KX Riders

Maintenance & Technical => KX250 / KX125 => Topic started by: KenV on April 08, 2010, 04:40:06 PM

Title: First gear swap on '01 KX250. Possible?
Post by: KenV on April 08, 2010, 04:40:06 PM

Hello all.

My 2001 KX has the usual ridiculous-tall first gear.  I read that the 1998 model has the same exact ratios for 2-5, but its first is a bit lower.  I'd like to know if anyone here has any knowledge about changing just the first gear on the KX trans.  I've rebuilt automotive stick transmissions so the mechanical side won't scare me off, but I'm no machinist so the parts would have to fit without making anything.

I have already received a 49T rear sprocket, and will probably get an 11oz FWW, but that gear chart made me think that there's more I could do without having to buy an RMX250, lol.  Any ideas appreciated, thanks.

Title: Re: First gear swap on '01 KX250. Possible?
Post by: pickledkiwi on April 29, 2010, 12:34:56 AM

Hi Ken

I installed a 2002 trans in my 1999 KX250. Has the same tall first gear but 4th gear is 1:1 and 5th gear is overdriven. This allows you to reduce your front sprocket down to get a more user friendly 1st without sacrificing the top end speed.

Your 01 has identical ratios to my 99 trans. 1st is 1.8:1 and 5th is 1:1. This gives a ratio spread of only 1.8 - In other words, a close ratio trans. The 1998 has a 1st of 2.133 and a 5th of 1:1 giving a spread of 2.133. The 2002 has a 1st of 1.8:1 and a 5th of 0.87:1, this gives a spread of 2.069. The difference between a spread of 1.800 to 2.069 may not seem like much but trust me, it makes a big difference to how you can ride/enjoy your bike.

I also run a FWW. No regrets there either!

Hope this helps

PK

Title: Re: First gear swap on '01 KX250. Possible?
Post by: ktmdude on May 05, 2010, 06:39:32 AM

I also have a 01 250 with a 11oz fww. Two thumbs up. Stock gearing. I am intrested in the first gear swap. Anybody out there done it?

Title: Re: First gear swap on '01 KX250. Possible?
Post by: KenV on June 23, 2010, 08:17:26 AM

Sorry for the tardiness, been busy...

Thanks for the ideas.  Once the FWW and 49T are on there I'll know what I want to do for sure.  Plus I could lie in wait for a trans on ebay and get wrenching when one pops up...thanks again!

Ken

Title: Re: First gear swap on '01 KX250. Possible?
Post by: The Flyin Hawaiian on June 23, 2010, 08:32:06 AM

There is a guy on TT that has done it, I cant remember his name. Do a search in the Kawasaki 2 stroke forums and you should find it. I believe its a straight forward swap.