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lapping intake valves

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I have a CRF with low hours. I have adjusted the exhaust valves once, but the intake valves have been ajusted 3 times and are out of adjustment again. I ordered the Kibblewhite intake kit and new seals.

When I remove the head can I lapp the new stainless steel valves myself and install them or do the valve seats have to cut by a machine shop?

I have lapped new oem valves in the past for a old Suzuki thumper and not had any trouble.

Thanks.

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You need to have the valve seats cut or else the new valves will live a very short life.

Mxtime.com can cut your valve seats for about $50, unless you can find someone local who is familiar with CRF heads.

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I have lapped in a lot of the TRX valves in the CRF heads without issue. Dont know about the kibbles, I did lap a set into a YZF head and it is still running 3 years later.

just inspect the seats for sure. If you have any doubt, then for sure get the seats cut.

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You need to have the valve seats cut or else the new valves will live a very short life.

If the valves seal, why would it matter if they were cut or lapped. Why would they have a short life?

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If the valves seal, why would it matter if they were cut or lapped. Why would they have a short life?

i am sure he is refering to valves with a machine/tool coating on them. The lapping compound would definately shorten the life of that coating and thus the valve.

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Lapping would help insure a good seal. Cutting the seats would remove suspect inbedded abrasives in the seat. I don't know that lapping alone would do this.

It is recommended to use a sacrificial SS valve to lap then install a fresh valve.

This is cumulative information regarding the subject.

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If you already have run through a set of stock valves, lapping will not take care of the seats for new valves...be it Ti or SS. Get them cut now and enjoy for several more years !

Simple rule:

NEVER lap Ti valves, EVER :ride:

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If you lap them, blue the seats with Dykem and do the lapping. Then you can inspect the lapped area on the seat and see if it is good. If not, the defect will show up real well, then it is Serdi time.

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Make sure to check the valve guides. If they are worn out they will let the valve flop around. They will pass a seal test because the valves will be pulled tight to the seat but when running the valves will not land square to the seat. That will cause them to cup or wear out fast.

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Make sure to check the valve guides. If they are worn out they will let the valve flop around. They will pass a seal test because the valves will be pulled tight to the seat but when running the valves will not land square to the seat. That will cause them to cup or wear out fast.

Exactly :ride:

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Make sure to check the valve guides. If they are worn out they will let the valve flop around. They will pass a seal test because the valves will be pulled tight to the seat but when running the valves will not land square to the seat. That will cause them to cup or wear out fast.

holy crapola man!....havent seen ur name in a while:thumbsup:

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