Service

SERVICE

Sobering up a Suzuki

Paul Dean

I ride my ’95 GSX-R1100 all around Illinois and Indiana, where some gas stations are required by law to sell gasoline with alcohol in it during certain times of the year. But some are not. And depending upon where I ride and when, it’s not always clear if the gas I’m buying contains alcohol.

I mention this because my bike occasionally runs erratically, and it usually seems to start doing so shortly after I’ve filled the tank. The worst symptom is an uneven idle that can make the engine stall (although it always starts right up again), but I also sometimes feel a mild surging when riding at a steady speed. Even though the symptoms eventually go away, they usually do so the same way in which they appear—shortly after filling the gas tank.

I’ve read that gasoline with alcohol in it can cause engines to run this way. So, my question is, do you know of an easy way to test gasoline for alcohol content? My mechanic has tried in vain to track down this intermittent erratic running, and I don’t want to keep paying him to diagnose the problem if it’s actually being caused by the gas.

Eric Stouffer Kankakee, Illinois

There are several tests for verifying the presence of alcohol in gasoline; one of the simplest is described in a recent technical newsletter, called The Wrench, published by Honda. The test is based on these three facts: 1) Alco-

hol blends with gasoline, but blends more easily with water; 2) water and gasoline do not mix; 3) when water, gasoline and alcohol aie mixed in the same container, the alcohol will combine with the water, and the resultant alcohol/water solution will separate from the gasoline.

To perform this test, find a graduated container that will allow you to shake its contents; an 8-ounce baby bottle is ideal. Being very precise, fill the bottle exactly to the 1.5-ounce mark with water, then fill it the rest of the way up to the 8-ounce mark with the gasoline you 're testing. The water will stay on the bottom of the bottle, while the gas will remain on top. Put the cap on the bottle and shake vigorously, then let the bottle sit upright for a few minutes.

If there is no alcohol in the fuel, the line of separation between the water and the gas will return to its original level, precisely at the l.5-ounce mark. But if alcohol is present in the fuel, the separation line will be noticeably above the l.5-ounce mark, because the alcohol will have separated from the fuel and combined with the water.

Adding some form of alcohol (usually ethanol) is just one of the methods that refineries use to “oxygenate " (increase the oxygen content of) gasoline, which helps reduce emissions through cleaner combustion. Gasoline producers also do this with "ethers," the most popular of which is Methyl Tertiary Butyl Ether, or MTBE for short. Generally, you have no way of knowing which type of oxygenate is in the gas you 're buying, and there is no simple test for ethers. Consequently, short of submitting fuel samples to a laboratory for very expensive analysis, there is no foolproof way of determining the presen ce of oxygen a tes.

The major motorcycle manufacturers approve of the use of oxygenated fuels in their bikes so long as the content of oxygenates does not exceed the legal limits, which are 10 percent for ethanol and 15 percent for MTBE. So, in the end, you 'll probably have to live with the occasional performance hitch.

Short story

My ’93 Honda VFR750 is ready for new tires. In an effort to lower the seat height, can I switch to tires with shorter sidewalls? I'm considering switching the front from a 120/70R17 to a 120/60R17, and the rear from a 170/60R17 to a 160/60R17. My cal-

culations indicate that the front axle will drop 12mm while the rear will drop only 6mm. I realize that the smaller front tire will throw the speedometer and odometer off, but will the inequity in axle heights cause any problems? Mark Voetter

Kirkwood, Missouri

Your figures indeed are correct; but because the seat is much closer to the rear wheel than to the front, your proposed tire swap would only lower the seat about 8mm—roughly the thickness of an M&M. Plain, not peanut.

That reduction in seat height would be imperceptible. And youd end up with noticeably quicker steering, resulting from the combination of the front tire’s shorter sidewalls and the slight forward tilt of the entire chassis caused by lowering the front axle more than the rear. What’s more, the shorter—and therefore less compliant—sidewalls would slightly harshen the ride, particularly at the front. And the handling would be affected, too, because the rear-tire contact patch would be slightly smaller, and the tread profile of the 160/60 would be flattened compared to that of the 170/60 because of having its sidewalls being pulled farther apart than intended.

My advice: Don’t do it. Corbin Pacific (800/538-7035) makes a seat for the VFR that will put you a lot closer to the ground-and give a more comfortable ride in the process.

E-Z does it

1 just dumped a bunch of money into my ’94 H-D Heritage Softail for hop-up equipment, including a new ignition that calls for less initial advance than stock. Problem is, Harleys only have timing marks for TDC and the stock setting. Is there an easier way to accurately set the timing besides going through all the hassle of using a degree wheel? R.L. Ballinger San Angelo, Texas

Sure is. Tech Products in Mesa, Arizona (602/649-3901), makes a nifty, $15 device called Ez-Tyme, a little metal plate that permanently attaches right next to the alternator rotor, inside the primary case. The plate is stamped with timing marks in 5-degree increments, from TDC to 50 degrees BTDC, and allows precise strobe-light timing through the rectangular inspection hole in the primary cover □