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Possible Carb switch

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Ok a little info on the bike. It is a 1989 YZ 250 WR. The carb is a Mikuni TM carb.  I ran it last year and could never get the bike to Start consistently.  Some time it would start first or second kick or it would be 20 or 30 kicks. On the times it would not start I would choke it then not choke the bike. I got to the point were i could get it to start when it was cold and it would start fine when it was hot after I learned to bike. But I could never get it to start when it was "semi warm". I have a feeling that the carb is just worn out. I could never get the bike to idle great. you could set the ideal screw to just about any position and it would not really change. I also rebuilt the top end last spring.

 

So now to get to my question. 

 

Do I rebuild the TM carb I have or do I switch to a PWK carb which I hear good things about. Also if I was to switch carbs what all do I need to make the switch.

 

Thanks

 

 

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I think PWK is a great carb. Only other carb I would run is a Lectron, Mikuni, Keihn PWM etc are just to much of a pain when the PWK is so easy to tune and seems to have a much broader sweet spot.

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What all would need to be changed to make the switch? would I need a new twist throttle and cable?

 

 

Thanks

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I swapped the Mikuni VM on my 97 WR250 (with 94 YZ engine) 2 stroke for a PWK "Air Striker" from a 2000 CR250--big difference in power from bottom to top. I used the entire setup from the CR--throttle / cable / carb--it's was easier than trying to adapt my cable to the new carb. This is the only year Honda used this carb. Look for the Air Striker model--this provides better low-mid air speed flow.

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I have seen some PWK carbs with an electrical hook ups and some with out. My bike does not have any electrical hook ups for the carb. so my question is do I need to buy one without the electrical connections or can I buy with them but just not use them?

 

Thanks for all the help

 

Dustin

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I have seen some PWK carbs with an electrical hook ups and some with out. My bike does not have any electrical hook ups for the carb. so my question is do I need to buy one without the electrical connections or can I buy with them but just not use them?

 

Thanks for all the help

 

Dustin

 

The PWK's with the power jets and TPS with a  Squarish top, held on by 2 screws are 75mm in total length. The twist top PWK's are 91mm in length. You will more than likely need a 91mm twist top pwk. Honda cr250's  in both 99' and 00', used those twist top pwk's, but the 99' carb came with a less desirable(richer) 5.5 slide. The 00' carb came with a 7.0 slide. The 00' carb can still be bought new, and at a reasonable price. http://powersportsdiscount.com/oemparts/a/hon/506c0a36f870023420a2cdb2/carburetor-1 . The jetting that come in this carb should even work in your bike. I believe all you would need to adapt that OEM Honda  pwk carb to your bike is a new throttle cable, but I'm not 100% sure on that for your bike. I know all of the throttle housings interchange on the later model 2t Jap bikes, but the cables are different.

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The electrical hook up is a throttle position sensor that activates the power jet. It's easier to buy the one without the TPS but you can use one with it with a little modification. Just remove the wire and sensor from the side of the carb then use jbweld to plug the power jet inside the carb.

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The PWK's with the power jets and TPS with a Squarish top, held on by 2 screws are 75mm in total length. The twist top PWK's are 91mm in length. You will more than likely need a 91mm twist top pwk. Honda cr250's in both 99' and 00', used those twist top pwk's, but the 99' carb came with a less desirable(richer) 5.5 slide. The 00' carb came with a 7.0 slide. The 00' carb can still be bought new, and at a reasonable price. http://powersportsdiscount.com/oemparts/a/hon/506c0a36f870023420a2cdb2/carburetor-1 . The jetting that come in this carb should even work in your bike. I believe all you would need to adapt that OEM Honda pwk carb to your bike is a new throttle cable, but I'm not 100% sure on that for your bike. I know all of the throttle housings interchange on the later model 2t Jap bikes, but the cables are different.

Hey man thanks for the info on the different lengths. My carb measures at 72mm right now so it looks like i would need the squish top with the two screws?

Thanks everyone for the replys

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