Some pictures of my 10 years with the Yamaha DS7, taken with a digital camera off a projected slide show. Click on the thumbnail for a larger picture.
Brand
new bike 1973, already put homemade fork covers on it.
First
big tour in 73 to Saskatchewan. This is north of Lake
Superior.
The
garbage bags held up well on the 73 tour. Note the tire pump.
I was used to about one flat every 600 miles on my CD175 in
Africa. I was expecting about 7 flats on the Quebec - Saskatchewan
and back tour. I had none.
In
1974, in Goderich Ontario, on the way to BC. Martin and
Jennifer on a CB350. We had real bags this year. (we carried
tent and sleeping bags as well as all the other stuff including
the tire pump again.)
In
1975 we toured the east coast with the new blue paint job, and
home made leg protectors. They also doubled as more storage
space. There was a home made fairing too, but you can only
see a corner of it.
This
is more or less how the bike looked until I sold it in 82.
It has a real fiberglass fairing. The rear tire is bigger
than the standard Yamaha 250. There is a pair of Koni shocks
on the rear with a home made extra preload spacer. And a
bracket for chain lube. The chain lasts a long time if you
spray it at every gas stop. If you look closely you can also
see a tire pump. I was still really afraid of flat tires.
I sold this bike in 1982. A young lad who wanted a beginner bike, and his father showed up to look at the Yamaha 250, in response to my ad. Much to my surprise, the father made the comment "The engine is only 250cc, are you sure it's big enough to keep up with traffic?" I was not pushing the performance thing what with the young kid involved, but he obviously was not too clued in. When I replied "It can keep up with a Corvette from a standing start to to 60 mph", we had a deal.
On this page I would like to share some hard earned knowledge of the DS7. My most remarkable achievement during the 10 years of owning and maintaining (entirely without help from professional mechanic), was to actually make the bike run cleanly on the same set of sparkplugs for over 1000 miles. Before that I had discarded buckets of plugs. I never bought any less than 4 plugs at a time after the first year. This bike would sometimes foul its plugs just switching to reserve. And once fouled, the plugs would not self-clean. Fouled plugs would not accept wide open throttle above a certain RPM, which I needed for traveling on the mountain roads near my home, just to keep up with traffic. The roads were quite steep, with curves at the bottom, and the traffic moved fast.
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.
Another problem that came up was hard starting. I was puzzled at first that sometimes I could kick until I was red in the face and nothing happened. Then I found out that water condensing under the points cover was partly to blame. This water would pool at the bottom inside the points cover. I was unable to keep it dry, so I made a hole in the bottom to let water drain out. I did not have too many problems starting after that.