Head Work - Valve Seats

Hello All,

Valuable LESSON LEARNED. Do not trust an automobile machine shop with your motorcycle head!

With my original head I asked for them to lightly "touch" the valve seats to give them a clean edge. I explained (to deaf ears) how it was a shim/bucket design and that there wasn't much room to remove. Well, they ground them down so low that I could no longer shim the valves to fit. Even after buying the smallest shims I could find and then valve tipping and modifying/ruining NEW valves to try and make it work. Only option for this head now is to pay $800 to have a motorcycle shop install new valve seats.

Second experience: the SAME! I took this ebay head to a different shop who assured me that they are not "idiots" and would never do that type of work. Well, after dropping my newly received and cleaned Ebay head to have the valve seats LIGHTLY TOUCHED, he did the exact same thing. I first banged my head against the wall, then cried, then exploded . . . he didn't really care

Third experience: I bought a Craigslist parts bike for $400 and simply lapped the valve seats myself. Not perfect, but GOOD ENOUGH and she runs well with 150psi all around. Lesson: DO NOT TRUST your local machine shop with a motorcycle head! Lesson learned.

BTW, I have 2 extra heads that need new valve seats if anyone is interested.

That sucks man. I don't trust most shops to do that sort of work. Better to pony up and send the head to APE or similar quality shop. Or, get some Neway cutters and do the work yourself! That's what I did anyway. I did trust a shop to clean up the valves using a centerless grinder. Hard to mess up with one of those.

P1020063 by nessism , on Flickr

P1020104 by nessism , on Flickr

Yes this sucks. A waste of money and a lesson learned twice.
I bought a set of Neway cutters 20 years ago and do all head work by my self.

I want some.:ohmy:
Steve

Valve seat cutters or patches?

Got the patches thanks.
Steve

New valve seats aren't necessary, it's not uncommon to have the valves tipped, meaning to have the stem ground back to a set height. APE sells a gauge to measure the stem heights so you can adjust them to tune with standard shims.

Les Holt

Jay from APE wrote in an older thread that when the valves are really sunk, and the valve stems trimmed somewhat drastically to get the valve back to the proper height, then it may also be necessary to grind the valve keepers otherwise they will stick up above the valve stem after the spring is installed. He said that Police bikes sometimes get this sort of work done to get more life out of the parts.

Yeah, I forgot to add the part about checking the keepers! I've only had 1 head that I had to do that too!
Scirocco, I have been using Neways for years and they do a good job, I found using a cordless drill on low gave me better results that the T-handle. You're able to keep constant pressure and you can control the speed well.

Les

I do the hand job with the T-handle, because only 2-3 turns max. are needed to get a smooth
seat surface and to correct the angles for the seat. The Tungsten carbide blades are very sharp and bite
easily into surface. I grid no more as necessary for a later valve job.

EDIT: I am searching for an Gizmatic 3 valve tool. It has a 2 sided valve cutter with 45 & 30 degree fixed angles.

here are some keepers and retainers i had to cut down on a j-model head.

leon

I have a zr550 head that had exhaust seats so pitted that they needed recut. So I took it to the local independent motorcycle shop (support local businesses and all) and he used a Nu-Way hand cutter to do them. And he cut them so off center that when I lapped the valves and did a gasoline leak test, none of the combustion chambers could hold gas for 30 seconds. The gas literally poured out of the valves in seconds.
So I took it to a automotive shop and he recut the seats on a Serdi (really deep to get past the off center portion) and then after careful measuring, I had him tip the valves and cut down the valve retainers. Not one issue since.