Jetting for a 240bbk

[Budget_Blaster]

Ok ive got my engine broke in and running good now its time for fine tuning.It feels kinda soft for a 2 stroke with the mods i have and plug chops show what i knew which is im running pig rich and i intentionally ran it rich for break in.

Right now i have the stock carb on it with a 340 main and a 32.5 pilot with the vitos needle in it and its rich.
It feels like its loading up at lower rpms but up high its better obviously.

My question is with my mods in my signature and lets say 50-70 degrees since thats what it varies here day to day what are you guys running for jetting with similar mods?Im looking for a ball park to start in.Thanks I:I

 

[Blaaster]

I don't like the Vito's needle.

Jetting seems OK, but try a stock needle on the middle clip.

You may find just what you need right here

http://www.blasterforum.com/engine-13/pipe-review-23423/

 

[Awk08]

not many peeps runnin a stock carb on a 240

and agreed....the vito's needle, and most "jet kits" are gimmicks

 

[Blaaster]

To get rid of the softness and unleash that 240, get your self into a 35mm or bigger carby.

 

[04YamahaRider]

To get rid of the softness and unleash that 240, get your self into a 35mm or bigger carby.

Agreed, you'll need a much bigger carb to get the full potential out of your bbk, stock just wont cut it.

 

[Budget_Blaster]

Itll be a little bit on the larger carb i have a pwk 35 but ive yet to buy a boot and air box to support it.

What do you mean jet kits are just gimmicks?

Im building on 3 mustangs right now and moneys tight between the 84 n/a coupe,the 89 nitrous coupe,and the supercharged 96 coupe.
Im just trying to fine tune what i have now.

 

[1995blaster]

you can use it. I have a vitos needle and i didnt notice a difference at all in jetting.

 

[Budget_Blaster]

you can use it. I have a vitos needle and i didnt notice a difference at all in jetting.

explain????????????????

 

[Awk08]

the jet kits i've heard everyone complain about came with too small and too large of jets for the intended use, like these company's are stuffing a plastic case with the least common, unsold jets and passing them off as some miracle cure all, they are not, don't waste your loot

if i was in your situation, i'd go to Carburetor Parts Warehouse
get their number and call that dude, he'll put you in a 3 jet range, for far less loot than one of them jet kits, and also suggest a needle for your application, (which is why i called them, the needle he sold me made a huge difference)
then plug chop to fine tune

 

[dbowhntr]

Get rid of that needle and your lower throttle richness will be cured. Happened to me.

 

[Blaaster]

I used a Vitos needle supplied with a kit, the jets that were in there fitted the bill just fine for my application but not with the needle supplied, it ran far too rich.

I put the stock needle back in and even though the needle is on its richest setting everything is fine!

 

[Budget_Blaster]

ive also got jets from jets r us.com along with the vitos that was supplied with my 240bbk.

Needles i know ive got the stocker and i belve ive got a cgl or dgl ill have to look if by chance i have those or any needle including the stocker whatclip setting do i run to begin with?

 

[dbowhntr]

Start in the middle clip .

 

[Braaaptor]

Start in the middle clip with the stock needle, as suggested. You may need to raise the needle a notch or two to richen up the mix at part-throttle (You do this by moving the clip DOWN, towards the tapered end of the needle).

A 340 main is about right. EvilElvis was, until recently, running a stock carb on a Vito's 240 top end. He had a 340 main in his and the engine seemed to like it. It ran well and hard all weekend at Busco kept right on going after the trip was over.

NOW, people may argue with me on the next statement I'm about to make, but I say get rid of that 32.5 pilot in favor of a 35 pilot. This will richen up your mix right off idle, where the engine needs it most (for snappy throttle response). You can adjust the airscrew and needle position accordingly and I guarantee the engine will like it. Lots of the bogging you are having trouble with is from running lean right off idle and switching the pilot will help.

 

[Budget_Blaster]

It never bogs it just feels like at lower rpms its loading up.Ill try the jet needle change and see where i am at.

 

[Awk08]

NOW, people may argue with me on the next statement I'm about to make, but I say get rid of that 32.5 pilot in favor of a 35 pilot. This will richen up your mix right off idle, where the engine needs it most (for snappy throttle response). You can adjust the airscrew and needle position accordingly and I guarantee the engine will like it. Lots of the bogging you are having trouble with is from running lean right off idle and switching the pilot will help.

i'm gonna take it that was aimed at me, cause i always preach.....
"anything but a highly modded motor will not need a pilot change"

a 240 kit could be considered a highly modded motor just for the fuel needed to feed the extra cc's

but remember, any change to the pilot or needle will also richen the jetting above them, so plug chop that main if you richen/lean either the pilot or needle

 

[Budget_Blaster]

ok i dug out the jet needles i have and most are for the keihins but i do have two mikunis one is silver and looks to be stock with no markings and the other is new and looks stock as well but says Y144 on it.

I do know ones the stocker and the others from a rebuild kit just dont remember which is which.

So which one do i use they both look almost identical.

 

[Awk08]

i'd say if a jet came with a rebuild kit, it is stock size

 

[Braaaptor]

i'd say if a jet came with a rebuild kit, it is stock size

^Agreed^ You'd have to measure the needles (with a dial or digital caliper) to see which one is thinner or thicker towards the tip. The thinner the needle, the richer the engine will run. The thicker it is, the leaner it will run. Install accordingly, or if they're both the same, check your manual. I believe that needle marked "Y144" is your stock one.

The service manual should, in the carb section, show you which needle comes stock in your carb. I believe the stock carb uses Mikuni's '4' series needles, but don't quote on that. You can go to Sudco.com and they have a nice little chart showing you all the different needle profiles available for your carburetor.

You can pick any needle you need out of the series of needle your carb uses. (3-series, 4-series, etc...). Sudco explains the measurements, and even groups each series of needle in order from leaner to richer, to make picking one that is "one size leaner" or "two sizes richer" easy.

Hope that helps! I:I

 

[nd jat]

My stock needle is J22, but my problem is with the emulsion tube being to small on the carb I'm running. Off idle is good but still leans out after 1/8th then picks back up.
Blaster carb use series 5 needles, basically about 50mm length or longer from what I've seen.