zenith main jet question

Sun Dec 29, 2013 9:57 pm

the Zenith carb I have to go on my super A has a #20 main jet in it. it will only run decent with the choke half closed - increasing the venture flow. the service manual calls for a #18 main jet for that carb. is that a larger jet, like in wire gauges?

Re: zenith main jet question

Sun Dec 29, 2013 10:19 pm

http://old-carburetors.com/1927-Dykes/1 ... es-064.htm

Don't know if the above post will help. Near the bottom of the 1st page, references to a chart listing diameters of main jets. I didn't go any further than the first page.

Re: zenith main jet question

Sun Dec 29, 2013 10:30 pm

Art, the higher the number, the bigger the hole. For example, a Honda motorcycle would use something bigger like between a #110 and #130.

Re: zenith main jet question

Sun Dec 29, 2013 10:35 pm

actually, that did help. the jet size is the number X 5/100, expressed in millimeters. so a #20 is larger than a #18.

thanks

Re: zenith main jet question

Mon Dec 30, 2013 5:47 pm

but I think I need a #22 or so for this application, even though the service manual calls for an 18. i'll experiment a little

Re: zenith main jet question

Mon Dec 30, 2013 6:24 pm

2 words Drill bit :D

Re: zenith main jet question

Mon Dec 30, 2013 6:59 pm

I've drilled jets before. Works good.

Re: zenith main jet question

Tue Dec 31, 2013 9:58 am

a good excuse for me to get a set of numbered drills :D

Re: zenith main jet question

Tue Dec 31, 2013 10:45 am

artc wrote:a good excuse for me to get a set of numbered drills :D


Art,

Never pass up a good (poor works too) excuse to add to the toy box toolbox.

Bill