To Lap? Or To Grind? That is the Question.


5 replies to this topic
  • Markopolo400

Posted April 18, 2007 - 04:19 PM

#1

Well, I am putting new valves in my 1999 yz400f (Steel Valves BTW), and I am wondering if I should have a local machine shop grind the valve seats, and then lap them?

Or if I should not have them grind the seats, but only lap them.

Thanks.

  • grayracer513

Posted April 18, 2007 - 04:29 PM

#2

With steel valves, you have the option of lapping or not lapping when fitting new, or grinding old valves.

(Excuse me a second)NEVER under ANY circumstances lap a Titanium valve! Ever.

OK, I'm back. If the machinist does a good job with regrinding the seats, there is really no need to lap the valves. If it's done right, there's no harm in it, either, but there is little or no benefit. It is a useful process in cases where the valves are seeping a little during a solvent test, and are not bad enough to need a full regrind, but too flaky to use.

  • Markopolo400

Posted April 18, 2007 - 04:52 PM

#3

(Excuse me a second)NEVER under ANY circumstances lap a Titanium valve! Ever.


Yup, I know that much...LOL

OK, I'm back. If the machinist does a good job with regrinding the seats, there is really no need to lap the valves. If it's done right, there's no harm in it, either, but there is little or no benefit. It is a useful process in cases where the valves are seeping a little during a solvent test, and are not bad enough to need a full regrind, but too flaky to use.


My valves actually weren't leaking at all with the solvent test. I sprayed brake cleaner in, and it actually presently surprised me. :thumbsup:

So should I just lap them?

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  • ThumperKid250F

Posted April 18, 2007 - 06:36 PM

#4

Yup, I know that much...LOL



My valves actually weren't leaking at all with the solvent test. I sprayed brake cleaner in, and it actually presently surprised me. :thumbsup:

So should I just lap them?




um for what i no brake cleaner drys up fast, use alcohol ( and no not the kind your drink)

  • grayracer513

Posted April 18, 2007 - 06:48 PM

#5

So should I just lap them?

That's what I would do if it were mine.

  • Markopolo400

Posted April 19, 2007 - 12:38 PM

#6

um for what i no brake cleaner drys up fast, use alcohol ( and no not the kind your drink)


If you spray enough in there, it makes a pool, and doesn't dry super fast like normal.

BTW, thanks Gray.





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