1972 Yamaha DS7


Dolor est Magister Optimus
Ok, I'm copy/pasting from another forum so if this seems choppy or skips around some... that's why. The "Start Date" on this project was roughly 2/21/09.



I was given the bike about 5 years ago in almost exactly the same condition you see it in the above pic. Lack of time, money, etc. kept it stored under my carport until recently. I know it was sitting up before I got it, but not sure exactly how long. I would guess that it was quite a while also. A few months ago I started doing some cleaning on her, and tinkering around trying to get some spark. That lead to more tinkering and trying to test/check the electrical/ignition system. I HATE electrical gremlins, and have no practical knowledge of how to operate a volt/ohm meter. This lead me to a techday at a buddies house. I figured somebody there could help me diagnose the problem. Well, we did more than that... we got her running!

More tinkering...


We were able to narrow down a couple of issues...
The ignition switch is toast, the clutch is locked up, the carb floats seem to be stuck, and the voltage regulator and rectifier will probably need to be replaced.
But the good news is, she's got great compression, no unusual or alarming sounds from the motor or gearbox, and the wiring harness is in surprisingly good shape.

Getting the old girl running was more than half the battle... now the fun stuff starts :)

Well after getting her running at the Techday, this was todays tinker...

I'm waiting on a battery to charge, so no electrical work this time. I wanted to do something though, so I got the new tank fitted, and installed the clubman bars (thanks Juice:)).



I need to get the tank over to the Locksmith to have a key made for it, and I need to locate the correct fuel petcock. After that, it'll start getting prepped for paint.
I think both the tank and the bars completely transformed the look of the bike :D

Well, jumping the brown and blue wires gave me power at the coil and lights! Headlight works too! On/off switch and high/low beam. Taillight powers up, but no brake lights from either switch... need to do some more tracing :)
I need to get it warmed up enough to idle again to test the alternator for proper output. I may have to hook it up to the Stepside for that since the old battery I had lying around doesn't seem to want to hold much of a charge. I kinda expected as much, it's been sitting for almost a year.
Here's a few fresh pics...


No, I wasn't making vroom vroom noises...

...everyone knows 2strokes go Wingdingdingdingding LOL:D:D:D

1) She has brake lights... It seems that they were operational the whole time, but the rear is misadjusted and the front isn't hooked to the lever (it's a weird setup).
2) Amazingly, the corroded/rusted mess of a regulator/rectifier actually WORKS! I got her running and hit the output wire with the testlight and got power. I verified proper operation by plugging it back into the harness and unhooking the jumper cables/battery... and she stayed running.
3) I also determined that it has no choke (I thought it was odd there was only a lever on one carb). It's actually a "prime" lever, and it works too.

The "bad" news is, I still don't have turn signals or a horn. I suspect the bar controls but still need to trace/jump some wires to narrow it down.


Bad News: Still no turnsignals. I found a wire terminal broken off the switch. I tried to solder it back on, but no luck. It's going to need to be replaced.

Good News: Horn works... sorta. The circuit works, but the horn itself is frozen. A new horn is in order.

Better News: I got the key made for the fuel tank. It only took $10 and ten minutes.
Now I can get it cleaned up and ready for painting.

"MacGyver is my Bitch" News: I got the ignition switch working!!
I pulled the headlight bucket off to get better access to the wiring (it had to come off to get painted anyway). While I still had wrenches in hand, I decided to remove the broken switch to get it out of the way. Well after getting the switch off I noticed there were two screws in the bottom holding the assembly together. I felt adventurous, so I took them out... the whole switch seperated. After surveying the circuits contact points, I determined that the "hot" going into the switch was corroded to the point of almost nonexistance. Which is why power was going in, but not out. Sooo, I planted a piece of solder on the top of what was left of the contact and filed it down to the height of the others.

After cleaning up the rest of the contacts I reassembled the switch and tried it out. It worked... but not well. It would flicker, and you had to play with the key to find the sweet spot. So I took it apart again. I then determined that it was missing a spring that holds pressure on the sliding contact. Sooo, one sacrificed "clicky-top" ink pen later, and that problem was solved.

After re-reassembling the switch... the darn thing works like a charm!

Now don't get me wrong, I don't plan to put full faith in this "fix". I'm still trying to locate a "correct" ignition switch (or I'll just "adapt" one and mount it on the frame or something) for permanent usage. But atleast now I don't have to keep moving a jumper wire around when I want different circuits to work :D


I cleaned up the eBay motor in anticipation of putting it in the bike soon. The plan is to run this engine while I tear down and rebuild the original engine.
This was what I bought...

This was after some clearcoat stripper and a pressure wash...

And this is after a few hours of painting and sanding/polishing accents...


(the gold painted heads are kind of an "homage" to the DG Performance heads)

After that I jumped on the electronics again.
I found a NOS switchgear on eBay for $20. It's originally for a '74-'76 Yamaha DT125, but it has all the correct functions. The only difference is it's black instead of silver. It wasn't hard to wire up either. Most of the color coding was the same, and the others weren't hard to figure out. So now I have fully functioning switchgear! But that uncovered two more issues...
1) The flasher relay isn't working. It's stuck open, so the signal lights will come on, but not flash. I'm going to order a digital relay since I plan on putting LED turnsignals in it anyway.
2) There's a problem with the turnsignal indicator in the gauge. It's apparently backfeeding the circuit because when either side of the TS switch is used, both sides light up. I started a "process of elimination" and narrowed it to the indicator light. After unplugging it from the circuit, each side lights like it's supposed to. I'll have to pull the light from the gauge and see what the problem is.

That's about it for now. The tires are on the way, and should be here early next week. Once they're in I'm going to pull the wheels and get them prepped/painted, and go through the brakes and bearings.


Allrighty! When I ordered the tires I was a little nervous because it calls for a 90/90 on the front, and I had to go with a 100/90. Mainly because none of the manufacturers made tires that were priced reasonably AND in the sizes I wanted. I took a bunch of measurements and decided to chance the 100 on the front.
Well, the tire clears the forks with no problem... but won't fit in the fender. Eh, oh well. I was on the fence about keeping the front fender on anyway, this just made the decision for me.
After getting the front wheel off I noticed another problem right away.
The friction material is supposed to stay on the shoes... right?

I tried using superglue, but that didn't last long.
(of course I'm kidding :D)
I used up some elbow grease and did some light sanding and polishing (Mothers Powerball to the rescue!) on the hubs, and I painted the spokes and outer hub area.




I also mounted both new tires... by hand. (boy was that a PITA! I wish I knew somebody with a tire machine:)) I did the sanding on the rear hubs, but haven't hit them with the polish yet. I also need to paint the rear spokes/hub. That's where I'll start tomorrow.

Side note: All the bearings/bushings in both wheels and brake assemblies are in perfect shape. No slack and smooth as glass. I just need to get the brake shoes to reassemble everything.


Well I accomplished my goal for the week... I took her down the street!
This is me leaving...

And this is me coming back...

lol :D
I put the wheels back on, hooked her up to the truck battery, and got her warmed up.
Once warmed up I topped off the float bowls, and with no front brakes, sketchy rear brakes, and a frozen clutch pack... I got a good rolling start down the driveway... hit the street and kicked it into 1st gear... and it chugged and died. *crap*
I pushed it back up the driveway and jumped her off the truck again. Second attempt... pretty much same result... BUT, the clutch let go!! Woohoo!!
Back up the driveway for another jump. Now that I have clutch control, I'm thinking I could give her some gas and ease the clutch out. Let's try that! Third attempt... GOLDEN!
She bucked a little bit, but rolled on out through 1st gear. Clicked her up into 2nd gear... she didn't like that too much (carbs are still kinda wonky), and I heard that little voice say "no brakes dumbass". So back into 1st she went. I made it to the end of the block... made the turn around... and tried easing the throttle back open while feathering out the clutch... and she stalled... oh well... start pushing home.
I was hoping to get a little more out of her, but hey, she has been sitting dormant for quite a while... baby steps... baby steps :D
Here she is resting from her little trip.

Next time we go all the way around the block... right girl ;)


Well the goal was, I wanted her to go down the street under her own power.
She's done that... TWICE!

The new goal is: I want her to COME BACK under her own power!!!

I bought the new battery today, and she'll start AND idle by the second kick
I filled the float bowls again and took her down the street. I got to the corner, made the turn around, and pluhhh... she died. But having the fresh battery helped me determine that she's running out of fuel by the time I get that far.
So I installed the petcock in the tank, and put the tank on the bike, and found out that the rear mount for the tank has to be changed.
It sits low in the rear and that puts the petcock resting on the engine. Not good.
Well, looks like I need to fab up a rear mount this weekend.


New brake shoes are installed. Fuel tank has been mocked up for bracket fabrication. The mock up has the tank temporarily mounted, so I put enough premix in it to make another test run... she made it down the block... AND BACK!!!
She's still running real wonky. She doesn't want to rev up from the lower RPM's, but once in the the upper RPM range, she seems to rev fine.
I need to get a fresh set of sparkplugs, and I need to pull the baffles out of the exhaust to see if it's clogged up.

Here's a few pics...
Fresh Fronts.

Fresh Rears.

And check this out... no need to remove the entire wheel assembly to change brakes!

Actually, you can then remove the wheel, and the sprocket assembly stays attached to the swingarm... with no need to re-adjust the chain.


While I'm waiting on parts, I decided to fabricate/install my LED mod to the taillight. Here's what I did...
I took a 4' round LED light originally for a trailer. These are the same LED lights you'll see on the back of tractor/trailers. The one I got was a low profile design, which required much less 'trimming' to get it into the stock housing. I then went about removing everything I didn't need... like the cover lens, and just enough perimeter material for it to slide all the way into the stock taillight lens. (I used my bech grinder for this) I also needed to clearance the fixture in three places for the screw channels. (I used my bench grinder for this also. A rat tail file makes a cleaner look, but I couldn't find mine)
Afterwards you end up with something like this...


Now as you can see in the pics... what I did for the pigtail connection, was I took an old 1157 bulb and broke the glass off of it. I then soldered wires to the filament leads, and shrink tubed and taped the connections. This allows the LED fixture to be attached just like an 1157 bulb, and can be removed just as easily.
This is the end result. It's 10 LED's, 9 around the perimeter and 1 in the center. It's all contained inside the stock taillight housing, and can be converted back to stock in about sixty seconds.
Running light...

Brake light...

MUCH brighter than the stock 1157 bulb :D


New seat is in :D

I'm still waiting on fuel tank mounts. I need the mounts to properly locate and attach the tank, and I can't mount the seat until the tank is mounted. But... this weekend I'll be removing the rear fender and starting to mock-up a new taillight mount and inner fender panel.

EDIT: I forgot to mention... last Sunday we loaded the DS7 and the pocketbike into the truck and brought them over the Zephyr Stadium parking lot. The boys ran around on the pocketbike while I did "reliability trials" on the DS7. I unloaded her and tooled around for for a full TWO MINUTES... and she died.

It would appear she likes to run with the fuel petcock in the ON position Doh

Once she was getting fuel she ran around for well over 30 minutes with no trouble at all. I was even doing low speed circles and dragging the pegs. She handles fairly well, even with the shitty forks:D
Check out the skinny "chicken strips"...:D


Fuel tank is mounted! Drug the bike over to a friends racecar shop and fabbed up some brackets. Basically, it's a piece of flat stock made to look pretty, drilled and tapped, and welded to the frame.


I also got the R6 rearsets mounted up. Fabbed up a couple of tabs, welded them to the frame and voila'...


I still have to dress the welds and hit them with some paint. Now I need to get the linkages worked out so they'll operate properly;)

Next Wednesday I'll be back over at the racecar shop to fab some more brackets to mount the new Cafe Seat:D


Yesterday I rebuilt the "new" forks and installed them. I had no idea how 'sticky' the old ones were. But the new ones ride smoooooth
I also installed new Uni pod filters, a working tach cable, and changed th oil.
No pics, because there really wasn't much to see. But Wednesday I'll be back over at the racecar shop to fabricate the mounts for the cafe seat. Pics will follow


Cafe seat is mounted. Made a couple of "bridges" across the frame, drilled and tapped, added some rubber bushings, and presto!


She's getting close ;)




The Good News is... All my linkages that I just fabbed up worked like a charm. (I'll post pics of them shortly) Nothing loosened up or fell off the bike at any time while I was on course. And she actually handles pretty good for an old girl.

As promised, here's the pics of my adapted rearsets. The rearsets are from an '05 R6. (many thanks to Docadams and Pablo) I fabbed up some tabs and had them welded to the frame. I then used spherical rod ends and some allthread to make the linkages.




I took it back over to the racecar shop today to add another bracket to the frame. I had previously removed the (broken) stock friction plate style steering damper in anticipation of installing something newer. I picked up a GSXR damper from Jeepers on RM. After doing a little test fitting, I realized two things... a) the existing bolt hole from the old damper is the same size as the new damper (no need to fab a bracket for that side) and b) the "ugly" side of the damper was going to be facing out. So I dropped it off with Rusty Jr. who took it apart and "flipped" the slider rod. After a quick session with a cutoff wheel, drill, and bench grinder, I had the only bracket needed for the install. A few zaps with the welder later and...

(a better looking bolt and some touch-up paint came later)


Played a little with the headlight bucket today. After a quick trip to Radio Shack to try and find a new "Highbeam Indicator" light, I also picked up two LED lights in amber. Since I haven't been able to dtermine why exactly the common turn signal indicator is backfeeding, I had the idea to add signal indicators into the headlight bucket next to the Highbeam indicator.
This is what I ended up with...

I also fabbed up a taillight bracket. This started out as a 1/4" thick, 6" wide aluminum L-bracket. After several hours of measuring, test fitting, drilling, dremeling, hacking it up with a Porta-ban, grinding, some mild bending, and a little paint.
This is what I ended up with...

This is the bracket and taillight mounted...
(disregard the rough cut on the seat. it's not done yet)


Tins are straightened (and painted)!

Oooooooo, Aaaaaaaahhhh...




All of the body panels are going to Ben next week for the Wrap.

I also did a bunch of wire re-routing and securing. Harness looks alot "cleaner" now. New LED flasher relay is in and working properly... awaiting turnsignals. "Engineered" the foot brakelight switch (adapted '05 R6 - '72 DS7), so now the brakelight works properly.
As of right now... the bodywork is going tomorrow to be Wrapped. The rest of the bike just needs alot of touch ups here and there, and a few minor adjustments. After the bodywork comes back, it'll get reassembled, and then a week or two later, it'll be registered/insured and ready for the road.


While I'm waiting on the wrap, I've been doing some cleaning/painting/polishing/etc.
This was Wednesdays project...

(not really a fair pic though. I did a bunch of cleaning on a few months ago. Check out the first pic in this thread to see what the shocks originally looked like.)


This was todays project...
I got the triples painted, the handlebar risers cleaned up, the gauge buckets polished, replaced some rusty nuts/bolts, and cleaned up others.

I got the levers and perches polished up, and cleaned up the broken ends on the levers (ground the ends round, smoothed them out with progressively finer sandpaper, and rubbed the whole essemblies with #0000 steel wool). I also worked some more on the steering damper. It's starting to get some shine to it :)

I should have the bodywork back early next week, so reassmbled pics should follow soon ;)


And here she is. All cleaned and primped... waiting on her new "Sunday Best" outfit.



I'll be picking up the bodywork tomorrow...

not sure I'll be able to sleep tonight ;D


Ok, here she is with her new clothes...






In case you couldn't tell, she's wrapped in Carbon Fiber! The idea behind it was a Old School meets High Tech look. It really came out nice. I got the bodywork back yesterday evening and did a rush reassemble for the bike event we had planned for today. I didn't get to ride her in the event because she's not registered/insured yet. But she did see alot of attention :mrgreen:
Here's a few shots of her from today...




I knew there was more than one reason to have Clubman bars...
(I see FOUR good reasons in these two pics alone!)


Well I hope the "surprise" was worth the wait.


Here's a couple of fresh pics from yesterday evening.
I got the "YAMAHA" and "250" decals yesterday and put them on. They're cut from the same "Stainless Steel" vinyl as the tank stripe. I also have "Stainless" tuning forks for the engine cases. Will try to get those on today.



And a gratuitus shot of the girls...
(I just hope the DS7 is getting speed secrets and the 'busa is not getting smoking tips :mrgreen:)


Here's a better pic of the Carbon Fiber pattern...

Update (thanks to Warmseth)





I scuffed them and applied the High Heat Satin Black finish, but I think I'm going to take them down again and paint them something a little lighter. I think they blend in too much as is.


Headlight Upgrade...
I finally upgraded the headlight to the one Florida Steve recommended from Parts-N-More. Very nice piece of equipment. The fit and finish is excellent, and basically bolted right up. It's a little bit deeper than the stocker, so it's a little snug on the backside. But nothing serious. The only mod necesary was drilling a hole in the shell to fit the Highbeam Indicator. I was also able to source the correct 35/35 H4 bulb from a local scooter shop for $10.


Legality Upgrade...
I finally got the License Plate mounted. I'll pick up a frame and some better looking bolts soon. But otherwise, this is it.


I still have to add turnsignals, but since I haven't decided exactly what I want to do on that subject... and they won't significantly change the appearance... I'm going to call the bike Done!
(well, as much as any bike can be called "done" ;D)


Threat Level: giggles and sunshine
Re: My 1972 Yamaha DS7 Cafe Racer

wow, she's gorgeous!!


Dolor est Magister Optimus
Re: My 1972 Yamaha DS7 Cafe Racer

Thanks, that's very nice of you to say :)

Here's some glamour shots taken by some friends...




And some taken by me...







Over 1,000 Posts
Re: My 1972 Yamaha DS7 Cafe Racer

Love it dude! It's great to be able to finally look at how she came together. Well done sir.


Dolor est Magister Optimus
Re: My 1972 Yamaha DS7 Cafe Racer

Thanks for the compliments guys.

The seat was an eBay find, but I sectioned out the rear of it to fit how/where I wanted the taillight to go.


Threat Level: giggles and sunshine
Re: My 1972 Yamaha DS7 Cafe Racer

i have to admit though.. i loved the black and orange


Coast to Coast
Re: My 1972 Yamaha DS7 Cafe Racer

Man i definately love the old yamaha 2 strokes. I am so gonna have to pick one up some day. That bike is all kinds of good lookin.


Dolor est Magister Optimus
Re: My 1972 Yamaha DS7 Cafe Racer

I'm gonna revive the dead thread ;)
I rode the the ol' girl for about 4 worry free years, with only a few upgrades/mods since this was last updated.
Sadly, about two years ago, she decided to give up 1st gear. Even more sadly, this was right about when I was finishing up the CB750, so she's been sitting ever since. She's been pouting, weeping, and giving me the stink eye the whole time. Finally though, she's gonna see some love again here soon :)
I picked up an R5C motor from Brad a while back (even before she crapped the trans) with the intention of swapping out the 250.

It's a very low mileage motor, but it sat up for a while. New seals were in order, and that got done last week.


Also cleaned/rebuilt the carbs.

And did some polishing on the cover accents.




I know, I accidently went a little savage on the "Yamaha" lettering. But I plan to address that issue later with something pretty cool ;)

I'm currently waiting on a bolt kit. partly to dress it up some, but mostly because it's missing a few.
I'm hoping to get the bullet installed this weekend. Stay tuned for more updates ;)


Dolor est Magister Optimus
Bolt kit came in...

Nice kit. Universal for the RD250/350/400. All individually packaged and labeled. I had to stop by Fastenal for a few of the ones I needed that are specific to the DS7/R5's.
All buttoned up and ready for the swap...


Active Member
Great thread and great work. I'm going to follow this one. You'll like the added power of that 350 motor.


New Member
I am thrilled to read your post...I have the exact bike in probably the exact same condition as yours was in when I got it. I am also getting ready to dig into her. Mine has a nice dent the tank and front fender (which need replacing) but the rest is quite stock..which is kind of the way I may keep her.

I am having trouble finding carb rebuild kits, pistons, seals, etc. and stock bits. Keep up the thread!



Over 1,000 Posts
Lovely, like a proper old school production racer.
When the cafe seat was in white it looked way out of proportion but colour matched it looks just right.


Dolor est Magister Optimus
Shoeman said:
...You'll like the added power of that 350 motor.
Thanks :)
Yea, the R5 swap will bump the HP about 50%, and the Torque about 30% over the DS7.
Should be interesting :p

Spondon83 said:
...I am having trouble finding carb rebuild kits, pistons, seals, etc. and stock bits.
Thanks :)
Check with both Economy Cycle and HVC Cycle. They specialize in repro and aftermarket parts for the 2smokers.
And if you have any questions, just holler ;)

Erskine and Joostan, Thanks for the kudos as well ;)


static fluff
I had that same bolt kit for my bike and I now have a heli coil in one of the side cover bolts and need to add another. I used never seize and went easy on it but that 43 year old metal isn't fond of stainless steel. Just be careful with them.

Sent from my SAMSUNG-SM-G920A using DO THE TON mobile app

DTT Bike Of The Month Gallery

DTT Light or Dark

Top Bottom