Service
SERVICE
With or without lead, please?
I’ve noticed that on some later-model motorcycles, the manufacturers have attached stickers that say
“unleaded fuel recommended.”
Why is this? Is it because some parts of the engines cannot take the lead? John R. Morgan Northfield, Massachusetts
For the most part, the motorcycle manufacturers recommend unleaded fuel because their engines cannot meet federal emissions requirements on fuel that contains lead. In the case of Yamaha's J984-'85 RZ350—the only motorcycle ever sold in the U.S. w ith a catalytic converter—the use of unleaded fuel w as mandatory to prevent permanent damage to the catalyst in the converter. But in virtually all other motorcycles, leaded fuel (of a sufficiently high octane, of course) can be
used without incurring any internal engine damage. Most racing gasolines, for example, are leaded fuels and can be used without fear of harming the engine.
Conversely, problems can occur when unleaded fuel is used in an engine that was designed to run on leaded fuel. These usually are older engines which use valve-guide material > that relies on the lead in the fuel for lubrication. When unleaded is run through these engines, the valve guides can wear at an excessive rate.
Another reason for the recommendation of unleaded fuel is simplv that the sale of leaded fuel is being phased out by the government. There are some areas of the country, in fact, where leaded fuels are either not sold at all in service stations, or are available only in lower octane ratings.
Hope springs internal
In your January of 1990 Service column. Andrew Seaton of Greenville, Tennessee, complained of a knock at idle in the engine of his Honda CBR600. My CBR started making a similar noise at 4500 miles, and a CBR-owning associate of mine also had the same problem at about the same mileage. So, I removed the oil-fed, spring-loaded cam-chain tensioner on my engine, and found chatter marks on the plunger shaft. I went down to the local True Value hardware store and found a spring (they have lots of them) that approximately doubled the stock tensioner spring’s rate but that would not coil-bind at full compression. Presto-changeo, no more knock or rattle. I performed the same magic on my associate’s CBR, with the same results. And after more than 1200 miles with this modification, neither bike has had any more rattle problems.
John Fucsalla
Janesville, Wisconsin
Short of leg but not of speed
I believe I have an answer for Pat Bleakney (November, 1989, Service ), who says he is too short for a full-size bike: Pat, get ahold of a Yamaha YSR50, then graft an old Yamaha 250 enduro engine into it. What you’ll get is a small bike that will do an honest 100 miles per hour and keep up with most 400-500cc motorcycles. And, yes, the stock brakes will stop the 250-powered YSR from high speed.
Mike Baldwin Poughkeepsie, New York
Not with any of us on it. E3
