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Author Topic: 1980 CB 650 C  (Read 1645 times)

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Offline Yotetalker

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1980 CB 650 C
« on: May 12, 2011, 04:23:52 PM »
I pulled my carbs off lastnight to change the rubber airbox connectors they were in bad shape. Now that I have done this the bike will not start without blowing air into the carb overflow tubes coming off the T....If someone could help I would be greatly appreciative.... I have tried choking the bike but seems to me like its getting way to much gas....
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Offline cb650

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Re: 1980 CB 650 C
« Reply #1 on: May 12, 2011, 04:35:31 PM »
What did you replace them with?   
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18 grand and 18 miles dont make you a biker

Offline Yotetalker

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Re: 1980 CB 650 C
« Reply #2 on: May 12, 2011, 04:55:48 PM »
The Honda shop ordered me new ones. Still using the stock air box just changed the rubbers that's why I'm lost on what's wrong.  Once I get it started it runs fine but getting it started is the problem
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Offline cb650

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Re: 1980 CB 650 C
« Reply #3 on: May 12, 2011, 08:08:38 PM »
I dont know unless you something in wrong.
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Offline Yotetalker

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Re: 1980 CB 650 C
« Reply #4 on: May 13, 2011, 03:20:44 AM »
I'm new to these bikes. But from what I read you don't adjust the gas flow u adjust the amount of air. Is the a detailed pic of carbs online somewhere. 
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Offline sinister902

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Re: 1980 CB 650 C
« Reply #5 on: May 13, 2011, 06:47:17 AM »
chances are, whomever adjusted the carbs last didnt realize the rubbers were cracked and allowing extra air in....so instead of replaceing them they adjusted the carbs to run properly with the air that was provided. mess with the idle/air mixture screws to lean it out a bit and see if that helps
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Offline flybox1

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Re: 1980 CB 650 C
« Reply #6 on: May 13, 2011, 07:22:11 AM »
when you pulled your carbs, did you clean them?   new filter?
did you verify that the pilot circuit and main jet are clean and clear?
Are your float heights correct?
and when reinstalling the carbs, did you ensure the boots on either side are sealed properly?
« Last Edit: May 13, 2011, 07:23:53 AM by flybox1 »
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'78 750K (F3 engine) PD42b's, Modified airbox w/K&N  filter, 40/110 jets, 1 needle shim, IMS@ 1 turn out. Kerker + Cone 18" QuietCore

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1974 550K0 (stock), 1973 CB350F (stock), 1983 Yamaha XS400K (POS)
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Offline Yotetalker

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Re: 1980 CB 650 C
« Reply #7 on: May 13, 2011, 02:52:59 PM »
The hind shop cleaned the carbs and I sprayed starting fluid around them to make sure of seal. No jump in ideal.  I've messed with it today an still no start when choke. But if I spray starting fluid in air box it will fire up runn for a few then die if I keep doing that soon as it get the motor warm I will stay running or if I blow a little air into the hoses it will runn but I have to keep sound it until it gets warm but until then it smell like it's running rich.   Thanks for all the input
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Offline Yotetalker

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Re: 1980 CB 650 C
« Reply #8 on: May 13, 2011, 06:35:21 PM »
Next ? I'm looking at a carb diagram and it shows the two lines joining together with a T then going back toward the air filter. Is this true or do the stay separate. These lines r the ones comeing up from the T that join the carbs 1&2. 3&4.
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Offline cb650

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Re: 1980 CB 650 C
« Reply #9 on: May 13, 2011, 08:07:45 PM »
The combine and go to the airbox.
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18 grand and 18 miles dont make you a biker

Offline Yotetalker

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Re: 1980 CB 650 C
« Reply #10 on: May 15, 2011, 05:16:37 PM »
Think i may have figured out the problem, not getting a good hot spark..I get a blue one but its very faint and its all over the place... I think I'm going to change the plug wires and get rid of these champion plugs someone put in.. Ive been reading on makeing your own wires and it seems everyone goes with 7MM and NGK  ( 5 ohm resistance) ends...Let me know what you guys think... I was checking my coils and noticed one has a crack in it an it was filled with silicone or something may have to order another.. :(   If you have any good places to order from that would be greatly appreciated..

Thanks in advanced
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Offline Yotetalker

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Re: 1980 CB 650 C
« Reply #11 on: May 18, 2011, 07:43:51 PM »
Its alive....Guess thats what i get for letting someone else redo the carbs....They may not be perfect but the r heck of alot closer than the had them....At least now i can start it up without blowing through the tubes......Now just sit around a tinker with it to I get the best that I can....Thanks for the info you guys gave me.....
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Offline Frankenkit

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Re: 1980 CB 650 C
« Reply #12 on: May 18, 2011, 08:25:20 PM »
Hey mate! I've got one of those bikes exactly.  They can be fun, when they're not a handful. Good call on replacing the rubbers. Since they're already jetted pretty lean, any air leaks at all make it very hard to start and/or run at all.  I got my 'new' coils from a local used bike parts shop, just make sure they're not cracked at all.  Check your igniters, too, under the seat, you may find they're melted out.  Sometimes you can scoop up the goo and stuff it back in since it's just an insulator, but sometimes the overheating damage has been too much and they're toast.  Fortunately lots of other bikes had these types of igniters.   

Once you get your coils and timing etc sorted, you may want to consider iridium plugs.  I know a lot of folks feel like they're snake oil, but I know I saw a great improvement in starting and idling. 

Good luck to you.  There are many a thread here on cb650 charging etc.
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Offline Yotetalker

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Re: 1980 CB 650 C
« Reply #13 on: May 19, 2011, 03:05:28 AM »
Thanks for the info.  Industrial kit.  Yes my igniters r starting to leak the goo and yes one coil has a crack in it I put silicon over the crack for now but need to get new coils
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