Oko 21mm jet size for sea level

DieselTech

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The screw that's missing does it go there in front of the carb opening, even with that clear line?
 

DAMIEN1307

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Can’t seem to just take pic. It’s asking for a url link
Hs-254b, rwj-4b, carbs I use with G2 reed. 66cc for the hs and 100cc steel sleeves with the rwj
Sorry I am a tard. Didn’t see the attach file. But u can see the screw missing. What’s that called? And would it prevent the carb from starting the bike?
You could go this route too. This is a tillotson hl-334ab race carb, there used on 80-125cc 2stroke racing go-karts & set up for reeds. There a 23mm venturi with at 25.5mm throttle bore. There exceptional carbs & no jets to mess with.
104 sounds big for a 66cc, is your plug wet?

You guys did all notice in his pics that his fuel filter is on upside down, RIGHT, ???...Flip the fuel filter around to correct the gas flow, replace lost screw, than re-tune the carbie as needed...end of problem...lol...DAMIEN

EDIT...Amazing the amount of information that one can derive from a picture...lol.
 

Karl Snarl

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Sep 20, 2019
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You guys did all notice in his pics that his fuel filter is on upside down, RIGHT, ???...Flip the fuel filter around to correct the gas flow than re-tune the carbie as needed...end of problem...lol...DAMIEN
On phone me at work, I don't bother looking at pics. They are so small and I'm so old, I can't see much.
 

Street Ryderz

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This screw? That is the power jet access, it normally wouldn't stop the engine from starting but being lean all ready this would for sure make it more difficult, Treatland would have the part, or any small 6mm cap screw would work.
Carb's are carb's they all basically work the same and require being jetted/tuned to the application, this carb one of my favorites has 5 points to be tuned the pilot jet, air screw, needle, main jet and the power jet. Tuning starts from the bottom up pilot jet first and the air screw, with a proper sized pilot jet the air screw should be around 2 turns out and idle properly then the needle is for tuning the transition from idle/pilot jet and upto 3/4 throttle then it's the main jet upto full throttle and the power jet adds fuel at WOT when the velocity is high enough to pull the extra fuel, and this is to help when on the pipe so as not to go lean at peak rpm.
You could try a pumper/diaphragm type carb as it needs no jet changes but you still need to tune it adjusting both the slow and high speed needles (much easier) but then they need a pulse line fitted to the case or base of cylinder and if the engine flows enough a secondary fuel pump may be required.
OKO power jet screw.jpg
 

Karl Snarl

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This screw? That is the power jet access, it normally wouldn't stop the engine from starting but being lean all ready this would for sure make it more difficult, Treatland would have the part, or any small 6mm cap screw would work.
Carb's are carb's they all basically work the same and require being jetted/tuned to the application, this carb one of my favorites has 5 points to be tuned the pilot jet, air screw, needle, main jet and the power jet. Tuning starts from the bottom up pilot jet first and the air screw, with a proper sized pilot jet the air screw should be around 2 turns out and idle properly then the needle is for tuning the transition from idle/pilot jet and upto 3/4 throttle then it's the main jet upto full throttle and the power jet adds fuel at WOT when the velocity is high enough to pull the extra fuel, and this is to help when on the pipe so as not to go lean at peak rpm.
You could try a pumper/diaphragm type carb as it needs no jet changes but you still need to tune it adjusting both the slow and high speed needles (much easier) but then they need a pulse line fitted to the case or base of cylinder and if the engine flows enough a secondary fuel pump may be required.View attachment 160100
All the carbs I talk about here are pulse on the intake. The rwj-4b has a return, but the hs ones I use do not have a return. Just easier to use a saw carb with pulse on the intake vs an extra line, for the motorbike application. Not to say the seperate pulse carbs wouldn't work, you just have to set up a signal line for it.
 

Wrench

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You guys did all notice in his pics that his fuel filter is on upside down, RIGHT,
Yes you are correct
@Ceeskiroy Fuel filter might not have an arrow on it to show direction of fuel flow
Here's a filter with an arrow
DSCF5506.JPG
The direction of fuel flow has to do with the filter element
If the element collapses fuel will still be filtered. The other direction (backwards) the element can burst (tear) and let dirt thru.
Fuel might not be restricted if their installed backwards, but they can rupture and let dirt thru.

It's also said if a fuel filter don't have an arrow, it don't matter which direction it's installed 🤷‍♂️
I think this applies to a screen filter, because not all are see thru.

Always replace a fuel filter regularly, It's not good to try and make em last for years and years
They might look OK but the element can break down and get in the carb
 

Ceeskiroy

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Oct 24, 2021
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Yes you are correct
@Ceeskiroy Fuel filter might not have an arrow on it to show direction of fuel flow
Here's a filter with an arrow
View attachment 160104
The direction of fuel flow has to do with the filter element
If the element collapses fuel will still be filtered. The other direction (backwards) the element can burst (tear) and let dirt thru.
Fuel might not be restricted if their installed backwards, but they can rupture and let dirt thru.

It's also said if a fuel filter don't have an arrow, it don't matter which direction it's installed 🤷‍♂️
I think this applies to a screen filter, because not all are see thru.

Always replace a fuel filter regularly, It's not good to try and make em last for years and years
They might look OK but the element can break down and get in the carb
I will correct but has nothing to do with it not starting. The bowl fills up immediately as expected. Plus I ran this carb 2 times. But It for some reason just decides to stop starting. Clean everything out then it started. Now its did it again a day or two later. Cleaned everything again but still wont start. Yes check ignition and its all working. I even change the jets to a large size. Nada.
 
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