Needle Jets

davomoto · Post by **davomoto** » Wed Apr 13, 2011 1:28 pm

Main jets are 135 , slow or pilot jets are 42. Needles should be second clip from bottom. Where are the origional jets and needles? Pics of the parts that are giving you problems and or that you have questions on please!

Davo

teazer · Post by **teazer** » Sat Apr 16, 2011 12:16 am

"most" keihin needle jets form that era appear to be 2.6mm bore and 3.6mm tall. Measure the needle at the root (the thick end) and if it's around 2.53mm it should slide all the way through but will not be very loose.

If the needles are the same diameter and one Needle jet is too small, it needs to be pressed out.

But are we talking the small pressed in jet (needle jet) or the long tube that unscrews (emulsion tube/main jet holder).

I'm sure I have spare needle jets (the small pressed in part) bit no main jet holders (the long tube).

If that's what you need, email me and I'll see what I have here - I'm north of Chi town closer to the WI border

Snakeoil · Post by **Snakeoil** » Sat Apr 16, 2011 7:21 pm

Today I was inside the carbs on my '67 CL77. One needle is numbered and the other is not. But I checked both dimensionally and they are identical. Here is what you should measure on your jet needles.

Needle is 24304 which agrees with what others have said here and Bill Silver's book.

OD on the straight section is 2.5mm
OD on the smallest end of the tapered section, just above the pointed tip is 1.21mm
Length of tapered portion is 26mm including the pointed tip. Pointed tip is about 1mm long.

With straight pipes, my engine prefers a 130 main jet. 135 is too big and causes a stumble up decel after WOT.

Slides are both 2.0 cutout.

Hope this is of some help.

regards,
Rob

Blanas · Post by **Blanas** » Sun Apr 24, 2011 10:53 am

Well I think I got it right. I replaced the needle jets with newer ones. I install D-9 jet needles in leiu of the longer ones that were there. I replaced the main jets with 130 instead of the 135. The bike starts well idels good runs preety good. The only problem is when I give it full throttle it hesitates. The clip on the needle jet is in the middle slot. Should I raise it one slot? Also how many teeth are on the stock front sprocket of a 1967 305 scrambler? 14? 15?

davomoto · Post by **davomoto** » Sun Apr 24, 2011 3:56 pm

Lower the clip, raise the needle. 15/30 is stock gearing.

Davo

Blanas · Post by **Blanas** » Mon Apr 25, 2011 9:09 am

I raised the needle clip one notch. No good. It runs worse. I know their is a relationship between the high and slow systems. Is it possible that if the slow system is putting out too much fuel (but idels well) that when you crank the throttle the bike overloads and hesitates? Maybe I should start the bike, let it warm up, and turn the air needle in while reving the motor to see if the hesitation stops? I know these bikes and their systems are old and maybe I,m chasing perfection that can,t be reached, but why not!!! I believe I can get this machine to run as good as it did when new or even better. Thanks for your help.

davomoto · Post by **davomoto** » Mon Apr 25, 2011 9:13 am

Just saw that it's a CL not a CB, so stock gearing is 15 / 37 sorry about that! Are you at altitude? The stock main jet is 135, clip in second notch from the bottom. Are you going wide open from idle or low RPM ? There's no acceerator pump on these carbs, so they will fall on thier face under those circumstances.
Try going the other way with the clip, and see if it gets better.

Davo