Determining Needle Jet Size

[KJDonovan]

Greetings,

Does anyone know how to determine the size of a needle jet in a type 84 Bing?  I purchased a new type 84 for my 72 Jack Piner a while back and was having some bogging problems.  So I adjusted the clip on the needle jet to the very top and the problem is almost completely gone.  Which leads me to believe that I may have gotten the wrong size jet.  I want to order a new one to clear this up completely, but I would like to be able to determine what size I already have.  I also need to know what the correct size for this bike is supposed to be. Any ideas?

Thanks,

KD


Kevin J. Donovan
Foster, Rhode Island
72 Jack Piner (My Ride)
72 Six Day (Wifes Ride)

[Jay Jones]

If its a #280 drop to a #276,is it a 4or a 5 slide needle?Whatever needle you have sounds ok,you just need to drop the needle jet one size smaller,or you could run a leaner slide with a bigger air cut away?or drop the pilot one and set your needle up?until shes rich again?the best would be get a smaller needle jet and a smaller pilot and play!Hope I helped ,also what ever slide needle you have now one leaner and one richer you can always use range?A #273-#276 came in them new,a#30-35-40 pilot you can get away with a little leaner setting if you still run the choke lever on the handle bar and richen it up when you get into it!If your still running the airslide choke?Jay:)

[KJDonovan]

Jay,

I am still not clear on how to determine what size I currently have.

Thanks,

KD

Kevin J. Donovan
Foster, Rhode Island
72 Jack Piner (My Ride)
72 Six Day (Wifes Ride)

[Jay Jones]

I would just drop the pilot jet one size and set up the needle you have?The needle jet is just a fine tuner?There are little numbers on the side of the jets ,and on the bottom of slide,and the count the small rings on the slide needle above clip positions that tell what number slide needle you have?Look at the small numbers on the jets you have and order jets one size smaller.Hope it helps clarify!Jay:)

[Merlin]

...........KJ,the needle jet is as you describe probably one size too big,the ideal needle jet will allow you to put the needle back to the center groove as well as low you to use the proper main jet. Be careful not to change the main jet as some may do masking the too large needle jet...............my 72 Jackpiner runs clean as a spoon with the following,#1 slide,#1 needle,#150 main jet,#2.80 needle jet,#35 pilot. Also if the carb is new current production it should have the new type vaporizor #40-404 with the single small hole and a half shrould with the cut side facing the engine..................this jetting is with a Twin-Air air filter and the airbox snorkle removed(non high breather)......................

[Merlin]

.............any progress KJ??..............

[Steve Minor]

Kevin....if I'm not mistaken, the size should be engraved (or stamped) somewhere on the jet. It might take a magnifying glass to find though.

Steve Minor
Wilmington, NC

[KJDonovan]

After closer inspection (the big magnfying glass) I found the size markings on my needle jet and main jet.  I had a 155 main that I replaced with a 150 and resolved the issue.  

Thanks for the help,

KD

Kevin J. Donovan
Foster, Rhode Island
72 Jack Piner (My Ride)
72 Six Day (Wifes Ride)