Forum

[simon]

I've finally after countless hours of fiddling around have finally got the 11/8" 389 working perfectly on the 350 Bullet (Bitsa). The final victory came with the replacement of the slide with a no.3 cutaway which has completely cured the flat spot between idle and power. It's been a fascinating process and made me understand how phenomenally adjustable all facets of the carburation are.

[Mark M]

It is isn't it, it's not 'til you really get into it that the complexity is apparent. I spent about a year getting some Del 'Ortos to work properly on a Guzzi once but the results were brilliant. Mind you, the Ortos have a staggering range of different values to virtually every component, unlike Amals which are quite simple really, and nothing wrong with that!
REgards, Mark

[Norm]

Hi Mark, I put a Del "Orto on a 612 a couple of years ago, it was ordered for a 612, put it on kicked it over, started straight up and have never had to touch it again

[simon]

Just in the process of a prolonged struggle with a pair of Delorto PHF32's on the 860 GT. I've put a new set of 87mm pistons in it which take it out to about 890cc from the original 864cc. Consequently the mixtures are all over the place and the unleaded stuff is so difficult to tune to. Still nearly there now.

[Alan R]

These are good---------- http://www.simonbbc.com/tools/gunson-co ... arb-tester --------------

[simon]

It's easy to say but it all sort of starts to make sense in the end even without a colour tune or an exhaust gas analyzer. The slide issue was solved by changing the 3 1/2 slide for a 4 and discovering that the flat spot got worse. Logic said that I should try a 3 and Bob was my uncle. The truly tricky thing was the miscellany of little things that were wrong that masked the main issues in the beginning. For instance I initially changed the slow running jet for one out of a 1" 376 that I had on the shelf and it appeared to make and improvement but it didn't last so I reversed that procedure. what i didn't realize was that i also had a slight head gasket leak so all tuning was a waste of time. I finally sussed it because of a slight oil seepage and painting a mixture of detergent and water on the join between the head and the barrel when idling proved it with bubbles. The trouble with these machines is that they will run and perform ok even with a host of little issues. It's both a blessing and a curse really.

[PeteF]

Simon,
Could you list the full specs for your set-up?

[simon]

Will do. I'll just have to check on the size of the idle jet. Watch this space. S:)

[apparently lucky eddie]

Simon, I hope you've done the extra stud mod. on the rear sprocket of your Duke - it will be quite embarrassing when the originals give way and leave you with the chain turning a loose sprocket and the wheel not turning

[simon]

I drive the Ducati with a fairly light throttle so nothing is terribly stressed. What is the extra stud mod though and where would it go?