Info for jetting carburetors.

[Bigbill]

Just some info what each section of the throttle position does as it relates to the carb

https://www.google.com/search?q=two...&hl=en-us&client=safari#imgrc=PSYCQwkKOS0OQM:

 

[Kartwheel68]

 

[justintendo]

Just some info what each section of the throttle position does as it relates to the carb

https://www.google.com/search?q=two stroke carb jetting&ie=UTF-8&oe=UTF-8&hl=en-us&client=safari#imgrc=PSYCQwkKOS0OQM:

a link to google search results?

 

[fran...k.]

I am sure the 1987 manual has sort a similar chart to post #2 here.

Maybe what is the best set up for getting the thing started is of more importance to someone besides me.

Area these bikes fussy as to the jetting compared to the average of this vintage. I have a 27cc pole saw that is very fussy but most small outdoor equipment I have never twisted an adjustment on.

 

[motomwo]

Something that a lot of people don't mention when doing base line jetting or testing is the weather conditions and altitude such as temperature, barometric pressure and relative humidity and altitude. Prior to testing I record the weather conditions and corrected altitude. I also mark my throttle grip so I can tell if I am at 1/4, 1/2, 3/4 full throttle. I use a straight section of gravel road/dirt road that has a gradual up hill climb about 1/8 mile or actually slightly more where I can get up into 6th gear with a hard pull on the motor and then can test at each throttle position. At the end of each "pull" I can cut the motor clean and then pull the plug and check it, then I coast back down the hill make the jetting change needed and repeat as many times as needed for each throttle position setting. Depending on how long this takes I may recheck the weather conditions. After I am satisfied with the jetting I record the weather, corrected altitude and density altitude. Now when I ride the bike again anywhere/anyday I can use my recordings and make the required main jet and sometimes clip position change based on the current conditions and corrected altitude. This way after the initial jetting/test I will always have spot on jetting.

Marty

 

[justintendo]

I am sure the 1987 manual has sort a similar chart to post #2 here.

Maybe what is the best set up for getting the thing started is of more importance to someone besides me.

Area these bikes fussy as to the jetting compared to the average of this vintage. I have a 27cc pole saw that is very fussy but most small outdoor equipment I have never twisted an adjustment on.

the later 90s italian manuals are nice, almost a shop manual. they definitely have a chart like you suggest, explaining environment changes and a nice jetting chart.
speaking of outdoor equipment, my husqy 326 line trimmer (swede made) really responded to adjustment from factory settings. it had those little wings and a roll pin limiting adjustment. i was surprised how lean the factory had it set up.

 

[Bigbill]

My older Husqvarna chain saws had adjustment screws for low speed mixture and high speed mixture.
Any power equipment with mixture screws. You start it up, warm it up, then turn the idle mixture screw in slowly till it almost stalls. Then back it out quickly 1/2 turn that's the adjustment on every piece of power equipment. Then adjust the idle speed. She should start one pull when it's hot. The high speed becareful not to lean it too much.

My new husky saws have no adjustment screws there sealed. They run in any weather/temp so far. It took 20 cords of firewood to break in three new husky saws. But with the turbo air injection system they cut faster. I run a husky 385XP with a 32" bar using the chisel skip tooth chain. What a machine it is.

I posted this visual jetting chart so you can see a picture of each stage of operation the carb goes through when we twist the twistis.

 

[DaveM]

Hi Justintendo,

The small plastic wings are there so it passes emissions testing.

They are the first thing I remove when working on small engines.

I have used a Dremel to cut a slot in the top of the mixture screws, so I can use a screw driver on them.

Just recently I bought 4 screw drivers with different ends for doing the mixture screws, much better.

 

[justintendo]

My older Husqvarna chain saws had adjustment screws for low speed mixture and high speed mixture.
Any power equipment with mixture screws. You start it up, warm it up, then turn the idle mixture screw in slowly till it almost stalls. Then back it out quickly 1/2 turn that's the adjustment on every piece of power equipment. Then adjust the idle speed. She should start one pull when it's hot. The high speed becareful not to lean it too much.

My new husky saws have no adjustment screws there sealed. They run in any weather/temp so far. It took 20 cords of firewood to break in three new husky saws. But with the turbo air injection system they cut faster. I run a husky 385XP with a 32" bar using the chisel skip tooth chain. What a machine it is.

I posted this visual jetting chart so you can see a picture of each stage of operation the carb goes through when we twist the twistis.

you didnt post any chart...just a link to search results. click on the link you posted

 

[justintendo]

Hi Justintendo,

The small plastic wings are there so it passes emissions testing.

They are the first thing I remove when working on small engines.

I have used a Dremel to cut a slot in the top of the mixture screws, so I can use a screw driver on them.

Just recently I bought 4 screw drivers with different ends for doing the mixture screws, much better.

ill tell you what, that line trimmer came alive! couldnt believe how much more fuel it wanted! its pretty bad when a 2 stroke gains rpm adding fuel, thats a really lean condition..
smells good burning that castor tho!
glad to hear im not the only one that cuts those wings off..

 

[Bigbill]

All the info comes up in the link I posted.

There's nothing like smelling castor at 9am.

 

[justintendo]

Something that a lot of people don't mention when doing base line jetting or testing is the weather conditions and altitude such as temperature, barometric pressure and relative humidity and altitude. Prior to testing I record the weather conditions and corrected altitude. I also mark my throttle grip so I can tell if I am at 1/4, 1/2, 3/4 full throttle. I use a straight section of gravel road/dirt road that has a gradual up hill climb about 1/8 mile or actually slightly more where I can get up into 6th gear with a hard pull on the motor and then can test at each throttle position. At the end of each "pull" I can cut the motor clean and then pull the plug and check it, then I coast back down the hill make the jetting change needed and repeat as many times as needed for each throttle position setting. Depending on how long this takes I may recheck the weather conditions. After I am satisfied with the jetting I record the weather, corrected altitude and density altitude. Now when I ride the bike again anywhere/anyday I can use my recordings and make the required main jet and sometimes clip position change based on the current conditions and corrected altitude. This way after the initial jetting/test I will always have spot on jetting.

Marty

i used to hang out with a kid that raced micro sprints on dirt track..he kept similar notes like you do..he used a "rad" gauge..(relative air density)..he was always pretty close with what main he needed.

 

[justintendo]

All the info comes up in the link I posted.

There's nothing like smelling castor at 9am.

all the info? how to type "two stroke carb jetting" on a search page?

 

[jo360]

Smellofdeath 2t jetting is a good source testing the carb with the main jet removed.i jet all my garden tools so the kids have a hard time starting them but i can do it first pull (makes me even more of a legend).

 

[Bigbill]

Ok "two stroke carb jetting" there ya go. Lol