426 piston/rings

Ok so Ive had my 426 for a week or two and notice that it leaks oil from the breather hose and is a little lumpy at steady throttle. It still starts first kick and goes hard under full throttle, but the bike is going on 7 years old so I would expect that it would be near due for a rebuild considering the symptoms and I know that last owner didnt do any work to it. That said, I am dropping it off to my local guy to check the jetting (Im still a bit inexperienced), but if he finds that jetting won't cure it then Id say I will be looking at a piston and rings, hopefully no more.

Does anyone know roughly what I would pay for a new piston and rings?

Do a leak down check before tearing anything apart, that will give you a good clue as to how well the rings and valves are sealing.

Here is a chart for the YZ426 for jetting, I imagine it's pretty close for the WR as well and will get you in the ballpark so you can fine tune it.


Breather tube drips is NORMAL, sounds like Jetting - I think your bike is probably fine, compression test it, check your valve clearances and if those come out fine, ride it like you stole it - We all do.

righto cheers guys. As I said im a bit inexperienced with the mechanics of the bike since Ive only had it for a week or two so Ill drop if off to my mechanic and ask him to do a compression test and sort out the jetting and hopefully that will make a difference. From what I can tell there is plenty of compression at TDC. Also the altitude where I live is a couple of hundred metres higher than where I bought the bike so Id say it wants rejetting anyway.

thanks for the advice

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