Ran ok then lost the plot

[Impman71]

Hi,
I have a 93 that I picked up a month or so ago as a non runner, it had been off the road for 5 years.
A wire was that badly corroded on the ignition switch plug that it had dropped off.
Sorted this, drained the petrol, cleaned & synced the carbs & cleaned up brake calipers & got it through an mot.
It would start fine, but the revs wouldn't drop quickly & I was told the mixture was too lean for the non standard can I have.
In order to get the revs to come down nicely I ended up going to 3 turns out on the pilot screws from 1 3/4.
I rode it to work yesterday & it was a bit hesistant on small throttle openings, so I guessed the screws needed winding back in a bit.
Riding home this morning, the first 4 miles were fine, then it lost the plot - had to keep the revs really high & just made it home!
I have had the plugs out this afternoon & they were very sooty, so I have obviously made it too rich & gone to 2 turns out.
It refuses to start, I get the very occasional backfire, but that is it
I am getting a spark & the plugs are getting wet, I'm at a bit of a loss!
I'm guessing that this is electrical rather then a fuelling issue.
Any ideas, please

[RedexRobB]

have you cleaned and reset the gaps on the plugs? Might be worth trying the original mixture screw settings. Not sure what you mean by the revs dropping too quickly though?

[Impman71]

Sorry for my delay in replying!
The revs would hang & slowly drop to tick over when you let go of the throttle, rather then drop quickly.
I have just downloaded the manual & if it isn't peeing down next week (some hope! ) I am going to take the rocker cover off & check that the valve timing is all lining up okay & that the chain hasn't jumped.
I never heard any bad noises & it sounds okay when cranking it over, but figure this is a good place to start.
If this is all okay then I plan to check my cdi against the readings in the manual with my test meter.
Cheers,
Colin

[RedexRobB]

Ahh, the revs are hanging then. Thats a fairly common problem and is usually down to an air leak. The inet rubbers (bits between the carbs and the head) usually leak at the surface between the rubber and the head and can be temporarily fixed with a little bit of sealant. But check your clamps are done up tightly round the carbs and the air box is properly seated first. You can try spraying a bit of carb cleaner round the inlet rubber while the engine is idling, if the revs change then thats definately your problem.

[masterofinsanity]

id be inclined to stick a new set of plugs in as well.

[Impman71]

I'm going to get a new set of plugs when I get paid.
The bike had stood 5 years & I don't know how many miles they have done.
It's just weird that it was riding fine, then really lost it. In total I rode about 20 miles from getting it running after it's layup to it going wrong.
I also have an old ignition switch that I want to look at, I know it doesn't work - dash lights come on & it cranks, but no spark with this one, so I want to take the back of it (if I can) & check the connections & also the resistor, to eliminate it being the ignition switch.
Will keep you posted.
Cheers,
Colin