KX Riders

Maintenance & Technical => KX250 / KX125 => Topic started by: 74-84kawracer on January 31, 2015, 05:01:23 AM

Title: Jetting for 1984 KX 125
Post by: 74-84kawracer on January 31, 2015, 05:01:23 AM

Hello all:

I'm new to the forum and recently restored a 1984 KX 125 which I race in GP2 EXP. 

There is an annoying jetting issue with the 34 mikuni - a hesitation/slight bog just before the mid-range hit.
I tried raising the needle, went to a richer needle jet  - Q8 to R0, an increased the pilot jet from 40 - 45.
That all helped some - but there is still that hesitation - unless I just slip the clutch past it.
I checked for air leaks and the motor idles fine.

I just noticed that the needle is slightly bent -- could that be the problem ?  I looked everwhere bu cannot find a replacement (6FL52).

Thanks

Title: Re: Jetting for 1984 KX 125
Post by: Foxx4Beaver on January 31, 2015, 05:46:05 AM

you want to get that needle outa there....you can find a replacement here...

http://pjmotorsports.com/  or...
http://www.sudco.com/

are you sure you've got the float height set correctly?

Title: Re: Jetting for 1984 KX 125
Post by: 74-84kawracer on January 31, 2015, 12:52:46 PM

Thanks - yeah the float level looks right seems fine - the idle is steady and it revs out on top end with no blubber or pinging --- just that hesitation bog just before the mid-range hit. 

I checked the PJ, Jets R Us & Sudco websites --- they have lots of 6 series needles - but not the 6FL52.  It must have been a special needle designed for the oval bore 34 Mikuni.

Andy

Title: Re: Jetting for 1984 KX 125
Post by: Foxx4Beaver on January 31, 2015, 12:57:47 PM

I would try calling either one of them places....I had trouble finding a matching needle before too, and PJ had me mail in the needle I had, so they could physically match it up with the correct one.
worth a shot...worst case, one of those places may be able to point you in the right direction where to find one.