1972 Yamaha DS7

Caution: Smoking is addictive, and basically requires a 12 Step Program to quit.
But I gotta admit, it's a decadent guilty pleasure


"Hi, my name is Chris... and I mix Oil and Gas..."

Did you ever consider an RD350 top end for that beastie for a little more get up and go?

I just happen to have a set of 350 jugs and a set of new Prox pistons and a spare set of intakes and reed cages with TDR reed valve petals looking for a home. And a 350 transmission and maybe even a set of carbs.... The barrels are new from China or HK or somewhere and the castings are excellent but mismatches between the liner and barrel need cleaning up and that's what I'm doing now for amusement. I'm not going as mad with the ports as I did on the last motor I built which made 52 HP on street gas. This one will be more mellow.

Just sayin'..............

teazer said:

Did you ever consider an RD350 top end for that beastie for a little more get up and go?

Click to expand...

You have my attention

I have a spare 350 bottom end that has a 400’s 6speed already stuffed in it.

With a glowing recommendation, I purchased these LED headlights...

Before:

After:


I know, it's not a really good comparison.
But we're currently under TS Barry, so no riding today :\

Just read through the your entire build. This had to be one of the coolest DS7’s I’ve ever came across!

Thanks, much appreciated ;D

I got your PM, when I get home this evening I'll get that jetting info for ya

I hadn't really played with the DS7 much since the last posting. Life and other interests took over and she got put into hibernation. About this time last year I had the realization that she would be 50 years old in 2022, and made the declaration that I would wake her up and get her out for her birthday. Well, life and other interests took over again, and here we are. I finally got off my ass and got her out of bed today. She came back to life fairly easily, with not much more than fresh fuel and a points cleaning/gapping. The sad news is, on my (coincidentally) last kick to check starting/idling the kicker bound up somehow and cracked the cover. Crap.
I have a spare cover (thanks to BradJ) that I'll get painted up while waiting for the new gasket and seal to arrive. Just gotta get in there and figure out what happened.
Hard deadline to get her back on the street is December 30th. But the target is November 12th, as that's the last car show of the year.
Carnage...

Ouch. Hope it's not serious

Gonna pull the cover tomorrow evening. Hopefully it's just the cover. But if it took the case out too, I guess I'll be "forced" to buy pistons for the RD350 engine and install it

Redbird said:

Gonna pull the cover tomorrow evening. Hopefully it's just the cover. But if it took the case out too, I guess I'll be "forced" to buy pistons for the RD350 engine and install it

Click to expand...

Ha, Forced.

No apparent carnage...



Couldn't find anything amiss. I'm gonna slap a cover back on an keep my fingers crossed.

How did this turn out? Was there any continued issues?

Not so far.
Someone on another forum mentioned that something similar happened to them after advancing the ignition just a little too much, and the motor kicked back and ran backwards. I've had the same ignition timing in it for a while now with no issues, but the points/condenser have been in there for about 15 years (+/-) and are showing their age. I get random misfires occasionally, which makes me wonder if the old parts didn't cause an advance spark issue, resulting in something similar. Ordered a new kit anyway, as it can't hurt. But it does pose an interesting question that couldn't readily find an answer to... will worn rubbing blocks and/or extensively "cleaned" contact points change the timing even after proper adjustment has been performed?

That's a great question. I think I'd have to land on a yes if it was my own conclusion, but I'm trying to picture if wearing them that much would advance or retard them.

Wearing down the rubbing blocks closes the points up and retards the timing. Cleaning the points surfaces could potentially open the gap a poofteenth or so and would advance the ignition. It's worth checking timing it just to be sure.

As for the cracked case, I would put that down to millions of kicks downwards causing fatigue for the case as well as the rider.. It would be interesting to know if yamaha made later model side covers any thicker.

teazer said:

Wearing down the rubbing blocks closes the points up and retards the timing. Cleaning the points surfaces could potentially open the gap a poofteenth or so and would advance the ignition. It's worth checking timing it just to be sure.

As for the cracked case, I would put that down to millions of kicks downwards causing fatigue for the case as well as the rider.. It would be interesting to know if yamaha made later model side covers any thicker.

Click to expand...

You always chime in with the best DS7/RD/RZ knowledge, It's really appreciated.