Next issue with my 99 m750

[timmer357]

Okay folks, thanks for the help on my starter solenoid issue.  Next...

The bike just seems to run like crap and I am wondering if it is the jetting being off or what.  I can let it warm up forever and it stills does the same crap.  Here are the symptoms:

Start it with the choke on full.  Warm up for a short stint and then start to back it off.  If you back it off all the way within the first 20 minutes (seriously) of riding it will die without revs.  If I ride it the choke has to be at least moderately engaged but then it is lurching and jumping corning.  Back it off all the way and it dies at lights and bogs BIG TIME under power.  Mainly freeway cruising in 4th and 5th gear it will almost die when I give it throttle if the choke is turned off.

It has been in the upper 30's to lower 50's for temp outside when I have been riding it.  The previous owner claims it will do better once it warms up here in Oregon but that seems unreasonable that it would be this bad. 

Any ideas?

[needtorque]

Well there are two things about that model.  If maintained and jetted properly the stock carbs are ok but the emulsion tubes and the needles tend to wear and need replacing.  If you struggle with this type of thing take it to a mechanic and have him check out the carbs.

The other thing is the coils.  They are not so great.  Dana coils are better and Chris at cacycleworks will give you a good price on those if you need to replace them.

He also carries another carb option, the FCR flat slides, which are much much better than stock.

You are going to have some money in this before it is all said and done but it will run so much better if you spend the money to fix it correctly and don't just patch it up.  Get a service manual for you bike.  Actually, I have a service manual from my 01' m750 which was also carbed and would apply to yours for the most part. (if you want it) Learn how to work on the bike yourself if you don't know already.  It is carbed so you will have a much easier time with driveability problems than if it were FI.

[Howie]

You definitely have a problem.  If your bike has stock jetting it will be cold blooded, but not that bad.  Simple stuff first:

How fresh is the fuel?
When is the last time the bike was serviced (if the belts are over 2 years old, change them)?
Fuel filter clean?
Fuel or vent lines obstructed?

Then look at the carbs.   

[Stangman]

Take a look at your spark plugs and change them if they look worn.

Dyna coils made a big difference on my bike too, starts easier and low to midrange is better.  Also, I when I had my bike tuned last year they replaced the emulsion tubes and he kept the old ones and showed them to me.  They were worn pretty bad (13,000 miles).  No hesitation now what so ever at low rpms or coming out of a turn anymore like I used to get.

[Duck-Stew]

Also, if the bike has spent some time just sitting.  It's likely that the fuel wasn't drained properly.  Since it's possible (read: probable) that the sitting occured on the side-stand, the fuel from the pet-cock onward (including both float bowls) will make it's way into the left float bowl (vertical cylinder) and will gum-up the low-speed or idle jet.

In addition to changing the plugs (don't bother just looking at them as they're cheap enough and sometimes a look doesn't catch a problem), when it is running try to determine if one exhaust pipe (near the head, and careful you don't get burned) is hotter than the other.  That would indicate that one cylinder is having a problem.

If it has sat for a while (even a couple months will do it really...), it is likely that fuel has gummed up the carbs to some extent which could be a very likely candidate for those symptoms.

[timmer357]

Decided to take it back to local mechanic (non-Ducati specific).  He is reasonable with pricing and he will undoubtedly do a great job making her smooth again.  The Ducati shop north of me suggested emulsion tubes, as did the local fella being that the bike has 27k miles.  We'll see about this time next week what the issue was.  Thanks for the help folks.

[Porsche Monkey]

Where is a good source for emulsion tubes other than the dealer?

[mxwinky]

Check Factory Pro out.  They have really nice jet kits and parts for these bikes.  You can order from their website and it'll get your bike sorted out.  Certainly at 27k miles this is a must-do if you ever want it running correctly.  Of course the Keihin FCR carbs and Dyna coils are the ultimate answer if you want your bike to really rip.  Let your wallet be your guide.

[clubhousemotorsports]

As you are describing a lean condition the elmusion tubes will not help.

It sounds like you had fuel clog up your pilot jet circuit, your mechanic should do a thourough cleaning of the carbs and make sure you have the proper pilot jet for your motorcycle. Some bikes use a 37.5 others use a 40pilot.

The clue is that it runs with the choke on, feeding the bike fuel it needs to run where with the choke off you are leaning out enough to kill the bike.

pilot jets
float height

[timmer357]

Mechanic said it was simple carb issues and it was pretty affordable.  Problem is that they found the next problem.  The tank is leaking and the doughnut head that had it before me tried to patch it with bondo which obviously didn't work.  Damn this thing is a pain and I haven't even put 25 miles on it since I bought it.

[ducpainter]

Mechanic said it was simple carb issues and it was pretty affordable.  Problem is that they found the next problem.  The tank is leaking and the doughnut head that had it before me tried to patch it with bondo which obviously didn't work.  Damn this thing is a pain and I haven't even put 25 miles on it since I bought it.

Tanks can be fixed.

[clubhousemotorsports]

LOL... even when doughnut heads use bondo to try and fix a leak.

Right DP?

[Howie]

If you want your tank to be better than new send it to the guy who said "Tanks can be fixed".

[timmer357]

If you want your tank to be better than new send it to the guy who said "Tanks can be fixed".

If I could afford it, I would.  Having my whole bike repainted is tempting with the tank needing to be fixed anyway.  I have those ugly silver wheels and bronze frame though.  It would have to be some sort of bronz/gold/brown custom job. 

The point of this bike was to downsize from my Thruxton that I am trying to sell.  At the rate I am going, I will have more into the old Duc than the 8 month old Thruxton is worth.