Jetting help for 2007 KX250

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7/5/2020 1:14 PM

Need jetting help for a 2007 Kawasaki KX250 at 1,050 ft elevation.

Bike has a brand new engine with 2 hours run time. New OEM parts: centercases, crankshaft assembly, covers, seals, bearings, all clutch components, and bolts. Also installed: Phathead cylinder head, Boyesen RAD valve, PC works pipe and FMF Turbinecore silencer.

Bike spooges quite a bit. Have it coming around the expansion chamber inlet as well as dripping out the exhaust. Smokes a good bit as well (more so than should be expected for a nearly new two stroke engine)

I run VP T2 race gas which is premixed at 40:1.

Current jetting:
Clip - highest position
Slide: #8
Main: 155
Pilot: 48

It does not foul plugs.

The bike f'ing RIPS, it is extremely fast with a violent powerband. It just spooges a lot.

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Ride like a girl!!!
2016 KTM 500 EXC-F
Current project: 2007 Kawasaki KX250-R7 retro build
Current project #2: 1987 Kawasaki KX250-E1 rider/racer resto
1989 KX125 resto
1987 RM250 resto

7/5/2020 4:28 PM

Did you try running 32:1?

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7/5/2020 5:55 PM

How big of a difference is there between 40:1 and 32:1? That's only 8 parts to one difference.

I'm game to try, but am also thinking I need to double check my float bowl height as well.

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Ride like a girl!!!
2016 KTM 500 EXC-F
Current project: 2007 Kawasaki KX250-R7 retro build
Current project #2: 1987 Kawasaki KX250-E1 rider/racer resto
1989 KX125 resto
1987 RM250 resto

7/5/2020 5:59 PM

40:1 has 97.5% gasoline to 2.5% oil
32:1 has 96.8% gasoline to 3.2% oil

Not a huge difference but I can give that a try.

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Ride like a girl!!!
2016 KTM 500 EXC-F
Current project: 2007 Kawasaki KX250-R7 retro build
Current project #2: 1987 Kawasaki KX250-E1 rider/racer resto
1989 KX125 resto
1987 RM250 resto

7/6/2020 7:47 AM

Pilot jet looks a bit rich to me, and main seems on lean side. But, it's been a while since i had a smoker

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Livin' the dream, two wheels at a time!

7/6/2020 8:35 AM

Are you losing transmission oil? Make sure the right side crank seal isn’t leaking. Some oils like maxima 927 have a high flash point and create more smoke and spooge. They’re better for wide open high revving racing

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7/6/2020 8:43 AM
Edited Date/Time: 7/6/2020 8:44 AM

Polishhammer wrote:

Are you losing transmission oil? Make sure the right side crank seal isn’t leaking. Some oils like maxima 927 have a high flash point and create more smoke and spooge. They’re better for wide open high revving racing

Not losing any transmission oil.

MXA mentioned that VP may use Maxima in T2, but they were not officially sure. Then again Maxima makes a range of two stroke oils.

Next time I'm near the shop I'll get 5 gallons of C12. What oils would you recommend that have lower flash points, and that could be run at 32:1?

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Ride like a girl!!!
2016 KTM 500 EXC-F
Current project: 2007 Kawasaki KX250-R7 retro build
Current project #2: 1987 Kawasaki KX250-E1 rider/racer resto
1989 KX125 resto
1987 RM250 resto

7/6/2020 3:28 PM
Edited Date/Time: 7/6/2020 3:39 PM

queen of spodes wrote:

Need jetting help for a 2007 Kawasaki KX250 at 1,050 ft elevation.

Bike has a brand new engine with 2 hours run time. New OEM parts: centercases, crankshaft assembly, covers, seals, bearings, all clutch components, and bolts. Also installed: Phathead cylinder head, Boyesen RAD valve, PC works pipe and FMF Turbinecore silencer.

Bike spooges quite a bit. Have it coming around the expansion chamber inlet as well as dripping out the exhaust. Smokes a good bit as well (more so than should be expected for a nearly new two stroke engine)

I run VP T2 race gas which is premixed at 40:1.

Current jetting:
Clip - highest position
Slide: #8
Main: 155
Pilot: 48

It does not foul plugs.

The bike f'ing RIPS, it is extremely fast with a violent powerband. It just spooges a lot.

For your bike and conditions I would recommend

Needle—A Suzuki NECJ needle in the #3 clip position.

https://www.motosport.com/oem-parts/part-number/13383-37FE0?mmy=suzuki%3Brm250%3B2007&group=carburetor&qty=1

Pilot—45
Main—160
Air screw—1.5 turns out from fully closed
This setup is to be used with your #8 slide

That Kawasaki NFxx series needle is not one of favorite Series needles. It make the bike hit really hard into the mid, which makes the bike hard to ride. The Suzuki needle will have a smoother transition into the mid with the same on topend.

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7/6/2020 4:09 PM
Edited Date/Time: 7/6/2020 4:23 PM

digger wrote:

For your bike and conditions I would recommend

Needle—A Suzuki NECJ needle in the #3 clip position.

https://www.motosport.com/oem-parts/part-number/13383-37FE0?mmy=suzuki%3Brm250%3B2007&group=carburetor&qty=1

Pilot—45
Main—160
Air screw—1.5 turns out from fully closed
This setup is to be used with your #8 slide

That Kawasaki NFxx series needle is not one of favorite Series needles. It make the bike hit really hard into the mid, which makes the bike hard to ride. The Suzuki needle will have a smoother transition into the mid with the same on topend.

With those jetting recommendations, would you recommend continuing to run T2 (premixed from VP at 40:1) or get some C12 and mix with Klotz R50 at 32:1? I'm a vet female and am not WFO very much. Goal is a well lubricated bottom and top, but with minimal spooge.

The bike hits so freaking hard in the middle, even with an 11oz flywheel weight. Plan to do some hare scrambles so a tamer power curve will be nice.

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Ride like a girl!!!
2016 KTM 500 EXC-F
Current project: 2007 Kawasaki KX250-R7 retro build
Current project #2: 1987 Kawasaki KX250-E1 rider/racer resto
1989 KX125 resto
1987 RM250 resto

7/6/2020 4:24 PM

queen of spodes wrote:

With those jetting recommendations, would you recommend continuing to run T2 (premixed from VP at 40:1) or get some C12 and mix with Klotz R50 at 32:1? I'm a vet female and am not WFO very much. Goal is a well lubricated bottom and top, but with minimal spooge.

The bike hits so freaking hard in the middle, even with an 11oz flywheel weight. Plan to do some hare scrambles so a tamer power curve will be nice.

I typically cut my fuel, 4 gal 93 octane, 1 gal of 110, but I don’t know where your squish is with your aftermarket head. kX’s always had high crank pressure, so it’s possible you may needs a touch more race fuel, say 3.5 to 1.5 to be on the safe side.
A Suzuki NExx needle will for sure make the bike easier to ride. Have you thought about taking a little timing out of the bike as well to make it easier to ride ? You could also go richer on the starting diameter of the needle. This would also deaden the hit into the middle a little more, but at the expense of some spooge coming out of the silencer, but it would make the bike easier to ride.

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7/7/2020 4:59 AM

digger wrote:

I typically cut my fuel, 4 gal 93 octane, 1 gal of 110, but I don’t know where your squish is with your aftermarket head. kX’s always had high crank pressure, so it’s possible you may needs a touch more race fuel, say 3.5 to 1.5 to be on the safe side.
A Suzuki NExx needle will for sure make the bike easier to ride. Have you thought about taking a little timing out of the bike as well to make it easier to ride ? You could also go richer on the starting diameter of the needle. This would also deaden the hit into the middle a little more, but at the expense of some spooge coming out of the silencer, but it would make the bike easier to ride.

Phathead cut a special lower compression insert which is installed currently. I also have standard and high compression inserts. I originally used the standard compression, but the hit was too abrupt for my liking.

I've ridden a new YZ250 smoker and was kind of bored with its power delivery.

Could you comment on a recommended ratio and oil for ideally less spooge, with your recommended jetting above?

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Ride like a girl!!!
2016 KTM 500 EXC-F
Current project: 2007 Kawasaki KX250-R7 retro build
Current project #2: 1987 Kawasaki KX250-E1 rider/racer resto
1989 KX125 resto
1987 RM250 resto

7/7/2020 7:41 AM

With the low compression head, you more than likely don't even need any race fuel to prevent detonation, which is what I would be worried about. I do all my test/riding at 40:1, which is 16oz of oil in 5 gal of fuel. Simply for consistency, I never change it. You'll be more than safe with, 4 gal 93 to 1 gal c12 at your chosen oil ratio.

I stand with what I mention above still. This will smooth the power out , but not neuter it.

NECJ in #3
45 pilot
160 main
A/S 1.5 turns out
and you #8 Slide.

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7/7/2020 9:31 AM

Thanks. Ordered the new needle. Will report back when I have it together and am able to test.

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Ride like a girl!!!
2016 KTM 500 EXC-F
Current project: 2007 Kawasaki KX250-R7 retro build
Current project #2: 1987 Kawasaki KX250-E1 rider/racer resto
1989 KX125 resto
1987 RM250 resto

7/7/2020 10:00 AM

queen of spodes wrote:

Need jetting help for a 2007 Kawasaki KX250 at 1,050 ft elevation.

Bike has a brand new engine with 2 hours run time. New OEM parts: centercases, crankshaft assembly, covers, seals, bearings, all clutch components, and bolts. Also installed: Phathead cylinder head, Boyesen RAD valve, PC works pipe and FMF Turbinecore silencer.

Bike spooges quite a bit. Have it coming around the expansion chamber inlet as well as dripping out the exhaust. Smokes a good bit as well (more so than should be expected for a nearly new two stroke engine)

I run VP T2 race gas which is premixed at 40:1.

Current jetting:
Clip - highest position
Slide: #8
Main: 155
Pilot: 48

It does not foul plugs.

The bike f'ing RIPS, it is extremely fast with a violent powerband. It just spooges a lot.

Pro Circuit has jetting recommendations on their website. I ran their setup in my 04 KX125 and it was perfect! Outside temp has to be within 10-15 degrees. Hotter is fine, but lower temps the bike is to lean. I switched back to stock jetting, to expand my range, but it does spooge at the higher temp temps, and does not run nearly as strong. I very highly recommend you start there. They have more time with this bike than anyone else.

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David
774 CC Powersports Kawasaki
Factory Backing Factory Seat
Acerbis Dunlop
Sunstar Braking
MX Engine Stands
Matrix Concepts

8/1/2020 11:47 AM
Edited Date/Time: 8/1/2020 11:49 AM

Been busy on other projects but got the updated jetting (digger's recommendation) installed. Hope to test it out tomorrow.

This plug reading is from last ride a month ago (old jetting). It last ran after I idled back to pits following a kinda slow last lap. Also note it was a B7ES. I plan to replace with a fresh B8ES.

Photo

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Ride like a girl!!!
2016 KTM 500 EXC-F
Current project: 2007 Kawasaki KX250-R7 retro build
Current project #2: 1987 Kawasaki KX250-E1 rider/racer resto
1989 KX125 resto
1987 RM250 resto

8/2/2020 8:14 PM

Back to the drawing board. Plug looks coffee colored, but I have even more spooge than before.

Today I tried a gallong of Motul 710 mixed at 32:1, and some Yamalube at 32:1. Both spooged a LOT, but the yamalube was a bit worse.

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Ride like a girl!!!
2016 KTM 500 EXC-F
Current project: 2007 Kawasaki KX250-R7 retro build
Current project #2: 1987 Kawasaki KX250-E1 rider/racer resto
1989 KX125 resto
1987 RM250 resto

8/2/2020 8:14 PM

Photo
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Ride like a girl!!!
2016 KTM 500 EXC-F
Current project: 2007 Kawasaki KX250-R7 retro build
Current project #2: 1987 Kawasaki KX250-E1 rider/racer resto
1989 KX125 resto
1987 RM250 resto

8/3/2020 5:38 AM

@digger, I def like the updated needle. The bike still pulls SUPER hard, but it's not a toggle switch anymore. Much more usable.

Spooges worse than before (see 2 posts right above) though.

Needle—A Suzuki NECJ clip #3
Pilot—45
Main—160
Air screw—1.5 turns out from fully closed
Slide---#8
premix 32:1 (tried Motul 710 and also Yamalube mixed with fresh C12)

Not sure what my next move is....

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Ride like a girl!!!
2016 KTM 500 EXC-F
Current project: 2007 Kawasaki KX250-R7 retro build
Current project #2: 1987 Kawasaki KX250-E1 rider/racer resto
1989 KX125 resto
1987 RM250 resto

8/3/2020 9:03 AM

queen of spodes wrote:

@digger, I def like the updated needle. The bike still pulls SUPER hard, but it's not a toggle switch anymore. Much more usable.

Spooges worse than before (see 2 posts right above) though.

Needle—A Suzuki NECJ clip #3
Pilot—45
Main—160
Air screw—1.5 turns out from fully closed
Slide---#8
premix 32:1 (tried Motul 710 and also Yamalube mixed with fresh C12)

Not sure what my next move is....

I don't really take much stock in reading plugs. There is just too much variation. I go by how the bike/engine feels feels and reacts. The pic of the plug you have above does look almost perfect though.
I don't really have any experience with Motul 2t oils, But I have used Yamalube before. I always found it to run a little dirtier than say Amsoil Dominator, which I currently use, But the wear properties of the Yamalube were always great. the topends always looked good at piston/ring replacement, but there was always a lot of spooge at the jetting settings I liked with it. When you combine the lower flashpoint of the c-12 with the Yamalube, I bet the silencer/swingarm is a mess. I'm not sure how hard you are on the bike rev wise, so you may very well need to use a 2t oil with a lower flashpoint.

How do you like the characteristics of the NExx series needle as compared to the NFxx needle. It should have really smoothed out the low to mid transition, while keeping the same topend feel. I'm pretty confident that your struggle with spooge is not jetting related, when looking at what you are using, jetting wise

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8/3/2020 9:53 AM

queen of spodes wrote:

@digger, I def like the updated needle. The bike still pulls SUPER hard, but it's not a toggle switch anymore. Much more usable.

Spooges worse than before (see 2 posts right above) though.

Needle—A Suzuki NECJ clip #3
Pilot—45
Main—160
Air screw—1.5 turns out from fully closed
Slide---#8
premix 32:1 (tried Motul 710 and also Yamalube mixed with fresh C12)

Not sure what my next move is....

digger wrote:

I don't really take much stock in reading plugs. There is just too much variation. I go by how the bike/engine feels feels and reacts. The pic of the plug you have above does look almost perfect though.
I don't really have any experience with Motul 2t oils, But I have used Yamalube before. I always found it to run a little dirtier than say Amsoil Dominator, which I currently use, But the wear properties of the Yamalube were always great. the topends always looked good at piston/ring replacement, but there was always a lot of spooge at the jetting settings I liked with it. When you combine the lower flashpoint of the c-12 with the Yamalube, I bet the silencer/swingarm is a mess. I'm not sure how hard you are on the bike rev wise, so you may very well need to use a 2t oil with a lower flashpoint.

How do you like the characteristics of the NExx series needle as compared to the NFxx needle. It should have really smoothed out the low to mid transition, while keeping the same topend feel. I'm pretty confident that your struggle with spooge is not jetting related, when looking at what you are using, jetting wise

Yep silencer was literally drooling after a 10 minute moto yesterday. Would be interested in any recommendations for low flash premix oils.

Power with the new needle is actually pretty great. It rounded off that toggle switch powerband before. Still pulls super hard, just not as violent from low to mid. I felt more comfortable powering out of corners directly up jumps.

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Ride like a girl!!!
2016 KTM 500 EXC-F
Current project: 2007 Kawasaki KX250-R7 retro build
Current project #2: 1987 Kawasaki KX250-E1 rider/racer resto
1989 KX125 resto
1987 RM250 resto

8/3/2020 10:27 AM

queen of spodes wrote:

Yep silencer was literally drooling after a 10 minute moto yesterday. Would be interested in any recommendations for low flash premix oils.

Power with the new needle is actually pretty great. It rounded off that toggle switch powerband before. Still pulls super hard, just not as violent from low to mid. I felt more comfortable powering out of corners directly up jumps.

I think your best bet for a quality low flashpoint premix oil might be Torco's GP-7. It has a flashpoint about 30 degs less than the Motul 710 and almost 100 degs less than the Yamalube. I would also use the least amount of c-12 that you can get away with to prevent detonation, if that's even a concern.

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8/3/2020 11:19 AM

digger wrote:

I think your best bet for a quality low flashpoint premix oil might be Torco's GP-7. It has a flashpoint about 30 degs less than the Motul 710 and almost 100 degs less than the Yamalube. I would also use the least amount of c-12 that you can get away with to prevent detonation, if that's even a concern.

I can def cut it down with 93 pump. My bikes always felt faster with race gas.

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Ride like a girl!!!
2016 KTM 500 EXC-F
Current project: 2007 Kawasaki KX250-R7 retro build
Current project #2: 1987 Kawasaki KX250-E1 rider/racer resto
1989 KX125 resto
1987 RM250 resto

8/8/2020 6:56 PM

Think I'm on track now. Bike runs so fucking crisp and pulls so hard. I love riding it so much.

But yeah, I had a little remnants of spooge out the silencer (yep, I repacked it before I rode today) but my guess is this was residual oil in the expansion chamber being pushed out from before.

Note pic below where there was a little drippage at the header, but it crusted up by the end of the day. Also getting some nice bluing on the pipe.

For ref, same jetting as in my last reply. Used Torco GP-7 at 40:1 with half C12 and half pump 93. I'm running a BR7ES plug. May switch that down to a BR8ES if the spooge holds off.

Photo

Photo

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Ride like a girl!!!
2016 KTM 500 EXC-F
Current project: 2007 Kawasaki KX250-R7 retro build
Current project #2: 1987 Kawasaki KX250-E1 rider/racer resto
1989 KX125 resto
1987 RM250 resto

8/8/2020 10:53 PM

Have you thought about giving Pro Honda HP2 a shot?

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8/9/2020 7:17 AM

Chance1216 wrote:

Have you thought about giving Pro Honda HP2 a shot?

HP2 has a MUCH higher flash point. Higher flash points generally mean more spooge on bikes that aren't ridden WFO everywhere.

I beleive I have a good combo with 50/50 C12/93 and Torco GP-7 at 40:1 (again with jetting outlined in replies above).


Photo

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Ride like a girl!!!
2016 KTM 500 EXC-F
Current project: 2007 Kawasaki KX250-R7 retro build
Current project #2: 1987 Kawasaki KX250-E1 rider/racer resto
1989 KX125 resto
1987 RM250 resto

8/9/2020 1:11 PM

queen of spodes wrote:

Think I'm on track now. Bike runs so fucking crisp and pulls so hard. I love riding it so much.

But yeah, I had a little remnants of spooge out the silencer (yep, I repacked it before I rode today) but my guess is this was residual oil in the expansion chamber being pushed out from before.

Note pic below where there was a little drippage at the header, but it crusted up by the end of the day. Also getting some nice bluing on the pipe.

For ref, same jetting as in my last reply. Used Torco GP-7 at 40:1 with half C12 and half pump 93. I'm running a BR7ES plug. May switch that down to a BR8ES if the spooge holds off.

Photo

Photo

It looks like you have a pretty good handle on it now. Nice job.

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8/9/2020 1:15 PM

digger wrote:

It looks like you have a pretty good handle on it now. Nice job.

Appreciate your help dialing this bike in.

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Ride like a girl!!!
2016 KTM 500 EXC-F
Current project: 2007 Kawasaki KX250-R7 retro build
Current project #2: 1987 Kawasaki KX250-E1 rider/racer resto
1989 KX125 resto
1987 RM250 resto

8/16/2020 1:21 PM
Edited Date/Time: 8/16/2020 1:31 PM

i have a TMR modified 2006 KX250, i run C12 mixed with Motorex cross power at 40:1 and below is what he recommended for sea level at 68 degrees. I was running motul 800 and it also had a lot of spooge and loaded up... i started chasing my tail with jetting. I have tried every needle known and every jet and slide.... what he recommended has worked best with adjustments for environmental conditions and elevation and the switch to motorex eliminated the excess spooge from the tail pipe and back of my jersey. My good friend who posts on here as DynoDan used to wrench for Casey Johnson in 2004 on a KX250 and he confirmed this combination, he did say the stock needle has an odd rich section at mid throttle but i was done chasing my tail and just run this combination.

edit: his recommendation for 7 slide was when i was living at 5000 ft elevation in northern nevada, i am in Vegas now and ride between 1800 and sea level and run the 8 and it’s good to go!

I hope this helps

Photo

Photo

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Don’t piss off the old people - the older they get the less “life in prison” is a deterrent for them!

2020.5 KTM 450 SXF FE
2006 KX250

8/18/2020 2:18 AM

Buy a ssecond spring for that pipe. That is why it's leaking.

Quit running a 7 to mask problems. Go to 8, such as BR8ECMIX as stock.

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8/18/2020 6:39 AM

bvm111 wrote:

i have a TMR modified 2006 KX250, i run C12 mixed with Motorex cross power at 40:1 and below is what he recommended for sea level at 68 degrees. I was running motul 800 and it also had a lot of spooge and loaded up... i started chasing my tail with jetting. I have tried every needle known and every jet and slide.... what he recommended has worked best with adjustments for environmental conditions and elevation and the switch to motorex eliminated the excess spooge from the tail pipe and back of my jersey. My good friend who posts on here as DynoDan used to wrench for Casey Johnson in 2004 on a KX250 and he confirmed this combination, he did say the stock needle has an odd rich section at mid throttle but i was done chasing my tail and just run this combination.

edit: his recommendation for 7 slide was when i was living at 5000 ft elevation in northern nevada, i am in Vegas now and ride between 1800 and sea level and run the 8 and it’s good to go!

I hope this helps

Photo

Photo

I see what he is trying to do there, but That is Still going to be one hard hitting engine into mid with that series needle. There is no getting around it, and still have the bike running cleanly off the bottom. I’m taking into account that the majority of people with that bike will be faster with the smoother Power from the Suzuki NExx series needle, especially a woman rider. The bike will also run cleaner with the J diameter needle.
With the jetting currently in her bike she shouldn’t have any reason not to run a BR8xx series plug.

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