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Author Topic: Keihin CR31 Special issue  (Read 3197 times)

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Offline voxonda

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Keihin CR31 Special issue
« on: June 22, 2011, 09:22:50 AM »
Guys, I really need some help here.
A friend of mine bought a set of brandnew CR31's thru me and finally came to mount these. And now........trouble in paradise. There is a problem, it seems, with carb #3. It runs but immidiately runs on 3 and drown the #3 cyl. Changed plugs, even ignition, coils. Nothing. Then mount a set of PD's and runs great on all fours. Back to CR special,.....................same problem. Mount a set of 'old' tickler 31's and run on all fours.
So seems to be the carb. Blew thru every single jet, and drilling in the body's. Interchanged jets but problem remains. Mains are 110 now. Suggestions?

Thanks in advance, Rob
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Offline scottly

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Re: Keihin CR31 Special issue
« Reply #1 on: June 22, 2011, 11:00:17 AM »
Have you checked the fuel level in the float bowl?
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Offline voxonda

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Re: Keihin CR31 Special issue
« Reply #2 on: June 22, 2011, 11:06:36 AM »
Hi Scott,

Yes, float level on all 4 is set equal, but I will have it checked again.

Cheers, Rob
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Offline H2Eric

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Re: Keihin CR31 Special issue
« Reply #3 on: June 22, 2011, 11:07:51 AM »
Sticking float needle perhaps?
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Offline scottly

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Re: Keihin CR31 Special issue
« Reply #4 on: June 22, 2011, 11:18:29 AM »
Do the CRs have the bowl drain plugs or screws? If so, check the actual fuel level with a piece of clear tubing, rather than just measuring float level.
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Offline voxonda

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Re: Keihin CR31 Special issue
« Reply #5 on: June 22, 2011, 11:37:49 AM »
Quote from: scottly on June 22, 2011, 11:18:29 AM
Do the CRs have the bowl drain plugs or screws? If so, check the actual fuel level with a piece of clear tubing, rather than just measuring float level.

They have drain plugs, I'll suggest it to my buddy. Do not have the carbs at my place. Thanks at to you too Eric.

Cheers, Rob
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Offline scottly

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Re: Keihin CR31 Special issue
« Reply #6 on: June 22, 2011, 11:40:41 AM »
If the fuel level checks out, have him look at the choke circuit.
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Offline simon#42

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Re: Keihin CR31 Special issue
« Reply #7 on: June 22, 2011, 01:53:34 PM »
Quote from: scottly on June 22, 2011, 11:40:41 AM
If the fuel level checks out, have him look at the choke circuit.

yes thats where i would look too , if the float hight was wrong enough to flood the cylinder it would also be coming out of the overflow
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Offline brandEn

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Re: Keihin CR31 Special issue
« Reply #8 on: June 23, 2011, 05:02:03 AM »
I was having similar problems with my new CR 29s. The number 3 carb kept flooding. After chasing my tail I finally dismantled the #3 and found a huge piece of string under the float valve seat. The only way it could have gotten in there was from the manufacturing process. I would suggest looking there.
« Last Edit: June 23, 2011, 05:03:52 AM by brandEn »
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Offline kos

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Re: Keihin CR31 Special issue
« Reply #9 on: June 24, 2011, 09:29:46 PM »
I had similar issues with a bike I delivered to a customer at Mid Ohio race track and found that the o rings that seal float needle and seat to carb body were dried out and fuel was going by the leaky o rings. Found some some replacement o rings and he was on the track!

MK
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Offline MRieck

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Re: Keihin CR31 Special issue
« Reply #10 on: June 27, 2011, 07:48:03 AM »
We ran into similar problems with a set 29's starting several weeks ago. I have to go through them this week. Carbs were new out of the box too.
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Offline turboguzzi

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Re: Keihin CR31 Special issue
« Reply #11 on: June 27, 2011, 08:17:51 AM »
Quote from: kos on June 24, 2011, 09:29:46 PM
I had similar issues with a bike I delivered to a customer at Mid Ohio race track and found that the o rings that seal float needle and seat to carb body were dried out and fuel was going by the leaky o rings. Found some some replacement o rings and he was on the track!

MK

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