Hi Guys, just bought a lovely little 1995 750 SS and need some advice..
Firstly when i turn the ignition on the fuel pump runs full time, should this be the case??
Secondly, when the bike gets hot and coming to a stop in neutral the engine revs drop to 2000rpm for about 2 seconds then drops to about 1200rpm for tick over!!
The bike has a full service history with 14000 miles but i think it has been sitting for about 6 months...
Hi Marty, and welcome to the forum. I did over 96,000 kms on a '94 model, and modified it very successfully (and worked on this series of Ducati for many years) so I 'know the model'.
They are a good thing, and can be improved upon if you are so inclined.
Yes, you should hear the fuel pump pressurising continuously when you turn the ignition on. It doesn't create as much pressure as a fuel-injected model, but you will hear it going without doing that 'squark' sound that the FI models do when they achieve full pressure.
As to the idle 'holding up', then dropping, this could be a great many things, I'm afraid. Apart from the obvious over-adjusted throttle cable. (They need a fraction of free-play).
It is probably related to getting excess oxygen into the chamber somehow.
I would make sure the valve clearances are set correctly by an experienced Ducati tuner. A 'riding' rear exhaust valve can give that symptom, and is vital for your engine's well-being to have set correctly.
The rear exhaust valve is usually the culprit as:
1. It gets hotter than the front cylinder due to its situation, and
2. It involves the removal of the rear shock to set, and sometimes gets neglected by unscrupulous repairers.
Getting the valve clearances set correctly is worth doing on any second-hand Desmo Ducati you have just purchased.
If the bike still has original carbs (the Keihin FCRs are a popular and worthwhile mod) there may be an issue with the CV diaphragms, or a partial blockage in the jetting. These carbs are prone to this if left sitting.
And ensure that there are no air leaks between the carbs and the intake ports.
So there's a couple of thoughts for you to try. Let us know how you go.
These are a worthwhile and tough little bike. With suitable maintenance they will do a high mileage with minimal issues. Low-tuned and only 5-speed, they go forever.
Of course you can fit 900 cams and higher compression pistons , and the Keihin carbs, if you want more.
I have the same (almost) engine in my dual purpose bike ('95 Cagiva Elefant 750, also with the FCR carbs) and have been far into the outback on it with no support.
A good thing.