Adjusting valves clearance

10/1/2019 2:38pm
Hi guys,
I own a 2011 Suzuki RMZ 250 which I recently bought. It is virtually impossible to start by kicking it and it is very hard to start by kick when the engine is hot. If I push it down the hill, no problem starting. That’s why I decided to check the valves and adjust the clearance. One of the intake valves measured at 0 mm clearance. The shim that was in there was 1.30 mm and I put a 1.20 mm one. However I am still measuring 0 mm clearance. What do you guys think it is going on? 1.20 mm is the smallest shim in the kit I got. Does this mean that the valve is bad and needs to be replaced or even something worst is going on?

Thank you!
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Paw Paw 271
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10/1/2019 3:57pm Edited Date/Time 10/1/2019 3:59pm
The valve has beaten the valve seat to the point where the valve has recessed into the seat. It is time for a complete valve job including...
new valves, new seats, new springs, new valve seals, new retainers and new clips.
I would further suggest replacing the cam chain with new as well as the piston and rings.

Paw Paw
2
10/1/2019 4:20pm
Thank you for the reply Paw Paw!
A complete valve job would mean all four valves regardless of the condition of the rest, correct?
Also what brand parts do you recommend or should I go with OEM?

Thanks again!
Paw Paw 271
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10/1/2019 7:18pm
In your case I would suggest OEM. You can go with aftermarket stainless valves, but you will loose a small amount of performance for the added life of the valves.
When you do a valve job, it is best to do them all at one time. Be sure that the person doing the job knows his stuff for a good job.

Paw Paw
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The Shop

Paul_Pitzonka
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10/2/2019 5:31am
If you’re good with a small air pencil grinder and you want some free power blend the bottom of the seats into the ports most have a terrible step in them from the factory... Some machine shops will do this when they install new seats some won’t...
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Lasse
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Fantasy
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10/3/2019 11:10pm
I had the exact same thing happen to me. I had two worn intakevalves.
1
10/4/2019 3:54am
Thanks again for the help so far guys! Another question - is the seats replacement required when replacing valves or is it optional depending on the condition of the existing? After watching some online videos on valves replacement I feel comfortable doing it myself but when it comes to seats replacement or even reconditioning I don’t think it is something I can tackle Smile
Paul_Pitzonka
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10/4/2019 4:35am
Thanks again for the help so far guys! Another question - is the seats replacement required when replacing valves or is it optional depending on the...
Thanks again for the help so far guys! Another question - is the seats replacement required when replacing valves or is it optional depending on the condition of the existing? After watching some online videos on valves replacement I feel comfortable doing it myself but when it comes to seats replacement or even reconditioning I don’t think it is something I can tackle Smile
You can have them re cut as well it all depends on then condition of the seats...
kb228
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10/4/2019 4:40am
If youre at 0 clearance with a 1.2mm shim your seats are too worn and need cut out and replaced. The more your seat wears the shorter the distance gets between the bottom of the valve and the cam. When that distance gets shorter so does your shim.

Typically you want a shop to do this because theres special machinery required to do a good job.
1
10/4/2019 4:49am
Sounds like I should remove the head and take it to somebody who has the tools and experience to replace the valves, seats and whatever else needs to be replaced.
Thanks again guys. This was very helpful.
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Paul_Pitzonka
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10/4/2019 5:10am
kb228 wrote:
If youre at 0 clearance with a 1.2mm shim your seats are too worn and need cut out and replaced. The more your seat wears the...
If youre at 0 clearance with a 1.2mm shim your seats are too worn and need cut out and replaced. The more your seat wears the shorter the distance gets between the bottom of the valve and the cam. When that distance gets shorter so does your shim.

Typically you want a shop to do this because theres special machinery required to do a good job.
This isn’t always the case... the valve normally takes majority of the damage mainly due to the fact that the valve loses ability of to cool/ transfer heat as the contact area between it and the seat becomes wider... Most seats can be re-cut and you still end up with a correct valve set height... just because he’s at 0 lash you can’t assume his seats are gone and no longer serviceable...
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kb228
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10/4/2019 5:18am
kb228 wrote:
If youre at 0 clearance with a 1.2mm shim your seats are too worn and need cut out and replaced. The more your seat wears the...
If youre at 0 clearance with a 1.2mm shim your seats are too worn and need cut out and replaced. The more your seat wears the shorter the distance gets between the bottom of the valve and the cam. When that distance gets shorter so does your shim.

Typically you want a shop to do this because theres special machinery required to do a good job.
This isn’t always the case... the valve normally takes majority of the damage mainly due to the fact that the valve loses ability of to cool/...
This isn’t always the case... the valve normally takes majority of the damage mainly due to the fact that the valve loses ability of to cool/ transfer heat as the contact area between it and the seat becomes wider... Most seats can be re-cut and you still end up with a correct valve set height... just because he’s at 0 lash you can’t assume his seats are gone and no longer serviceable...
Anything is an assumption without having the parts in my hand.

Even if his valve is trashed, the seat is probably in a similar condition. The seat at minimum needs recut and valves need replaced. If youre at the point where the margin is gone and its mushroomed over you might as well do it all up right. The cost of new seats is likely the same as buying the seat cutter and guide.
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harescrambled
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10/4/2019 9:11am
kb228 wrote:
Anything is an assumption without having the parts in my hand. Even if his valve is trashed, the seat is probably in a similar condition. The...
Anything is an assumption without having the parts in my hand.

Even if his valve is trashed, the seat is probably in a similar condition. The seat at minimum needs recut and valves need replaced. If youre at the point where the margin is gone and its mushroomed over you might as well do it all up right. The cost of new seats is likely the same as buying the seat cutter and guide.
The only way to tell for certain is to get obtain new valves and test fit them to check the installed height vs factory spec. That'll tell you whether you need new seats, or if they can be recut. I have the cutter kit, knowledge, and experience to do this job if the OP wants to get in touch
Keith72
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10/7/2019 10:25am
Check out fastheads.com
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