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Wed Jul 03, 2013 10:21 am

Hello, I have a question for you I'm at the final stage of the engine.
engine:
74x94mm
W130
Scat 1,25:1
40x35,5 SS full ported
CR:10,8
Dellorto drla 40 (at the beginning)
mellory ignition

Carburetors are standard,What the Jets use in these Dellorto ??

Venturii.main jet, fuel jet .....itp/

Thank you best regards

Wed Jul 03, 2013 10:56 am

Id start with 60/145-if 34 vents & 200 air corrections. 9164.2 emulsion tubes. 50 pumps.

Wed Jul 03, 2013 11:51 am

I agree with the recommendation.

Also, those carbs are plenty good to supply the air/fuel for your combo.
No future upgrade needed IMO.

Plenty of 150-160 HP naturally aspirated engines with 40 dells.

Wed Jul 03, 2013 12:03 pm

Do You Recommend DRLA update kit CB7345 or not ??
improve performance?

What powers can be get with this engine configuration ?

Wed Jul 03, 2013 12:19 pm

I'm looking on Dellorto site and:

DRLA 40 Venturi / choke 34mm
7644 idle jet size 60
7484 main jet size 145
DRLA Emulsion tube 9164.2
7485 air corrector jet size 200
7851 pump jet size 50

everything is good??Do I need something else?

Wed Jul 03, 2013 1:39 pm

Don,
Dont buy anything till u se whats in there first. Start pulling stacks and your pump jets first. The jet doctors are a worthwhile buy.

Thu Jul 04, 2013 2:58 am

Thank you for your help

will I need any other jet sizes for calibration?What gives Ubdate kit on dellorto, is it needed??? whether it is a superfluous addition?

Ihave now on my dellorto:

main jet 118
idle jet size 46
pump jet size 35
Emulsion tube 9164.1
Air corrector (long) 175
Starter emulsion tube 7482.3
starter jet size 95
Venturi / choke 28mm (can I use a lathe to do 34mm venturi?? )

Sorry for the spelling :)

Thu Jul 04, 2013 3:01 pm

The "update kit" is different venturis and different auxiliary venturis. Please do NOT buy this. THe purpose is to have more airflow, but it will not fit, and is no as good as using larger size carburetors.
Your carburetors are not the same as those sold in the USA, ours have different type of auxilliary venturi.

yes, you can use lathe to make the venturi 34mm.
Your emulsion tubes are ok also, only difference between #1 and #2 is one hole at the top, this hole can be drilled or soldered closed to change between #1 and #2.

Thu Jul 04, 2013 4:11 pm

Don,
Do what Modok says to do but buy the 200 air jets, I have a feeling you will need the 50 pumps but can try to use the 35s in the mean time. 60 idles and dont worry about your choke starter circuit unless you intend to rig something up to accomodate cold starts. Wire it closed permanently if not using. The only part i consider worth to use on the update kit is the jet doctors which you can buy seperately. But if you dont plan to drive on dirt roads, then you wont need it. Venturis are 9$ US a piece, if its cheaper to use a lathe then do so.

The emulsion tubes you can either solder and jet as normal or leave as be and step your idle down one and step up your main jet one.
So If I were you since you need to buy jets anyway, buy:
4x 55, 4x60 idles
4x 135s and 4 x 140s
open your vents to 34 with a lathe or buy the ones on CB performance site
4x 200 air and 4x 50 pumps

Sat Jul 06, 2013 3:14 pm

Everything is order parts I have to wait two weeks for delivery:), some tips when first activating the engine??

Thank you very much :)

Sat Jul 06, 2013 6:36 pm

dondiegozalabamy wrote: Everything is order parts I have to wait two weeks for delivery:), some tips when first activating the engine??

Thank you very much :)

Sometimes when a carb set sits for a bit, the fuel circuits leading from the pump diaphram to pump jets gets plugged. Be prepared to have to take the top base cover out and spray some carb cleaner down above the brass plunger. Its always better to hand prime the fuel in too before you start to make sure its pumping fuel. Sometimes the passage leading from the float bowl to the diaphram is plugged and needs some compressed air coaxing to allow fuel in. Etc etc. PITA carbs really but once you get em dialed in, they work very very well.