boring out your jet

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sk8freak8989

Guest
other than riding my motorized bicycle i like to race pocket bikes. while i was serching on the form i go on for pocket bike racing i found a re jeting article. here it is.

Easiest way to rejet is to drill the jet larger using Wire Gauge drill bits which can usually be found at your local hobby store. They are numbered #1-#80. You'll only need the #60s-70s range for rejetting. The Wire Gauge number is NOT the actual jet size. Minimoto/pocketbike jets are measured in one hundreths of a millimeter, for example, a 66 jet has a 0.66mm hole diameter.

Below is a chart showing which Wire Gauge # drill bit to use for specific jet sizes. As you can see, you are only limited to a certain amount of jet sizes. Although you may never need to jet higher than the 70 range, I included larger sizes anyways.
Note: Wire Gauge drill bits are for precision use and are very very small which will break easily if not careful. Be sure to drill at the lowest speed setting possible. Sometimes it may be easier to drill using them by hand speed using a drill pin vise (X-Acto No.73220). Remember, always go up only one size and test, once you drill there's no going back.

Wire Gauge #= inch = mm = jet size
#73 = .0240 = .6096 = 61
#72 = .0250 = .6350 = 64
#71 = .0260 = .6604 = 66
#70 = .0280 = .7112 = 71
#69 = .0295 = .7493 = 75
#68 = .0310 = .7874 = 79
#67 = .0320 = .8128 = 81
#66 = .0330 = .8382 = 84
#65 = .0350 = .8890 = 89
#64 = .0360 = .9144 = 91
#63 = .0370 = .9398 = 94
#62 = .0380 = .9652 = 97
#61 = .0390 = .9906 = 99
#60 = .0400 = 1.016 = 102
 


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Herrmanator8

Guest
do these stock carbs on these engines have jets??? i know nothing about jets.

jon
 
A

andyinchville1

Guest
HI,
yes, we have a jet...It is the needle looking piece inside the carb with the 3 or 4
grooves in it that the e clip attaches to. the e clip lets you raise or lower the jet
to make the engine run richer (when the pin is pulled up by the e clip if you put it closer to the bottom of the pin) or leaner (if you put the e clip closer to the top).
Hope this helps.
Andrew
 
A

andyinchville1

Guest
Hmmm....I forgot to say...Why are you worrying about jets anyways?...I thought you were working on the fuel injection! ;-)

I couldn't resist! ;-) ......Death Race will be ours next year!

Andrew
 

drimpact

Member
Joined
Apr 23, 2007
Messages
506
HI,
yes, we have a jet...It is the needle looking piece inside the carb with the 3 or 4
grooves in it that the e clip attaches to. the e clip lets you raise or lower the jet
to make the engine run richer (when the pin is pulled up by the e clip if you put it closer to the bottom of the pin) or leaner (if you put the e clip closer to the top).
Hope this helps.
Andrew
Actually I believe the jet is the part the point of the needle slides into when the throttle is closed
 
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