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post #1 of 11 (permalink) Old 03-03-2013, 11:01 AM Thread Starter
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carb size

ok well i found out today when i went to put my thumb trottle and stock pipe on today i have a oversized carb dam it well i am getting a stock carb for it and getting rid or the fmf fatty pipe but can anyone tell me how to find out exactley what size my over sized carb is i got a few numbers but cant make any sence out of them the numbers are PJ 27AAAH thanks for any help but i think my power problems where from the fmf gold header with the over sized carb with stock jets i hope making these changes will help my atv run better and more even power band thanks for any and all help also i forgot i think 34 mm is the stock carb size is that correct

Last edited by brent; 03-03-2013 at 11:06 AM.
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post #2 of 11 (permalink) Old 03-03-2013, 02:32 PM
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A quick look on Google at the PJ27AAAH Kehein's tells me this was an probably an upgraded item for this quad. I don't know much about the older Kehein's but this is an oval slide carb and it's pretty desirable amongst the 2 stroke kids. They were popular in 32,34,36 mm sizes in that model # which I know doesn't help you figure out what size it is. Most owners manuals will give the carb size in millimeters in the carb specs. My guess is its a 36mm which seems small as most 250 cc 2 strokes are 38 mm carbs so I don't know whats going on there. I'll get back to later on some jetting specs for this carb, I'll dig around over on Sudco's web site and see what I can find out about what your quad would need maybe. What year is it by the way?

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post #3 of 11 (permalink) Old 03-03-2013, 04:41 PM Thread Starter
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It is a 86 250r motor in a 88 atv
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post #4 of 11 (permalink) Old 03-03-2013, 05:07 PM
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Alright, I have a few minutes now let me look at the manual and do some digging.

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post #5 of 11 (permalink) Old 03-03-2013, 05:14 PM
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Seems the stock size is a 34mm. Need to see what size you have if you think its not the stock carb. You can do this by measuring the engine side opening inside diameter. Also, I found that the PJ series was stock on these motors too. Im downloading the manual for your motor year. What size jets are you running now ?

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post #6 of 11 (permalink) Old 03-03-2013, 06:13 PM Thread Starter
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well i did looks at my book for the 86 motor and you are right it is a 34 mm carb but it also shows a round carb the one on it is a oval type carb and also i got a stock thumb throttle with stock cabel and cap also got a new cable and cap for the 86 and both the caps for the 86 are to small to screw on to the top of the carb it had a twist throttle on it when i got it so this is what made me think it was not stock and they had a fmf gold pipe on it with a k@n alumminum open air box on it so i think they where trying to make it faster
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post #7 of 11 (permalink) Old 03-03-2013, 07:55 PM
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Hmmm ok, IM a little out of sorts here trying to figure this out. I still think you need to measure your carb cosidering what you have said about the stock caps not fitting this carb.

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post #8 of 11 (permalink) Old 03-03-2013, 08:23 PM
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Quote:
Originally Posted by brent View Post
well i did looks at my book for the 86 motor and you are right it is a 34 mm carb but it also shows a round carb the one on it is a oval type carb and also i got a stock thumb throttle with stock cabel and cap also got a new cable and cap for the 86 and both the caps for the 86 are to small to screw on to the top of the carb it had a twist throttle on it when i got it so this is what made me think it was not stock and they had a fmf gold pipe on it with a k@n alumminum open air box on it so i think they where trying to make it faster
Brent, all the 250R's were 34MM stock. I think I gave you jet sizes to start out with in a previous post. As for the size of yours, you'll have to measure the ID of the intake side to determine what size it is. Honda did use a round slide Keihin on 250R's, but that was on the '85 ATC250R, all 86's three and four wheelers were PJ oval slides. And yes, on a machine equipped with a stock carb, the cap and throttle cable are all one piece, and probably won't fit an oversize carb.

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post #9 of 11 (permalink) Old 03-03-2013, 08:29 PM Thread Starter
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well i want to go back to stock so i am going to get the oem carb from a 86 a guy i know has but i am trying to find out what i have so i can post the size and i can sell it on ebay i will messure it tomarrow but i am sure it is ovresized due to the fact the caps dont fit if u think i may be wrong let me know the cap would fit if it where a stock carb the guy o know the cap fits that carb
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post #10 of 11 (permalink) Old 03-03-2013, 10:08 PM
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well i want to go back to stock so i am going to get the oem carb from a 86 a guy i know has but i am trying to find out what i have so i can post the size and i can sell it on ebay i will messure it tomarrow but i am sure it is ovresized due to the fact the caps dont fit if u think i may be wrong let me know the cap would fit if it where a stock carb the guy o know the cap fits that carb
It could be a 38mm, those would require a larger than stock cap. Possibly a 36mm, but I seem to remember those interchanging with a 34. I could be wrong on this, it's been a while since I've seen a 36.

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2007 TRX450R
2005 TRX450R
2004 TRX450R
2003 Lonestar 250R
2001 Lonestar 250R.....now a 310
1986 TRX250R (restored to new)
1986 TRX250R (still in pieces)
1999 CR500
1999 CR250
1996 CR250
1986 ATC250R
1975 MR50
1999 Banshee
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