i was wondering does that carb gives you guys problems in cold starts? whats your guys' routine for starting it up when the engines cold?
is it daily driver friendly or more of a race setup carb?
and last, what would be the best setup carb for a large port 12a daily driver?

 

 

it'll be fine for temecula. cold starts pump it 5 times, turn key, cross fingers. enjoy the smoke cloud. it'll stumble for the first minute minimum, feather the pedal. spark plugs in 7 or 8 heat range really helped out cold starts too - retain heat and keep plugs cleaner.

very daily driver friendly, once motor is warm it'll scoot. the cold start routine can get annoying sometimes but i call it CHARACTER.

RB has jetting specs in their catalog and on website. they don't go over idle or accelerator circuit though. 120 idle jet holder (comes with new carb) and 70 idle fuel is too rich, 120 and 65 is too lean. I'm gonna try 100 idle jet holder and 65 to compromise.

accelerator circuit, the new made in spain carbs come with 50 pump jets too lean. push gas pedal and engine bogs, studders, hesitates. once main circuit comes online then it's fine. i've drilled out to 55 and 60, better but not crispy. just drilled to 65, will drive it in a week or 2 to try it out.

lastly, some peoples will say to run 42mm or larger chokes. which work great at 5000rpms and higher but BOGS below that. great for drag racing. try out the 38mm's, much better fuel atomization, low and mid range rocks and it still pulls hard above 5k.

 

this post should be archived!
100% accurate and well explained !

 

Got to disagree on that one. You can eliminate the bogging with larger idle jets.

 

wacky, larger chokes decrease intake velocity, decrease fuel atomization, and ^ bog. larger idle jets richen up idle, progression, steady state operation and even blend into lower end of the main circuit.

but larger idle jets doesn't eliminate the large venturi bog. i respectfully disagree.

 

drive fast7 i very vaguely understand what your talking about with the jetting specs but i'm trying to put 2 and 2 together. anyway, about you saying your gonna try out your 100 idle jet holder and 65 idle fuel, lemme know how that goes

 

you may not feel the power with larger chokes at low end but you're not limited on top end such as a open road. Watch the video of my RX-3 when I was revving the hell out of it while parked. No bogging. In fact, I have ran my 13-B streetport without the venturies. No bogging issues until I get to near a dead stop. Running 38 venturies maybe ok on the track but on street use, you will loose 100%.

 

Also, for stock 12-A, I had good results with 40-42mm venturies. so even for stock motor, 38 is a NO NO for me. but again, that is just me coz Im wacky

 

Wait... What is this large port you speak of?

 

large streetport not from that small *** RB template

 

Under load is much different than free revving. A buddy with 13b stock port went from 42 down to 38 due to bog.

Near Dead stop is light throttle to no throttle which is what most street driving is at. I tried 41mm chokes on the auto-x and it was too slow and not responsive. Poor fuel atomization and low velocity. Switched to 38.

Now, drag racing I'd say by all means go big chokes cause it's 100% wide open throttle.

I've been speed limited with 39mm chokes in the dellorto after WOT in 4th gear 100 MPH+ but really how often do we do that?

 

100+ MPH??? I do that all the time.

 

Of Course! 100MPH every day and twice on Sunday!

 

so wacky..you suggest a weber 48 ida on a stock port 12a?...how about a 45 dcoe?

 

Hmmm

 

ill answer for wacky.. for max power a 48mm

but a 45 will sufice a stockport 12A

 

Well, I like to spend my $$$ wiseley so I highly recommend buying a 48 IDA. Shall you decide to sale it, its re-sale value aint bad either.