Where's the carbon from?

  • VTEC
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Re: Where's the carbon from?

07 May 2016 17:31
#725110
Let me ask you guys this one?

Had the carbs off way too many times tuning, and whenever I looked in the port I would see droplets hanging from the guides, after normal riding. Is that normal to have fuel droplets there, or was it oil from around the guides. It stuck around for a long time. Would have thought it would have evaporated on a hot engine if it was fuel.
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  • SWest
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Re: Where's the carbon from?

07 May 2016 17:39
#725112
Could be getting past the guides in the head. Might have to go oversized and make sure the bores are clean. (no burrs)
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: Where's the carbon from?

07 May 2016 17:40
#725113
swest wrote: Could be getting past the guides in the head. Might have to go oversized and make sure the bores are clean. (no burrs)

Yeah, I'm gonna figure out a good way to pressure test around the guides to confirm.
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Re: Where's the carbon from?

07 May 2016 17:49
#725115
Were they replaced? Easy to pull out metal when doing it.
Steve
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kzrider.com/forum/11-projects/598262-kz-...-will-it-live#672882
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Re: Where's the carbon from?

07 May 2016 17:56
#725117
Yes, APE bronze with the oversized valves. I understand you can score the bore and cause leaks if you don't clean the original guide real good before knocking it out.
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Re: Where's the carbon from?

07 May 2016 18:20
#725122
I did mine in 87. One came out with metal on it. It happens.
Steve
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Re: Where's the carbon from?

08 May 2016 08:53
#725181
Build up of carbon on the back side of the valves is perfectly normal and nothing to worry about. If the engine is running well and not burning oil then you don't have a problem.
Ed
Carb O-ring Kits : www.kzrider.com/forum/14-vendor-forum/62...rburetor-o-ring-kits

www.kzrider.com/forum/faq-wiki/618026-new-owner-things-to-know

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www.kzrider.com/forum/11-projects/604901...z750e-project-thread

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Re: Where's the carbon from?

08 May 2016 14:49
#725223
Nessism wrote: Build up of carbon on the back side of the valves is perfectly normal and nothing to worry about. If the engine is running well and not burning oil then you don't have a problem.

This happened immediately after running a new engine. I think there was oil consumption, and the carbon was enough to kill a piston. The guides being the source also doesn't make sense because there was no blue smoke on start up, but oil got dark quick, like a blow-by issue.
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Re: Where's the carbon from?

08 May 2016 16:03
#725225
Perhaps before the rings were seated

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Re: Where's the carbon from?

08 May 2016 17:17
#725233
Most likely seals. A little oil won't cause smoke.
Steve
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kzrider.com/forum/11-projects/598262-kz-...-will-it-live#672882
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