by Doug Lofgren

In spite of the time I spend with motorcycles, I still enjoy the same things about motorcycles that my customers do, the variety of mechanisms that make up the whole and their relationships with each other.

Spending a rainy spring Saturday cleaning and adjusting your bike can be a very satisfying experience. And there are plenty of maintenance items to which a motorcycle will respond. Chain adjustment, properly done, can improve shifting, eliminate clanking noises, and take the lurch out of the drive train. Clutch adjustment can improve shifting and smooth take-offs. Brake lever adjustments, shift lever positioning, brake bleeding, etc.

All these things pay dividends in ride quality. Together they can change the feel of a bike from clunky to crisp. With so many fascinating, rewarding details to learn about, why is it that so many motorcycle enthusiasts decide to go right to the fuel system?

The question is rhetorical. But, it may be some cultural thing, a right of passage that comes with a certain level of experience, seniority. Maybe naivet√©? Whatever the cause, I have an idea of how this kind of process starts. It goes back to another ‘basic’ of the sport. Everyone who rides a motorcycle wants ‘more’. Don’t be too quick to claim that you are only one impervious to the lure of the motorcycle, the only one who rides for purely practical reasons.

Although it’s usually more power, it can be more sound, more mileage or more individuality. The most common addition is an other than stock muffler. This gives more noise, more individuality, and more power. Usually, in that order. Typically, ‘jetting’ problems start with the installation of a ‘pipe’. Either a ‘glass-pack’ muffler (loose term) or a ‘full system’.

To those of us who see a small portion of the results of this process, the cost of such a modification isn’t simply the cost of the ‘slip-on’. It should include the re-calibration required to extract the performance and more important recover lost drivability. It’s no different than buying your first motorcycle while forgetting that you need a helmet, jacket, boots, gloves and rain suit. It happens all the time because people are ‘optimistic’.

Why do I think “Do-It-Yourself” fuel system calibration by the owner/operator has a low probability of success? Hint; it’s experience. Some time in my early years in the motorcycle industry I began to understand that the concept of ‘tuning’ existed, I wanted to learn how to do it, and I had an idea of how far I was from doing it. Along with that understanding, came the realization that the only way to catch-up with those with considerably more experience was to utilize the best equipment available.

Within a few years, WIW (long departed Kawasaki shop. Ed) had moved to 15th and Lake Street and acquired a dynamometer. With that equipment, it seemed like we had been working in a dark warehouse and the lights were just turned on. That was twenty-one years ago, 1981

In the later ’80s I worked in the Engineering Department at Onan Corporation. If I had any doubts about the efficacy of good test equipment, working in ‘big-bucks’ dyno cells put the ‘frosting on the cake’. I have been convinced from that point on that there is no substitute for good test equipment.

Each phase in the discovery process turns on more lights. In retrospect, the first ‘light’ was just a candle in the pitch dark. I’ve managed to distill the whole painful experience of ‘jetting’ into a process, that takes a finite amount of time, that amount being closer to a day than it is to a season or a lifetime.

So, I don’t take the process lightly. I certainly don’t expect that many of the most senior motorcyclists I know have the equipment or education/training to do this. And, I do not look down on someone who can’t jet their own carbs, rather I respect a person who ‘knows her/his limitations’.

This article is not about my abilities but rather an endorsement for ‘the process’ and the results. There are several excellent ‘tuners’ in the Minneapolis area. Motorcycles are not a means of saving money. They don’t have to be expensive but the culture compels us to try to personalize and customize them. If you can’t afford to have the fuel system calibrated properly, leave it alone. Save the money you spent on the pipe. Your bike has a better chance of being different if you leave it alone, anyway.

There was a genuine do-it-yourself guy in the shop the other day asking about the price of jetting service. They are easily recognized by the bikes they ride, this one being a Norton. After his initial response, he demonstrated remarkable insight by saying, “But then it would be done.”

The next time you’re faced with a rainy Saturday you could always change your fork oil. Ever done that?


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