[Ducati] NDC- possible carb issues with CCM? Help please

[Garth Williams]

Rich,

I'll check all of the vacuum routing, but I don't think that much has
changed. I've removed the carb several times to clean and inspect, usually
with nothing much going on inside.  I've not changed any jetting whatsoever
and the bike ran fine before I started fiddling with things.  For that
matter, A/F screw is in the same position it's been the whole time (now,
after I returned it to what it was).

So, all jets are the same.  Hose routing is generally clear without kinks.
Carb is clean internally.

This is a typical petcock/vacuum fuel delivery-type setup and it starts and
initially runs fine.

Again, any suggestions are appreciated!

Garth

On 10/1/07, Rich Roberts <bigredxrunner at yahoo.com> wrote:
>
> Hmmmmm, these sorts of things can be so many causes, but my focus would be
> the carb, how is breather on bowl routed? how does fuel get from tank to
> bowl? Vacuum style petcock? Pump? Is all of that in order? When you pull
> carbs what do you do? I ask because I have a DRZ400SM and the slow jet has a
> real tendency to clog, also the original location of vaccum for petcock was
> sorry routing and it would pinch and you would lose vacuum to petcock
> erratically which will eventually cut off fuel flow. I ended up rerouting
> entirely and after running kehein CRs and Yosh ti pipe sold all and went
> back and rejetted the stock carb with much success. Do not forget slow jets
> have a huge imact on jetting that is often overlooked as jets somewhat
> overlap. a poorly chosen slow jet can cause top end issues. I saw this on a
> NSR 250 years ago, mains, needles nothing would correct the fact it just
> would not pull in high gear, it would fall flat on its face, upsized the
> slow jet
> and miraculous recovery. Also some of these small jets are esp sensitive
> to the minutest of crap. I cleaned the original slow jet on the DRZ a number
> of times, each time it would be fine for awhile and then....same symptom.
> starting problematic needing excessive choke, throttle response sucks etc
> etc. So the point, look at carbs closely, clean them out well. granted pilot
> air screw can have a profound effect esp if slow jet is right size. if not
> the air screw will just be crap to crap or little to no effect. get it close
> and you will see the effect in and out. Also sometimes you have a couople of
> jet options, depends on how many turns of the air screw you make, esp if
> sizes in 2.5 increments like you find on some small jets.
>
>