2 Stroke Madness

[ancosta]

Bought my very 1st 2-stroker, a 1972 Yamaha DS7. See pic attached.

3333 miles on the clock, in decent shape overall. Will see how it runs once I replace the battery and get the carbs back on.

Any suggestions on learning more about these bikes would be helpful. I have heard some things about switching to electronic ignition to prevent piston burn scenarios. My goal is to make it run, see how well it goes, and evaluate from there.

[Ri_De_bike]

Rd250 75
whatcha need? links?
look for a dial gauge...metric; timing is CRITICAL. 1.8mm before tdc
buy NGK plugs; or go electronic <chinoy in india makes em.
i run royal purple syn, flush your tank (oil) first

USA 2 STROKERS < best for yamaha
HVCcycle: Historic,Vintage, Competition, Motorcycle Support. < NEW parts, best remanufactured stuff!

man, you and i should talk!

[KillBill]

Ah dude, i love that style bike. Congrats on the purchase.

Must be a blast to ride.

[SSearchVT]

Cool find!!!
Be very careful letting the clutch out after you start the bike. Some of the old two stroke streetbikes would backfire when they were being started - and the engines would end up running backwards...

[Ri_De_bike]

Cool find!!!
Be very careful letting the clutch out after you start the bike. Some of the old two stroke streetbikes would backfire when they were being started - and the engines would end up running backwards...

Yikes i just saw a two stroke go by my house backwards.... how weird is that?

[ancosta]

Thanks for the warm wishes and backfire advisory. Ri_de_bike, I got your PM then looked at this. Thanks for the links will get into them this evening. I would love to hear this thing fired up and cranking along. All I can think of is the guy at track day with the white Bultaco 390 and cable actuated drum brakes. If this bike could go half as stink as that one I'd be in business

[Tabby]

Rd250 75
whatcha need? links?
look for a dial gauge...metric; timing is CRITICAL. 1.8mm before tdc
buy NGK plugs; or go electronic <chinoy in india makes em.
i run royal purple syn, flush your tank (oil) first

USA 2 STROKERS < best for yamaha
HVCcycle: Historic,Vintage, Competition,* Motorcycle Support. < NEW parts, best remanufactured stuff!

man, you and i should talk!

Isn't that before they put reed valves in them{piston ported?}, and became the RD?

[Ri_De_bike]

Isn't that before they put reed valves in them{piston ported?}, and became the RD?

the ys and rd are very close. both have reed valve and ports.

Holy shite there goes that two stroke backwards past my house again. somebody better tell that guy to be careful!!!!!
RD stands for Race Developed ;-) ya rly
take a guess what ys means? i don't know, not going there <heh>

[TLRMan]

I know a little something about Yamaha 2 strokes...almost a 10 second run, on an RD 350.
3rd gear burnouts anyone?

Set 2 national records O-modified / N-Modified Dragbike that were documented...most were refused because it lowered the index too much.
12,800 rpm redline, Krober magneto
36mm Mikuni 1st./ Lectron carbs later, airshifter, New England Performance custom swing arm and wheelie bars.
TZ crank welded, and balanced, TZ rods, modified Yamaha Racing TR3 cylinders and heads. Modified Yamaha racing pistons (very modified).
Compression ratio. WHO KNOWS!
Modified Yamaha racing expansion chambers
Semi automatic transmission w/ split gears..1st 3 gears auto, last 3 with kill.
Custom machined clutch basket, Barnett clutch plates, springs...Kept bending the spring bolts, and shattering the fingers on the clutch basket.
Goodyear slick, D4 compound.
First two years of trying to get it running well, I broke EVERYTHING!
Including cases, pistons, twisting cranks, cracking cylinder heads, bending rods, and snapping spokes.
Lots of parts were one of. Pistons had to be swapped out after 20 passes, to be safe. Went thru a lot of them...Started to make our own with alloy 390
aluminum.

Weight with me on it, 461 lbs
fuel capacity, 1 gallon
fuel VP
Gear box oil, Ford ATF
Pre Mix, Castrol R

This was all done in 1982....

Also had an 84 RZ 350 KR

I would give anything to be back there again...
The dragbike is still alive and well, there was another owner, but he let it go to hell, and never raced it.
Then another guy who vowed he'd own that bike one day, tracked it down, and paid more than SEVERAL THOUSAND DOLLARS for it.
It now sits, fully restored, and in running condition, in a nice and cozy home, retired...I almost shit when I saw it.
This guy looked me up through other people that knew me, and asked to meet up with me. I didn't have a clue...
He said he wanted me to look at a bike for him....I was in tears when I saw that bike. It was perfect, and it was 1982 all over again.
And as far as we know, the records still stand today...

[Evil_Weasel]

welcome to the obscure two-stroke club.

[Ri_De_bike]

TLRMan.....
wow, just wow

[ancosta]

TLRMan - that story is pretty amazing, and the bikes look great in those pics.

The hardest part of this bike is putting it in a garage for a month before I can start fiddling with it. Damn life obligations getting in the way.....

Will try to get some more pics going. I havent been this excited to fire up a motor since I was 16 years old and it was a 406" 66 Nova.

[Tabby]

TLRMan.....
wow, just wow

+1

[TLRMan]

TLRMan - that story is pretty amazing, and the bikes look great in those pics.

The hardest part of this bike is putting it in a garage for a month before I can start fiddling with it. Damn life obligations getting in the way.....

Will try to get some more pics going. I havent been this excited to fire up a motor since I was 16 years old and it was a 406" 66 Nova.

Keep us up to date, I got some "tuning" tricks...
I also have the metric drop indicator, or in inches, if you wish, plus the deal that holds it in the plug hole. If you want to use them, they will be available.

Had a bunch of other shit, but long gone I'm afraid. Although I just dug up some head gaskets for the Dragbike last week.... Go figure..

[OreoGaborio]

Then another guy who vowed he'd own that bike one day, tracked it down, and paid more than SEVERAL THOUSAND DOLLARS for it.
It now sits, fully restored, and in running condition, in a nice and cozy home, retired...I almost shit when I saw it.
This guy looked me up through other people that knew me, and asked to meet up with me. I didn't have a clue...
He said he wanted me to look at a bike for him....I was in tears when I saw that bike. It was perfect, and it was 1982 all over again.
And as far as we know, the records still stand today...

Holy shit Mahk, when was this?!?!?!?! That's friggin amazing!

[TLRMan]

Holy shit Mahk, when was this?!?!?!?! That's friggin amazing!

The guy grabbed it about 4 or 5 years ago.
As you can see, it was quite a mess.
I don't have any recent shots of it though. I should look him up...
He restores and builds hotrods, as well as custom tuned pipes for racing outboards too.

[OreoGaborio]

Man, that's awesome. I'd love to see it fully restored. Did he restore it to exactly how you had it w/ the same numbers & everything?

[TLRMan]

Man, that's awesome. I'd love to see it fully restored. Did he restore it to exactly how you had it w/ the same numbers & everything?

Has has my old NMRA racing number plate,#1353 If you walk into his office, he's got about 15 8 x 10's of it, and copies of any articles written about it.
It's the same, except for some clutch parts to make it complete. Airshifter still works, but the PVC air tanks are illegal now.

This has sparked my curiosity again...I'm gonna have to look him up again.

[KB]

HOLY FAK!!! 10 seconds on a 350 two stroke. That is Crazzzzzzzzzzzzzzy

KB

[TLRMan]

HOLY FAK!!! 10 seconds on a 350 two stroke. That is Crazzzzzzzzzzzzzzy

KB

Yeah..I wasn't very sane back then, and I didn't want to take a "no way can you get a 350 into the 11's, never mind the 12's"
I showed them! 10+ grand later.. It was more of a challenge thing..I could have been happy running an 1100 for chris-sakes...Although back then, stock, they were lucky to run in the 11's in the 1/4. The record of 11.84 for my class was set by a 750 4 stroke Triumph triple "Trident". The Modified weight break goes as how much you weigh by how much you displace, so if they made an 1100 heavy enough, they could run in my class. Record for pro mod 750 was a 10.6 ET, and pro stock was into the 9's. Top fuel didn't break 200 mph yet, now there are running 240!

[a13x]

Great stuff!

[TLRMan]

Sorry!
I really hijacked this thread!
Looks like I owe someone some engine tuning....

[Ri_De_bike]

Sorry!
I really hijacked this thread!
Looks like I owe someone some engine tuning....

lol hardly a hijack.
rd parts these days are hard to come by though. maybe porting is out of the question until spares are found. even then getting a stock bike running right before modding probally isn't a bad idea. tune up parts are easy to come by. engine parts; pistons, cranks and rods not so much.

Ancosta i found a manual for the yamaha model up to 200 that covers the year you have, MOST of the info; layout, specs and procedures are the same.
your welcome to it.

2-stroke timing < very clear info on timing

[ancosta]

I agree hardly a threadjack, but I will gladly take any tuning offers once I am ready to go. The bike is closer to TLRMan (Salem) now, but heading closer to Ri_de_bike where I live (RI). Let me know what kind of beer or other offerings to scrounge up....!

One thing I noticed yesterday - the frame has a bend in it which to me looks like it was by design, but not so sure. The pic below shows it. Any ideas?

My plan is to get it running, see how she goes, and if it seems to be a fairly solid bike, then I may tear it down, clean it up a bit, and see what I want to do next.

One thing that seems like it could be a major $$$ sink is the re-chroming of parts....perhaps nickel finish would be cheaper and look decent enough? I'll cross that bridge once I get the motor running first though

Also the guy I bought this from has a Suzuki 750 "Water Buffalo" 3-cyl 2 stroke for sale, similar story of being in the basement of some guy's house for 25 years, etc. He probably wants about 400 for it I am thinking. If interested let me know and I can put you in touch with him.

[joeswamp]

Those old 70's two strokes are a lot of fun, really light and quick. The best part is that you can lay down a smokescreen like a destroyer in a naval blockade.

Back in the 80's I used to tool around on one of these babies before I upgraded to a Honda CB400F:



I almost got a Mach III, those triples were crazy fast and had really flexible frames. I think I read an article that said that Kawasaki's test track at the time was an old airport runway, so they never could test the handling too well. 20 years ago these bikes were everywhere and they were incredibly dirt cheap. I think I bought my A7 for like $50 (although I think I had to spend another $50 to fix it).

Pretty cool that TLRMan is like the Burt Munro of Yamaha two strokes