Unless they're fooling with me (it is the first of April after all), my bike has been crowned Bike of the Month for April 2008 on the newly renovated Yahoo! Yamaha R5 Group.
For the unaware, this Yahoo! group is populated with folks who are most knowledgeable in all things vintage Yamaha. Without their help many of the problems with and parts missing from my R5 would never have been sorted. I thank them very much!
Be sure to check them out, and to sign up if you haven't already!
Here's a great comparison test of all the "hot new superbike" 350s from December of 1970! Each page is individually scanned, so you have to download each one separately, but it's definitely a good read. I don't think you'll be too surprised when you discover which bike won the top honors in the review...
I thought this article well-timed after having to stop twice on my last ride to switch out fouled plugs. The Kneeslider has a good article summing up why some of us are compelled to keep our ol' bucket of bolts running, and doing it ourselves:
Buying an old motorcycle may not make complete economic sense when some new or relatively recent bikes are available, but the promise of getting that old bike running again as it was designed to do and once did, hearing an engine that hasn't made a sound in decades come to life, you just can’t buy that kind of happiness.
I came across this DS7 page while helping out Nate, who recently picked up a DS7. There's a good section at the bottom that offers some tips that could be of some use for later Yamaha 2-stroke riders:
Riding technique is important. If you are not in the power band (6000 rpm up), twisting the grip to full throttle is not useful, and actually just helps foul the plugs. Be very patient and wait, or shift gears, until the engine gets to at least 5000 before hitting wide open. Otherwise you are just dumping extra oil into the cylinders and ruining your plugs.
The mufflers are too restrictive even when absolutely clean. They rapidly strangle the machine as they plug up with oily soot. So you need to drill a couple of holes about one eighth or 3/16 of an inch in diameter in the end of each baffle so some exhaust gas can bypass the baffle. It's best to not drill in the chrome area, just beside the exit hole is OK. Then you have to keep the baffles pretty clean, and maybe make a scraping tool to clean them out without always having to remove them. A long screw was what I used. (about 10 inches) I used it kind of like a little rake to scrape out the baffle.
Metallic ash can foul the spark plugs. There are two sources of this, one is leaded gas, which you can't find any more so no worries there. The second source is the 2 stroke oil. Yamaha says use oil "BIA Certified for service TC-W" I don't even need to look that up, 20 years later it's still engraved in my memory. Actually, you sometimes can't find this stuff but what you are looking for is "Ash free" oil. You can check the label. The DS7 ran with lots of oil, and that what partly contributed to fouling but also made the engine last a long time under severe use.
Found some good info on motorcycle anti-theft: a site by a guy who lost his bike to theft, and a comprehensive article from Motorcycle Cruiser magazine... good to know, as I’ll be parking on-street or in an open parking lot...
This is a site dedicated to the 1970-72 Yamaha 350 R5 two-strokes. These bikes are surprisingly fast for their size and age, lifting the front wheel in the first two gears and keeping up with modern bikes twice their size. It's also extremely flickable and great fun around the city or carving up canyon roads. It was the direct descendant of the Yamaha factory TR production racers. Dirty, loud, crazy quick and relatively affordable when new (and more so now!), it was, and still is, a giant-killer.
I picked up an R5C for my first motorcycle a few years ago, and was frustrated with the lack of information on these bikes available on the web. The original purpose of this site was to document the process of bringing the R5 back to life. But as I spent time gathering as much relevant and entertaining information as possible into one place for my own reference, I thought it would be helpful to share it with people who are also interested in these bikes, as well as Yamahas, vintage bikes, and motorcycles in general.