#4 spark plug smokes !


AshishNJ
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#4 spark plug smokes !

Post by AshishNJ »

I am suspecting there may be an issue with plug seat.
The spark plug sits in nicely and no cross thread issues. I torque it down to 13 NM and all good.
Once bike heats up , I see smoke come from somewhere near #4 plug. The speed of smoke rises and falls with throttle. No visual sign of any oil leak from cam cover either.
Any ideas ? I am suspecting the seat on the head where plug threads may have some uneven surface ?
1979 CBX (faster Red)
1981 CBX Streetfighter
2017 Aprilia Tuono.
Past rides : FZ1, BMWS100rr,S1000r,k1300S,YAMA RD350,Enfield 350

AshishNJ
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Re: #4 spark plug smokes !

Post by AshishNJ »

1979 CBX (faster Red)
1981 CBX Streetfighter
2017 Aprilia Tuono.
Past rides : FZ1, BMWS100rr,S1000r,k1300S,YAMA RD350,Enfield 350

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SteveG
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Re: #4 spark plug smokes !

Post by SteveG »

I say it is leftover oil / remnants cooking off. How far have you ridden the bike since putting it back together? If all of the plugs are tight, then ride it a good bit (100 miles at one stretch) and see if it still smokes.
My .02$
Nice bike!
Steve
82 CBX, 82 CB900F Project, 81 CB900(985)F, 79 CB750(810)F, 06 Wee-Strom

AshishNJ
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Re: #4 spark plug smokes !

Post by AshishNJ »

Steve
Bike has been going through a customization. Motor was not run in last 3 years . I did valve adjustment, carb rebuild, oil pan cleaning , filter oil changes new plugs . Where would this leftover be burning ? Outside on valve cover ? Not sure why it would smoke only at near #4 cylinder
1979 CBX (faster Red)
1981 CBX Streetfighter
2017 Aprilia Tuono.
Past rides : FZ1, BMWS100rr,S1000r,k1300S,YAMA RD350,Enfield 350

daves79x
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Re: #4 spark plug smokes !

Post by daves79x »

Are you sure you don't have a loose exhaust collar that blowing exhaust back through the head fins? That's what it looks like to me.

Dave

AshishNJ
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Re: #4 spark plug smokes !

Post by AshishNJ »

Dave
I will check that . These are new pipes with new copper round shape gaskets and I had tightened them fairly good while aligning.
1979 CBX (faster Red)
1981 CBX Streetfighter
2017 Aprilia Tuono.
Past rides : FZ1, BMWS100rr,S1000r,k1300S,YAMA RD350,Enfield 350

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Jeff Bennetts
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Re: #4 spark plug smokes !

Post by Jeff Bennetts »

AshishNJ wrote:
Fri Jun 26, 2020 8:16 am
Dave
I will check that . These are new pipes with new copper round shape gaskets and I had tightened them fairly good while aligning.
The exhaust collars should be re-torqued after a couple heat cycles, don't over torque those small studs though!

AshishNJ
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Re: #4 spark plug smokes !

Post by AshishNJ »

Will try again. Collars are retightened as per manual. In the process, found that one of the stud On cyl #1 was turning free. Luckily I had a 6mm helicoil kit that took care of it .
1979 CBX (faster Red)
1981 CBX Streetfighter
2017 Aprilia Tuono.
Past rides : FZ1, BMWS100rr,S1000r,k1300S,YAMA RD350,Enfield 350

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SteveG
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Re: #4 spark plug smokes !

Post by SteveG »

AshishNJ wrote:
Thu Jun 25, 2020 8:56 pm
Steve
Bike has been going through a customization. Motor was not run in last 3 years . I did valve adjustment, carb rebuild, oil pan cleaning , filter oil changes new plugs . Where would this leftover be burning ? Outside on valve cover ? Not sure why it would smoke only at near #4 cylinder
Since you had the valve cover off to do the valve adjustment, some oil could have oozed/seeped/ran..... down into the #4 plug well/area while you were working.

Is it still smoking after checking the exhaust crush washers as Dave suggested?

Steve
82 CBX, 82 CB900F Project, 81 CB900(985)F, 79 CB750(810)F, 06 Wee-Strom

AshishNJ
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Re: #4 spark plug smokes !

Post by AshishNJ »

Steve. Haven’t had a chance to try due to rain. I hope it does not but we will see. I will setup an slr to take better video this time
1979 CBX (faster Red)
1981 CBX Streetfighter
2017 Aprilia Tuono.
Past rides : FZ1, BMWS100rr,S1000r,k1300S,YAMA RD350,Enfield 350

AshishNJ
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Re: #4 spark plug smokes !

Post by AshishNJ »

I tested it out today and once engine heats up after 5 minutes or so, there is smoke from around spark plugs. No leaky exhaust. What I suspect is the inside of the valve cover gasket is seeping oil when it is him and hot and burns up. I touch around the gasket and I could see the oil ! I am guessing when I give it a throttle pump builds more oil pressure and immediately that leak also increases. Does my theory has a leg ?
1979 CBX (faster Red)
1981 CBX Streetfighter
2017 Aprilia Tuono.
Past rides : FZ1, BMWS100rr,S1000r,k1300S,YAMA RD350,Enfield 350

daves79x
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Re: #4 spark plug smokes !

Post by daves79x »

Shouldn't be noticeable pressure build-up in the top end. Your valve cover gasket should not be seeping hardly any oil even if a cursory bit of care was taken during installation. Both cover and gasket should be thoroughly cleaned, then the gasket glued into the cover. Then just a dab of sealant around the 4 half-moons on the gasket and that should seal everything. I would suspect a pinched gasket somewhere causing the cover to not tighten down properly. Or else you have a very warped valve cover.

Dave

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Re: #4 spark plug smokes !

Post by AshishNJ »

Dave. You have a point. The original valve cover I had was black color and was peeling off. I figured the engine should win beauty contest and decided to use another silver cover . It is possible the 2nd cover may have been warped, though it did not appear so. On a glass table it sat straight but at this point I will go back to older cover with new gasket. Those gaskets are not cheap ! Thanks for the advice.
1979 CBX (faster Red)
1981 CBX Streetfighter
2017 Aprilia Tuono.
Past rides : FZ1, BMWS100rr,S1000r,k1300S,YAMA RD350,Enfield 350

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Re: #4 spark plug smokes !

Post by Larry Zimmer »

While you have the cover off, be certain that the head surface is OK. A little nick, a scrape, etc. to cause a leak.
Larry Zimmer
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AshishNJ
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Re: #4 spark plug smokes !

Post by AshishNJ »

I will. Thanks
1979 CBX (faster Red)
1981 CBX Streetfighter
2017 Aprilia Tuono.
Past rides : FZ1, BMWS100rr,S1000r,k1300S,YAMA RD350,Enfield 350

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