drops, you have to do the whole engine top to bottom (possibly even a new head - rework at a minimum)- I wouldn't even hesitate on that - the force of the hit has to go somewhere - usually the bottom end.

hotcams really don't make the job any more/less difficult. honestly - it's all pretty simple, as long as you follow the manual all will be good.

Anyone have a link to a manual cam chain tensioner for sale. Thuper dose not have one for a WR 400. and I Googled but can't find one.


Anyone have a link to a manual cam chain tensioner for sale. Thuper dose not have one for a WR 400. and I Googled but can't find one.


They don't sell them because you don't need one.

The camchain will last as long as a piston and rings.

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