From:Chris Gans e-mail:nagamon@execpc.com
Subject:RE: RE: RE: RE: Zenith T4X jets Date:Sat Sep 22 19:53:34 2012
Response to:4270
That actually makes a lot of sense. As with car engines, porting and polishing is done on a flow bench (at least many years ago it was) to assure clear and even flow. It also reduces "gumming up" later on. Dennis mentioned solder which will retain a smoother finish when drilled. Normally flow is controlled by jet size but these other thoughts will also make a difference. Another trick is to find a piece of wire just smaller than the jet hole,pin vise it into a drill or rotary tool, dip it in polishing compound and run it through the jet hole. Impurities have a tendency to build up on rough surfaces changing the performance of a motor.

----- ORIGINAL MESSAGE FOLLOWS -----
In some of my research regarding jets, I have read that the hole size although one of the factors is not the only thing to consider. It sounds simple enough to just drill the jet out to your favorite pin gauge size but that is not all. It depends more on "flow" rather than jet size. Drills generally leave a very rough hole. A smoother reamed hole and a drilled hole will have very different flow rates. There are many times also small chamfers on the back side of the hole that affect flow by design. From what I understand it is more important to match the flow rate of a jet. Perhaps I'm spitting hairs but but worth mentioning.

----- ORIGINAL MESSAGE FOLLOWS -----
You can also fill the jets with solder and redrill for a smaller size. This is how I was able to fit a glass bowl Ford carburetor onto my Crosley powered motorcycle. It's takes some trial and error but you can narrow it down to the proper size. Many miles on this bike without a problem.


----- ORIGINAL MESSAGE FOLLOWS -----
Keep in mind those jets are the same as used on many car Zenith carbs and can easily be re-drilled to increased sizes to find the one suitable for your Henderson.
Drills are available in steps 0,05mm below 1 mm either trough the internet or at a well assorted hardware store / machine shop.
This is how I played to get a correct main jet for my Tx4.
I allso found the cuffing when accelerating is depending on the idle jet setting (the external one).

Sverre

----- ORIGINAL MESSAGE FOLLOWS -----
For my Henderson deluxe 1928 I need a spare compensating jet #20, #21 or #22 in order to try curing "hesitation" before the main jet takes over. Originals or replicas - whatever is available.
Carl Henrik Stormer - Oslo, Norway