Which Is Better, Cutting or Grinding?

  • Dr. Frankenstein
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Which Is Better, Cutting or Grinding?

28 Apr 2022 18:51
#866326
This '79 KZ400H I'm working on has some pretty fugly valve seats, so I'm considering two options - grinding or cutting the seats. I tried lapping them but I'm still getting fluid around the valves on one or two, and want to get a tight seal but I'm thinking I'll have to either cut or grind them. Grinders you have to talk financing for, while cutters are fairly affordable - anybody ever do any cutting by hand?
   

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  • Nessism
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Re: Which Is Better, Cutting or Grinding?

28 Apr 2022 18:54 - 28 Apr 2022 18:55
#866327
I use Neway cutters.  Photos and details in the rebuild thread in my signature.  Check starting page 4
Last edit: 28 Apr 2022 18:55 by Nessism.

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  • zed1015
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Re: Which Is Better, Cutting or Grinding?

28 Apr 2022 23:19 - 28 Apr 2022 23:19
#866335
Best to use Cutters,
Like Nessism i use Neway.
You need to remove the bare minimum to avoid cutting too deep and losing all your clearance .
Grinding is too aggressive whilst hand cutting is far more controllable.
You need to cut the 30 and 60 to leave a narrow seating area on the 45 or the reduced seat pressure can still allow seat leakage which is the usual problem with over lapping.


 
AIR CORRECTOR JETS FOR VM CARBS AND ETHANOL RESISTANT VITON CHOKE PLUNGER SEAL REPLACMENT FOR ALL CLASSIC AND MODERN MOTORCYCLE CARBURETTORS
www.kzrider.com/23-for-sale/611992-air-c...lide-mikunis?start=0





Last edit: 28 Apr 2022 23:19 by zed1015.
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Re: Which Is Better, Cutting or Grinding?

29 Apr 2022 05:14
#866352
Nessism, that's a great thread! Nice Build! Nice images of the seat cutting too. Yes, I know Neway is the best, but I don't have $1,300 for a Neway cutting kit. I'll probably explore having them done somewhere, but I'd kind of like to do it myself and learn a new skill. There's a bunch of affordable cutting kits on Ebay I'm considering, but right now I'm just trying to get her all apart to work on cleaning and general condition assessment.  

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Re: Which Is Better, Cutting or Grinding?

29 Apr 2022 06:49 - 29 Apr 2022 08:55
#866355
There's a bunch of affordable cutting kits on Ebay I'm considering, but right now I'm just trying to get her all apart to work on cleaning and general condition assessment.  
Don't touch any of those ebay seat cutters unless they are Neway or have tungsten carbide inserts.
Those kits you see with serrated cutters ( generally from india or for vintage bikes and cars with soft seats) are no good for the Hardened seats that are fitted to these engines.
They are intended for use on cast iron heads where the seat is just cut into the base metal.
AIR CORRECTOR JETS FOR VM CARBS AND ETHANOL RESISTANT VITON CHOKE PLUNGER SEAL REPLACMENT FOR ALL CLASSIC AND MODERN MOTORCYCLE CARBURETTORS
www.kzrider.com/23-for-sale/611992-air-c...lide-mikunis?start=0





Last edit: 29 Apr 2022 08:55 by zed1015.

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  • katit
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Re: Which Is Better, Cutting or Grinding?

29 Apr 2022 10:43
#866370
Nessism, that's a great thread! Nice Build! Nice images of the seat cutting too. Yes, I know Neway is the best, but I don't have $1,300 for a Neway cutting kit..  

You don't need a kit. Depending on what you do - you can get by with 2 cutters. I bought everything needed and still ahead comparing to what shop would charge.

kzrider.com/forum/11-projects/615161-kat...ect?start=120#850070
78 KZ650B2A - resto in progress
www.kzrider.com/forum/11-projects/615161...s-1978-kz650-project
Other bikes: 1978 BMW R100/7, 1978 Moto Guzzi T3, 2016 DRZ400s

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