Carb balancing readings not making sense

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Cucciolo - the Lil Pup
Posts: 22
Joined: Fri Nov 20, 2009 1:16 am
Location: Mackay, Qld, Australia

Carb balancing readings not making sense

Post by mdal »

Hi All
Need some help. I have finally got my Darmah project bike running after 6 years. The bike was stripped down to bare frame and rebuilt. The engine only had a topend overhaul with new piston rings, valve guides and a couple of new valves. The bottom end was untouched.
I fitted kits to the carbs, new exhaust gaskets, new exhausts,new intake manifold rubbers etc.
My problem is trying to balance carbs as per Steves instructions. I bought a morgan carbtune unit and the readings aren't making any sense. The bike will start with choke and then run by holding throttle open. I can it to run at a fast idle by winding in adjuster screws.
The front cylinder doesn't want to play the game when balancing. When backing out the throttle cable adjuster on the front cylinder the rear cylinder vacuum level increases and the front cylinder vacuum stays the same??? I have checked that I haven't crossed over tubes, that the restrictor isn't blocked etc..
I have tried numerous times without success adjusting cable free play etc., all the time following Steves instructions.
Any help would be appreciated.
Cagiva Alazzura
Posts: 703
Joined: Sun Sep 10, 2006 5:40 pm

Re: Carb balancing readings not making sense

Post by wdietz186 »

Make absolutely sure the choke pistons are fully seated. If the rubber seal in the bottom of them is deformed they will not seat/seal and you will have a vacuum leak and run really rich. Also make sure the idle circuits are clear[both holes behind the slide] through to the air vent in the front and the mixture screw down to the pilot jet. double check the float level too. Finally check the manifolds aren't leaking at the rubber joint at the head.
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