Bike dies with choke off. Help Please!

[BornOnThe4th]

I have a 1967 CL90 with a single carb, I've cleaned it twice, pilots clean, soaked everything over night, blew it out with compressed air.

I set the pilot screw back 1 1/2, it idles fine with the choke open but as soon as its closed it dies. I checked the the gas flow from the petcock, checked for vacuum leaks, all fine.

If I leave the choke open just a bit I can run it all the way up through full throttle, just cant shut the choke off.

If anyone can help me out with what I should do to trouble shoot this that would be great. Thanks!

 

[treitz]

I just dealt with this a bit on my build. R u running the stock air box, or pods?

If pods, u probably need to rejet as u are running lean.

 

[Koestum]

Just to clarify... Choke closed (on) means less air, choke open (off) means more air.

If it runs when the choke is open a little and you can run it through full throttle then the mixture is more correct with less air than if you open the choke (much more air) and it dies.

Yes, it does sound like you need to restrict air flow.

(Sorry, I've had a few Fireball whisky shots)

 

[teazer]

Born, Please confirm which way you mean with On and OFF. If it dies with the choke plate down (ON) that's not surprising but if it dies with the Choke plate up (off) then it's too lean.

 

[Koestum]

OR your passages/jets still aren't clean.

 

[BornOnThe4th]

Thanks for the replies. The bike dies when the choke is closed, covering the carb opening. It will run with it open to about the top of the cutaway. My bad for any confusion.

 

[Koestum]

Then I would say your passages may be clogged or your jets still not clean.

It sounds like the cheapest and easiest fix would be to simply not quite close the choke when you start it.

If you really want it perfect you need to tear it all the way down, remove all pastic/rubber components, soak it overnight with the carb cleaner gallon from Autozone (it works great!), blow each and every passage out with compressed air and make sure every hole that's a real hole actually allows air to come one somewhere else.

There is no other way to do this than take your time and make sure everything is clean.

I took two weeks to clean 750 and 400f carbs (4 each). It takes a lot of time and you have to be very thorough but it's extremely rewarding when finished and your bike starts on the first kick for the next three years and you've kick that carb's butt.

 

[BornOnThe4th]

Thanks so much! I'll give it a shot. All the best

 

[VonYinzer]

Make sure you check the jets very carefully as well. The brass can degrade over time, or they couldve been damaged by a previous owner. Jets are cheap, so replacing them may be an easy way of helping you get the bike running right.

 

[teazer]

When it's cold, the bike should need full choke to start but should die (As in choked to death) as it gets warm. It is normal for it not to run at WOT with the choke ON. If that is what you are describing, it's OK.

If it is starting fine when it's cold and the air is cold and with no choke, the mixture is too rich.

Most likely causes would be from people ramming bits of wire through jets to clean them or float level too high. I'd buy a new pilot jet and new main jet and see how that works. While the carb is off pay attention to cleaning out all the little drillings.