17' TC250 Jetting Help

Dexter
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Dexter 1/27/2018 2:39am
1/27/2018 2:39am Edited Date/Time 1/27/2018 2:40am
samcampbell wrote:
You want a flat top Keihin 36mm on the TC250. After testing both the 38mm and 36mm on my 17 TC250, the 36mm had quite a...
You want a flat top Keihin 36mm on the TC250. After testing both the 38mm and 36mm on my 17 TC250, the 36mm had quite a bit more low end response and didn't really lack much top end in comparison.

It is the best upgrade I made to the bike, didn't take very long to figure out the jetting and I have only adjusted the main since and has worked great since. Much less sensitive to elevation and temperature changes and the bike now runs how a 250 should. Would highly recommend it and I can imagine it would work about the same on the 125 as well.
Can you share your jetting please, I dont master jett tunning well so I dont want to get lost if I put a Keihin. Thanks
mxstate
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mxstate 1/27/2018 3:12am
1/27/2018 3:12am Edited Date/Time 1/27/2018 3:12am
samcampbell wrote:
You want a flat top Keihin 36mm on the TC250. After testing both the 38mm and 36mm on my 17 TC250, the 36mm had quite a...
You want a flat top Keihin 36mm on the TC250. After testing both the 38mm and 36mm on my 17 TC250, the 36mm had quite a bit more low end response and didn't really lack much top end in comparison.

It is the best upgrade I made to the bike, didn't take very long to figure out the jetting and I have only adjusted the main since and has worked great since. Much less sensitive to elevation and temperature changes and the bike now runs how a 250 should. Would highly recommend it and I can imagine it would work about the same on the 125 as well.
Dexter wrote:
Can you share your jetting please, I dont master jett tunning well so I dont want to get lost if I put a Keihin. Thanks
Dexter,
I pm'd you, check your e-mail
jeffro503
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jeffro503 1/27/2018 10:47am
1/27/2018 10:47am
Mike257s wrote:
I picked up a [used] 2017 TC250 and had the stock Mikuni TMX. I ran several practices and 2 races (Vet MX) all the time battling...
I picked up a [used] 2017 TC250 and had the stock Mikuni TMX.
I ran several practices and 2 races (Vet MX) all the time battling with the finicky TMX. Granted, I didn't put in the time and effort that a lot of you have done with the TMX. Because... been there done that!

As I spent way to much time and energy trying to make a Mikuni TMX work on my 2004 CR250. No-go.
1 year of frustration. Ordered a PWK 38 from JD, installed... rode... done. Haven't looked back. I don't have to touch anything on that carb, -Maybe- a 1/4 turn on the airscrew but that's it!

I decided to pull the trigger I ordered a PWK from JD for the TC.
---> This one: https://www.jdjetting.com/xcart5/jdkh38-keihin-38mm-pwk-airstryker-ag-s…

Admittedly, it wasn't as turn-key as my CR250 but in all fairness (long story short) the squish clearance on my TC250 was about 0.095" (about 2.4mm) !!!
I sent the head to RB Design and had it cut to apx. 0.045" (1.15mm)

I haven't had a chance to test ride it. But the "garage test" and the run around the neighborhood annoying the neighbors I could already tell the difference. Mainly the pipe bang is reduced drastically, and I can probably get that fine tuned out of there once I get a chance to take the bike out again.



Thanks for the info man! I think once you ride it , especially with the correct squish , you'll find it to be a totally different bike. Once you get some laps in on her , fill us in on how that carb and head did. please!
Joko
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Joko 1/27/2018 10:02pm
1/27/2018 10:02pm
Anyone have their cylinder ported ?
Is there room for improvement by porting this model, or is it already pretty much optimized?

The Shop

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riv187
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riv187 2/1/2018 7:59am
2/1/2018 7:59am
jeffro503 wrote:
Guys.....if a dude was willing to swap out the Mikuni for a Keihn carb on this bike.....which model # would work? I'm almost tempted to do...
Guys.....if a dude was willing to swap out the Mikuni for a Keihn carb on this bike.....which model # would work? I'm almost tempted to do the same damn thing on my TC 125. The old Keihn I have on my 2006 RM 250 , is seriously " set it and forget it ". I have ridden the same jetting at 40 degree's to about 95 degree's and it never needed tuning. I don't ride in the cold weather , and once it got up over 100 here , the only thing I have ever done is gone down one size on the main jet. Never really affected the bottom to much.
Mike257s wrote:
I picked up a [used] 2017 TC250 and had the stock Mikuni TMX. I ran several practices and 2 races (Vet MX) all the time battling...
I picked up a [used] 2017 TC250 and had the stock Mikuni TMX.
I ran several practices and 2 races (Vet MX) all the time battling with the finicky TMX. Granted, I didn't put in the time and effort that a lot of you have done with the TMX. Because... been there done that!

As I spent way to much time and energy trying to make a Mikuni TMX work on my 2004 CR250. No-go.
1 year of frustration. Ordered a PWK 38 from JD, installed... rode... done. Haven't looked back. I don't have to touch anything on that carb, -Maybe- a 1/4 turn on the airscrew but that's it!

I decided to pull the trigger I ordered a PWK from JD for the TC.
---> This one: https://www.jdjetting.com/xcart5/jdkh38-keihin-38mm-pwk-airstryker-ag-s…

Admittedly, it wasn't as turn-key as my CR250 but in all fairness (long story short) the squish clearance on my TC250 was about 0.095" (about 2.4mm) !!!
I sent the head to RB Design and had it cut to apx. 0.045" (1.15mm)

I haven't had a chance to test ride it. But the "garage test" and the run around the neighborhood annoying the neighbors I could already tell the difference. Mainly the pipe bang is reduced drastically, and I can probably get that fine tuned out of there once I get a chance to take the bike out again.



Hi, Did you get to test the bike with PWK and new squish?
Superdave19
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Superdave19 2/1/2018 8:59am
2/1/2018 8:59am
Joko wrote:
Anyone have their cylinder ported ?
Is there room for improvement by porting this model, or is it already pretty much optimized?
I'm getting mine 'massaged' as we speak- Will keep you posted.
Mike257s
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Mike257s 2/1/2018 1:37pm
2/1/2018 1:37pm
riv187 wrote:
Hi, Did you get to test the bike with PWK and new squish?
Not yet - but I am attending a private ride day tomorrow at Prairie City MX (aka Hangtown) tomorrow. (Friday)

I will post what I find.
erik_94COBRA
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erik_94COBRA 2/1/2018 7:25pm
2/1/2018 7:25pm
Joko wrote:
Anyone have their cylinder ported ?
Is there room for improvement by porting this model, or is it already pretty much optimized?
Superdave19 wrote:
I'm getting mine 'massaged' as we speak- Will keep you posted.
Who is doing your cylinder?

I have a 300 on mine now and am thinking of having 250 tweaked to have a comparison. Am going to make separate post on 300 soon.
UPSman334
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UPSman334 2/1/2018 8:06pm
2/1/2018 8:06pm
My 18 250sx runs like shit, i would have bought a YZ but i’m trying to go to loretta’s in 2 stroke and the yamaha is so slow compared to the KTM
sdhuskyrider
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sdhuskyrider 2/2/2018 5:15pm
2/2/2018 5:15pm
Glad to see this thread is alive and well. I'll have some updates this weekend. Anyone going to San Diego SX this weekend?!
AJ565
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AJ565 2/4/2018 4:25pm
2/4/2018 4:25pm
So this is the jetting I ended up with Saturday. I ran C12 most of the day and then after I knew it was running good I changed my main to a 490, my PJ to 37.5, and my AS to 1.5. Drained all my fuel out and filled the tank with VP U4.4. All I can say is wow this bike runs like a raped ape with it. It’s also cheaper than C12 as if it wasn’t amazing enough with the oxygen content. I think I might order a 35 PJ and a 5.5 slide to see how much it changes, but I think I’m good with where I’m at. I’m also thinking that that fuel in a stock bike would solve the problems everyone has.

MJ 490
PJ 37.5
Needle 42-75
Clip 4th position
Needle jet s-4
AS 1.5
U4.4 mixed 60:1 with amsoil donionator
Elevation 560'
bmklegenden 2/6/2018 4:29am
2/6/2018 4:29am
alittle off topic but when i bought my TC125 16' it was perfect and had great throttle response but they also sold me some IPONE two stroke oil and when i started to use that oil my bike started to bog alittle and get a worse throttle response. Is the oil the problem or have something else just happend with the bike?

Thanks
AJ565
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AJ565 2/6/2018 6:52am
2/6/2018 6:52am
You'll have to try and go back to what you used before you switched to that oil. If thats the only change that you made to the bike then thats what I'd lean towards being the cause. What ratio are you mixing it at?
bmklegenden 2/6/2018 7:12am
2/6/2018 7:12am
AJ565 wrote:
You'll have to try and go back to what you used before you switched to that oil. If thats the only change that you made to...
You'll have to try and go back to what you used before you switched to that oil. If thats the only change that you made to the bike then thats what I'd lean towards being the cause. What ratio are you mixing it at?
Yeah, that's what im thinking. I think my ratio is 50:1 if i read the measurement properly on the IPONE bottle.

5L with 100ml oil
Jensenyo
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Jensenyo 2/6/2018 7:33am
2/6/2018 7:33am
AJ565 wrote:
You'll have to try and go back to what you used before you switched to that oil. If thats the only change that you made to...
You'll have to try and go back to what you used before you switched to that oil. If thats the only change that you made to the bike then thats what I'd lean towards being the cause. What ratio are you mixing it at?
bmklegenden wrote:
Yeah, that's what im thinking. I think my ratio is 50:1 if i read the measurement properly on the IPONE bottle.

5L with 100ml oil
I recall that the 125/150sx calls for 1:40 mix ratio, but I can be wrong. Check your manual.
bmklegenden 2/6/2018 7:38am
2/6/2018 7:38am
Jensenyo wrote:
I recall that the 125/150sx calls for 1:40 mix ratio, but I can be wrong. Check your manual.
Checked the manual now and it says 1:40, thanks! Could that be the issue tho? if i go down to 1:40 it wont bog and have better response on the throttle?
sandman768
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sandman768 2/13/2018 5:20am
2/13/2018 5:20am
And MXA goes richer on the pilot jet.........
opyguy
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opyguy 2/13/2018 8:20am
2/13/2018 8:20am
sandman768 wrote:
And MXA goes richer on the pilot jet.........
no kidding, I almost fell out of my chair reading their review, the inconsistencies are mind boggling when you read it back to back w/the 17 review. Look @ what they say about adjusting the PV, totally opposite of what they said in 17.

Pit Row

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sandman768
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sandman768 2/13/2018 1:32pm
2/13/2018 1:32pm
They also have a typo in the new article/test of the 18. It states " the only jetting change we made was to go to a bigger 55 pilot jet. But in the last page of the test where they list setup specs they have the pilot jet being a 45 not a 55, which makes more sense....just to confuse us a little more....could it be... We are going in the wrong direction? Should we go richer off idle? .....I did have a similar experience with my TMR engine 96 cr250. It had a flat spot off idle, I kept going leaner, With no results, TMR stated I was going in the wrong direction, My off idle flat spot was a lean bog, I went to his suggested richer pilot jet & it improved drastically. TMR stated a 2 stroke should not be ideling and if it is, It"s pilot is too lean. Have to take MXA"s jetting advice with a grain of salt, here in the northeast we have much cooler temps and a lot of deep mud/sand that requires richer jetting ...
sdhuskyrider
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sdhuskyrider 2/24/2018 8:15am
2/24/2018 8:15am Edited Date/Time 2/24/2018 8:16am
AJ565 wrote:
So this is the jetting I ended up with Saturday. I ran C12 most of the day and then after I knew it was running good...
So this is the jetting I ended up with Saturday. I ran C12 most of the day and then after I knew it was running good I changed my main to a 490, my PJ to 37.5, and my AS to 1.5. Drained all my fuel out and filled the tank with VP U4.4. All I can say is wow this bike runs like a raped ape with it. It’s also cheaper than C12 as if it wasn’t amazing enough with the oxygen content. I think I might order a 35 PJ and a 5.5 slide to see how much it changes, but I think I’m good with where I’m at. I’m also thinking that that fuel in a stock bike would solve the problems everyone has.

MJ 490
PJ 37.5
Needle 42-75
Clip 4th position
Needle jet s-4
AS 1.5
U4.4 mixed 60:1 with amsoil donionator
Elevation 560'
What was the temp when you ran this setup? And what premix ratio do you run?
AJ565
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AJ565 2/24/2018 10:01am
2/24/2018 10:01am
sdhuskyrider wrote:
What was the temp when you ran this setup? And what premix ratio do you run?
Upper 60's -low 70's. I'm still running 60:1. I think a 500 main would work for me, but I'm holding off on ordering one since its starting to get warmer now.
AJ565
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AJ565 3/5/2018 6:59am
3/5/2018 6:59am
Just wanted to update my jetting for warmer temp. It was in the low-mid 70's this past weekend and I wasn't getting the pull from the top end I should have been. Dropped the clip one spot to the 3rd position and all is good now and turned in the PV 1/4 turn for a total of 1 3/4 turns in.

MJ 490
PJ 37.5
Needle 42-75
Clip 3rd position
Needle jet s-4
AS 1.5
U4.4 mixed 60:1 with amsoil donionator
Elevation 560'
paddyB745
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paddyB745 3/5/2018 7:24am
3/5/2018 7:24am
For anyone curious about the PWK swap I found a 38mm from an 02 rm250 that I tried in my 17 TC250. Initial reaction was wow this thing starts WAY easier, with the Mikuni I had to give it a little throttle for it to start with the PWK it fires no problem. At the track, the jetting I had felt good, way more consistent overall than the Mikuni. It just ran smoother, no noticeable power difference but it ran the same every time out on the track. Had a buddy cut the head .020” to get the squish right around .045” and huge difference. With the PWK and the head cut this thing finally runs like a normal 2 stroke. The bottom end power is cleaned up no more blubbering off the bottom and if you are a gear high exiting a corner just a little clutching will get you right back on the power. Fuel mileage is way better now also, did an hour and a half hare scramble and only used half of the 300 tank so about 1.3 gal. Overall I’m very happy with the upgrades and would recommend the PWK to anyone that’s tired of playing with the Mikuni.
Running Sunoco 112 50/50 with 92 ethanol free fuel
Motorex cross power 2t 50:1
rollin64caddy
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rollin64caddy 3/5/2018 6:48pm
3/5/2018 6:48pm
paddyB745 wrote:
For anyone curious about the PWK swap I found a 38mm from an 02 rm250 that I tried in my 17 TC250. Initial reaction was wow...
For anyone curious about the PWK swap I found a 38mm from an 02 rm250 that I tried in my 17 TC250. Initial reaction was wow this thing starts WAY easier, with the Mikuni I had to give it a little throttle for it to start with the PWK it fires no problem. At the track, the jetting I had felt good, way more consistent overall than the Mikuni. It just ran smoother, no noticeable power difference but it ran the same every time out on the track. Had a buddy cut the head .020” to get the squish right around .045” and huge difference. With the PWK and the head cut this thing finally runs like a normal 2 stroke. The bottom end power is cleaned up no more blubbering off the bottom and if you are a gear high exiting a corner just a little clutching will get you right back on the power. Fuel mileage is way better now also, did an hour and a half hare scramble and only used half of the 300 tank so about 1.3 gal. Overall I’m very happy with the upgrades and would recommend the PWK to anyone that’s tired of playing with the Mikuni.
Running Sunoco 112 50/50 with 92 ethanol free fuel
Motorex cross power 2t 50:1
Did you have to replace the throttle cable or assembly? Im am considering this for my tc.
paddyB745
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paddyB745 3/5/2018 9:15pm
3/5/2018 9:15pm
rollin64caddy wrote:
Did you have to replace the throttle cable or assembly? Im am considering this for my tc.
Yes. I had to use the throttle cable and assembly that came with the carb.
mxstate
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mxstate 3/6/2018 8:46am
3/6/2018 8:46am
rollin64caddy wrote:
Did you have to replace the throttle cable or assembly? Im am considering this for my tc.
paddyB745 wrote:
Yes. I had to use the throttle cable and assembly that came with the carb.
36 mm here but stock cable works fine.
Adjusted free play knob to min but still have enough free play with the throttle
Slides bottoms out fine even when handlebar on left/right max position




rollin64caddy
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rollin64caddy 3/6/2018 3:16pm
3/6/2018 3:16pm
rollin64caddy wrote:
Did you have to replace the throttle cable or assembly? Im am considering this for my tc.
paddyB745 wrote:
Yes. I had to use the throttle cable and assembly that came with the carb.
mxstate wrote:
36 mm here but stock cable works fine. Adjusted free play knob to min but still have enough free play with the throttle Slides bottoms out...
36 mm here but stock cable works fine.
Adjusted free play knob to min but still have enough free play with the throttle
Slides bottoms out fine even when handlebar on left/right max position




Do you know if the 38mm is the same, As far as connecting the stock husky throttle cable up to it?
paddyB745
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paddyB745 3/6/2018 3:36pm
3/6/2018 3:36pm
paddyB745 wrote:
Yes. I had to use the throttle cable and assembly that came with the carb.
mxstate wrote:
36 mm here but stock cable works fine. Adjusted free play knob to min but still have enough free play with the throttle Slides bottoms out...
36 mm here but stock cable works fine.
Adjusted free play knob to min but still have enough free play with the throttle
Slides bottoms out fine even when handlebar on left/right max position




rollin64caddy wrote:
Do you know if the 38mm is the same, As far as connecting the stock husky throttle cable up to it?
Should be. Main reason I used the RM cable and throttle is because it came with the carb and was in good shape. Plus it’s the longer cable which routes the traditional way which I like better. Im sure I could have made the stock set up work but I didn’t need to.
alexk417
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alexk417 3/7/2018 5:42am
3/7/2018 5:42am
digger wrote:
The slides you are looking for ( 5.5--5.75 and 6.0 ) are an OEM part for a 04' Kawasaki KX125. here are the part #'s https://www.motosport.com/dirtbike/oem-parts/kawasaki/2004/kx125/carburetor...
The slides you are looking for ( 5.5--5.75 and 6.0 ) are an OEM part for a 04' Kawasaki KX125. here are the part #'s
https://www.motosport.com/dirtbike/oem-parts/kawasaki/2004/kx125/carbur… . They are about $20 cheaper thru Rocky MT, and I stock. RM wouldn't let me post a direct link to their Kawasaki OEM page.
Digger - Will these Kawi Mikuni slides drop right into the 17/18 TC250 TMX carb without any mods to the slide?

Would you recommend the 6.0 16025-0004 for Central PA elevation 500-1000 primarily? My primary vendor has one in stock, but not the 5.5 or 5.75.

I think I want to give your "base" a try and start ordering up the components. Cheerful

AJ565
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AJ565 3/7/2018 6:14am
3/7/2018 6:14am
alexk417 wrote:
Digger - Will these Kawi Mikuni slides drop right into the 17/18 TC250 TMX carb without any mods to the slide? Would you recommend the 6.0...
Digger - Will these Kawi Mikuni slides drop right into the 17/18 TC250 TMX carb without any mods to the slide?

Would you recommend the 6.0 16025-0004 for Central PA elevation 500-1000 primarily? My primary vendor has one in stock, but not the 5.5 or 5.75.

I think I want to give your "base" a try and start ordering up the components. Cheerful

Yes they slide right in. I'm at the same elevation and so far the 5.75 I have is just about spot on if not on a tad on the lean side. I'd try and find a 5.5 or the 5.75 if I were you. I plan on ordering a 5.5 myself just to try.

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