Jetting for Dellorto PHM 40

[ducinthebay]

I'm dropping a 900 motor into my 1990 Sport, and have aquired a pair of Dellorto 40 PHM carbs.
What is the recommended jetting?
Slides, needles, main, pilot, etc.
Thanks,

BTW, For some odd reason you can buy PHM 40's for about $100 apiece on ebay. Search Husqvarna carburetor, or Husaberg carb. They fit the 501 and 601 engines. I have a couple headed my way. I'll let you know how well the carburate.

[jcslocum]

Would the jetting from a 900 monster be approximatley the same??? I may have that manual laying around.

[ducinthebay]

That will certainly get me close. I can figure it out from there. Thanks,

Phil

[guzzitech]

This will get you in the ballpark. Check on a dyno or with plug checks top be sure. Adjust mains and/or needle position until it's spot on. I usually jet the rear cylinder one size (increment of 5) richer.

K4 needle, bottom clip
128 mains
68 idle
50/3 slide
265 atomizers

[ducinthebay]

Thanks,
The carbs I have now have 50/1 slides. What would be the difference in how they behave? Unfortunately, slides cost a lot for new ones, so I will try to make a go with the ones I have. ($70 each.) Stay tuned.

Phil

[guzzitech]

You have 50mm cutaway slides, and so does that recipe. Only difference is accelerator pump ramps (/number). Ramp action is fairly inconsequential.

Further, most twins I have seen with big 40mm carbs will go way lean anyway when the throttle is whacked open suddenly (what the accel pumps are supposed to correct for). You have to crank acccel pumps way up for them to have any meaningful effect.

ed

[dave906]

Hi Ducinthebay
I have only just seen this post, but have some info that may still be of use. I have a 906 with PHM40 Delortos. They were installed and setup for me by Gowanlochs in Sydney Australia and seem to work pretty well.

The info here is from my notes last time I gave the carbies a clean and I am away from my bike for a few years so I can't check anything else at present. There are some similarities with Ed's post so suggests things are on the right track.

Main jet 152 (Vertical) 148 (Horizontal) (Vert cylinder runs hotter due to less airflow so richer jet)
Needle K5 (clip on middle slot)
Atomiser AB265
Idle Jet 68
Choke Jet 60
Pump Jet 45
Float weight 1gr 8.5
Float Needle valve 250
Float height 18mm
Mixture Screw about 1/2 turn out or to suit.

cheers
Dave