Determining Jet Size.... By Gti (Read 1,644 times)

[Gti]

I am so confused as to what size to get and how to size the one I have. How do I know what size I have.

[buford1488]

you got too give some more info....what carb-how big-what motor...ect-ect...stock? may have a # on the jet. main or pilot?

[Alleyoop]

Gti,
I believe he has a 30mm carb on it, Gti check the Jets they may have the size scribed on them some have the numbers on top by the slot some on the side. If no numbers are visible then what some poeple do is get MINI drill bits to determine the size of the jets. If NOT what i would suggest for your build is get a #35, #38 and #40 Pilot Jet that should be more than enough for that motor.
Alleyoop

[Gti]

I looked at the jet there isn't any writing on it at all, I just ran a piece of welding MIG welding wire through it and if memory serves me correct it is .030 or .035 and the wire passed through and still had wiggle around inside.

As of right now here is what I have done to the engine.

P157QMJ engine 63mm bore
180cc
+4mm crank with a shaved piston
should be a true 200cc or slightly larger
63mm Head
high torque starter
high torque starter clutch
30mm carb
NCY variator with lightened drive face
NCY blue manifold
NCY Direct fire coil
NCY No rev CDI

[Alleyoop]

Well I do not believe the PILOT JET is a #30 that you will find on 50cc carbs which are 18-20mms those carbs usually come with a Pilot jets 30-32.
On the 150s 24mm carbs they are usually #35, so on the 30mm carbs they would in my believe have to be bigger. So like I said get a #35,#38 and #40 Pilot Jet that should be more than enough for that motor. If you have the original 24mm carb I would take the PILOT JET out of that one and stick it in the 30mm carb and try it.

My motor has a 62mm and a +2 crank bringing it to 182ccs and I am using the 24mm carb it had on there. Just upjetted the carb with a #38 Pilot Jet and a 122.5 Main jet A #125 main jet was to much fuel and I have plenty of adjustment in either direction to richen or lean it out. In the Summer I lean it out 1 full turn and in the Winter time I richen it 1 full turn for the temp changes. Runs like a RAPED APE, starts on a dime ;D .
Alleyoop

[Gti]

The jet I took out and measured is the one in the center of the float bowl. Which are the pilot jets? Is that the one they call the slow jet?

[Alleyoop]

Here is a picture of what is under the CARB BOWL.

The Green Arrow points to the PILOT JET
The Red Arrow points to the MAIN JET

You are concerned with the PILOT JET (Green Arrow) It is lower than the MAIN JET .

[Gti]

Ok what I pulled was the main jet. Where can I find a few of those pilot jets? Walter has some of the main jets but I can not find any pilot/idle jets for the CVK?

[Alleyoop]

www.buggypartsnw.com/home?page=shop.product_details&flypage=flypage.tpl&product_id=251&category_id=6

[jct842]

Some where around is a jet size chart. Most jets are sized to correspond in mm. What I did for my 150 was to get a oraface drill set. Actually I have now 3 sets. (you have to use a pin vice and do it by finger pressure, and no electric drill) I knew I had to go bigger so after finding a drill that was the same size I drilled it out bigger. I went too far, so instead of having to wait for a new jet to come in the mail I soldered it shut and re-drilled smaller. That was probably 4 years ago and I have forgotten what size I ended up with, but it is still just fine today.

[Alleyoop]

Bit Size..Inches....Millimeters..Jet Size
#80.......0.0135.....0.3429.......34.29
#79.......0.0145.....0.3683.......36.83
1/64".....0.0156.....0.3969.......39.69
#78.......0.016.......0.4064.......40.64
#77.......0.018.......0.4572.......45.72
Alleyoop

[Gti]

Thanks Alley, I had looked around for those jets and got frustrated and found a deal on a OKO Flatside. I am going to be throwing it on this afternoon. My biggest concern is messing with the throttle cable. Hopefully I will have this thing running today.

[Alleyoop]

OH BOY, you went with a FLATSIDE, good luck Bro those are fincky carbs to adjust right. Reason is that any little movement of the throttle pulls on the cylinder and raises or lowers the needle. Would have been much easier to put a jet.
Alleyoop

[Gti]

this is my last ditch effort to go for the a carb if this doesn't wok the project is going to be over and I am gong to settle either on a Ruckus or and Ice Bear. The carb came with a #138 and I downsized to a #122. I have to wait until Tuesday to get the cable in but once that is in I will try it and see what I can do.

[Alleyoop]

GTI, I gave you the LINK where to get the #35,#38 and #40 Pilot jets?? The Flatside Carbs are a different animal all together but maybe you will get lucky.

WHAT SIZE OKO FLATSIZE did you get.
Alleyoop