Smoke and Odor

If it's broken or just needs tweaked

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JBirdCB650
Posts: 3
Joined: Tue Mar 20, 2018 1:21 pm

Smoke and Odor

Postby JBirdCB650 » Wed Mar 28, 2018 10:26 am

Hey all, first off I am new to the bike world and purchased a 1982 CB650 that hasn't been on the road in a few years. It does currently run and drive and I have begun doing some overhaul.

I sent the Carbs away to be professionally done and I put them back on the bike the other day, the mechanic stated that once on the bike they will need to be further adjusted. When I fired up the bike it idled really high, around 3k, I played with the idle adjustment screw and it didn't change. It ran like that for a few minutes and then started idling down and finally died out. I was able to keep it running if I stayed onto the throttle so I think these were the adjustments he was talking about.

Finally to my point about this post. I started the bike up again the other day just to let it run and try to adjust the idle myself. (Carbs still not fully synced at this point). I noticed some smoke coming out from where the exhaust mounts to the cylinder 4 and had a very strange odor to it. I'm not convinced it was just exhaust leaking by I feel like something was possibly burning, like a chemical type smell. My first thought would be Cylinder rings, the bike has plenty of fresh oil but I wasn't sure if anyone has run into anything similar in their builds or how you might be able to diagnose a problem like this without striping the motor down. Thanks guys for any advice you can give, and like I said, I'm a newbie, so don't razz me too hard :lol:

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GeorgeSweety
Posts: 324
Joined: Tue Aug 08, 2017 11:47 am
Location: UK.

Re: Smoke and Odor

Postby GeorgeSweety » Wed Mar 28, 2018 12:22 pm

Hi JB and welcome to the forum and the World of Two Wheeled Nutjobs :lol: How long was the bike stood for? Did you do anything to the engine other than have the carbs cleaned? Have you checked for a bit of freeplay in both of your throttle cables and your choke cable? doesn't need to be a lot. If you have freeplay does turning the handlebars from side to side make any difference to the revs? Tighten up that damn exhaust! :D

JBirdCB650
Posts: 3
Joined: Tue Mar 20, 2018 1:21 pm

Re: Smoke and Odor

Postby JBirdCB650 » Wed Mar 28, 2018 1:12 pm

The bike was last registered in 2003, even if its been run every now and then its been sitting a while. I have done a tank cleaning and lining, I have replaced both throttle cables and have good response in the throttle, the choke cable could probably be replaced but seems to pull and return alright. At this point the whole exhaust probably needs to be changed out.

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GeorgeSweety
Posts: 324
Joined: Tue Aug 08, 2017 11:47 am
Location: UK.

Re: Smoke and Odor

Postby GeorgeSweety » Wed Mar 28, 2018 1:38 pm

Have you put a new air filter on it? You need to eliminate any air leaks at your airbox, airbox rubbers and inlet boots and fix your leaky exhaust before you try to set up your carbs properly.
The choke may seem to pull and return but have you actually checked to see if the choke pulley has returned to its normal off position?

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Folsoml
Posts: 1633
Joined: Sat Apr 07, 2012 9:02 pm
Location: North Florida

Re: Smoke and Odor

Postby Folsoml » Wed Mar 28, 2018 6:20 pm

Welcome to the forum!

it's unlikely that what you are seeing on the exhaust is related to anything going on inside the cylinder. If there WAS something going on, the evidence of it would come out the tail pipe rather than where the pipe meets the head. Has anyone had the exhaust off lately? If so, did they use new copper gaskets when they put it back on? Those gaskets are not reusable.

Your idle problem sounds like an air leak at one or more of the insulators. Try starting the engine and then spraying brake cleaner on the carb insulators one at a time. Any change in idle indicates a leak.
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My Current Bikes: 2005 HD FLHTCUI Electra Glide Ultra Classic, 2007 Yamaha Vino,


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