81 engine takes forever to warm up and run smooth?

If it's broken or just needs tweaked

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coreyr6624
Posts: 13
Joined: Thu Dec 17, 2015 7:29 pm

81 engine takes forever to warm up and run smooth?

Postby coreyr6624 » Fri Dec 18, 2015 6:21 am

New to older bikes. Can anyone lead me in what direction they would go to try to resolve the long warm up time of my engine. When I try to run the bike I have to choke it for about 4-5 minutes until it will run without the choke. Is it, air cleaners, carbeurators need work?

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

Re: 81 engine takes forever to warm up and run smooth?

Postby Folsoml » Fri Dec 18, 2015 8:17 am

Welcome here! What kind of air cleaner system do you have? The 81 models had CV carbs, and if you are trying to run pods on them, you may have difficulty getting it to run right. The CV carbs run best with the stock air box.
Have a problem with your CB650? Have a technical question? Click here!


My Current Bikes: 2005 HD FLHTCUI Electra Glide Ultra Classic, 2007 Yamaha Vino,

coreyr6624
Posts: 13
Joined: Thu Dec 17, 2015 7:29 pm

Re: 81 engine takes forever to warm up and run smooth?

Postby coreyr6624 » Fri Dec 18, 2015 9:20 am

I believe it is the stock air box.

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

Re: 81 engine takes forever to warm up and run smooth?

Postby Folsoml » Fri Dec 18, 2015 12:06 pm

You may have an air leak or two around your insulators. Start the bike and let it warm up until it is idling as best it can. Then spray carb cleaner around the insulators that go from each carb to the cylinder head. Any change in idle indicates a leak.

What is the history of this bike?
Have a problem with your CB650? Have a technical question? Click here!


My Current Bikes: 2005 HD FLHTCUI Electra Glide Ultra Classic, 2007 Yamaha Vino,

coreyr6624
Posts: 13
Joined: Thu Dec 17, 2015 7:29 pm

Re: 81 engine takes forever to warm up and run smooth?

Postby coreyr6624 » Fri Dec 18, 2015 7:06 pm

Thank you, i'll check that.

CB650CPastor
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Re: 81 engine takes forever to warm up and run smooth?

Postby CB650CPastor » Sun Dec 27, 2015 6:50 pm

Partially clogged idle circuit (pilot/low speed) jets could cause this as well. I have the mechanical carbs and you have the CV, so YMMV, but the stock jetting is pretty lean to start with. Of the several bikes that I have owned, this CB650 seems to take the longest to get warm.
Tim
Current:1980 Honda CB650C Custom, 1969 Toyota Corona Deluxe Sedan
Past: '07 Honda Rebel 250, '80 Yamaha XS1100 Special, '69 Honda CB160, '67 K15 Suzuki Hillbilly


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