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What do you think of this valve job?
- chikosneff
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I am attaching images for each valve and seat let me know what you think!
Thank you.
1978 KZ400 B
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- JOE MKII
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Did you see if they leak by using a bit of gas down the ports and looking closely fir seeping?
I think there’s a spec’ed width for the contact area , did you measure the contact patch?
I’ll be watching to see what the experts say!
I believe its called "Oppositional Defiance Disorder"
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- Nessism
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- SWest
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- 10 22 2014
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Steve
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- chikosneff
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The intake valves seats are slightly out of spec at 1.08 - 1.15 mm, service limit is 1 mm.Nessism wrote: As long as the seat width isn't out of spec and you didn't wear a groove in the valve it should be fine. Personally, I like to find a local machine shop use a centerless grinder on the valves to renew them. It only costs about $4 each so it's worth it.
I did not know that resurfacing at a shop would be that cheap thanks for the info, but I really enjoy the satisfaction of doing everything by myself so I'd take my chances and test them out.
1978 KZ400 B
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- chikosneff
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They match the seat perfectly, but they look wider because in the picture you can see that the new freshly lapped seat is slightly offset from the old one making it look wider. I can't feel any slack between the valve stem and the guide but I don't have a bore gauge to measure it accurately, valve stems are in spec and look pristine.SWest wrote: How much rock is there in the guides using the valves? Looks to me the seat print on the valves are wider than the seats in the head. The ones on the head look good.
Steve
My only concern is that I can see rings cut on the valve surface by the lapping compound, these are not grooves as you cannot feel them with your fingernail but ideally, I know I would like this surface to be completely smooth and dull, right? I am using fine compound, I wonder if I should look for a finer one.
1978 KZ400 B
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- SWest
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- 10 22 2014
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Steve
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- missionkz
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Bruce
1977 KZ1000A1
2016 Triumph T120 Bonneville
Far North East Metro Denver Colorado
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- chikosneff
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got it thank you!. I did not make then any wider but, unfortunately, the intake seats were already slightly out of spec, I believe it will still be OK for now. Next time I will have the seats re-cut and I'll pop new valves in. My only dissatisfaction with this first time lapping experience is that I can see "rings" on the intake valves' lapped surface whereas I believe it should look completely dull and smooth. I am not sure how to correct this maybe I have bought a low-quality compound that does not breakdown correctly in finer and finer grit as I lap the valve.missionkz wrote: Don’t go crazy with this. Keep in mind that the reason margin dimensions are given are to insure a proper and tight valve to seat seal ... based on the spring pressure vs the total square area of the valve to seat surface area. In other words, pretty and wide “grey” is not ideal for super tight sealing. While skinny will seal tight for a while but wear faster and can cause exhaust valve overheating.
1978 KZ400 B
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- chikosneff
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1978 KZ400 B
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- Nessism
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- chikosneff
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Nessism wrote: Look for someone with a centerless valve grinder. Good chance those valves will clean up like new.
Funny this video is made by the shop down the street
1978 KZ400 B
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