Ducati.ms - The Ultimate Ducati Forum banner

1 - 10 of 10 Posts

·
Registered
Joined
·
4 Posts
Discussion Starter #1
recently bought a 500 pantah with rebuilt motor but cannot get it to run properly both cylinders are running very rich to the point where the plugs carbon up and fail. it does not matter where you set idle and mixture screws it still runs rich. have checked float levels all good there can anyone give me a starting point to sort problem
 

·
Registered
Joined
·
2,143 Posts
Hi,

I would say almost certainly that your problem is with the cold-start jets. If you don't know how they work, the choke cables lift plungers off of jets that allow fuel through to richen the mixture; these choke plungers have a rubber pad at the bottom that seals the jets and shuts them off, but the rubber deteriorates with age and lets fuel through. I would buy two new choke plungers and when fitting them, really make sure that the cables are slack enough to allow the plungers to sit on the jets to block the flow of fuel, because if the cables are tight, the plungers will be held off the jets and give you a rich mixture.
 

·
Registered
Joined
·
1,435 Posts
the plungers can get tight in their holes too. and i saw one recently where the fuel drilling was off centre, so the wear lump in the rubber at the bottom of the plunger wasn't in the middle, and removing then refitting it meant it was very hard to get it in the right place to seal. new ones are cheap.

aside from the choke plungers, worn needles and needle jets will foul plugs. worth doing to an old bike anyway.

what are the float levels?
 

·
Registered
Joined
·
343 Posts
And be aware that it's a job that needs to be done with a certain degree of ... delicacy. The needle needs to be just closed. And that can be more difficult to judge than you might imagine ....

The best way to do this IME is to:
a) Use a gauge to measure the height. Using a rule or tape is too chancy.
b) When you take the measure, be blowing lightly down a tube that you've connected to the fuel inlet so you can judge exactly when the valve closes.

HTH and apologies if I'm teaching my grandmother how to suck eggs ..
 

·
Registered
Joined
·
1,435 Posts
i just hold the carb with the inlet facing up so the floats fall onto the needle and measure with my little snap on rule to the back of the float. seems to work.
 

·
Registered
Joined
·
1,435 Posts
you can test them easily. remove the float bowl, hold the float up and turn the fuel on. let the float drop so the fuel starts flowing, then lift again - fuel should stop. if it doesn't, replace. or use a mityvac to vacuum test them.
 
1 - 10 of 10 Posts
Top