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Author Topic: Blue Exhaust 1982 CB650  (Read 1077 times)

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the.barrage.pdx

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Blue Exhaust 1982 CB650
« on: August 10, 2009, 10:43:57 PM »
So I just got done (maybe  ;) ) rebuilding the top end of my 1982 CB650 due to breaking a cam tensioner bolt and a head bolt.  I figured hey, while I've got the top end off I might as well do what I can.   I've had a few problems with getting the timing correct, breaking a bolt or two due a #$%* poor torque wrench, and listening to people I shouldn't have.

I'm new to this.  This is not only my first top end rebuild, but really it's my first time ever turning a wrench. 

Long story short...I finally got to the point where I could turn it over tonight.  It fired right up, but wouldn't stay on.  So giving it a little throttle and varying the RPM's very very low (I've heard it needs a break in period) but it started blowing blue exhaust.  not all the time, but when it was it was pretty darn blue. 

My limited knowledge makes my mind scream "oil in the combustion chamber!!!!"  but then I've never rebuilt a top end, so it could be normal.  I'm unaware.

What else could it be? 
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Offline bucky katt

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Re: Blue Exhaust 1982 CB650
« Reply #1 on: August 11, 2009, 01:59:19 AM »
when you rebuilt the top end did you do hone the cylinders and do rings? it will take a little time for the new rings to seat and you'll get a little blowby at first.
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the.barrage.pdx

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Re: Blue Exhaust 1982 CB650
« Reply #2 on: August 11, 2009, 08:08:43 AM »
I didn't hone the cylinder or redo the rings.  The cylinders were cleaned, but only with some chemical, no removing of any layers or metal.

I also forgot.  I have CARBS on their from my other CB650 and have not hooked up the pods to it yet.  So it might be running a little lean?  It did seem to get better the more I ran it, but I didn't want to run it too much in fear that it could be something serious.  So it sounds like I may be correct in that is the rings, but that it might not be a problem as they begin to seat and create a seal?

I guess I'll just watch it closely and see if it seems like it is getting worse.


Thanks for the feedback.
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Offline tlbranth

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Re: Blue Exhaust 1982 CB650
« Reply #3 on: August 11, 2009, 10:21:54 AM »
If you didn't put in new rings, what exactly did you do? Head rebuild?
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the.barrage.pdx

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Re: Blue Exhaust 1982 CB650
« Reply #4 on: August 11, 2009, 10:44:07 AM »
Yes, the head was completely rebuilt.  and everything was given a chemical bath.  The rings and cylinders were in really good shape, so I didn't want to mess with something that previously didn't give me any problems.
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Offline tlbranth

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Re: Blue Exhaust 1982 CB650
« Reply #5 on: August 11, 2009, 05:50:02 PM »
Hmm. Well you shouldn't get blue smoke for more than a few minutes then. If you do, something's amiss.
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Don't own a Vanagon
Don't work at Boeing
Life is good

1970 CB750 K0
1975 GL1000
1999 GL1500
2002 VT750-CDA ACE - Momma's bike
Terry

Offline OldSchool_IsCool

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Re: Blue Exhaust 1982 CB650
« Reply #6 on: August 11, 2009, 06:11:33 PM »
Quote from: tlbranth on August 11, 2009, 05:50:02 PM
Hmm. Well you shouldn't get blue smoke for more than a few minutes then. If you do, something's amiss.

+1.  If there is no screeching metal, then run her a bit more to see if the smoke goes away.  Double check your ignition timing to get her to run better.
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the.barrage.pdx

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Re: Blue Exhaust 1982 CB650
« Reply #7 on: August 11, 2009, 09:33:41 PM »
Hey guys,

I think I figured it out after reading another post on here.  My number 1 cylinder isn't firing.  I checked the exhaust after running it for a bit and that header was stone cold.

I'm thinking I start with new spark plugs and see where if that works.  After that?
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Offline RM81

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Re: Blue Exhaust 1982 CB650
« Reply #8 on: August 12, 2009, 06:56:28 AM »
Quote from: the.barrage.pdx on August 11, 2009, 09:33:41 PM


I'm thinking I start with new spark plugs and see where if that works.  After that?

Trace it back.  Caps, Wires, Coils.
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