Kidding Me I Not Have a Dynamometer

In some previous story, the tuning of a carburetor, I talked about using a Dyno, we got several reactions about this. A Dyno by motorcycle mechanics or dynamometer for English Professors, is a machine used to measure torque and rotational speed (rpm) from which power produced by an engine.

Okay this Dyno's are not something you would buy just to tune your carburetor, hence it is cheaper to visit multiple motorcycle tuning shops, until you have the right performance.

So if you don't have free access to a dynamometer, don't worry, I did years without also. With a stopwatch, tachometer, and some imagination you, too, can measure the power output of your engine accurately enough to get your carburetor dialed in correctly.

Consistency is the key to these types of performance tests. When doing any of these tests take into account air temperature and humidity.

Cold air temperature with humidity will result in faster times. Hot air and high humidity will slow performance down. Also, the state of your engine will be a factor.

Don't make a test run on spark plugs that have 20,000 kilometers on them. While the numbers you will get from these tests won't mean anything to anybody but you, they will provide a way to evaluate any performance changes you make. This type of testing takes a fair amount of time, so be patient and you'll reap the horsepower rewards.

Stopwatch
You can use a stopwatch to measure the effect of changing the ignition timing curve, fuel map, carburetor jets, or any other performance mods you make. Get a cheap "Chinatown" digital watch with a timing function. Tape it to the left side of your handlebars where you can reach it with your thumb. Find two road signs about 200 meters apart. In second gear, roll up to the first sign at 33 km/h and nail the throttle. Shift up though the gears until you come to the second road sign. As you pass the sign press the stopwatch to shut it down. Stop and record the time for your run. You will need to make at least three runs and average the times. As you make tunning changes, see if your average time gets better or fails off.

Tachometer
If your bike has a tachometer you can try this test. Find a deserted, flat, straight rad that's about 3.5 kilometers long with no dogs, elephants, noodle or som-tam shops. In fourth ger, with a steady throttle, get the engine turning at 2000 rpm. Open the throttle all the way and start counting "one sawadee krab," "two sawadee krab" etc. Stop counting as your tachometer needle passes 5000 rpm. Each "Sawadee Krab" is worth about one second. Remember which part of the "Sawadee Krab's" you where on when the needle hit 5000 rpm. Make at least three runs and average the results. Use this as a measuring stick against any performance changes you make to your motorcycle carburetor.

P.S. A cheap Chinatown stopwatch works better than counting Sawadee Krab, but anybody knows that.....