CR250R Air Striker Help

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1/24/2019 9:14 AM

So i have a 2007 CR250R and would like to install an air striker on my bike. With all the horror stories ive heard about the oem carb, i actually have my bike running really crisp and have no jetting issues with the stock carb. The only reason i want to try installing the air striker is because i have heard great reviews how much better it makes the CR's, and i also got the carb for free so it's worth a shot testing out. The air striker i am installing is the short body tps carb off a 13 yz250. I live in southern California and mainly ride Milestone. Ive done lots of research already on this carb, but there is a lot of different opinions on settings. Im hoping someone on here can help me out because i know there is a lot of Vital users with this same set up or with the knowledge.
My question to you guys is:
-What is the best jetting settings for my area?
-Will the carb even make a difference if i already have my bike running really crisp?
-Does anyone have any info on how to make the TPS connect? or know who or where to buy an adapter harness from? (I prefer not to splice and cut wires if i dont have to)

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1/24/2019 10:59 AM

Several threads on ThumperTalk about the swap.

I liked the TMX on my '05 CR250. Read more here: https://thumpertalk.com/forums/topic/1191880-carburetor-heresy-i-like-my-mikuni-tmx-better-than-the-keihin-pwk-36mm-38mm/

That being said, I'm playing with a PWK on my '17 Husky TC250 and think I might like the PWK better for this bike.

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1/24/2019 2:12 PM

I had the PWK on my 03 for a while. Ended up going back to the mikuni. Not sure if you can change the needle jet on the 07 mikuni carb but the S7 was the key to making it really good. But since you have the carb and it was free it couldn't hurt to try it out.

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No brains, No headaches.

1/24/2019 7:22 PM
Edited Date/Time: 1/24/2019 7:23 PM

I ran a 172-175 main, 42-45 pilot I think. I don't have notes but I think those would be a good place to start. I just can't remember the needle. I think it was a standard 01 CR250 needle. I also ran avgas in mine at 40:1 with Maxima SuperM.
If you go to Chaparral they should have a box of jets for you to pick from. If you try to order Yamaha parts they will be more expensive.
Have you run your bike in the summer? I think in cool weather it would be OK.
I didn't bother with the TPS but there was a guy on Thumpertalk selling harnesses or you could make one if you are handy enough. The parts should be available at an auto electric place.

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The older I get, the faster I was.

1/24/2019 7:57 PM

Thank you guys for the help so far. So i installed the carb today and am surprised that it actually performs better then the stock carb. It's not a huge difference, but it definitely is an improvement. I havent got to actually put the bike to the test on a track, but just from reving the bike out and riding it up and down my street i feel the bike has a little more bottom end and crisper throttle response. My jetting settings as of now are 175 main, 45 pilot, with what ever needle comes stock on a 13yz250, and powerjet is also sealed shut. TPS is still disconnected as of now, but i have bought the proper connectors to make my own harness. Hopefully their will be an even better improvement once i connect the TPS.

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1/24/2019 7:58 PM

captmoto wrote:

I ran a 172-175 main, 42-45 pilot I think. I don't have notes but I think those would be a good place to start. I just can't remember the needle. I think it was a standard 01 CR250 needle. I also ran avgas in mine at 40:1 with Maxima SuperM.
If you go to Chaparral they should have a box of jets for you to pick from. If you try to order Yamaha parts they will be more expensive.
Have you run your bike in the summer? I think in cool weather it would be OK.
I didn't bother with the TPS but there was a guy on Thumpertalk selling harnesses or you could make one if you are handy enough. The parts should be available at an auto electric place.

Thanks for the tips, i have read about the cr250 needle so ima give that a shot after i can get the TPS harness sorted out.

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1/24/2019 11:06 PM

captmoto wrote:

I ran a 172-175 main, 42-45 pilot I think. I don't have notes but I think those would be a good place to start. I just can't remember the needle. I think it was a standard 01 CR250 needle. I also ran avgas in mine at 40:1 with Maxima SuperM.
If you go to Chaparral they should have a box of jets for you to pick from. If you try to order Yamaha parts they will be more expensive.
Have you run your bike in the summer? I think in cool weather it would be OK.
I didn't bother with the TPS but there was a guy on Thumpertalk selling harnesses or you could make one if you are handy enough. The parts should be available at an auto electric place.

NoeOrtiz wrote:

Thanks for the tips, i have read about the cr250 needle so ima give that a shot after i can get the TPS harness sorted out.

*2000 CR250 needle. 2001 had a Mikuni carb, whereas 2000 was Keihin long body screw top PWK...

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1/25/2019 2:04 AM
Edited Date/Time: 1/25/2019 2:08 AM

crc245 wrote:

*2000 CR250 needle. 2001 had a Mikuni carb, whereas 2000 was Keihin long body screw top PWK...

Yes. Ran the 00 needle with a 45 pj & 175 mj when I tried the PWK on an 03 model with decent results. I tested this set up about 10 yrs back, but ended up going back to the Mikuni tmx.. The oem carb provides better topend power in comparison.

Jetting specs were for sea level with relatively no humidity, moderate temps 70-80 deg. @ 0-1K elevation. 32:1 premix.

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Speak softly and carry a big stick.

1/25/2019 10:13 AM

H4L wrote:

Yes. Ran the 00 needle with a 45 pj & 175 mj when I tried the PWK on an 03 model with decent results. I tested this set up about 10 yrs back, but ended up going back to the Mikuni tmx.. The oem carb provides better topend power in comparison.

Jetting specs were for sea level with relatively no humidity, moderate temps 70-80 deg. @ 0-1K elevation. 32:1 premix.

Good info there, I knew you would know. I'm trying to pull this stuff from my half hardened brain as I don't have the bike or notes anymore.
Mine pulled pretty hard with that set up and a PC pipe and silencer.

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The older I get, the faster I was.

1/25/2019 4:20 PM
Edited Date/Time: 1/26/2019 4:56 AM

I have a ton of experience with these bikes, using both the Mikuni and the PWK. The only place that I thought the Mikuni worked better than the PWK, was for for pure outdoors style mx.The reason being, every 38mm Mikuni TMX-x carb that I have put a dial indicator too has measured out to over 40mm. Where as the 38mm PWK's measure out to right around 37.70mm, with the exception being the late model oem PWK's that came on RM 250's. they measure about 1mm or so larger, at 38.7.

If you do decide to use the PWK carb, there are a bunch of different jetting combos that will work. The 02-07 engine is very tolerant, weather and jetting wise, when using the PWK. It's not nearly as tolerant when using the Mikuni.

The N3EW that comes in the 13' YZ250 carb that you have, will work decent in your bike, especially with a #8 slide. For someone who just wants to jet it and forget it, I would recommend a Suzuki NECW needle in the #3 clip position. along with a 42 pilot jet, and a 172 main jet and set the airscrew a 1.5 turns out. IMO,There is very little to be gained by hooking up the TPS. Some people may not even notice a difference with it hooked up and not.

FWW, one of my least favorite needles to use, was the 689/ 715 Honda oem needle from an 00' cr250. It just wasn't very good when compared back to back with many other needles.

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1/25/2019 11:42 PM

digger wrote:

I have a ton of experience with these bikes, using both the Mikuni and the PWK. The only place that I thought the Mikuni worked better than the PWK, was for for pure outdoors style mx.The reason being, every 38mm Mikuni TMX-x carb that I have put a dial indicator too has measured out to over 40mm. Where as the 38mm PWK's measure out to right around 37.70mm, with the exception being the late model oem PWK's that came on RM 250's. they measure about 1mm or so larger, at 38.7.

If you do decide to use the PWK carb, there are a bunch of different jetting combos that will work. The 02-07 engine is very tolerant, weather and jetting wise, when using the PWK. It's not nearly as tolerant when using the Mikuni.

The N3EW that comes in the 13' YZ250 carb that you have, will work decent in your bike, especially with a #8 slide. For someone who just wants to jet it and forget it, I would recommend a Suzuki NECW needle in the #3 clip position. along with a 42 pilot jet, and a 172 main jet and set the airscrew a 1.5 turns out. IMO,There is very little to be gained by hooking up the TPS. Some people may not even notice a difference with it hooked up and not.

FWW, one of my least favorite needles to use, was the 689/ 715 Honda oem needle from an 00' cr250. It just wasn't very good when compared back to back with many other needles.

So i tested out the bike today, and like you said i do feel like the Tmx had much better top end power and pulled a lot longer. The PWK seems like it has more bottom end and a harder snap of power at the crack of the throttle. The bike is still very crisp, but it does rev out a bit quicker. Overall i think ima stick with the PWK for now and maybe keep messing with jettings and settings. Overall do you think that the suzuki needle will be a big improvement from the needle im running now? Also if i decide to keep the YZ needle in the carb would you recommend going down to a 42 172 or am i fine with the jetting i have now?

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1/25/2019 11:44 PM

I know its all personal preference but do you guys recommend v force or the boyesen rad valve for my bike? Personally i am leaning towards the rad valve, but i would love to hear your guys opinions.

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