CB200 carb issues

[Johnwebley]

Get the 500 out JW. You know it makes sense.

Did about 25 miles on the 500,

Like riding an electric motor,


The 200,after removing caps to measure, and refitting carefully ran  better,

Under load full throttle nearly 7k,

Pull the clutch in,revs increased to 9k but not rapidly,

Coming back down a slope it revved to nearly 8k on two thirds throttle, pulling the clutch in,the revs shot up to nearly 10k quickly

Your thoughts, gentlemen

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[Oddjob]

You checked for an air leak John?

[K2-K6]

Initially sounds lean at top end.

[K2-K6]

Any plug colour after it's been running at full temp ?

[Oddjob]

Without trawling through the whole thread have you checked the jet sizes to see if they are standard? Same for clip position, it's an old bike and old owners could have altered all sort of things back in the day.

[Sesman]

Definitely seems to have moved to fuelling.

[Johnwebley]

Okay

Standard jets
Full standard air cleaners



I thought lean,so I operated the choke, no benefit

New manifold and carb O rings



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[Oddjob]

Is clip position alterable?

[Johnwebley]

Is clip position alterable?

Tried it previously


Lifted the needle one slot,

Sooty plugs and rough running
also tried  95 MJ instead of 88,  no difference,

sure the spark is not failing under load?





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[K2-K6]

Mixed signals in whats happening there John.

Obviously, as noted by Ted, the only real way of eliminating the coil conclusively is by substitution to assess that effect.

Try running it in the dark to see if you're getting any HT leakage, I've been caught out on some leads like that before, seemed to function well but looked like a hairy caterpillar in the dark  they were leaking a fine "mist" along entire length in damp air.

[Johnwebley]

Yes,

So far, every thing apart from the points has been renewed

Plus MJ and needle moved and adjusted

Really confusing

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[Johnwebley]

Right, issues cleared,out for a fine weather run,now running sweetly

I  replaced the coil with a cheap Chinese replica, £13 from Aliexpress,3.5 ohm primary circuit

Checked the cables to the condenser,
Fitted X24 Denso

Lo and behold, it finally ran as it should




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[McCabe-Thiele (Ted)]

Pleased to read it was sorted with an inexpensive coil fix.

[Johnwebley]

Pleased to read it was sorted with an inexpensive coil fix.

Thanks Ted,

That's after mega bucks NOS airfilters,

Coils with higher resistance

Carb jets

Boy,it was a money pit

But glad I sorted it

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[McCabe-Thiele (Ted)]

Yes but you did need some air filters did you not?
We've all done it with petrol engines have we not?

I had a Manta GT/E that was a pig to start in winter having an early design Bosch fuel injection system. I started with plugs then plug caps then plug leads then coil. Changed the fuel filter then finally found a bad connection on the cold start injector. A squirt of contact cleaner - all sorted.