rich then lean (New to this)

Correctly servicing the Carburettors on these bikes is paramount to good running and fuel economy so any work done will pay back in better mileage :)
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rich then lean (New to this)

Postby newt500 » Fri Nov 22, 2013 3:50 am

Recently rebuilt carbs on a 1979 cx500, adjusted valves, and synced. Everything was great until today, started the bike and fuel came pouring out of the left float bowl. Removed and cleaned, leaked stopped but now runs firing on one cylinder, if your ref theres some throttle lag, then release the throttle the other cylinder kicks in. If you apply choke, both fire then it switches and the other (previously not firing cylinder) fires and the initial cylinder stops. This would mean that on start, the left cylinder is running rich and the right lean, then choke is applied and the right becomes strong and the left becomes to rich? If i shoot some throttle body cleaner into the air box while its running, both cylinders fire nicely and the throttle lag fades.

My questions are, is it bad to have the fuel mixture screws set unevenly to fix this, and would it even help (they are currently 2.5 turns out)? Is this still a cleaning issue, clogged low jet in the non firing cylinder? When hooked up to a bottle manometer they are perfectly balanced at idle and slightly uneven at high revs)

Thanks for your help, I am well and truly lost here!!!
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Re: rich then lean (New to this)

Postby Gman » Sat Nov 23, 2013 10:07 pm

It's not a problem if you have the mixture screws uneven so long as they are not massively different.It is better,of course,to get the carbs and the intakes etc as close to 100%.

See these links, ... bMain.html ... floats.htm

The most common fault after working on these carbs is to introduce an air-leak problem at the carb boots on reassembly.If you get full performance and the plug colours are even after running the bike under load and hot an checking them them then no worries.I take a plug spanner out with me and pull into a safe parking spot once the engine has reached running temps e.g the small line on the Temp gauge.Then whip the plugs out and check they are a,"Tan" colour.Care taken as they will be hot.
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Location: Hull.Yorkshire.UK.2x1980 CX500ZABs:Citroen ZX TD(250,000 miles)

Re: rich then lean (New to this)

Postby newt500 » Sun Nov 24, 2013 8:46 pm

Great links, thank you!
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