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mch

2012+ WR450F tips for piston change

10 posts in this topic

I'm going to change the piston and timing chain this week and 1st time taking a cylinder and head off (did many two stroke top ends).  Do any of you have any tips to make the job easier?  I'm guessing the head will be sliding out to one of the sides, and not coming out straight up.  I figure that may kind of suck when trying to fish the cam chain up though the head.

 

I'm assuming I can do i with the radiators on (drained),

 

Do I have to remove the coil?

Does the fuel injection pop out of the boot like a carb going into the head?

 

And yes... I have a service manual, and will be looking at that as well.

 

Thanks

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Rough guess would be 350-400. Had it since 08/2012 and ride pretty much every weekend (both days) and holidays. Each ride is about 2 hours. I do oil changes in the 12-15 hour range and have checked the valves 4 times. Bike is still running fine, but cylinder just had that noise like piston may be sloppy. In thinking about sending the head off to be checked for any issues. Might be wise to replace valves, guides, etc.

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Rough guess would be 350-400. Had it since 08/2012 and ride pretty much every weekend (both days) and holidays. Each ride is about 2 hours. I do oil changes in the 12-15 hour range and have checked the valves 4 times. Bike is still running fine, but cylinder just had that noise like piston may be sloppy. In thinking about sending the head off to be checked for any issues. Might be wise to replace valves, guides, etc.

Be careful who you send your head to. Mostly I have seen people mess up a valve guide change. Usually not needed anyways. Maybe valves if you have reshimed it a couple of times.

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Be careful who you send your head to. Mostly I have seen people mess up a valve guide change. Usually not needed anyways. Maybe valves if you have reshimed it a couple of times.

Any tips on head work? I have shimmed 1 or two a couple of times over the 2 years since I bought it. Should I be taking out the valves and cleaning all carbon, etc, or just send it off? Seems like fast heads in St. George has a good reputation. I have the cams out and the head un-bolted, but haven't pulled the head out.

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You might just send in your head and have them cut the seats and put in all new valves. It seems yours wore a little quick if shimed twice. But I wouldn't be talked into different valve guides or seats. Stock is very long lasting.

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You might just send in your head and have them cut the seats and put in all new valves. It seems yours wore a little quick if shimed twice. But I wouldn't be talked into different valve guides or seats. Stock is very long lasting.

 

I probably should have made notes on which valves I had to shim a couple times.  I believe it was on the intake side and never one of the exhaust valves.  The head will probably be a pain to get it back in; I'll likely get someone to help me "navigate" it back on.  The cables, hoses, wires, etc. that run down the top right are kind of in the way.  I took the head up, then managed to wiggle out the throttle side of the frame.  I did end up unbolting the coil for a little bit more play.  I'll pull the flywheel and the cylinder tomorrow.  I will probably wait another 2 years to do this again, just kind of wondering if I should just stick the head back on, or go for new valves / get it serviced.  I'm guessing I will have 6-8 hours into this by the time is all said and done.  I can't imagine what a shop would charge; probably a small fortune (if they did it right).

 

IMG_20141208_203346.jpg

 

IMG_20141208_203456.jpg

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Shops charge a pretty penny. You are much better off doing it yourself.

 

You could take some contact cleaner and check for leakage of the valves. More than likely you could have gone four years on it all. But if you don't want to take any chances then you need to change stuff out.

 

People I know just run em. Except a road racer making boo koo HP he does the maintenance dance big time.

 

By the way I take the radiators off on my 07- 11 models. You can temporary zip tie wires and cables out of the way. You may find this much easier as you have done it once.

Edited by stevethe

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I just stuck the head back on after changing the timing chain and piston.  Went pretty smooth, other than not having the correct size flywheel puller (I figured it would be the same size as my YZ.. but I was wrong.  The WR needs a 33mm puller).  Another thing was the front timing chain guide has to be in the front channel of the cylinder before the head is placed on.  I was about to tighten down the head when I noticed the guide wasn't locked in.  I thought the only channel was down behind the flywheel, but it has to be in the cylinder slot too.  A second pair of hands getting the head on is also recommended. It was also nice not having to remove the radiators.

 

It's running now, just need to take it easy for a tank or so.

Edited by mch
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