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  #1  
Old 21-02-2018
Brooza77 Brooza77 is offline
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Should I shim all my Valves

Hey guys,

Did another valve clearance check on my 2012 WR450F after now about 3,500km. The exhaust valves are right in the middle of the spec and .23

The intakes, No 1 (closest to cam gear) is nearly at the min at .11 the other 2 are at .13. I' thinking now that most of it is in bits anyway may as well shim the worst one at least. Should I just shim all 3 intake back to .15.? should I do the exhaust valves back up to .25 or leave for now.?

Its getting harder to start when its hot (cranks for a lot longer now) and doesn't seem to have the power it used too either.

Thanks.
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  #2  
Old 21-02-2018
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Arctra Arctra is offline
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Whilst you're in there with the cam cover off you may as well correct all of the clearances to get them in the middle of the recommended range. It'll mean you won't need to go in there again anytime soon. You might find you'll be able to swap shims around between the valves and only end up needing to buy 1 or 2 anyway.

Just my 2c
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Old 21-02-2018
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Quote:
Originally Posted by Brooza77 View Post
Hey guys,

Did another valve clearance check on my 2012 WR450F after now about 3,500km. The exhaust valves are right in the middle of the spec and .23

The intakes, No 1 (closest to cam gear) is nearly at the min at .11 the other 2 are at .13. I' thinking now that most of it is in bits anyway may as well shim the worst one at least. Should I just shim all 3 intake back to .15.? should I do the exhaust valves back up to .25 or leave for now.?

Its getting harder to start when its hot (cranks for a lot longer now) and doesn't seem to have the power it used too either.

Thanks.
That's not because of your valve clearances, they have clearance.
Do a leakdown.
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Old 21-02-2018
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Quote:
Originally Posted by Tom68 View Post
That's not because of your valve clearances, they have clearance.
Do a leakdown.
This! 👆
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Old 21-02-2018
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Worn rings you reckon Tom68?
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Old 22-02-2018
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Originally Posted by Pygmygod View Post
Worn rings you reckon Tom68?
Or leaking valves. How many times have they been shimmed?
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Old 22-02-2018
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I am admittedly a total gumby non-mechanic, but I do like to think of myself as pragmatic. What would performing a leak-down test achieve? It'll tell you whether you have sufficient compression, right? The logical next question once you determine that you don't have sufficient compression is what... pull the whole top-end off and do a total top-end rebuild that includes replacing piston rings and re-seating your new valves? Talk about having a bit of heartburn and deciding the best option it to have a total coronary bypass operation!

Adjusting your valve clearances is the easiest and cheapest first step to see if that is the cause of your problem and if it'll resolve the starting/running problem. Sure, it won't solve EVERY problem your engine has, but given it is a known and common source of compression problems in modern 4T engines, to the point where the OEM's recommend regular clearance checks, provide acceptable tolerance ranges, and provide a cheap and easy mechanism to correcting clearances to be within tolerance via the differing shim thickness options, why would you NOT try that first?

And as I said, whilst you have the cams off you may as well adjust all of teh valve clearances to be more-or-less in the middle of the manufacturer recommended range and record what those clearances are so that next time you do a check you can see how much the valve clearances have moved to know where your problem might be. On a balance of probabilities simply adjusting your clearances to be within spec will solve your problem.

But hell, by all means, do a compression test, then a leak down test, then get a new piston and rings, send the cylinder head off to have the valve seats reconditioned, replace the valves and the valve guides with new one, replace the valve springs too as they're probably knackered too, and whilst you have the bore off send it off to be resurfaced. And hell, if you've gone that far you may as well split the case, replace your big-end bearing, have your stator rewired to make sure the problem isn't actually that your battery isn't being charged properly. Then, get a new battery and a new starter motor coz the problem is with starting the bike, right? You probably need a new spart plug too, and whilst we're on the electrics you might have an intermittent electrical fault which can be nearly impossible to diagnose coz they aren't repeatable, so maybe replace the whole wiring harness, all the fuses, and just to be safe the ignition probably needs replacing too.

Obviously I'm being facetious and obnoxious with that last rant - just in case anyone thought I was being serious. But in all seriousness, your quickest an easiest solution is the path you've started down already by checking the valve clearances and identifying that at least one of them is out of spec. Occam's razor bro - it's a principle from philosophy. "Suppose there exists two explanations for an occurrence. In this case the simpler one is usually better. Another way of saying it is that the more assumptions you have to make, the more unlikely an explanation is.

Anyway, as I said, I am a gumby non-mechanic so you probably shouldn't listen to me.
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Old 22-02-2018
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Agree with the pragmatist ^^

Take the variables our first. Doing a hot leak-down on a WR450 is a PITA.

More so with 5V WRs but all Yammys are hard to start when hot, once the inlets get under 0.13mm(cold).

Shim it to spec first, by all means do a cold leak down at the same time. FFS, what 'special' person goes through all the grief of taking the hat off a WR and only does one valve?
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  #9  
Old 26-02-2018
Brooza77 Brooza77 is offline
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All shimmed back to .15 Its the first time its been shimmed.

Haven't started it again yet.

Thanks for all the responses.
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Old 26-02-2018
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isn't the exhaust bigger than 0.15?

Edit: just re-read your first post and you are already spot on for exhausts
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