Keihin jet size

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49txpan
Posts: 24
Joined: Wed Jun 15, 2005 3:21 am
Location: Houston

Keihin jet size

#1

Post by 49txpan » Tue Nov 29, 2005 2:47 am

I am going through everything on my 49 Pan project and have now got to the carb rebuild. I have what appears to be a late 70's Keihin. I would like to run something else but will go with this carb for now and point the $'s towards other areas. Anyway, I pulled the pilot jet and it has been drilled out. It must be something equivalent to 50. Before I tore the bike down it was running very rich so I am thinking about going to a size 45 or even down to 40. My question is, is anyone running a Keihin and can you suggest a good pilot jet to go with the 74" and drag pipes?

Thanks,

Txpan



57pan
Posts: 230
Joined: Tue Aug 10, 2004 5:11 pm
Location: Michigan, USA
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Re: Keihin jet size

#2

Post by 57pan » Wed Nov 30, 2005 6:55 pm

Here is a link to a thread where I went thru the same thing you're doing: Keihin carb tuning

My Keihin had a 100 jet in it when I got it and was WAY too rich. I put a 70 jet in and that was too lean (coughing, sneezing). I reamed it out to 80 and that was still too lean. I went up to 85 and that is just right.

I think you just have to pick a starting point and go from there. Ride it, read the plugs, tweak it - eventually you'll get it dialed in. Any changes to the exhaust system, or even the air filter system can require rejetting.

BTW, the numbers that you're throwing out seem awfully small. My 100 jet and 70 jet had the number stamped on them and from that I deduced that it refered to millimeters, that is: 100 = 1.00 mm and 70 = .70 mm.

49txpan
Posts: 24
Joined: Wed Jun 15, 2005 3:21 am
Location: Houston

Re: Keihin jet size

#3

Post by 49txpan » Thu Dec 01, 2005 4:14 am

Thanks Dave. The pilot is non-readable and it probably is something much bigger than a 40-ish. The slow jet is a 185. I will try 70 and tweak from there.

Thanks,

Russ

Billy
Posts: 781
Joined: Tue Mar 23, 2004 6:57 am

Re: Keihin jet size

#4

Post by Billy » Thu Dec 01, 2005 6:09 am

Just a word of warning.

Don't mix the early Kehin's jets, w/late CV Kehin jets..

Oil & water= don't mix

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