TOPIC:

"Sherman, set the WABAC machine to 1979!"

I was attending the University of Maine at Orono, as an Anthropology major. The greater Bangor (BANG-gore, not "Banger" like every other city so named) was just entering the Malling of America phase of development.

I was riding a Suzuki GT-380 2-stroke triple that I had picked up cheap at the end of Summer. Studying the engineering aspects of the bike, I was shocked (as are many KZ1300 fans) with the small size of the "snorkel" on the airbox. The cross-sectional area was smaller than that of only two of the three Mikuni carbs.

Unlike the KZ1300, the snorkel was a molded rubber piece that was very easily detached from the airbox without any surgery. I took it out one weekend, and loved the louder intake sound. However, after living with it for a couple weeks, I realized that the bike was actually down on power.

This was also the Golden Age of magazines, and in addition to Car Craft, Hot Rod, and Popular Hot-Rodding (and five more), I was also getting Cycle, Cycle World, and Cycle Guide.

While leafing through one of these, I was intrigued to see that somebody was advertising Mikuni-compatible main jets made out of some kind of plastic. Through the wonders of injection-molding technology, they claimed to offer jets with much closer flow tolerances than machined brass jets, at a lower price. I called every motorcycle dealer within a radius of 20 miles, but none of them had ever heard of these plastic jets, and couldn't even be bothered to keep a complete selection of Mikuni brass jets on hand. The best advice I got was "come on over and we'll see what we can do."

I tried raising the needles without much success, so I sadly went back to the snorkel.

In 2019, I have zero results searching for plastic jets. I seem to recall that they were called something like Uni-Jets, but I could easily be wrong.

Anybody else remember these?
Richard

An interesting post. But I don’t like the sound of plastic jets ; I wouldn’t have confidence in their long-term dimensional accuracy. The reason I have this doubt is that I used to work on chainsaw engines years ago, and Tillotson - a carb manufacturer - made a modular carb, the HK series. The module part was initially made of metal, but then they began making it of plastic. Presumably the plastic part was cheaper to make, but with the passage of time and the influence of fuel, the plastic distorted resulting in tiny air leaks , which played havoc with the fuel / air mix. So I’d be wary of plastic jets!
On the matter of the air box inlet, I recall reading that the Yamaha XS1100 responded well to enlargement of the rubber air box duct.

Even if plastic jets were available today, with the muck and crap they are putting in petrol in the UK now, they would probably melt away to nothing very quickly like our rubber parts are. !

Brass rules !

Pete F
UK