Dellorto adjustment for altitude

Post your 'Carburettor & Fuel System' FAQs, comments & questions regarding Ducati motorcycles here.
Post Reply
Charlie
Cucciolo - the Lil Pup
Posts: 4
Joined: Wed Jun 29, 2011 8:53 am

Dellorto adjustment for altitude

Post by Charlie »

I've moved from sea level to 8000 ft, and need to re-jet. I have a Laguna Seca with a Dellorto PHM40.

(I tried dropping the needle one step and that was no good. Then - duh - read the Dellorto tuning manual and they say "reduce the jet size")

I went to a bunch of local shops.. no one is familiar with Dellortos. One guy had a Kehin chart that showed a 25% drop in jet size. All in the end said - just play with it and read the plug.

I'd like to know if there is a chart from Dellorto, and if not, where should I start? down 25%?

How 'bout the idle jet?

Interesting, that the local knowledge says I might have to richen the idle jet some. WTFO?

Right now what's in it is 145 main & 75 idle.

Grazzi!!

Charlie
Charlie
Cucciolo - the Lil Pup
Posts: 4
Joined: Wed Jun 29, 2011 8:53 am

Post by Charlie »

FYI,

Here is where I ended up. Took a 10 mile ride, and performance was good, and reading spark plugs showed I was at least close.

Slide: 70/1 (OEM = 60/1)
Main Jet Front Cyl: 145 (OEM = 148)
Main Jet Rear Cyl: 152 (OEM = 155)
Needle: K5 (Same as OEM)
Atomizer: 265 (Same as OEM)
Pilot Jet: 75 (OEM = 65)

Not as big a change as I had originally thought!

Charlie
Post Reply

Return to “Carburettor & Fuel System Shop”