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My 200 SX experimentation thread.

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2008 144SX converted to a 200.

Joe has contributed to my experimentation with some parts on loan, a FWW for a 2k2 FW (which I will buy), a 36mm carb, and a Boyesen rad valve.

These hybrid builds have a different personality than a normal 200 and like their own unique level of tuning, or seem to.

Where do you think or want me to start? I am thinking reed block since it is easy to swap.

When I got this bike, it was in all intents and purposes an SX short of the silencer and FW.

Gearing had been changed to a 46 out back from the stock 50 for the 144. I have settled for stock 200 gearing, 14/48. Improvement for the terrain I ride (and my weight 👍).

Stock 144 comes with a 39mm carb. I got it working fairly well, but could never get rid of a bog off bottom at low rpms, load, and throttle. Just didn't provide enough air velocity at lower rpms, IMHO. I have switched to a 38 mm carb and it is much improved, and back to what I am used to. If I rode the bike up in the rpm's most of the time, it wouldn't be as much an issue.

Added a 9oz FWW to the stock 2k1 FW. It helped with stalling, though not a huge difference. Also didn't hurt the way it spools up. I actually like more stall prevention, which is why I am going to a 2k2 + 9oz FWW. That combination will be 9oz heavier than the combo I have now.

I have noticed this bike is very sensitive to PV setting. It has been discussed that the spring associated with the centrifugal timer is lighter or different than the 200. My findings seem to align with this as I have to run it higher to get the low end response I am used to, and I can't deviate far from that without losing the low end response. Joe has stated that the springs for his 144's and 125's have different color markings on them. I may end up experimenting with the different springs, but I will stick with the other things for now.

I plan on trying each changes separately and then in combination.

My goal is to turn this somewhat hyper 200 into a grunty 250 style powerplant with good low to mid power that will still rev out if I want to (kind of how my 05 was). I am really pleased at this point, just want to see what these changes do. I do want to get the FW swapped, but the carb and reed block is just for kicks.

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If the 36 carb cleans up the bottom all the more, I would have to wonder if a 36/38 keyhole carb mod might be worth investigating. Will be interesting to hear where the carb gets you by itself. Sounds like a fun way to tinker away some time. Good luck. Since alot of us followed the original buildup of the bike, I think there will be alot of room for you to bring the package together by experimentation.👍

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Where would I like to see you go with this thread? Hmmmm,

1. Take pictures of individual parts as you install them. If you swap from a V-Force to a Boysen then post pics of each and then a summary that includes the pics afterwards even if the pics are from a quote.

2. Give us a description of your riding style, terrain, weight, speed (you gotta be honest though 👍) and anything else you think is relevant.

3. After you make a change don't be afraid to switch back to something else. For instance, if you swap gear ratios don't be afraid to remove the flywheel.

The thing is there are so many options that one can't really tell. Truth be told go have fun and swap parts, give us the 411 and inspire us to do the same.

Travis.

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I can add a couple of pics.

These are the v force 3 reeds on the left that came with my 08 144 and the 09 200 boysen reeds on the right.

Joe........

IMG_9213.JPG

IMG_9212.JPG

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Right now I am pretty happy with the 39mm carb on the 200 hybrid engine. This engine is a 2008 200 XC cylinder, head, and crank with a Vetex piston also running an FMF gnraly pipe all bolted onto a 2007 125 SX bottom end. This engine is bolted into a 2008 144 SX chassis. At the moment I have a 2k1 stator / flywheel and I am running the 144 CDI.

I still have the 24 hour race at the end of the month and a double race weekend in November to end the season so I am not going to make any changes right now.

gmoss the flywheel weight is a gift;) That thing has been sitting in my garage for a couple of years now doing nobody any good. I'm just glad to see someone using it.

My son has the 2k2 stator / flywheel on his 150 engine at the moment. I will be pulling both the OEM stators and installing the trailtech setup this weekend.

I am looking forward to the testing from gmoss! This winter will allow me some time to make some changes.

Joe........

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I can add a couple of pics.

These are the v force 3 reeds on the left that came with my 08 144 and the 09 200 boysen reeds on the right.

Joe........

IMG_9213.JPG

IMG_9212.JPG

Your 09 Boysen reeds look very similar to my 01 reeds and cage? One thing I would really like to know is the difference in the reeds/cages throughout the different years, it seem as if this can be as much of a tuning tool as carburetors??

There are so many options, carbs, reed cages, heads, PV springs etc. One thing that is cool with the KTM's is how often one part will work in another application.

I can recall seeing a post on another website where a guy was swapping springs on a 200 to change the PV timing, several folks said he was wrong and didn't know what he was talking about. In the end he did and a few folks were surprised. I don't know how the whole PV works but I do know there is a spring on the 200 that has some effect. I've got a good guess Joe and GMoss are on the right track.

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Gmoss; have you experimented with one of those Powernow inserts? I've only read about them but came to mind when you mentioned air velocity. Perhaps the 36, 38 and 39 carbs provide enough options without such a device IDK.

Looking forward to this thread!

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Gmoss; have you experimented with one of those Powernow inserts? I've only read about them but came to mind when you mentioned air velocity. Perhaps the 36, 38 and 39 carbs provide enough options without such a device IDK.

Looking forward to this thread!

I've wondered the same thing, though it seems most carb mods are oval bored 36-39 with the plates.

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Your 09 Boysen reeds look very similar to my 01 reeds and cage? One thing I would really like to know is the difference in the reeds/cages throughout the different years, it seem as if this can be as much of a tuning tool as carburetors??

There are so many options, carbs, reed cages, heads, PV springs etc. One thing that is cool with the KTM's is how often one part will work in another application.

I can recall seeing a post on another website where a guy was swapping springs on a 200 to change the PV timing, several folks said he was wrong and didn't know what he was talking about. In the end he did and a few folks were surprised. I don't know how the whole PV works but I do know there is a spring on the 200 that has some effect. I've got a good guess Joe and GMoss are on the right track.

I tried to find the springs but could only find the timing mechanism sold as a unit.

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Once I get my 200 sorted we'll have to swap CDI units to see just how much effect it has. I should have the Kawi needles installed by the weekend, now just need to bum a ride as the Subaru clutch is shot.:ride::bonk::worthy:

Another thing we can try is swap my "optimized" 36mm carb for your 38mm in back to back testing. It'll have to be on a non-muddy day though.

You'll also have to try some porting.👍

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Ski/moss

It's nice you 2 can swap parts and compare bikes. I used to have that luxury with my old riding buddy.

For best all around the keyhole carb, the PN inserts are more hype than fact on a 2T but it may have merit on the 39 carb. If anything use the one between the engine and carb, not the one from carb to airbox. Been there, done that.

As for the V3 and Rad Valve. There is not much difference really. The V3 has more reed surface and a lower angle which helps low end a little. The Rad Valve benefits mid to upper rpm and is a better design to direct flow into the crankcase. There is not a night and day difference and I've said it's not worth the investment to change over, but you have both, so do your test. For you the V3 is probably the "better" choice.

Do you have access to the timer springs? As mentioned the individual parts are not available, only the timer as a unit.

I prefer the 2k3 FW but you won't go wrong with your 2k2 setup, especially for the price.

You never did say what you didn't like with the 1370dka. It may have been too rich for your conditions at the time and the eka and 71 diameter would have been better. You should also try Ski's Kaw needles along with your DCL, DDL with the 36 and the K diameter with the 38. If you have the Yam N3E/CH or N2ZH or N8RH give a try. Do you have or can borrow a 6.5 slide?

The PO, BB made mention he was going to do "porting" work himself. If he did you don't know if he did "good" or "bad" for YOUR style riding. You and him are on opposite sides of the fence as for riding requirements. Did you have the head done by Mike yet?

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Where would I like to see you go with this thread? Hmmmm,

1. Take pictures of individual parts as you install them. If you swap from a V-Force to a Boysen then post pics of each and then a summary that includes the pics afterwards even if the pics are from a quote.

The reed cage is fairly straight forward and Joe gave us some pics. I added a pic below showing the intake tract, which is notable.

2. Give us a description of your riding style, terrain, weight, speed (you gotta be honest though :ride:) and anything else you think is relevant.

My riding style ranges from running a gear high, staying smooth on good ST, to ripping corner to corner on the faster double track. I ride primarily in the eastern foothills and mountains of NC which has plenty of hills, with roots, rocks, slickrock granite, sand, red clay. Really varied and plenty of technical trials. Not a lot of opportunities to really open it up and I can't ride it on the pipe for any length of time without feeling out of control. In the technical terrain, it just works better to carry speed, a gear high, staying smooth. I run a trials tire, the Vee Rubber 19" TT.

I weigh about 240-45 geared up. I run a mid pack B speed when I feel good and I trail ride at a fast C pace.

Here's some vid's of Brown Mtn OHV (not me):

[/url]

3. After you make a change don't be afraid to switch back to something else. For instance, if you swap gear ratios don't be afraid to remove the flywheel.

The thing is there are so many options that one can't really tell. Truth be told go have fun and swap parts, give us the 411 and inspire us to do the same.

Travis.

Dang, got my work cut out for me. :worthy: shouldn't have opened my mouth. hehe

Right now I am pretty happy with the 39mm carb on the 200 hybrid engine. This engine is a 2008 200 XC cylinder, head, and crank with a Vetex piston also running an FMF gnraly pipe all bolted onto a 2007 125 SX bottom end. This engine is bolted into a 2008 144 SX chassis. At the moment I have a 2k1 stator / flywheel and I am running the 144 CDI.

I still have the 24 hour race at the end of the month and a double race weekend in November to end the season so I am not going to make any changes right now.

gmoss the flywheel weight is a gift;) That thing has been sitting in my garage for a couple of years now doing nobody any good. I'm just glad to see someone using it.

My son has the 2k2 stator / flywheel on his 150 engine at the moment. I will be pulling both the OEM stators and installing the trailtech setup this weekend.

I am looking forward to the testing from gmoss! This winter will allow me some time to make some changes.

Joe........

Thanks Joe. Got to get the mounting hardware, but no worries, got to pick up a 2k2 FW first. Right now, I am focusing on the reed cage.

Gmoss; have you experimented with one of those Powernow inserts? I've only read about them but came to mind when you mentioned air velocity. Perhaps the 36, 38 and 39 carbs provide enough options without such a device IDK.

Looking forward to this thread!

Have not tried the PN inserts. IMHO, just too much coin for what they are.

Once I get my 200 sorted we'll have to swap CDI units to see just how much effect it has. I should have the Kawi needles installed by the weekend, now just need to bum a ride as the Subaru clutch is shot.:worthy::bonk::worthy:

Another thing we can try is swap my "optimized" 36mm carb for your 38mm in back to back testing. It'll have to be on a non-muddy day though.

You'll also have to try some porting.:worthy:

We can do that at some point Bob. I have a 36mm carb that I will be testing soon enough.

Ski/moss

It's nice you 2 can swap parts and compare bikes. I used to have that luxury with my old riding buddy.

For best all around the keyhole carb, the PN inserts are more hype than fact on a 2T but it may have merit on the 39 carb. If anything use the one between the engine and carb, not the one from carb to airbox. Been there, done that.

As for the V3 and Rad Valve. There is not much difference really. The V3 has more reed surface and a lower angle which helps low end a little. The Rad Valve benefits mid to upper rpm and is a better design to direct flow into the crankcase. There is not a night and day difference and I've said it's not worth the investment to change over, but you have both, so do your test. For you the V3 is probably the "better" choice.

IDK if there is going to be a big difference after my "driveway" runs this eve.

Do you have access to the timer springs? As mentioned the individual parts are not available, only the timer as a unit.

If I can talk Joe into sending them to me, then yes, I can experiment with those as well. :worthy: Would like to have one out of a 200. I believe he has that as well as a 125 spring.

I prefer the 2k3 FW but you won't go wrong with your 2k2 setup, especially for the price.

I thought about one, but simply too much money for what I wanted. Since I wanted more weight than it provided, I could keep my stator with the 2k2, and didn't want lights, it made sense to just go with the 2k2.

You never did say what you didn't like with the 1370dka. It may have been too rich for your conditions at the time and the eka and 71 diameter would have been better. You should also try Ski's Kaw needles along with your DCL, DDL with the 36 and the K diameter with the 38. If you have the Yam N3E/CH or N2ZH or N8RH give a try. Do you have or can borrow a 6.5 slide?

The 1370dka didn't play well with the 39mm carb. Was just too rich, then Ski needed it back. hehe The 38 has a 6.5 slide in it now. I don't have the other needles, just the Sudco's at this point. I may experiment with jetting later, but for now, I am just going to make adjustments as necessary for the changes I am making.

The PO, BB made mention he was going to do "porting" work himself. If he did you don't know if he did "good" or "bad" for YOUR style riding. You and him are on opposite sides of the fence as for riding requirements. Did you have the head done by Mike yet?

No porting when I got it. I did some light work on the main ports and the exhaust flange, nothing drastic at all. I also have the head milled by Mike, set at 1mm squish.

I installed the Rad valve this eve. I would like to try the reed cage that came on the 05, not the rad valve or the VF, but this will be ok.

Had to rig the cage with washers behind the bolts as they were too long coming from the force. After a few good runs up and down the driveway, I can tell I am going to have to lean out the mid to upper range of the carb. Had a bad stutter, cutting out from mid to top. Does this sound right moving from the V to the Rad? I really didn't expect that.

I will make the jetting adjustments to clean it up and test it possibly this weekend. Picked a great time to start this, very busy without much time to tinker lately. 👍

From the pic, you can see that the Rad valve has a better flow path, interesting.

reed_cages.jpg

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To get FW effect it's not all about weight, but where the weight is placed, the advantage of the K3, but the FWW on the K2 is a cheaper way out and more so now with your gift. It's not all about having lights. There doesn't appear to be as many parting out 300's these days. The '08 to present 200's come factory with the K3.

I've been talking to Ski about jetting. It's been a long time since I found and used the Honda needles. Just for kicks I wanted to test against the current needle I've been using. Temps were around 80* and a bit humid. Those conditions call for the 1371eka 3 but I mistakenly put in 1371dka 3. It ran ok but a bit rich and being with a group I had to run the day. Not bad but soft and sluggish, a little smoky and a little spooge. When I got home I found my mistake

.

When I suggest needles I always suggest getting the 1/2 clip different twin to fine tune for conditions. With the Honda needle the majority for some reason settled on just the 1370dka 3. If their happy, great, but I know they are seriously compromised under some riding conditions. This is why I think you weren't happy and you just confirmed. Believe it or not the size of the carb has little affect on needle choice. At most a 1/2 clip difference. By far the biggest change is in the mj. Even the pj at most a 1 size change. With cooler temps on the way you may want to retest the Honda needle.

To properly compare the carbs you really need to be actually riding, not a driveway test AND you have to have the jetting tweaked for each carb. The 36 and 38 are close to about 3/8 then from about 1/2 the 38 begins to pull harder. The difference is subtle off the bottom and if your sensitive you can tell the difference the 36 is pulling just a bit better. This is why the oval bore shines. Think of it as a 2 barrel carb. Low throttle it runs off the primary, then you punch it and the secondary opens up.

There was just too much drama in BB's bike blow up/rebuild and all he was going to do against advice. I didn't follow his threads but he PM'ed time to time and I had to scan his threads. I do remember him saying he was going to do some light porting, apparently he took others advice and left well enough alone. This is in YOUR favor.

Yes as mentioned the Rad Valve was specifically designed for offset carbs like the KTM to better direct flow into the crankcase. I think the ideal would be the V3 combined with the Rad Valve. It's been a long time since I swapped, but I do remember not being all that impressed, at least not what all the V3 hype is about. Just a tad better off idle, but that's it. I don't remember making any drastic jetting changes but to be honest I was still testing various needles and swapping carbs at the time, so any change if needed was absorbed by my other changes. However if you feel a need to lean the mid to upper range with the Rad Valve, that would go hand in hand with the better efficiency of the Rad Valve at higher rpm. The V3 on the other hand "may" need a leaner tweak at lower throttle openings. Another possible reason the 1370dka wasn't to your liking.

You have a lot going on and there is a lot that affects jetting. This is why you need to be happy with everything else on the engine and make no changes other than jetting to fully get a feel for what's going on. Ideally you need to do all your jetting changes the same day, back to back and as quickly as possible before temp, humidity and other riding conditions change as the day progresses. If you only have a needle or two, it's relatively easy, but when you have a handful and need to tweak the a/s, pj, clip position, needle diameter and mj, it takes at least half a day. Then throw in slide changes, LOL. However my results to help others I kept the stock 7 slide. For my personal setup I change slides for different needles. The reason, with multi-taper needles, the ONLY way you can effectively change the 1/8 to 1/4 area is by slide changes. This is because you are on the first taper which is in control. The Sudco jetting graph does not accurately apply to multi-taper needles in this particular area as it does with the single taper needles. The taper on most single taper needles starts just before 1/4 throttle vs before or at 1/8 with multi-taper needles.

If interested I'll look through my collection and loan you a few for testing.

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I like the feel of the 2k3 on Skidaddy's 08 200 and don't know that I would put a FWW on it. But, I haven't ridden it since he made the changes.

The savings, even buying a used FWW, is that I don't have to buy another stator. This still made it cheaper than buying a 2k3 setup used, at least what I could find.

I have a loop I can ride to test jetting, but I use my 1000'+ long gravel drive to get a baseline before getting on the trails. This allows me to find the rich or lean spots in the throttle range. Plus, I don't have any neighbors to worry about, so I can do WOT 6th gear runs if I want. 👍

I will be using the Sudocos to start and may try some other needles once I get close with them.

I will post my results with the Rad valve once I get a good ride on it.

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What hardware you need? I have a lot of stuff from parting out bikes. I guess I take that for granted and think everyone has a pile of nuts and bolts;)

Don't go buying stators, I have them all. Winter is coming and we can play.

I like the way the 2k1 spins up but I do find myself killing it every now and then coming into a turn hot and getting on the rear brake. The last race I did it two times,,, not bad for a 1.5 hour race. With a heavier flywheel I get less stalling.

Something to note. The 2k1 and the 2k2 are the very close to being the same. The 2k1 coil assembly is the same minus the copper wire on some of the posts. The 2k2 flywheel is the same as a 2k1 with a flywheel weight added OEM. You can take a 2k2 flywheel and use it with a 2k1 stator. That flywheel weight I sent should make a 2k1 feel like a 2k2

Joe........

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Anyone ever notice the big lip in the intake track on the right side case lower section and how different it is from the left? It blows me away that they are so different.

Joe...........

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Anyone ever notice the big lip in the intake track on the right side case lower section and how different it is from the left? It blows me away that they are so different.

Joe...........

Actually no and I've had the cases apart, just never noticed. Do you have a picture? I may have to study Supertrunks pictorial thread, I'm sure he has a picture of it. LOL

If anyone's interested I have a 2k1 FW, actually it was a 2k2 that Clay machined off the weight. I think it's maybe a 1/2 oz lighter but just figure it's the same. I intended to use with an autoclutch to offset the FW effect but never installed the autoclutch. I do have the 2k2 stator but want to keep for now. Trade for ???

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What hardware you need? I have a lot of stuff from parting out bikes. I guess I take that for granted and think everyone has a pile of nuts and bolts;)

Don't go buying stators, I have them all. Winter is coming and we can play.

I like the way the 2k1 spins up but I do find myself killing it every now and then coming into a turn hot and getting on the rear brake. The last race I did it two times,,, not bad for a 1.5 hour race. With a heavier flywheel I get less stalling.

Something to note. The 2k1 and the 2k2 are the very close to being the same. The 2k1 coil assembly is the same minus the copper wire on some of the posts. The 2k2 flywheel is the same as a 2k1 with a flywheel weight added OEM. You can take a 2k2 flywheel and use it with a 2k1 stator. That flywheel weight I sent should make a 2k1 feel like a 2k2

Joe........

It's no biggie, but with the 2k2 FWW, it comes with a bracket, 2 bolts, and an allen wrench. I will call Steahly once I pick up a 2k2 FW.

Ok, my jetting with the V3 was

6.5 slide

190m

DCJ 3rd

42 p

AS 1.5

I am trying to get a baseline for my ride this weekend and wanted to keep the same needle for this experiment. Still may be some tweaking, but to start and get it close.

drop to a 185m, cleaned up the mid to top stutter and stubble. Still had a slight stumble prior to that, so I dropped the needle to the 2nd clip. AS is 2-2.5 out to get a good response, so, if I have time before the ride, I may try a 40 p. Likely won't, so this experiment will likely last a couple of ride weekends.

If I understand this correctly, with having to lean out the Boyesen, does that mean it is helping create more vacuum, pulling more fuel thru the system? Otherwise, my thinking is that if it flowed more air, I would have to richen it up. Could be so also, but the 2 stage reeds must be playing a big role?

more to come.

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It's no biggie, but with the 2k2 FWW, it comes with a bracket, 2 bolts, and an allen wrench. I will call Steahly once I pick up a 2k2 FW.

hmm, That was on a 380 I parted out. The FWW is held on by set screws. The bracket and two bolts was not on there when I got the bike. I've never used those before so who knows, it may have been installed wrong by the previous owner. However it was on there pretty darn good when I removed it. Chuck would be able to tell you all about that FWW.

Joe........

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That flywheel weight I sent should make a 2k1 feel like a 2k2

I just noticed I messed that up. That FWW should make a 2k2 feel more like a 2k3;)

Joe........

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