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Carb swap on a cr125 2002

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Is a carb swap really worth the money? I hear people talking bout it on here all the time. What's the pros and cons and which carb is good for this year and motor? I'm assuming it a fairly easy swap.

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Is a carb swap really worth the money? I hear people talking bout it on here all the time. What's the pros and cons and which carb is good for this year and motor? I'm assuming it a fairly easy swap.

 

This is a good thread that should help you.

 

http://www.thumpertalk.com/topic/978692-38-pwk-as-in-a-02-cr125/page-1?hl=+cr125 +pwk +swap

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carb swaps, done correctly, are always a bunch of work because the jetting out of the box with your replacement carb is always off the map. sure many people will say "how hard could it be" and these are usually going to be individuals who have not seen a project like this through. if you are having probs with your current carb and can't get them figured out do not do a carb swap to fix things because is indicative of your basic mastery of jetting and fuel systems.  that is an advanced project. you definitely risk melting an engine while getting the new carb sorted out because they usually require extensive recalibration. the shortest amount of time it's taken me to get jetting alone sorted out from a carb swap, not counting all the work I did of making a clean install and making everything fit (a nice little pile of work in itself) was a full weekend. I also had a nice pile of jets including normal mains and pilots as well as a myriad of needles and needle jets. I probably spent nearly as much money on jets and needles as the carb itself. unless your a badass, don't do a carb conversion. don't do it. a better option would be making sure the stock carb works properly, verifying a baseline for the jetting (like the stock settings for example) and then fine tuning that baseline with little changes at a  time. this is definitely the shorter, easier, cheaper, less time consuming, less ambiguous, more straightforward, approach to nice results. so in conclusion, no it's not worth the money and especially not worth the time.  and secondly, your assumption is very wrong about it being not much work. it may be easy to slap a different carb on and get it to run. getting it to run well is a different story.

 

frdbtr yes that link is perfect for illustrating my point. it seems all the successful conversions involve a lot of time and jetting revisions. stick with the stock carb and get it sorted out.

Edited by MrMotorhed

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I switched carbs on both my bikes (94 cr125 with a 144cc big bore kit and an 06 cr250), and frankly I didn't think it was that hard on either of them.  There is so much jetting data on this site, you should not have any issues with "melting pistons".  The hardest fitment part is fitting the 38mm carb where the 36mm carb used to go but it can be done, I did it easily with my 125.  I could take a 2002 CR125 and put a 00cr250 carb on it with a 99-00 JD jet kit for jetting and have it running perfect in a couple of hours. 

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I was just wondering what all the rave of doing it was about. I may or may not do it but thank you for all the info! It's much appreciated. I just need to hurry up and get my bike back together since summer is here! Gosh dang stripped bolts get in the way though. Person before me musta over tighten liked crazy. A simple clean and re greae the linkage turn from a day or two project to a few months.....

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I switched carbs on both my bikes (94 cr125 with a 144cc big bore kit and an 06 cr250), and frankly I didn't think it was that hard on either of them.  There is so much jetting data on this site, you should not have any issues with "melting pistons".  The hardest fitment part is fitting the 38mm carb where the 36mm carb used to go but it can be done, I did it easily with my 125.  I could take a 2002 CR125 and put a 00cr250 carb on it with a 99-00 JD jet kit for jetting and have it running perfect in a couple of hours. 

you say that assuming this guy knows what lean and rich sounds or feels like and most who ask questions like that don't in fact most riders don't and lots of the "jetting data" may be posted by folks like this. and i'm telling you to get the jetting truly nice and not just "oh that runs fine" will take more work than the effort you mentioned of getting it to fit on the bike. how do I know what your perfect is? how does he know ? how do you know? jd jetting makes a jet kit for a carb swap? also people who know how to tune carbs don't need or use kits on offroad bikes. those are for laymen wich is useful in the real world because as I said before most riders are clueless about this and just ride. spot on jetting feels better than one carb size or the other. I would expect any real tuner to agree with me.  ask james who makes your favorite kits. ask mitch payton (as if he would have time available for a call like that, ha.) ask any well established tuner or engine guy. forget what I say. assume i'm a douchebag. ask somebody who you know is a badass.

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you say that assuming this guy knows what lean and rich sounds or feels like and most who ask questions like that don't in fact most riders don't and lots of the "jetting data" may be posted by folks like this. and i'm telling you to get the jetting truly nice and not just "oh that runs fine" will take more work than the effort you mentioned of getting it to fit on the bike. how do I know what your perfect is? how does he know ? how do you know? jd jetting makes a jet kit for a carb swap? also people who know how to tune carbs don't need or use kits on offroad bikes. those are for laymen wich is useful in the real world because as I said before most riders are clueless about this and just ride. spot on jetting feels better than one carb size or the other. I would expect any real tuner to agree with me.  ask james who makes your favorite kits. ask mitch payton (as if he would have time available for a call like that, ha.) ask any well established tuner or engine guy. forget what I say. assume i'm a douchebag. ask somebody who you know is a badass.

 

Yes, JD jetting makes PWK needles and they work really well.  The link I posted has a bunch of needles that will get the jetting good enough not to "melt a piston" and will probably be better and more stable than the carb that is on the bike which most people have trouble jetting, even when they know what they are doing.  You make it sound like it will be impossible to switch carbs and only top motorhead experts should even try it, well I don't claim to be that and I have switched both my bikes from their carbs to the PWK and have been thrilled with the results.  The jetting thread I posted and multiple others have shown that the 38mm PWK is a really good swap on the 00-04 CR125's since they seem to like more air and the larger carb helps provide that, and it gives more stable jetting which also increases power.  There is enough jetting info on this site available to anyone who does a simple search to get it ballpark jetted. 

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carb swaps, done correctly, are always a bunch of work because the jetting out of the box with your replacement carb is always off the map. sure many people will say "how hard could it be" and these are usually going to be individuals who have not seen a project like this through. if you are having probs with your current carb and can't get them figured out do not do a carb swap to fix things because is indicative of your basic mastery of jetting and fuel systems. that is an advanced project. you definitely risk melting an engine while getting the new carb sorted out because they usually require extensive recalibration. the shortest amount of time it's taken me to get jetting alone sorted out from a carb swap, not counting all the work I did of making a clean install and making everything fit (a nice little pile of work in itself) was a full weekend. I also had a nice pile of jets including normal mains and pilots as well as a myriad of needles and needle jets. I probably spent nearly as much money on jets and needles as the carb itself. unless your a badass, don't do a carb conversion. don't do it. a better option would be making sure the stock carb works properly, verifying a baseline for the jetting (like the stock settings for example) and then fine tuning that baseline with little changes at a time. this is definitely the shorter, easier, cheaper, less time consuming, less ambiguous, more straightforward, approach to nice results. so in conclusion, no it's not worth the money and especially not worth the time. and secondly, your assumption is very wrong about it being not much work. it may be easy to slap a different carb on and get it to run. getting it to run well is a different story.

frdbtr yes that link is perfect for illustrating my point. it seems all the successful conversions involve a lot of time and jetting revisions. stick with the stock carb and get it sorted out.

What a load of hoarse poo.

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Is a carb swap really worth the money? I hear people talking bout it on here all the time. What's the pros and cons and which carb is good for this year and motor? I'm assuming it a fairly easy swap.

For the 02, you don't have to worry about a TPS, so a PWK from a ktm will work as a short body (75mm).  I'm guessing that is same length as your stock mikuni.  If not, go with the long body (91mm) from a 99 CR250 to get it with a #5.5 slide.

Edited by magpie5

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Yes, JD jetting makes PWK needles and they work really well.  The link I posted has a bunch of needles that will get the jetting good enough not to "melt a piston" and will probably be better and more stable than the carb that is on the bike which most people have trouble jetting, even when they know what they are doing.  You make it sound like it will be impossible to switch carbs and only top motorhead experts should even try it, well I don't claim to be that and I have switched both my bikes from their carbs to the PWK and have been thrilled with the results.  The jetting thread I posted and multiple others have shown that the 38mm PWK is a really good swap on the 00-04 CR125's since they seem to like more air and the larger carb helps provide that, and it gives more stable jetting which also increases power.  There is enough jetting info on this site available to anyone who does a simple search to get it ballpark jetted. 

yes of course jd makes needles that fit pwk carburetors beautifully. that wasn't my point. my point was that james dean probably has not tested using his kit in the way you suggested and if asked i'm sure he might say he has no clue whether or not that would work well and your on your own. I can see your perspective on all your points. the op mentioned the previous owner stripping bolts. most of the time when a bike has stuff like that going on it's got more interesting stuff elsewhere also. sure the engine might be able to use more air from a bigger carb. can the rider? most riders are clueless, and when their bike runs at all, that's great for them. i'm pickier and I have high standards. of course you don't have to have high standards. it's a free country.

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yes of course jd makes needles that fit pwk carburetors beautifully. that wasn't my point. my point was that james dean probably has not tested using his kit in the way you suggested and if asked i'm sure he might say he has no clue whether or not that would work well and your on your own. I can see your perspective on all your points. the op mentioned the previous owner stripping bolts. most of the time when a bike has stuff like that going on it's got more interesting stuff elsewhere also. sure the engine might be able to use more air from a bigger carb. can the rider? most riders are clueless, and when their bike runs at all, that's great for them. i'm pickier and I have high standards. of course you don't have to have high standards. it's a free country.

 

No, I'm sure if the op talked to JD about his bike and what he wanted from the jetting, he would get very helpful advice which would help him find the settings that would work for his bike.  I have had many conversations with him and he knows his stuff.  I'm afraid that the OP isn't the only one here who is clueless.  You are talking to someone who has done what you say can't be done and done it successfully without much issue.  You are talking to someone who uses JD's needles on both a 125 and a 250 and they work well on both.  You are talking to someone who has had multiple conversations with James Dean at JD jetting and had his advice work out really well.  From the way you are posting, you have done none of these and really don't know what you are talking about.  All you are saying is that everyone else is too ignorant to even try something that you personally have never tried and telling us all that it is too hard to do right.

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I got a PWK from JD for my 05 CR125 before I did the 144 big bore kit.  Carb came jetted perfectly for my location at the time.  Later moved and dropped the needle from 4th to 3rd.  Perfect again.  Only thing is it came with a #7 slide, and a 125 should have a #5 or #6 slide.  I'm sure JD would consider that if you brought it to his attention.

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No, I'm sure if the op talked to JD about his bike and what he wanted from the jetting, he would get very helpful advice which would help him find the settings that would work for his bike.  I have had many conversations with him and he knows his stuff.  I'm afraid that the OP isn't the only one here who is clueless.  You are talking to someone who has done what you say can't be done and done it successfully without much issue.  You are talking to someone who uses JD's needles on both a 125 and a 250 and they work well on both.  You are talking to someone who has had multiple conversations with James Dean at JD jetting and had his advice work out really well.  From the way you are posting, you have done none of these and really don't know what you are talking about.  All you are saying is that everyone else is too ignorant to even try something that you personally have never tried and telling us all that it is too hard to do right.

no I didn't say that man. sorry. I did advise you to assume I'm a douche as I recall. thanks for sharing.

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