November 30, 2012

Resurrecting an Ancient Yamaha DS-7

Oct 21, 2011

Got home from Colorado Springs last night, and was surprised to find this nasty looking thing sitting in my driveway:




A few minutes later there was a knock on my door -- a nineteen year old kid from down the street, who I've known since he was about six. He told he he bought it during the week and intended to fix it up. But one problem: his parents told him he can't keep it at their house, so he hopes he can keep it here at mine.

Cool!!


It's not running at the moment ... all sorts of problems: no key, no kickstart lever, no battery. Those are the obvious ones. Probably plenty more that we'll discover along the way.
It's a 250cc yamaha something-or-other, from 1976 (he thinks). Two-cylinder, 2-stroke (yep, 2-stroke!).


Jeff

Sent to Neighbors, etc Sep 10, 2012


Very thrilling development last evening:

<<it started !!>>

It's the improbable outcome --after eleven months and much toil-- of the project that began with a surprising discovery in my driveway one night last October (see original message below).

Jeff


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Sent to Brownells on 9/15/2012:
Subj: Photos for the family album

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Sent to Scott on 9/16/2012:
Subj: The Petcock with two rifle shells



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Sent to the Kovio guys, Nov 2012

Hey, I think I've told each of you motorheads about the kid from down the block, who dropped off an atrocious old motorcycle in my driveway about a year ago. Said he'd just bought it, and wanted to bring it back to life. Kind of a strange surprise, but of course it turned into an incredibly fun project! It's not over yet, but we're pretty close and we know we'll ultimately declare victory.

Here are some interesting pictures. They start by showing the original condition of the bike: the horrors we discovered while dis-assembling it.

Hey, I think I've told each of you motorheads about the kid from down the block, who dropped off an atrocious old motorcycle in my driveway about a year ago. Said he'd just bought it, and wanted to bring it back to life. Kind of a strange surprise, but of course it turned into an incredibly fun project! It's not over yet, but we're pretty close and we know we'll ultimately declare victory.

Here are some interesting pictures. They start by showing the original condition of the bike: the horrors we discovered while dis-assembling it.

It looks like there was a massive battery failure at one time ... all sorts of stuff is corroded from battery acid, including the throat and slide of one of the carbs. The slide wouldn't budge; it was siezed in place. The airbox and carbs also looked like a mouse had made a next inside ... we found a bunch of leaves, twigs, mud, and a couple of nuts. And down in the float bowls, found gobs of thick, white sludge and a lot of little white pebbles. I can't figure out what they are ... maybe some solid residue that formed when the fuel turned to sludge.



The carburetors:





The airbox (we found a mouse nest in it):


The points and cam:


The engine:





The petcock:



The shift Lever:


- How in the world did this thing ever work:

- Looks like it might be solved with a little brute force:
- Voila!


The Regulator and Rectifier:


Who would guess that this basket-case would ever start.

-=-=-=-=-
After about 11-months of toil, it was time to try kicking it over. It was nowhere near being finished, but ready to test whether the engine would start. Here's what we had:

  • a fuel tank from an old weed-whacker
  • duct tape from the airbox to the carbs
  • my car battery, connected to the bike by jumpers
  • dozens of other jumpers thruout the wiring harnesses. Hoping they're wired correctly ...















Another week or so of work, then we dared to try riding it.

Made it to the end of the driveway!
Stop for a photo, before venturing into the street ...



Wow, it works! Better order a helmet for the next ride ...


Hey, this thing's pretty fun!








Some scenes from the resurrection process:









Repairing the Broken Fuel Petcock with Two Old Rifle Shells:









Rebuilding the oil pump on a very chilly November evening:























Sent May 6, 2014


Hello motorheads:

Look at this piston, with the hole blown thru it!

We discovered this yesterday when we disassembled Scott Brownell's motorcycle (he's the kid resurrected a scrungy old Yamaha DS-7; I showed you some photos a few months ago).

Last week, he was riding the bike to school when it made it made a big explosion sound and sputtered to a stop. Wouldn't restart. Yesterday's autopsy revealed this.

I can't imagine why a piston would fail like this! Have either of you guys heard of such a thing?? Any ideas?? Remember this is a 2-stroke engine, FWIW.
everything else looked perfect. Neither the head or spark plug showed any sign of contact or trauma.


See ya ...
Jeff

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