Affordable Valve Job

[Don Williams]

I blew my head gasket on my 82 gs1100e. I checked out 3 bike shops in my area to do the valve job and that was in the $300-$400 range. I took my head to a local machine shop and this is what was done: combustion chambers bead blasted, all 16 valves resurfaced, springs checked, installed valve seals I supplied, surface and he honed and surface the block all for $200. I took the parts to my mechanic and he was happy. So why so much for a bike machinist?

[Billy Ricks]

How were the seats handled? That's the most important part of the job.

[Dink]

Why so much for a bike machinist?? Simple really they dissassemble it send it to a machinist, get it charged to them and then put a markup on it and charge you.
You however cut out the middle man.

Dink

[lecroy]

Why pay so much? Because you want a good seal....

http://www.serdi.com/cust/home.aspx

[txironhead]

There's a local machine shop that I called about machining the cylinders and head on my GS750E if it needed it. He said that he could do the 3-angle valve job, plane the head if needed, bore/hone the cylinders, deck/match everything and reassemble the head for about $375 cheaper than the dealership. Then he let me in on a little secret: The dealership sends all of their machine work to him! And they don't disassemble a damn thing, just take the head and cylinder off and send it to him dirty. They've even asked him if he could get oversize rings to fit the factory slugs just so they could save a few bucks and charge the customer for the new slugs. The only reason he still does work for them is he's the only local shop that will do bikes and people need their wheels.

[Big Jay]

You do not mention machining the valve seats. If they didn't do that, you didn't get a valve job.

To do sophisticated seat work requires very hi tech equipment. That cost money.

[first timer]

Hey resident Speed Merchant :-D

do you really need a fancy machine to do a valve job/recut the seats? One of my mechanic buddies has a hand set of valve seat tools, basically there are several router like bits you attach to a handle and guide, then you slide the guide into the valve guide and just turn. As you turn it, it recuts the seat nice and round for you. Change the bit to another one that has a different angle and repeat, lets you do a 3 maybe 5 angle valve job. What does a fancy computer operated tool do that you need, that this hand tool can't.

-ryan

[Big Jay]

When you do the seats with those multiple cutters like that, you have to do your 45, then top it with a 30 or so, then do a bottom cut to narrow up the 45 to the correct width, etc. Same as they used to do with stones. It is almost impossible to get all of the seats the same doing it like that, and get then concentric to the guide.

If you are careful, you can get it to seal up, if that is all you want. That takes a very long time to try and get then all close. That is one reason that those small shops that still use those things have to charge so much, because of the time.

With the "fancy machine" the seat shape, all angles, etc, are in the cutter. A sophisticated air float system centers precisely on the center of the guide, then the cutter comes down, machines the seat perfectly concentric, and every seat is exactly the same.

With todays high performance racing heads, pro stock, etc, you will find that there is a full radius below the 45 instead of angels. You can not do that with those hand cutters.

Had a guy bring us an 1150 head in that he was doing a valve job on with the hand cutters. He had the exhaust side done and it looked pretty good. Fairly consistent, etc. Best I had ever seen with hand cutters. I asked him how long it took, he said all afternoon. He was going to spend the next afternoon doing the intakes. I talked him out of that, took his head in the back, and while he had a cup of coffee, I did his intakes with full radius seats. Way nicer than his side. He was blown away.

Bottom line, if you just want to make it seal up, and have lots of free time, you can make the hand cutters work. If you want a performance valve job that will both seal and promote the best flow across the seats and all be the same..... no contest.

There is a reason all leading performance shops use these machines.

Jay

[rustybronco]

years and years ago we used to use one of the old kent tools? stone type seat refacers that you used to spin up with an electric hand held motor, the one you refaced the seat cutting stones with a diamond cutter, later years it was with a kwik? way carbide cutter, spun by a low rpm motor 150rpm? no reason a hand turned cutter and valve lapping compound would not be as good and if memory serves me i thought briggs & stratton seats were refaced using a hand turned cutter as a service tool.

[Don Williams]

I thought they only handle the seats if you are getting a performance or so called competion valve job. The machinist wanted to port for $250.

[txironhead]

A three angle valve job is mandatory when you're rebuilding the heads. It lets the valves seat better, the head flows better, and the head will last longer. I'd rather have a three angle valve job than just having the heads ported, because what good is better flow if the valves are leaking?

[madjack57754]

I agree with Jay, but only to a certain point. Seal is everything when it comes to your valves. The better the seal the more efficient the engine. Where I disagree is about the hand cutters. I've used the Nuway hand cutters for years. They are great for touch up work on the seats. Where most people get into trouble is they think the job is finished after using the cutters. Lap, lap, and lap some more. You can not get enough seal when it comes to your valves. You also need to pay attention to the condition of your valve guides. No mater how good of a valve job, if the guides are junk so is your seal.
I recognize the need for the "fancy" equipment, and last year, I bought an old Quikway head machine off Ebay (for) 700 bucks, I'm just now learning how to cut out old seats and install new ones. Very precise work. Actually a nice machine for the money, as it was hardly used. If I did this kind of work for a living, I would have something a little more modern, But hey, it's just for my toy build shop

[rosco15]

I thought the same thing about the cost. I found a local machine shop that builds race engines for cars. We got him to buy the cutters neede for the bikes and we turned a bunch of the local guys on to him. There is a local guy going all motor 8.20's. There is also two other guys running in the eights as well with his work. One is 8.50's and the other 8.80's. Oh and he doesn't do a three angle valve job. He puts a radius on it. It seems to work well. Seals good and makes good power. The only down side is once he found out what the bike shops charge he raised his price. I still save on shipping at least. I have him bore out my blocks as well.

[madjack57754]

Thought you would like to see what a cheap head machine looks like. Thats a small block chevy head that I'm putting guides in on the air table

[Big Jay]

I thought the same thing about the cost. I found a local machine shop that builds race engines for cars. We got him to buy the cutters neede for the bikes and we turned a bunch of the local guys on to him. There is a local guy going all motor 8.20's. There is also two other guys running in the eights as well with his work. One is 8.50's and the other 8.80's. Oh and he doesn't do a three angle valve job. He puts a radius on it. It seems to work well. Seals good and makes good power. The only down side is once he found out what the bike shops charge he raised his price. I still save on shipping at least. I have him bore out my blocks as well.

Yes, all the perforemance shops are getting away from the multi angle seats and going to radius seats.

Jay