1978 kz750 smoke

Soxx4u
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1978 kz750 smoke

21 May 2015 17:12

#673049

Help please. 78 kz750 blows white smoke out of one cylinder. Compression test showed 90 psi. Where can I find rings

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Re: 1978 kz750 smoke

21 May 2015 18:15

#673063

ebay

1979 KZ-750 Twin

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Re: 1978 kz750 smoke

21 May 2015 20:04

#673078

Before you blindly assume it's rings, I recommend you check the valves and valve seals. Also: how many miles on the engine?

1979 KZ-750 Twin

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Soxx4u
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Re: 1978 kz750 smoke

21 May 2015 20:45

#673086

I checked the valves they are within spec they measure .10 How would I know if my vavle seals are bad and i do not know how many miles are on the motor.

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Re: 1978 kz750 smoke

21 May 2015 21:15

#673091

You can pull the carbs and see oil on the valves, exhaust if you take off the pipes.
Steve

Z1b1000 1975 Z1b
kzrider.com/forum/11-projects/598262-kz-...-will-it-live#672882
kzrider.com/forum/2-engine/597654-poser?start=240#704229

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Re: 1978 kz750 smoke

21 May 2015 21:16

#673092

Constant smoking does suggest rings.
Steve

Z1b1000 1975 Z1b
kzrider.com/forum/11-projects/598262-kz-...-will-it-live#672882
kzrider.com/forum/2-engine/597654-poser?start=240#704229

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Soxx4u
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Re: 1978 kz750 smoke

21 May 2015 21:35

#673094

I have oil in my exhaust pipe and it smoke a lot of white all the time. I only ran the motor for about 2 mins though

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Re: 1978 kz750 smoke

21 May 2015 22:17

#673095

I only ran the motor for about 2 mins though :laugh:

Any oil that you put in your bores during the 'wet' compression test will take some time to clear.

Low compression could be gummed up rings, common on bikes that have been unused for any length of time, often they free themselves just with use.

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

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Re: 1978 kz750 smoke

21 May 2015 22:49 - 21 May 2015 22:51

#673096

Soxx4u wrote: I checked the valves they are within spec they measure .10 How would I know if my vavle seals are bad and i do not know how many miles are on the motor.

I did not mean valve clearance, I mean valves, seats and seals. The valve stem seals on these twins are notorious for failing and then they leak oil through the seats and build up gunk until they don't seal well.

Look at the spark plugs and see if you find any oil residue. That will likely mean a seal has failed.

I would change the oil and run it a while before doing anything.

1979 KZ-750 Twin

Last edit: 21 May 2015 22:51 by bountyhunter.

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Soxx4u
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Re: 1978 kz750 smoke

22 May 2015 08:38

#673142

Do you think if I use marvel mystery oil that might help

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Re: 1978 kz750 smoke

22 May 2015 11:43

#673167

I've had it do some amazing things. Old Gas crawler 4 cylinder sitting for years. Put some in the cylinders, had to turn it back and forth to free it up, let it sit overnight, rebuilt the carb, it fired right up and bladed our road at Hole In The Hills. Worth a shot.
Steve

Z1b1000 1975 Z1b
kzrider.com/forum/11-projects/598262-kz-...-will-it-live#672882
kzrider.com/forum/2-engine/597654-poser?start=240#704229

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Re: 1978 kz750 smoke

22 May 2015 13:06

#673177

Soxx4u wrote: Do you think if I use marvel mystery oil that might help

I have read people shoot Pb blaster down the spark plug holes to free up stuck rings. Just make sure you change the engine oil before running if you are going to do "soaks" with solvents, cleaners or other chemicals.

1979 KZ-750 Twin

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