Hey there Guest!
Hey - did you know if you click on the title of a thread it will take you to the first unread post since you last visited that thread?
but were afraid to ask: 
STOP!! Never post your email address in open forums. Bots can "harvest" your email! If you must share your email use a Private Message or use the 
smilie in place of the real @
Pretty Please - add it to our Events forum(s) and add to the calendar! >> 
twas_brillig
Jedi Knight
Offline
Jetting Weber DCOE for 948 and 1275 cc
Further to my Dec. 12/08 note requesting help in “Jetting a Weber 45 DCOE for a stock 1275 cc", I’ve listed what is currently in the 40 DCOE on our stock 948 cc Bug-Eye (it’s been a reliable set up for several decades, but not a lot of miles at our 3600 ft. elevation) immediately below, plus the Haynes Weber recommendations, and then thoughts from "scubabatdan”
Stock 948 cc; goose-neck manifold:
30 mm = Choke
4.5 = Aux Venturi
135 = Main Jet
175 = Air correction Jet
F2 = Emulsion Tube
45 = Pump Jet
45F9 = Idle Jet 45F9
?? = Ex.Valve (there were absolutely no markings on this one; I pulled the same thing out of the 45 DCOE that prompted this whole escapade, and it had a number but no joy on this one in the 40)
**************************************************************
What the Haynes Weber Manual recommends for all Mk. 1, 2, & 3 Sprites and Mk 1 & 2 Midgets, which I believe are the 948 and 1098 cc engines:
32 mm = Choke
5.0 = Aux Venturi
1.40 = Main Jet
1.80 = Air correction Jet
F16 = Emulsion Tube
0.40 = Accelerator Pump Jet
0.45F6 = Idle Jet
.50 = Accelerator pump inlet valve with exhaust orifice
What the Haynes Weber Manual recommends for Sprite Mk 4 and Midget Mk 3s (1275 cc engine):
34 mm = Choke
3.5 = Aux Venturi
1.30 = Main Jet
1.75 = Air correction Jet
F2 = Emulsion Tube
0.50 = Accelerator Pump Jet
0.5F9 = Idle Jet
.50 = Accelerator pump inlet valve with exhaust orifice
*************************************************
And what scubabatdan (2008-12-15 21:28:47) was good enough to advise of in response to my earlier cry for help:
Here is a setup for a stock 1275 DCOE45
33mm = Choke
3.5 = Aux Venturi
155 = Main Jet
185 = Air correction Jet
F2 = Emulsion Tube F2's are made for top end according to the weber plant
50 = Pump Jet
45F9 = Idler Jet 45F9
50 = Ex.Valve
Might be a good place to start...
Here is what I have in my DCOE40 for my 1275:
30mm = Choke
4.5 = Aux Vent
120 = Main Jet
190 = Air correction Jet
F16 = Emulsion Tube
40F8 = Idler Jet
35 = Pump Jet
Plugged = accelerator pump discharge
***************************************************
The carb I’ve got that I’d like to put on the forthcoming 1275 currently has:
33 mm = Choke
3 = Aux Venturi
1.35 = Main Jet
1.65 = Air correction Jet
F16 = Emulsion Tube
0.35 = Accelerator Pump Jet
0.50F9= Idle Jet
.50 = Accelerator pump inlet valve with exhaust orifice
I think I’ll follow scubabatdan’s advice and just bolt ‘er on and see what happens….
Further to my Dec. 12/08 note requesting help in “Jetting a Weber 45 DCOE for a stock 1275 cc", I’ve listed what is currently in the 40 DCOE on our stock 948 cc Bug-Eye (it’s been a reliable set up for several decades, but not a lot of miles at our 3600 ft. elevation) immediately below, plus the Haynes Weber recommendations, and then thoughts from "scubabatdan”
Stock 948 cc; goose-neck manifold:
30 mm = Choke
4.5 = Aux Venturi
135 = Main Jet
175 = Air correction Jet
F2 = Emulsion Tube
45 = Pump Jet
45F9 = Idle Jet 45F9
?? = Ex.Valve (there were absolutely no markings on this one; I pulled the same thing out of the 45 DCOE that prompted this whole escapade, and it had a number but no joy on this one in the 40)
**************************************************************
What the Haynes Weber Manual recommends for all Mk. 1, 2, & 3 Sprites and Mk 1 & 2 Midgets, which I believe are the 948 and 1098 cc engines:
32 mm = Choke
5.0 = Aux Venturi
1.40 = Main Jet
1.80 = Air correction Jet
F16 = Emulsion Tube
0.40 = Accelerator Pump Jet
0.45F6 = Idle Jet
.50 = Accelerator pump inlet valve with exhaust orifice
What the Haynes Weber Manual recommends for Sprite Mk 4 and Midget Mk 3s (1275 cc engine):
34 mm = Choke
3.5 = Aux Venturi
1.30 = Main Jet
1.75 = Air correction Jet
F2 = Emulsion Tube
0.50 = Accelerator Pump Jet
0.5F9 = Idle Jet
.50 = Accelerator pump inlet valve with exhaust orifice
*************************************************
And what scubabatdan (2008-12-15 21:28:47) was good enough to advise of in response to my earlier cry for help:
Here is a setup for a stock 1275 DCOE45
33mm = Choke
3.5 = Aux Venturi
155 = Main Jet
185 = Air correction Jet
F2 = Emulsion Tube F2's are made for top end according to the weber plant
50 = Pump Jet
45F9 = Idler Jet 45F9
50 = Ex.Valve
Might be a good place to start...
Here is what I have in my DCOE40 for my 1275:
30mm = Choke
4.5 = Aux Vent
120 = Main Jet
190 = Air correction Jet
F16 = Emulsion Tube
40F8 = Idler Jet
35 = Pump Jet
Plugged = accelerator pump discharge
***************************************************
The carb I’ve got that I’d like to put on the forthcoming 1275 currently has:
33 mm = Choke
3 = Aux Venturi
1.35 = Main Jet
1.65 = Air correction Jet
F16 = Emulsion Tube
0.35 = Accelerator Pump Jet
0.50F9= Idle Jet
.50 = Accelerator pump inlet valve with exhaust orifice
I think I’ll follow scubabatdan’s advice and just bolt ‘er on and see what happens….
A friendly reminder - be careful what links you click on here. If a link is posted by someone you don't know, or the URL looks fishy, DON'T CLICK. Spammers sometimes post links that lead to sites that can infect your computer, so be mindful what you click.