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No clearance on one intake valve

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I recently bought a 05 wr450. I always go over everything before trusting a bike out on long runs. Upon checking valve clearances one intake valve has little or no clearance. It already has the thinnest shim available. So I pull the head it is seated and sealed. Why would it have such little clearance if any and what will that effect. Bike seemed to run okay otherwise but only did short test drive going thru the gears and listening.

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Centre valve?

Dirt being sucked in either thru the filter or bypassing it

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Thinnest shim and next to no clearance means it is time to have the valves done on the bike. The PO probably knew it and hence selling the bike instead of dropping $400 to $600 into it as regular maintenance. When you send the head, send the cam caps, buckets, cams so the builder can shim it to spec. Sometimes they need to cut the valve stems due to having to cut the seats.

Did you actually measure the shim to confirm the thickness was as indicated? I ask because there are some that will 'sand down' a shim to get it to work instead of doing it right.

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So I pulled the head all looked good no leak down no dirt. Guess its got to be sent in. Damn I was looking forward to riding it this weekend too.

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2 hours ago, GuyGraham said:

Centre valve?

Dirt being sucked in either thru the filter or bypassing it

No dirt suprisingly clean 

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1 hour ago, Frank Mcquillan said:

Ok should I take this complete head to dealer or do you guys know someone better more trusted

DO NOT TAKE TO THE DEALER!......unless you personally know the mechanics ability. They will try and lap the seats, which is no bueno.

 

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14 minutes ago, THE KRAN said:

DO NOT TAKE TO THE DEALER!......unless you personally know the mechanics ability. They will try and lap the seats, which is no bueno.

 

I m starting to believe these valves were lapped, resulting in the loss of clearance. Now what grind a fraction from the stem????

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17 minutes ago, THE KRAN said:

DO NOT TAKE TO THE DEALER!......unless you personally know the mechanics ability. They will try and lap the seats, which is no bueno.

 

I m starting to believe these valves were lapped, resulting in the loss of clearance. Now what grind a fraction from the stem????

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If valves were lapped then the coating which protects them has been removed and they are scrap so grinding the top of the stem wont work

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Send the head to a reputable rebuilder like APE, FastHeads or BigBoreThumpers.

I'd pull the barrel too, check the plating and put in fresh rings and a new cam chain along with a new tensioner.

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3 hours ago, William1 said:

Send the head to a reputable rebuilder like APE, FastHeads or BigBoreThumpers.

I'd pull the barrel too, check the plating and put in fresh rings and a new cam chain along with a new tensioner.

^^^ Do that and be happy ^^

If you let the rings go, you will get blow by and oil will start getting everywhere you don't want it.

' ask me how I know this....'

 

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On 1/31/2018 at 3:23 PM, GuyGraham said:

If valves were lapped then the coating which protects them has been removed and they are scrap so grinding the top of the stem wont work

 

Yamaha seems to think it is OK...     

from the WR450 service manual:

valve.jpg

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1 hour ago, DeepPurplishBlue said:

 

Yamaha seems to think it is OK...     

from the WR450 service manual:

valve.jpg

This has been in their manuals for years!   It does work!   When dealing with minor imperfections with the seat.

But what is not said clearly, it is using a sacrificial valve.

You never lap a titanium valve!

 

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1 hour ago, motorock said:

This has been in their manuals for years!   It does work!   When dealing with minor imperfections with the seat.

But what is not said clearly, it is using a sacrificial valve.

You never lap a titanium valve!

 

 

It actually isn't said at all... 

in fact, they do clearly state that you will be lapping the valve face in addition to the valve seat

normally lapping is done to mate the valve to the seat, removing minor imperfections with BOTH that would prevent perfect sealing and is ALWAYS done with the valve that is supposed to be in that location.   It is pretty much pointless to do it with a valve that will not be used on that seat.

 

having said that, conventional wisdom is do not lap titanium valves, but the point is Yamaha themselves makes no mention of that

 

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That being the case I choose to purchase a head off ebay complete with valves and cams also already set to within specs. I will confirm the specs once it arrives but no reason to doubt the guy with over 10000 feedback and no negatives.

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On 1/31/2018 at 0:17 PM, Frank Mcquillan said:

Ok should I take this complete head to dealer or do you guys know someone better more trusted

Mxtime does good work

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On 2/3/2018 at 8:26 PM, Frank Mcquillan said:

That being the case I choose to purchase a head off ebay complete with valves and cams also already set to within specs. I will confirm the specs once it arrives but no reason to doubt the guy with over 10000 feedback and no negatives.

:facepalm:

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Why is it so hard to understand that the Titanium valves are worn out and need replacement. The valve seats on the head need to be ground straight.

Engine repair 101. now you have two cylinder heads that need exactly the same work.

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