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Author Topic: 1969 Yamaha DS6C  (Read 710 times)

Offline Virago1113

  • Posts: 87
1969 Yamaha DS6C
« on: Feb 10, 2017, 21:30:46 »
Picked up a 2-stroke barn find. PO says that in 1978, it was driven into the garage and parked there. Hasn't seen the light of day since. For the price I couldn't pass it up.

The good...she seems to be complete. Only thing I can see missing are the air filters.

The bad...She is completely locked up. Shifter won't budge and the back wheel won't move. Thankfully the master link was where I could pop it off to remove the chain so I could move it over into the corner of the garage.

As per usual, it fell into my lap, so there hasn't been much research.

I have to leave for work out of town for the next month, so this will give me time to read up on a few things and order parts. Not sure where I'm going to go with it, leaning towards cafe but she's supposed to be a scrambler.

If there is someone out there that can point me in the right direction for parts/manuals/insight/etc, that would be helpful. I'm definitely tearing this one apart (rings, gaskets, carbs rebuilt, etc) Not as easy as the last one. I'm not sure even where to start.



Thanks in advance!

"If you rode the Black Shadow at top speed for any length of time, you would almost certainly die."

Hunter S. Thompson

Offline Shoeman

  • Posts: 95
    • My old RD tuning pages from the 90's
Re: 1969 Yamaha DS6C
« Reply #1 on: Feb 12, 2017, 10:04:59 »
Nice find.  I have a couple boxes of YDS6 parts somewhere around here.  Cylinders, heads and ignition I think, but it's been a few years since I eyeballed them.  We converted the street version into a TD2 roadracer and kept the street bike engine parts.
I like cilp-ons, clubman's and superbike bars depending on the bike.  And rear-sets.

Offline Virago1113

  • Posts: 87
Re: 1969 Yamaha DS6C
« Reply #2 on: Feb 15, 2017, 21:39:23 »
So I have searched the internet and I haven't had much luck in finding any of these bikes customized as cafe/scramblers. I did find a Yahoo group that is very much like this forum with guys that are dedicated to the YDS bikes. I'm hoping to find knowledge and parts from these fine people.

So it looks like this one will be one of the first DS6Cs, unlike my Virago which has been customized a lot already by many people. I did find a couple of RDs that I liked, so I will be taking my inspiration from these once I get it running...





I ordered the service and parts manuals from Ebay. I just now have to wait until I get home from my month long job in Twentynine Palms, CA before I can dive in.

I have searched the forum here but I haven't seen any builds of this bike, but if anyone knows where a build is hiding, please pass it along.
"If you rode the Black Shadow at top speed for any length of time, you would almost certainly die."

Hunter S. Thompson

Offline Virago1113

  • Posts: 87
Re: 1969 Yamaha DS6C
« Reply #3 on: May 08, 2017, 09:43:21 »
Finally started working on this. The bike had been sitting exactly where I parked it the day I bought it in February. I think this is going to be a long painful thread...

The carbs were hanging by the throttle cables. I was able to get the slider out of one and disconnect, the other slider will only come out so far and then is stuck. I can push it down, but only up to a point...

Ignition is really corroded, but I don't know points that well...never owned one old enough to have points.

Oil pump looks good though. I still need to figure out if it works after all these years.

Pulled the motor this past weekend. When I took off the exhaust I found that the right tube was rotted through. The left pipe had some water in it. The PO had removed it from the garage in November and it sat under a tarp until I bought it, so it probably had some exposure at some point.

Popped the heads off and the pistons are stuck to the jugs. I put the heads back on and poured some Marvel Mystery Oil in the spark plug holes. I will give it a few days and see what it looks like.

Any and all suggestions/tips would be helpful! I'm definitely going with a different design once I figure out the motor and get it running.






"If you rode the Black Shadow at top speed for any length of time, you would almost certainly die."

Hunter S. Thompson

Offline Virago1113

  • Posts: 87
Re: 1969 Yamaha DS6C
« Reply #4 on: May 12, 2017, 16:18:13 »
I popped the heads back off last night and took my rubber hammer to the jugs. One side seems to be moving if ever so slightly. The other is too hard to tell the piston is sitting low in the jug. I decided I am going to mount it to my engine stand and I figured I should drain the oil first. I got some water coming out when I pulled the plug...
"If you rode the Black Shadow at top speed for any length of time, you would almost certainly die."

Hunter S. Thompson

Offline Virago1113

  • Posts: 87
Re: 1969 Yamaha DS6C
« Reply #5 on: May 12, 2017, 16:39:50 »
While I am waiting for the pistons to soak...

I am no expert on points. I know that a lot of people say that points are easy. I found this and I'm thinking that if the engine isn't toast and I decide to go further with this project, then maybe I will convert the ignition to this:

https://www.powerdynamo-shop.com/shop/show_product.php?cPath=4_41&products_id=282

The website claims that it fits the DS6, there is a dealer in US, but they don't mention the DS...I've emailed them to see if I can get an answer.

If anyone has dealt with these it would be great to know.

I have found a Yahoo group that the members all own YDS bikes. Lots of knowledge and parts!
"If you rode the Black Shadow at top speed for any length of time, you would almost certainly die."

Hunter S. Thompson

Offline SONIC.

  • DTT SUPPORTER
  • *
  • Posts: 5803
  • Reminds me of...me No, I'm sure of it. I hate him
Re: 1969 Yamaha DS6C
« Reply #6 on: May 12, 2017, 17:47:12 »
Cool little bike!
Keep soaking the pistons in oil, throw some atf/acetone in there and see if that helps.
Once you get them moving it's time for a FULL tear down, you're going to need all new seals and likely all new bearings as well since there is water in the cases. So splitting the cases etc becomes necessary.
Points are easy, so long as everything moves freely you can replace the condenser and points and get it running.

Offline Virago1113

  • Posts: 87
Re: 1969 Yamaha DS6C
« Reply #7 on: May 12, 2017, 22:23:35 »
I mounted it on my engine stand tonight and pulled off the left side cover. I was able to get the left jug off after a lot of sweating and swearing by rocking the crank. That piston was up near top dead center, so the penetrating oil was able to sit there. The right jug was lower and the ports are showing, so the oil had places to escape. I poured some Marvel in and will let it sit for a few days. I also leveled the engine on the stand so the jug was straight up instead of at an angle so the oil wouldn't just dump into the port.

Looks like this is going to be a complete rebuild. From what I can see inside its not as bad as I thought but is still going to need a good once over.

Once I get it together I will try and go with the points. If I don't have a ton of money in this and the points seem to be a pain, I might swing the money to modernize the the ignition.
"If you rode the Black Shadow at top speed for any length of time, you would almost certainly die."

Hunter S. Thompson

Offline Virago1113

  • Posts: 87
Re: 1969 Yamaha DS6C
« Reply #8 on: Jun 05, 2017, 09:43:54 »
So after some time of not having any success with getting the right jug off myself, I took it to a friend and we decided that he will help me go through the whole engine. He was able to get the jug off last night. We honed the cylinder after it came off and I will definitely need to bore this out. So it looks like I'm going to need a set of pistons and bore it .25 over. He said the needle bearing did not look good on the right side either. We are going to disassemble the rest and get a shopping list of what I will need.
"If you rode the Black Shadow at top speed for any length of time, you would almost certainly die."

Hunter S. Thompson