250-500cc 2009 Wr300 Water Pump & Engine Rattle

Hi All, I have a 2009 WR300 with about 80 hours on it. The bike is in very good shape and has been well maintained. Two concerns before I dive into any repairs.

• My transmission fluid is milky, experience tells me that it is likely a water pump seals. Would it be wise to order a water shaft as well?? (Shipping times are likely to be slow in this new world of ours and i don't wish for a long down time)
• When accelerating at off idle speed and with light to medium load there is a light engine rattle (does not sound like a spark knock nor has higher octane fuel has no affect on eliminating the rattle). The exhaust springs are new, the pipe guard is tight. It sound like it may be coming from the power valve. It maybe the top end. Thoughts?
• Lastly the bike has now become very difficult to start when cold. (Same jetting, never was like that before). I have to prime the engine of fuel by lying the bike on its side several times before it will start. I'm thinking choke issue or intake boot/reed block leak. Bike runs well and has lots of power when warm. Thoughts?

Thanks for your time!

1 milky fluid? did you take the bike swimming? like lot's of water crossings? if not check the seal

2 that rattling noise is the power valve on mine too, also was on my Sherco same hours

3 take your carb off and flip it over, take your pilot jet out and see if there is a build up on it, a cheap trick, turn your air screw in 1 turn and try to start it cold
if that works, clean your carb

Also one thing to check is your breather fitting on the crankcase just below the carb ... they have a habit of popping off

I had that bike and at the start I also faced milky transmission oil, in my case it was not because of the seal, but because of that breather hole Chisler is showing, the fitment was very loose and I replaced it with a new plastic elbow, using a small amount of RTV. Another thing I did is to re-route that breather tube up into the airbox, as I did some water crossings where the engine is actually under water up to that breather hole...

The rubber seal on the power valve actuator arm on the left side of the engine is also a weak spot where water can get inside the casings, I also exchanged the rubber part with a new one and applied RTV on all the contact areas.. After that I did not get any more water in my oil.


Regarding the rattle noise, make sure all your engine mount bolts are tight, if they become loose you will have noise and lots of vibrations.

Starting issues can be carburation, air leak, or often bad intake reed petals, but with 80hrs on it I doubt that they are already shot..

Cheers !

Thanks for the responses! Choke jet was plugged, Pilot was too small at #35 and the carb jet block gasket was torn. Who is a good distributor of parts for the old Huskies in Canada?