Walneck's Classic Cycle Trader - June 2008 - (Page 74) MONTHLY FEATURES BENCH RACING Bench Racing #99 June 2008 Triumph Trouble Mark, I read your column regularly in my Walnecks, you've "saved my bacon" many times with your advice for old vintage bikes. Back some time ago you had a recommendation for stuck pistons, an oil or substance that could potentially free up the stuck point. I cut that out and saved it, but of course can't find it now when I need it. I have a Triumph 500, which was free before Christmas (I try and turn it over every 60 days or so), but is now stuck. I don't want to force it, so hence my question about the oil, etc. your reply will be greatly appreciated. Presents Q By: Mark Zimmerman an hour or so put the bike in fourth gear, rock the engine back and forth and I’ll bet you a back of Evermores, that the engine turns over sweet as a nut. Good thumper-bad thumper Mark, I just bought your book on Motorcycle Maintenance. Excellent work. I have a question regarding Thumpers. Why is it that some Thumpers are hard to start when hot? I have two bikes of the same make, Yamaha XT350’s and one starts well whatever the conditions and the other is hard starting when hot. Bench Racing Q thing like a Gold Star or Velo Thruxton were sometimes hard to start when hot because they used highly tuned engines, recalcitrant magnetos and “sporting carburetors.” They also had low kickstart ratios, which made them difficult to get spinning fast enough to light the fire, especially when the fuel had been percolating in the float bowl while the bike sat in the sun. So the bottom line was that at kick start speeds they simply had low intake velocity, which made the fuel/air mix reluctant to atomize or ignite and the bike hard to start when hot. They could be tough to start when cold too, but that’s another issue. Modern singles, particularly the highly tuned off-road ones suffer from many of the same problems, although their ignitions and carburetors are much better. However things like hotstart buttons, and electric starts make living with them a lot easier. Generally when a modern single is hard starting (hot) I look first at the pilot mixture and idle speed, and because modern thumpers are extremely sensitive to throttle position when starting, especially when they’re hot, the owners starting technique. But that doesn’t answer your second question as to why one of two similar bikes starts hard when it’s hot while the other doesn’t. The short answer is that no two engines are as alike as we think they are. One of your engines has its hot start parameters dialed right in, the other doesn’t. For starters (no pun intended) make sure the George Gaissert Fort Worth, TX Via e-mail I’ve become a big fan of a penetrating oil called PB Blaster (www.blasterchemical.com). It comes in aerosol form and really gets the rust busting done like nothing I’ve ever seen. I recently saw it free up the frozen throttle shaft of an early 1900’s hit and miss engine that had been sitting outside for the last 75 years in under an hour. Most auto parts stores carry the stuff or you can order it online. I’d pull the plugs, fill the cylinders with Blaster and let it work while I had a cup of coffee and a cheap cigar. After half A Paul Via e-mail A I Your first question is somewhat loaded. Older singles, think of someWALNECKS.COM 74 JUNE 2008 I WALNECK’S CLASSIC CYCLE TRADER® http://www.blasterchemical.com http://WALNECKS.COM
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