Who cuts their own valve seats?

garagedog
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3/15/2022 9:38pm
I'm busy enough working on bikes to invest in a kit for cutting valve seats. Does anyone here have a suggestion? New way at $900 is a little high. What do you guys use?
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walent215
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3/16/2022 5:20am
I’m in the same boat but I have a great machinist that I constantly work with who does all my work at a great pricing schedule which makes it hard to justify or even want to do it myself .
Gary Duck
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3/16/2022 7:41am
If you're going to do it buy the Neway. The right tool for the job...
3/16/2022 8:12am
My professional/employment side is screaming no no no!! A simple hand tool that uses the valve guide to center the cutting tool is a terrible idea. You will never get the seat face concentric with the guide bore. Most likely you will do more harm than good. The end result of using such tooling will be poorly formed seats, out of round seating faces, and none concentric to guides. This combo will create excessive valve wear, guide wear, and worse case a dropped valve due to the bending moment at the grind bend.

To do a valve seat job correctly will require a Serdi type machine dedicated to cutting seats. And the end result will largely depend on the operater, correct setup, and care taken during the machining.

My farm and backyard mechanic side is saying... Sure people have done it this way before and it works right? Good enough for me.

Really it all depends on what you are trying to accomplish. If you are rebuilding XRs, lawn equipment, low speed engines then sure if it makes you feel good to cut the seats, go for it. If you are building hotrod 250f's I would strongly discourage you from trying to cut seats by yourself.

It all comes down to expectations. Don't expect a Neway cutter to give you the same results as a Serdi or a new OEM head, it won't happen.


btroxler
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Saltillo, MS US
3/16/2022 9:33am
I do. Look into the Goodson Tools 3D Fast cut system, this uses a pilot in the valve guide to center the cutting head. I use mine in my bridgeport mill. Basically setup is same as Serdi or Rottler just don't have the air float table that those machines use, so my setup takes longer but I also don't do heads every day. But this system provides a very concentric face and valve seal is extremely well.

Please stay away from the neway seat cutters, they maybe fine for a tiller or lawnmower but not for high performance engines.
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harescrambled
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3/17/2022 12:35pm
crawfishoo wrote:
My professional/employment side is screaming no no no!! A simple hand tool that uses the valve guide to center the cutting tool is a terrible idea...
My professional/employment side is screaming no no no!! A simple hand tool that uses the valve guide to center the cutting tool is a terrible idea. You will never get the seat face concentric with the guide bore. Most likely you will do more harm than good. The end result of using such tooling will be poorly formed seats, out of round seating faces, and none concentric to guides. This combo will create excessive valve wear, guide wear, and worse case a dropped valve due to the bending moment at the grind bend.

To do a valve seat job correctly will require a Serdi type machine dedicated to cutting seats. And the end result will largely depend on the operater, correct setup, and care taken during the machining.

My farm and backyard mechanic side is saying... Sure people have done it this way before and it works right? Good enough for me.

Really it all depends on what you are trying to accomplish. If you are rebuilding XRs, lawn equipment, low speed engines then sure if it makes you feel good to cut the seats, go for it. If you are building hotrod 250f's I would strongly discourage you from trying to cut seats by yourself.

It all comes down to expectations. Don't expect a Neway cutter to give you the same results as a Serdi or a new OEM head, it won't happen.


No it doesn't. I own a Neway kit, and been doing my own and a few for friends for years. Never had any problems. Just takes skill and some patience. Also when using the Neway tool, your guides do need to be in good shape. If they're too bad you will absolutely have problems using the hand tools.
kb228
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3/17/2022 2:34pm
crawfishoo wrote:
My professional/employment side is screaming no no no!! A simple hand tool that uses the valve guide to center the cutting tool is a terrible idea...
My professional/employment side is screaming no no no!! A simple hand tool that uses the valve guide to center the cutting tool is a terrible idea. You will never get the seat face concentric with the guide bore. Most likely you will do more harm than good. The end result of using such tooling will be poorly formed seats, out of round seating faces, and none concentric to guides. This combo will create excessive valve wear, guide wear, and worse case a dropped valve due to the bending moment at the grind bend.

To do a valve seat job correctly will require a Serdi type machine dedicated to cutting seats. And the end result will largely depend on the operater, correct setup, and care taken during the machining.

My farm and backyard mechanic side is saying... Sure people have done it this way before and it works right? Good enough for me.

Really it all depends on what you are trying to accomplish. If you are rebuilding XRs, lawn equipment, low speed engines then sure if it makes you feel good to cut the seats, go for it. If you are building hotrod 250f's I would strongly discourage you from trying to cut seats by yourself.

It all comes down to expectations. Don't expect a Neway cutter to give you the same results as a Serdi or a new OEM head, it won't happen.


A hand tool should have the same diametral tolerance as a valve. Any concentricity/positioning issues with the hand tool would transfer directly to the valve. As a matter of fact the kawasaki service manuals all have hand tools in it. Im sure the other OEMs to too. Going off feel, i bet theres .0005-.0008” clearance between the guide and valve. Shouldnt be an issue. If the tool and valve are slopping around in the guide then the mode of future failure is going to be a worn out guide that leads to a worn seat or bent valve
harescrambled
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3/17/2022 4:42pm
kb228 wrote:
A hand tool should have the same diametral tolerance as a valve. Any concentricity/positioning issues with the hand tool would transfer directly to the valve. As...
A hand tool should have the same diametral tolerance as a valve. Any concentricity/positioning issues with the hand tool would transfer directly to the valve. As a matter of fact the kawasaki service manuals all have hand tools in it. Im sure the other OEMs to too. Going off feel, i bet theres .0005-.0008” clearance between the guide and valve. Shouldnt be an issue. If the tool and valve are slopping around in the guide then the mode of future failure is going to be a worn out guide that leads to a worn seat or bent valve
The people talking about Serti machines or similar probably own one. It's only natural to protect your investment
3/19/2022 7:28am
I have done many, but mostly smaller bore engines like XR100/200/250s and such. The neway kits are high quality, but for a one time use, they can get very pricey. If you plan to do many, then like any investment, it may be worth it if you put the time in and learn to do a quality job. If someone wants to rebuild their 250F race bike, I send to my machinist.
Yeti831
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UT US
3/19/2022 4:44pm
Question: if you’re using a concentric bore guide and can also measure the depth of your cut, what’s the issue?
kb228
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3/22/2022 6:15am
Yeti831 wrote:
Question: if you’re using a concentric bore guide and can also measure the depth of your cut, what’s the issue?
There is none..
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