Gregory Bender

Dellorto PHF 32 carburetor jetting for the 850 T3

Moto Guzzi V7 Sport, 750 S, 750 S3, 850 T, 850 T3, 850 T3 California, V1000 I-Convert, V1000 G5, 1000 SP, Le Mans, Le Mans II, Le Mans CX 100, Le Mans 1000, 1000 SP III, 1000 S, California II, California III, California 1100, California Jackal, California EV, California EV Touring, California Aluminium, California Titanium, California Special, California Special Sport, California Stone-Metal, California Stone-Touring, California Classic, California Touring, and California Vintage models



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Thanks to Doug Foskey for sending me this information in a private e-mail. This information originated with Bob Dickman (California) and was shared with Pete Roper (Australia) who forwarded the information to Doug Foskey (Australia), who then sent the information to me (Arizona). It is - indeed - a small Guzzi world. I shared a hotel room with Bob Dickman at the 2010 Moto Guzzi Grappa Gruppo Gathering in Baker, Nevada and I met Pete Roper at the 2004 MGNOC national rally in South Dakota. Hopefully someday I'll meet Doug as well. Thanks to Bob, Pete, and Doug.

Bob's note to Pete explaining things ():

YOU want info from ME? Gee, gotta tell everyone I know. (Just kiddin'.) Below is documentation for what I did on my T3 with the 32 PHF's. This bike runs beautifully, very smoothly & willingly up to 6500 RPM or a bit more. Not as much peak HP as my big valve 1000S (I know you prefer the small valves anyway), buy way more seat of the pants willing over 4500 than with stock VHB's. I get about 40 MPG (US, not Imperial) no matter how I ride it, just cruising or flogging it. Since my 1000S, 40 mm pumpers & all, gets 45-50 MPG consistently, seems like I should get better than 40 with the T3. Somewhere along the line I was going to try AB264 needle jets in the T3, see if that got me better mileage without a significant HP hit. Haven't got around to it yet - probably because it is such a joy to ride as it is. One other mod besides what is mentioned below - sometime after I changed carbs, bored & sleeved out to (approx) 1,000 cc. This was of course not the Gilardonis, rather forged Mahle pistons that Moe at Cycle Garden gets somewhere or other, come flat top, & Moe had some local machine shop custom cut the tops to more or less match the stock piston shape. As far as I can recall that did not create a big jetting issue. Just for my curiosity, how were these female inlet carbs mounted on your 850 T? Mine has the stock metal intake manifolds welded up like with a metal donut, then cut down to accept the 32PHF's as I got them.

Just, just barely clears the starter solenoid/tranny case, with the big, angled oval K&N's tucked neatly away under the tank where the stock air box used to be. Very neat, glad I had someone else to do it for me.

Hope this saves you some time. I'd be interested to here where you wind up jetting the T.

Bob's carburetor specifications ():

My bike runs very well, except for a very slight, usually subtle just off idle hesitation when I bring the throttle down almost to idle, then bring it slowly back up. (SEE BELOW-SOLVED BY REPLACING K6, OTHERWISE FINE, WITH K1) It is most noticeable in top gear at freeway speeds, not noticeable at all when ridden hard. Compared to the square slide 30's the bike came with, I lose 10 MPG & a little low end, say below 3500 RPM. I think it is about even 3500-4200, then all plus from there on up, esp over 5000 RPM. Below is the jetting I have, & have tried. This bike retains stock cam, exhaust & heads, except for being lightly ported. It has been twin plugged - but that does little except put money in Charlie Rice's pocket - truly an evil result. I do have K&N air filters & Dyna ignition.

Idle jet
55 (have been as high as 62)
Main jet
150 (was 122 before I converted from 850 cc to 1,000 cc)
K-1, middle slot. (Replaced K6 with K1 on , at 135800 mi, solving remaining off idle hesitation problem.) This was really the big thing. Carbs came from bevel drive Ducati with K-16 - almost unrideable, no low end whatsoever. Also tried K3, K5, then K6 for a long time until .
Needle jet
Choke jet
Spray needle
38 (tried 35)
Float Weight
Float position
18 mm
Float level
65 cc
60/3 (tried 70/2, 50/3, made 65/3)
Float needle
250 Idle screw-short, pre-EPA

Additional details from Bob when I asked him about publishing his data ():

  1. In order for the bigger than stock 32 PHFs to (just barely) clear the starter solenoid on the left side you have to double up the gaskets between head & intake manifold. Not necessary on the right, though you can also double up if you think that preserves some sort of balance. I think it makes no noticeable difference.
  2. I mentioned in what you already have that the change to 32's cost me about 10% gas mileage. Initially it went from mid 40's or so with stock VHB's to 39-40 MPG. Later on it went back up to mid 40's, sometimes even close to 50. So that makes the change all plus.
  3. Finally, the 32 PHF's require a different cable than do the stock VHB's. On my T3 FB, with the high & wide police type bars that meant getting completely one off custom cables made. Can't really remember the details, handled by a long gone bike shop. I have since made a spare by having a local vintage bike shop copy them. On a regular foot peg T3 with the more standard type bars there might be something stock on some other model that might work. Maybe.
  4. I am really happy with the jetting as finally worked out. In theory the 150 mains seem too big - on my big valve 1000S with 40 mm PHM carbs I went from 145 mains down to 128. So someday I might try smaller mains in the 32's. Or not - it really runs well now. To change jetting on the right side is easy - but on the left side you have to either pull the 2 starter motor bolts so you can drop the starter down - or pull the 3 intake manifold bolts to lift the carb up. Not really hard to do. Oh, yeah, not all that hard to strip those intake manifold bolts out - though fairly easy to helicoil repair.