are these valves OK ?

Janz3n
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are these valves OK ?

28 Sep 2014 12:54

Tore apart my 305 today. Found some things I wasn't expecting on my rebuild.

Valves look pretty bad, are they OK to lap and reuse?

81 kz305 ltd

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bountyhunter
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Re: are these valves OK ?

28 Sep 2014 12:56

#649035

Those look a lot better than ones I've seen.

1979 KZ-750 Twin

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Tyrell Corp
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Re: are these valves OK ?

28 Sep 2014 13:16

#649036

Take them out, look closely at the contact surfaces and the seats.

You have 1/2 a GPz550 motor there, looks pretty normal deposits to me.

1980 Gpz550 D1, 1981 GPz550 D1. 1982 GPz750R1. 1983 z1000R R2. all four aces

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Janz3n
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Re: are these valves OK ?

28 Sep 2014 13:18

#649037

ok thanks!

next question, is this front cam chain guide going to last much longer? having a hard time finding a new one.

would really love to replace it.

81 kz305 ltd

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PLUMMEN
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Re: are these valves OK ?

28 Sep 2014 14:35

#649044

Glass bead the valves and combustion chambers,then check the valves and guides.Have valves and seats ground.

Still recovering,some days are better than others.

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Tyrell Corp
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Re: are these valves OK ?

28 Sep 2014 18:21

#649072

Camchain guide err a bit difficult to see from your pic. does it feel smooth? They are not a common failure point on the bigger GPz. IIRC I think there were some issues with premature top end cam and journal wear on the 305, maybe check it out.

1980 Gpz550 D1, 1981 GPz550 D1. 1982 GPz750R1. 1983 z1000R R2. all four aces

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Janz3n
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Re: are these valves OK ?

29 Sep 2014 03:38

#649090

Its hard to get a good picture of the guide. If you look at the middle there are two cracks on it.

81 kz305 ltd

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Janz3n
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Re: are these valves OK ?

30 Sep 2014 12:24

#649212

Well the valves cleaned up OK. Lapped them as well.

81 kz305 ltd

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PLUMMEN
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Re: are these valves OK ?

30 Sep 2014 13:31

#649223

put the valves/springs back in the head.Flip it over on the bench with exhaust ports pointing up and fill exhaust ports with solvent..
Blow compressed air around the exhaust valve edges where they meet the valve seat,look for bubbles in the solvent while doing this.
If you see no bubbles valves are sealing,flip head over and repeat on intake ports.

Still recovering,some days are better than others.

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Tyrell Corp
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Re: are these valves OK ?

30 Sep 2014 14:54

#649237

I see some pitting on right hand side inlet eeat, but not sure if it is bad enough to justify recutting the seats though, hopefully we can have some more opinions on this.

It is easy throwing money at a project and getting everything just right, the clever bit is judging what you can 'get away' with for maybe 10 000 miles more of road use.

1980 Gpz550 D1, 1981 GPz550 D1. 1982 GPz750R1. 1983 z1000R R2. all four aces

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Janz3n
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Re: are these valves OK ?

30 Sep 2014 17:48

#649252

thanks plummen i'll give that a try.

that pit might just be some dirt. my plan is to rebuild the head and replace most of the seals on the engine so im trying to keep cost down as much as possible. will probably sell the bike in a year or two. i was getting tired of topping up the oil before every ride.

81 kz305 ltd

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Janz3n
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Re: are these valves OK ?

08 Oct 2014 08:50

#650065

Put the valves back together and put water in the ports and blew compressed air around the seats. All valves seem to leak and bubble through. All seats look evenenly cut to me. Any suggestions?

81 kz305 ltd

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