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Carb Swap??? #150478 02/18/21 09:02 PM
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guitback Offline OP
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Does anybody have experience with installing a flat slide (Keihin or Mikuni OR Chinese knock off) on an XT225 or XT250? I have scoured this and several other boards trying to ascertain how "do-able" the swap is on this particular bike. I'm not a fan of CV carbs off-road. I know their value in meeting emissions standards as well as being more gentle (predictable?) in their power delivery. For my needs though, I like the responsive nature of flat-slide carbs. I love the XT225 and I really like to do, for lack of a better term, "trials-like" riding on it. Consequently, I'd like to dump the CV on both my DR200 AND my XT225. I'm hoping someone has done a swap with a PWK (or clone) probably around a 28cc to 32cc range.

Last edited by guitback; 02/18/21 09:02 PM.
Re: Carb Swap??? [Re: guitback] #150485 02/18/21 11:32 PM
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peejman Offline
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Best I recall, a couple people here have tried aftermarket carbs and walked away unhappy.

I like to do trials type stuff as well, but a true trials bike is a completely different animal. Best thing I can think of is a huge gearing change... 14/58 or something like that.


This shall pass, be still and know.
2006 XT225, UNI filter, ProTaper bars, MSR handguards, SS front brake line, Shinko 241's.
Re: Carb Swap??? [Re: guitback] #150487 02/19/21 03:55 PM
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Az4x4 Offline
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Originally Posted by guitback
.......I like the responsive nature of flat-slide carbs. I love the XT225 and I really like to do, for lack of a better term, "trials-like" riding on it. Consequently, I'd like to dump the CV on both my DR200 AND my XT225. I'm hoping someone has done a swap with a PWK (or clone) probably around a 28cc to 32cc range..

Like Peejman, I don't recall just offhand anyone here commenting on swapping the CV carb on their XT225 for a flat-slide carb. I suppose it could be done, and with your interest in such a change over you may be the first do it. If you tackle this project please document for the rest of us with photos and descriptions how that change over turns out. I doubt you'll ever get true trials bike performance out of your XT225, but it never hurts to try something new and different!..


The voyage of discovery that truly matters is not in seeking new lands but in seeing with new eyes.
Re: Carb Swap??? [Re: guitback] #150492 02/19/21 04:59 PM
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guitback Offline OP
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Thanks for responding peejman and AZ4x4! Just so you know, when I indicated "trials-like" in my initial post, I definitely know that the XT225 will never be an out-and-out trials bike. I think something like "Trials...ish" might have been more accurate. I'm just aiming for a more tractable and precise power delivery, rather than the "twist now and wait a second" nature that CV carbs can have. My initial dirt bike riding was with a DT series Yamaha, a Bultaco (right-side-shift) Alpina 250 and a Honda TL-125. I also had a friend that had a Kawasaki 100 Trailboss (with the dual range tranny). I'm not looking to get the crawl ratio of the TL-125, but I do like to do my trail riding in a somewhat more delicate way than simply bull-rushing through with a ton of speed. I love the "mountain goat" nature of the XT225 and I want to maximize its willingness to go wherever it is pointed.

Re: Carb Swap??? [Re: guitback] #150495 02/19/21 05:34 PM
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peejman Offline
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I've been to a few trials events, I have a couple friends that do it, and it looks like tons of fun. I tried a free newbie trials day a couple years ago on my XT. I thought I did ok... the turning radius and gearing that isn't ultra low definitely make a difference. I really like the thoughtfulness and planning required to make it through a stage. As you say, it's definitely not the "bull rush" method.

One of my friends let me ride his trials bike and it's sooo different. You'd think a 2-stroke only makes power "on the boil", but that trials bike may as well have been electric. Instant torque and tons of it. The brakes are similarly powerful.

One of these years I'll get down to trials training days. It's free and only a couple hours away, but I've had something else on my calendar that weekend for the past few years. https://trialstrainingcenter.com/schedule/trials-training-days/

I also really these instructional videos. I practice some of this stuff when I'm riding... https://www.youtube.com/channel/UCc32Jp7u-1ANgy64s_54eDw


This shall pass, be still and know.
2006 XT225, UNI filter, ProTaper bars, MSR handguards, SS front brake line, Shinko 241's.
Re: Carb Swap??? [Re: guitback] #150497 02/19/21 05:46 PM
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I'd love a more tractable and precise power delivery with my 2007 also. Seems my 1992 XT225 was better in that respect than the 2007. Some of my riding is following horse trails (we have thousands of wild mustangs around here) which are 1-2 feet wide and weave in and out of washes and around sagebrush which can lead to out-of-the-way but interesting locations. The XT225 throttle response is very jerky at very low speeds and makes this difficult. So if someone comes up with a solution I'd love to hear about it.

[Linked Image from i.imgur.com]


Worshipper of sun and wild country.
Re: Carb Swap??? [Re: guitback] #150508 02/20/21 03:25 AM
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I have never been a fan of CV carburetors. I think they are over complicated and not nearly as responsive as a flat slide carb. But I still think they are a million times better than EFI.

I don't have any experience with installing a different carburetor on an XT225. It would have to have exactly the same dimensions to fit without eliminating the airbox and going to a pod type filter, something I certainly don't recommend on a bike ridden off road.

I bought a new 2013 Royal Enfield Bullet with EFI. It was barely rideable. Almost everybody on the RE forum had problems with it. I won't go into the details, they would fill a book. Suffice it to say, IMO, it was absolute junk. Fortunately it was a retrofit, meaning it was designed to fit an existing bike, not the other way around. Using a kit from a place in the UK. (the Royal Enfield was a British brand at one time, now made in India) I replaced it with an Amal Concentric Mk1 flat slide carb. The results were nothing short of amazing. It went from being the worst running bike I've ever had to one of the best. The hesitation, flat spots, and on/off throttle lurching were gone. The engine pulled strong and hard from idle to redline. It fattened up the midrange and turned the sputtering wheezing bike into one of the most enjoyable bikes I've ever ridden. The feel and sound completely changed. The exhaust note filled out and sounded like it should. Throttle response was instantaneous. And this came from a carburetor designed in the UK in the early 1950s. They perfected carburetors a long time ago, then spent the next several decades messing them up.

From my experience, the CV carb on the XT is not that bad. It could be better, but as long as it has that slow moving vacuum diaphragm, it will never have instant throttle response. I would not change the stock jets. I tried that, and it made things worse. You might gain a little bit from shimming the needle and turning the pilot screw out a bit. I used a thumbscrew on mine to replace the stock screw, so I could adjust it with the engine idling. So I don't really know how many turns out it is. I got the screw from Kientech. http://kientech.com/ it was made for a Suzuki but fit the 34mm Mikuni on the XT perfectly.

It does not surprise me that a 1992 would be better than a 2007. I'm sure they tightened the emissions restrictions since 1992. You might want to check the jet sizes from the '92 to the '07. '07. I suspect the pilot screw setting is different. .

I would not expect much from a Chinese carb. I've learned not to expect much from a Chinese anything. So far all the ones I have seen are just cheap copies of the oem Mikuni, and they would likely have the same settings as the '07. Nothing is perfect, but for me the oem XT carb is not bad. I'm just glad it has a carb. I have been able to attain a perfectly stable low idle speed with my '94 carb, something that is difficult with a CV carb, and impossible with EFI.


The above is my opinion. Your mileage may vary.
1994/2001 custom built XT225 with a ton of aftermarket parts.



Re: Carb Swap??? [Re: guitback] #150581 02/23/21 09:12 PM
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http://www.xt225.com/forums/ubbthreads.php?ubb=showflat&Number=135219 I would look at this first. Muniac had a write up on using the TM-33 but it seemed to require a lot of adjustments. I know he sold a kit for awhile but that is long gone. I know this guy tried the Lectron and I believe the TM-33 without sucess http://www.xt225.com/forums/ubbthre...Words=lectron&Search=true#Post132049 And finally all that is involved in theTM 33 http://www.xt225.com/projects/mikuni.htm

Last edited by Rubicon; 02/23/21 09:14 PM.
Re: Carb Swap??? [Re: Deserteagle56] #150584 02/23/21 11:29 PM
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peejman Offline
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Originally Posted by Deserteagle56
I'd love a more tractable and precise power delivery with my 2007 also. Seems my 1992 XT225 was better in that respect than the 2007. Some of my riding is following horse trails (we have thousands of wild mustangs around here) which are 1-2 feet wide and weave in and out of washes and around sagebrush which can lead to out-of-the-way but interesting locations. The XT225 throttle response is very jerky at very low speeds and makes this difficult. So if someone comes up with a solution I'd love to hear about it.

[Linked Image from i.imgur.com]


Try to minimize the amount of free play in the throttle cables. Being precise right off idle while weaving around obstacles is tough. You can feather the clutch a little to soften the delivery a bit.

One of the things I practice is full lock figure 8's. I stand up, push the bike down under me and try to turn as tight as I can, as slow as I can. I try to go at idle speed or below. On a good day I can stop completely for a moment every now and then.


This shall pass, be still and know.
2006 XT225, UNI filter, ProTaper bars, MSR handguards, SS front brake line, Shinko 241's.
Re: Carb Swap??? [Re: guitback] #150592 Yesterday at 02:38 PM
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peejman Offline
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Another technique I thought of.... keep your elbows up and rotate your right elbow out so that twisting the throttle is more like twisting a door knob. You'll find you've got more control with that motion.


This shall pass, be still and know.
2006 XT225, UNI filter, ProTaper bars, MSR handguards, SS front brake line, Shinko 241's.

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