|Drilling out jets
Increasing jet size will make a difference in your bike's performance. It's also something you'll want to do if you run with straight pipes, otherwise you may not be able to achieve a sufficiently rich fuel mixture which leads to higher temperatures and a possible piston meltdown. (Trust me on this one.) Stock CJ carbs come with a variety of jet sizes, and sometimes even pairs of carbs will have different sized jets! You can buy jets that'll fit your carbs, but unless you know exactly what to order, it can be a gamble. (Some 1.02mm jets I found on eBay were $8.75 each.) Hey! Why not just drill out an existing set?
|Look at all these jets! I harvested them from some junk carbs I had laying around.|
|Here's a Dremel tool, something no shop should be without.|
|These are #57 bits (1.0922mm.) Unfortunately, that's too small for the Dremel's chuck so I wrapped it with masking tape to increase its diameter.|
|It worked like a charm.|
|This carb part was used to hold the jet. I believe it's known as a whatchamajigger.|
|Here it is with a jet screwed in. Note there's no fiber washer, something you'd definitely not want to forget when you put your carb back together.|
|Here's the whole enchilada in my Craftsman visemade in China!|
|Done. These are all essentially 1.1mm jets now. I took this picture in order to show you the different markings on the jets (or, in one case, no marking at all.) What the heck are they supposed to mean?!|
I also wanted to include along these little nuggets from Miin Leong regarding carburetors and jets:
"CJ carbs use Keihin jets. Sizes are crazy on CJs. Many times I've seen two sizes on the same bike! IMO, an OHV with 28mm carbs runs best (sea level to 2000 feet) with 1.0mm jets and the needles setting #2 from the top. SVs with 28mm carbs0.95 to 0.97 jets."
"With the Keihin jet, P/N 99101-393-XXX. XXX will be the size of the jets. Dynojets also make these jets. Almost all local bike shops can order them for $3-4 each or sometimes have them in stock. They are very common jets."