36mm Carb Jetting

[Eforce13]

Quote:

730cc
proted heads stock valves
cwr 450 lift cams
big gun rev box
drag pipe
stock unported intake boots
42 piolets
130-135 jets

i believe the reason for so many diffrant jettings are the carbs not all have the same type of 36mm carbs and not all have the same needles so it kinda makes it a guessing game
[/b]

Yes the needle makes a big difference. I have several sets of neddles from factory pro and the ones with a smaller tip requires smaller mains and the larger tiped needles require as much as 10#'s larger (140's to 150's). So yes your right. The stock 36mm carbs come with a non adjustable needle with one shim under them. But their is still two different ones. There is a CA needle which is leaner wot and a richer one for the rest of the country due to emmisions for CA. So, if you are running the stock needles in the F4 carbs you could be in anywere from 130's to 150's, and that is just with the stock needles.

[gomerkfx700]

mine are the real small ones on the tip id say the last 3/8" or the needle is less the half the diamiter then the rest of the needle

[krewzlo]

Quote:

<div class='quotemain'>
730cc
proted heads stock valves
cwr 450 lift cams
big gun rev box
drag pipe
stock unported intake boots
42 piolets
130-135 jets

i believe the reason for so many diffrant jettings are the carbs not all have the same type of 36mm carbs and not all have the same needles so it kinda makes it a guessing game
[/b]

Yes the needle makes a big difference. I have several sets of neddles from factory pro and the ones with a smaller tip requires smaller mains and the larger tiped needles require as much as 10#'s larger (140's to 150's). So yes your right. The stock 36mm carbs come with a non adjustable needle with one shim under them. But their is still two different ones. There is a CA needle which is leaner wot and a richer one for the rest of the country due to emmisions for CA. So, if you are running the stock needles in the F4 carbs you could be in anywere from 130's to 150's, and that is just with the stock needles.
[/b][/quote]

Hey did you ever get that midrange lean problem figured out? I never did on mine but want to try 36's again this summer. Just curious if you found out anything.

[Eforce13]

It wasnt the carbs at all, it was my porting that was messed up. Someone, (I'm not calling names) put my heads on a flow bench and then filled in the intake ports to make them flow better (higher #'s on that damn machine) and more even. So after that stuff was ground out of my intake ports it was fixed. I kinda new it wasnt the carbs or any tunning problems for that matter because I had been using the 36's before the problem and they worked perfect.

[Mikeyboy_esq]

FST 800
No Porting
Stage 3 cams
Supertrapp IDSX full exhaust
Dyna CDI
Stock Intake boots
Stock Airbox (modified to fit on 36mm carbs) with 23 hole lid
36's w/ #42 pilots
1 Shim Per Needle
128ft /130rr @200 ft
Tuned on a Supertrapp Dyno (supposedly made 72.7 RWHP)

[Psi-700]

800 bbk stg3 cams porting twin hmf 36mm carbs with 2 inch adapter between boots and carbs gtyr filter 188f 192r and still nosing over a bit up top waiting on more jets

[OHVFORCE]

Quote:

800 bbk stg3 cams porting twin hmf 36mm carbs with 2 inch adapter between boots and carbs gtyr filter 188f 192r and still nosing over a bit up top waiting on more jets
[/b]

That seems a bit much for main jetting.

[bb 650]

Adding the 2" rise to the intake will want more fuel like he is saying and it worked pretty good when I tested but never really finished testing,hope it works out for you.

[Psi-700]

bought the carbs of vtprarie03 they had 155f 160r couldnt go over half throttle backfiring and the more i crept up in size the better it gets i rekon it will pan out close to 192f 195r but i dont know how much dif it makes if at all but im only 100 feet above sea level

[OHVFORCE]

Quote:

Adding the 2" rise to the intake will want more fuel like he is saying and it worked pretty good when I tested but never really finished testing,hope it works out for you.
[/b]

hmm my intakes are atleast a two inch rise maybe more on 36's Glenn had to port my air box cover so the carbs would fit Im at 135/138 with ported heads though. 850 above sea level.

Quote:

bought the carbs of vtprarie03 they had 155f 160r couldnt go over half throttle backfiring and the more i crept up in size the better it gets i rekon it will pan out close to 192f 195r but i dont know how much dif it makes if at all but im only 100 feet above sea level
[/b]

If you have bits a #48 drill bit is a 195 main jet.......