V/V seat cutters

[Anonymous]

Has anyone cut thier own v/v seats with v/v seat cutters as I have the head off my 81 GS1000G and need to have them cut. A mate of mine (ex bike mechanic) took the v/v's to his friends workshop and ground the v/v's. I have started to lap them and have found that the exhaust seats need a cut to lift the sealing ring up on the v/v face.

Is it worth buying the cutters? How much are they? I was quoted approx AUS$400 or US$300 to cut those seats. Is this too much?

Forgot to mention, all the v/v measurements are within spec.

[mcycle-nut]

I think the seat cutters would be expensive. Unless you're going to be doing a lot of heads, it probably won't be worth it. That quote for cutting the seats sounds a little out of line, but then again I had mine done for practically nothing. One of those "it depends on who you know" scenarios. 8)

[duaneage]

It is not recommended that you lap the valves on these engines. It removes the hardness tretment and will cause failure.
As to the head, I would find another that is in better shape to start with. You can use the old head for parts. If you cut the seats and change valves you will most certainly need to reshim the valves and that will cost more money. Buy another head and the shims from the old one will be good spares.

my .02 that s all

[Anonymous]

WHY WOULD it be bad to lap the valve seats...you can do it to any engine....i did it to mine it doesnt take any material off it just shines it up and smoothens any burrs...i think that part about engile failure because of it is not true..mine isnt aluminum there anyway theres a steal insert or somthing wherre the valve seats........ :?

[duaneage]

Heat treating and hardening metal produces a hardness layer that is very thin. Remove this and you expose the valve to increased wear. I have seen this warning in manuals concerning suzuki valves, so there must be something to it.

The lack of lead in gasoline caused manufacturers to try a number of different mehods to protect the valves. Exhaust valves relied upon tetraetheylene (lead) additives to coat the exhaust valves and seal and cool the seats. Leaded gasoline produced beautiful white ports in tuned engines (haven't seen a head with white ports in 20 years ... sigh). When lead was reduced and withdrawn manufacturers went to hardened or stainless steel valves and seats. The different methods of hardening include heat treating and induction hardening. This only tempers the surface of the face ( I think it is somewhere between 40 and 60 rockwell) not the entire valve. I converted the heads for my old 63 fairlane to unleaded fuel after I lost the first set of exhaust valves to no-lead gas.

New valves on these bikes need to have the clearances on the followers checked after 600 miles. It is at this point the valves are seated and compresson is up.

[Anonymous]

so ur saying now that i did that my engine is done for...theres no way it will be fine after cleanin on the seats a bit...it barly removes anything tho..plus is an older engine i just dont understand why only this engine cant have the valves lapped i use premium fuel does it matter? I just dont under stand my valves are hardened steal im sure of it they cling when touched together i just thaught it would be fine..so they dont use leaded gas anymore? whats the differencwe between bronze and premium gas?

[Anonymous]

So if somthing does happen what will it be..do i have to go and buy newer valves or somthing.. now i feel like the engine is junk and i dont trust riding it now that i found out about that

[Pete Logan]

Only my opinion, and not Suzuki specific, but I would not have thought lapping would be a problem, assuming we're reading off the same page and talking about polishing up with paste and a hand tool.

Recutting, on the other hand, would be a problem as it would likely destroy the hardened layer required to run unleaded fuel without burning out the valve seats.

A common procedure with auto engines is to do the cut, and then press in hardened inserts and cut them to the correct profile, but I don't know whether this would work with the hotter motorcycle engines, and it may well be more expensive than a good second hand head anyway.

Pete

[Anonymous]

According to the GS1000 service manual I have, it has a procedure for v/v seat servicing which reads as follows:

The valve seats for both intake and exhaust valves are angled to present three bevels, 15, 45 and 75 degrees. To reface the seat, proceed as follows;

1. Using the 45 deg cutter, descale and cleanup the seat with one or two turns.

2. Inspect the seat by the previous seat width measurement procedure. If the seat is pitted or burned, additional seat conditioning with the 45 deg cutter is required. If the contact area is too low, use the 75 deg cutter to raise and narrow the contact area. If the contact area is too high, use the 15 deg cutter to lower and narrow the contact area. After cutting the 75 and 15 deg angles, it is possible that the valve seat (45 deg) is too narrow. If so recut the seat to the correct width.

3. After the desired seat position and width is achieved, use the 45 deg cutter very lightly to clean up any burrd caused by the previous cutting operations. DO NOT use lapping compound after the final cut is made. The finished valve seat should have a velvety smooth finish and not a highly polished or shiny finish. This will provide a soft surface for the final seating of the valve which will occur during the first few seconds of engine operation.


So as you can see there was no mention of hardening processes or destroying the hard surface by cutting the seats. As for lapping you don't lap after making the final cut to the seat.

Hope this helps

Brad.

[bucketsofgs1000]

If the seat inserts are in fact stainless steel, lapping them could actually work harden them, increasing the hardness of the seat. Also, I suspect if the seats are hardenened they are not simply surface hardened, but probably quenched so the entire seat insert will be hardened, not just the surface. But, like I said, lapping may add some surface hardening due to the work hardening nature of stainless steel.

[Anonymous]

In my Cylmers manual it says u can actually cut the valve seat in the head with three differerent degree cutters , therefore that would obviously remove that protectant layer before laping so i went ahead...also i figured the valves were hardened and i figured it wouldnt hurt...all it did was make a shiny line nice and even where the valve seats...its like toothpaste im sure all it does is polish...cuz how could a paste actually remove hardened steal...?

[Anonymous]

And the only word of caution is that your not supposed to grind the valves down at all like you would with the head they have to be replaced instead.....The words cutter and grind ....made me feel confident when i was polishing the valve seats and head seats...this was the end result the paste did this...........

[Anonymous]

I agree bboxer872002, the valves themselves can't be ground, as they are surface hardened, unfortunately I have already ground them before fully researching the procedures, so these valves will have to be replaced. As for the valve seats it is o.k. to cut and grind them. Lapping of the valves is o.k. if you have not cut the valve seats and the valve surface is not burnt or pitted. Lapping is mearly a cleanup operation to ensure you have a gas tight sealing ring.

[Addy Leung]

In the Suzuki manual, it said it can lap the valve seat with the valve, and it can also use the valve cutter to cut the valve seats at 30/45/70degree, major is 45 degree.
However, the valve cutter set mentioned in the Suzuki manual is about $500 to $600 dollar as checked with the local Suzuki dealer.
I think it may be very interesting to do the valve job by yourself but where can find good tools? Dose anyone have suggest?

[Addy Leung]

found a very good link about valve job and it show very detials.
Hope I can also do this.

http://home.hiwaay.net/~langford/corvair/valvejob.html