Kz1000 new exhaust valve lapping

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Kz1000 new exhaust valve lapping

09 Mar 2015 17:51
#663908
I am fitting new exhaust valves to my KZ1000 head aft I managed to bend some of them through a piss poor shim changing exercise. A couple of questions about fitting new exhaust valves to my KZ1000 head. First, do I measure the valve stem height with the valve spring seat removed?

second (I think I know this one) should I lap in the new valves even though I have already lapped them in with the old valves before I bent them?

Thanks
'72 Z1

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  • SWest
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Re: Kz1000 new exhaust valve lapping

09 Mar 2015 20:18
#663923
What makes you think you need to measure the stem height? Lapping can remove seat area thus making the seat too wide. I'd use fine lapping compound just to see how wide the seat is on the valve, then act accordingly.
Steve

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  • Yorkie
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Re: Kz1000 new exhaust valve lapping

09 Mar 2015 20:54
#663934
Thanks for the reply. I had read that the valves are typically a little too long and if the stem height is greater than 38.06mm then even the thinnest shims can still not create enough clearance. I might have misunderstood what I read so I'm keen to learn. Your point about using some light compound to check the seal band makes sense. Thanks
'72 Z1

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Re: Kz1000 new exhaust valve lapping

09 Mar 2015 21:59
#663942
I put in new valves, springs and seals. When I lapped them in, I could tell it was good. If not, I would have had to have the seats redone and valves "tipped.
Steve

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Re: Kz1000 new exhaust valve lapping

09 Mar 2015 22:01
#663943
You might put the head together on the bench and check out if the adjustments are still within range.
Steve

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  • zed1015
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Re: Kz1000 new exhaust valve lapping

10 Mar 2015 10:31 - 10 Mar 2015 10:32
#663976
The installed height is measured without the spring seat .
Ideally you need the proper height tool to measure with as results with a vernier can be inconsistent.
You can buy the tool from APE or make your own if you have a lathe.
37.17mm is the minimum height if this is for the early Z900/1000 kicker motor and you want to be closer to that figure if possible for maximum shims sizes and plenty of future adjustment.
If you are using those pattern (non stainless) Doremi valves etc they are usually longer than OEM valves above the collet groove and need tipping to get anywhere near the correct height before you even start.
You need to get the valves seating correctly before tackling the heights.
A very light lapping of the new valves should be all that is needed .
AIR CORRECTOR JETS FOR VM CARBS AND ETHANOL RESISTANT VITON CHOKE PLUNGER SEAL REPLACMENT FOR ALL CLASSIC AND MODERN MOTORCYCLE CARBURETTORS
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Last edit: 10 Mar 2015 10:32 by zed1015.
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Re: Kz1000 new exhaust valve lapping

10 Mar 2015 11:27
#663983
My Doremi valves were the same as stock but I should have had them "tipped. I will when I install my Wiseco pistons but they work for now.
Steve

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Re: Kz1000 new exhaust valve lapping

10 Mar 2015 11:38
#663984
I put in new Kibblewhite stainless stock replacement valves in and they had to be clipped......they did appear longer than original kawi stems above the keeper grooves
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Re: Kz1000 new exhaust valve lapping

10 Mar 2015 11:51
#663986
Some valves are sold as blanks. They have to be ground and fitted. The Doremi were supposed to be "drop in". They were cheap by comparison and if I go bigger bore, I'll have to get larger ones and have a shop do the work.
Steve

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Re: Kz1000 new exhaust valve lapping

11 Mar 2015 13:22
#664109
Measured the complete length of my new valves (Marshall is the brand supplied by Z1 enterprises) and they are virtually identical to the ones I took out so I think these are "Drop-Ins" Thanks for all your help.
'72 Z1

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