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Author Topic: Grey smoke from mufflers?  (Read 1568 times)

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fastfred

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Grey smoke from mufflers?
« on: January 30, 2010, 01:01:34 PM »
Got my 76 CB750 running after finding a bad connection leading to the coils.  Just bought it.

It has been sittings for months and sounds okay. I got good advice yesterday on this site about getting it running on all 4 cylinders before worrying about noises when only firing on two.

However it is giving off gray smoke from the mufflers when running.  Not black (rich) or blue (burning oil).  Could be from old coatings in the mufflers from sitting?

Any suggestions?   Being a 1976, does this make it a Cb 750 C model?

Thanks folks
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Offline TwoTired

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Re: Grey smoke from mufflers?
« Reply #1 on: January 30, 2010, 01:24:26 PM »
Run it long enough, hot enough, to vaporize all the condensation in the exhaust?
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Lloyd... (SOHC4 #11 Original Mail List)
72 500, 74 550, 75 550K, 75 550F, 76 550F, 77 550F X2, 78 550K, 77 750F X2, 78 750F, 79CX500, 85 700SC, GL1100

Those that learn from history are doomed to repeat it by those that don't learn from history.

Offline Duke McDukiedook

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Re: Grey smoke from mufflers?
« Reply #2 on: January 30, 2010, 01:28:22 PM »
+1.

If it is running on all fours, take it out for 30 minutes or more and then check your exhaust.
Kinda tough to see what is truly going on when you are just in the garage revving it.
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"Well, Mr. Carpetbagger. We got somethin' in this territory called the Missouri boat ride."   Josey Wales

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CB750 K3 crat | (2) 1986 VFR750F

Offline BlackMax

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Re: Grey smoke from mufflers?
« Reply #3 on: January 30, 2010, 09:31:27 PM »
Run it for 30 minutes, best if you actually drive it for increased cylinder pressure and temps.   That usually clears it up.  If not, oil's getting around the valve guides.
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1978 CB750SS, 4-1 Yoshi, Pods, 3-angle valve job, ported chambers, ported intake, 41a cam

Offline YogiBear

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Re: Grey smoke from mufflers?
« Reply #4 on: January 31, 2010, 01:13:14 AM »
Quote from: fastfred on January 30, 2010, 01:01:34 PM
Being a 1976, does this make it a Cb 750 C model?

Thanks folks



 ??? No. the CB750C is only in the 80-82 DOHC models. Yours is either a K or F.
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1974 Honda CB750K4        1973 Honda CB500 Four
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