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Keihin Carb

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Im sure there has already been some question asked about this. I have a 2002 CR250R with the stock Mikuni. No real problems, but was curious abuot installing a keihin carb. What am I looking for? Is there a bolt on carb for this year from somebody? Do I have to have an adapter for the intake part of the carb or for the connectoin between the carb and air cleaner boot?

Just wondering, thank for any help.

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I tried the kehin carb & didn't like it. If you ride the bike in the lower r's it is a good swap. The mukini felt like it ran better on the higher r's when your @ wot. The JD kit is the best solution for the mukini carb. Just my $.02.

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I have tried both on my stock 2005. THe stock mikuni with a JD kit and a 38mm pwk keihin with a YZ250 jd jet kit installed.

When the mikuni is jetted just right with the JD kit, it runs awesome. But I found that when the temp or humidity changed much, the carb required regular tweeking. One day it would be perfect on the main and pilot, the next day it would be lean on the main and pilot without much change in the temp or humidity.

When the keihin is jetted just right, I might do a quick airscrew adjust when I start out the day, but after that I am done for the day. This carb works very well on this bike even before I put the JD kit in it.

As was said the keihin seems to work better at the lower RPM's than the mikuni. I ride tighter trails when possible and dont get in the upper RPM's much so the Keihin is what I use.

The mikuni is about one centimeter shorter in length than the keihin, takes a little work to get it in the first time.

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Thanks for the tip. Is this a bolt on carb or do I have fight and wrestle to get it in there. Any mods to the throttle cable? I may do a search on E-bay for a carb. Thanks for all your help guys.

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The keihin is about 1 cm longer, so it did take a little playing to get it on, but not to bad.

I also had installed the 2000 cr250 airboot to cure the 02+ airbox leaks known to these bikes. The two boots looked to be the same height and size when sitting next to each other other than the single lip vs double lip seal.

After having the keihin on the bike for a few months, I reinstalled the mikuni with the JD kit, not sure if it was a result of the retrofitted airboot or the longer keihin carb, but the gap between the air boot and the intake boot was too long for the stock carb. Had to install the back of the carb to the air boot, then push it forward with a pry bar into the intake boot and then tighten. Dont know if the longer keihin actually deformed the airboot slightly or if the airboot was just a bit shorter.

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Correct me if I'm wrong, but my impression was that the air intake boot leak was corrected after '03 and with '05 on up, the boot got revised altogether. 👍:worthy: Is there really a need to change the boot even after they've been updated ?

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Correct me if I'm wrong, but my impression was that the air intake boot leak was corrected after '03 and with '05 on up, the boot got revised altogether. :worthy::busted: Is there really a need to change the boot even after they've been updated ?

honda put a bandaid fix(barely) on the 03 and newer bikes. the addition of slightly stronger glue and a gasket kind of works for a while, but it fails eventually. the only good fixes are to reseal it and install one of the aftermarket sealing rings that wont deform. pc racing makes a good one, or you could eliminate all the worries and go with the full mod of using a 00-01 airboot.👍

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The keihin is about 1 cm longer, so it did take a little playing to get it on, but not to bad.

I also had installed the 2000 cr250 airboot to cure the 02+ airbox leaks known to these bikes. The two boots looked to be the same height and size when sitting next to each other other than the single lip vs double lip seal.

After having the keihin on the bike for a few months, I reinstalled the mikuni with the JD kit, not sure if it was a result of the retrofitted airboot or the longer keihin carb, but the gap between the air boot and the intake boot was too long for the stock carb. Had to install the back of the carb to the air boot, then push it forward with a pry bar into the intake boot and then tighten. Dont know if the longer keihin actually deformed the airboot slightly or if the airboot was just a bit shorter.

After putting on the stock carb with the JD kit, was the bike the same, or better than the Keihin? I would rather put about 75.00 in jetting than 250.00 in another carb.

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