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Thread: Keihin PJ 34mm (stock 250R) w/ modified 250SX questions

  1. #1
    bbechtel16 is offline At The Back Of The Pack Arm chair racerAt the back of the pack
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    Keihin PJ 34mm (stock 250R) w/ modified 250SX questions

    I recently freeloaded a Keihin PJ series 34mm carb (stock 85/86 ATC 250R) from a friend who got an upgrade. Therefore, I plan to put it on the SX. I have some questions in doing this:

    1. What should I do as far as a new throttle cable is concerned? Because I need a different cable for this carb. Is a 250R cable the best route?

    2. If you have the stock setting available for the carb in the R please share so I have a half decent place to start.

    I guess that is it for now...Thanks in advance for the replies!
    -'86 ATC 250SX: No longer mine... Complete 350X front end, Corbra Megaphone system, 350X carb with UNI dual stage foam & outerwear bolted driectly up, Powroll/Rocky 260cc bore 10.5 to 1 compression piston.

  2. #2
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    hmmmm, that is a 2 stroke carb that you plan to put on a 4 stroke. i am pretty sure you could make it run but i doubt it would be any better.
    83 ATC70
    85 ATC70
    85 200x vintage racer
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  3. #3
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    the PJ series of carbs were designed especially for two strokes and although it will work on a four stroke it is not a good choice.

    as far as 250R stock jetting it would not matter as it won't even be close for a 250SX

  4. #4
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    i do have an old yamaha tt250 carb that i would let go pretty cheap. it would probaly be an upgrade.
    83 ATC70
    85 ATC70
    85 200x vintage racer
    86 500r
    Lots of parts

    My 500R


  5. #5
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    Re: Keihin PJ 34mm (stock 250R) w/ modified 250SX questions

    Quote Originally Posted by bbechtel16
    I recently freeloaded a Keihin PJ series 34mm carb (stock 85/86 ATC 250R) from a friend who got an upgrade. Therefore, I plan to put it on the SX. I have some questions in doing this:

    1. What should I do as far as a new throttle cable is concerned? Because I need a different cable for this carb. Is a 250R cable the best route?

    2. If you have the stock setting available for the carb in the R please share so I have a half decent place to start.

    I guess that is it for now...Thanks in advance for the replies!
    Hey bud whats up? Yeah it's kinda funny you mention it - I just took apart my 250R carb to clean it and thought - where the hell are all the jets?? The 250SX has like 3 more drilled orifaces versus a 250R 2 stroke, not sure if that carb will do you any good at all - wrong size, type of engine and cable issues....... Where is your mind my son!!!!!!! didn't you read my post??? 350X carbs bolt right up and have larger jets that may work with your mods and the cable fits too - do I have to kick you, just post in the classifieds and someone will hook you up with there spare 350X carb - hope that helps

  6. #6
    bbechtel16 is offline At The Back Of The Pack Arm chair racerAt the back of the pack
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    Re: Keihin PJ 34mm (stock 250R) w/ modified 250SX questions

    Quote Originally Posted by Dirtcrasher
    Quote Originally Posted by bbechtel16
    I recently freeloaded a Keihin PJ series 34mm carb (stock 85/86 ATC 250R) from a friend who got an upgrade. Therefore, I plan to put it on the SX. I have some questions in doing this:

    1. What should I do as far as a new throttle cable is concerned? Because I need a different cable for this carb. Is a 250R cable the best route?

    2. If you have the stock setting available for the carb in the R please share so I have a half decent place to start.

    I guess that is it for now...Thanks in advance for the replies!
    Hey bud whats up? Yeah it's kinda funny you mention it - I just took apart my 250R carb to clean it and thought - where the hell are all the jets?? The 250SX has like 3 more drilled orifaces versus a 250R 2 stroke, not sure if that carb will do you any good at all - wrong size, type of engine and cable issues....... Where is your mind my son!!!!!!! didn't you read my post??? 350X carbs bolt right up and have larger jets that may work with your mods and the cable fits too - do I have to kick you, just post in the classifieds and someone will hook you up with there spare 350X carb - hope that helps
    LOL, ok ok guys. I'll try to trade my carb with the guy that gave it to me for his 350X carb. He doesn't want to give it up for some reason, don't know why, he doesn't have any use for it right now. I figured the R carb would work just as well or better than the X carb since its same size but flat-slide. Man, I'm really disappointed now; I had more adjustments figured out on that than on my carb I'm using now. I also spent many hours admiring the enormous bowl.
    -'86 ATC 250SX: No longer mine... Complete 350X front end, Corbra Megaphone system, 350X carb with UNI dual stage foam & outerwear bolted driectly up, Powroll/Rocky 260cc bore 10.5 to 1 compression piston.

  7. #7
    mkramm is offline At The Back Of The Pack Arm chair racerFirst time rider
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    Just as long as its only gas that goes in that bowl :shock:

  8. #8
    bbechtel16 is offline At The Back Of The Pack Arm chair racerAt the back of the pack
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    Quote Originally Posted by mkramm
    Just as long as its only gas that goes in that bowl :shock:
    LOL: Don't worry, only gas for me. :-D
    -'86 ATC 250SX: No longer mine... Complete 350X front end, Corbra Megaphone system, 350X carb with UNI dual stage foam & outerwear bolted driectly up, Powroll/Rocky 260cc bore 10.5 to 1 compression piston.

  9. #9
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    Smile 250r carb cross over

    If I am going to swap in a 1985-85 250r 34mm carb on to my 1981 250R do I have to swap out the carb boot??

    IF any one knows of a thread that covered this point me so I may learn!!

  10. #10
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    you don't have to change the carb boot but i believe you have to run a reed spacer due to some clearance issues.

  11. #11
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    when i installer an 86r carb on an 81r i used the 86 boot and reed spacer that worked too

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