1972 Yamaha R5:



I picked this little thing up for $1,400 Friday afternoon. A little under 10k on the clock, and in really good shape. This thing is about bone stock except for the bars. Paint is good, the chrome is good, and it starts and runs great. The thing doesn't weigh any more than 300lbs and it isn't fast like the monster, but for what it is it is quick. I think they came about 30hp stock. The original idea was to strip it down to about 250 - 275lbs and mod the engine to bring it more like a tz motor (60hp). But now after getting it and seeing how good of shape it is in I don't think I can really do that...


Okay, I wrote that but didn't post it yesterday. This is todays update:



I took it out for its first real ride today. First thing is the ergo's. I'm built more like an ogre than anything. 6'4" and 240lbs. This thing is small. But honestly I feel comfortable on it. It rides great, pulls well, and handles good for what it is. The front brakes are shot, but the rear does it's job. Low beam is out, and the petcock leaks a little. But the ride is going well...

Until, in a fast (70mph) sweeping left, it looses powers, makes a helluva noise, and dies. I pulled in the clutch as it was loosing power. Which is a good thing. When I stop and try to kick it over I find the motor seized.

I got it home and pulled the plugs. #1 is black, oily. #2 is a nice shade of brown. So I pull the #1 head to find a pile of metal. Not good.
Pull the carb off, loosen the exhaust and look inside the exhaust port. What I see is worse.
Pull the cylinder to find that the piston is broke at the wrist pin. Why is this? Well, the con-rod is seized and has about 1/4" of vertical play in it.



Whoops.

Glad I got the clutch in before it seized. That would of been nasty.
I still think that for what I got it is a good buy. I was gonna replace the piston's anyways pretty soon. Now I just gotta get a few more parts...

Congrats and bummer.

the good news is. you can fix it for hella cheap and hella easy.

Hey, it ran for a while.  I'm sure when you're done that will be a nice bike.

The wonderful thing about the old R5 and RD engines is how easy they are to work on.  The engine is horizontally split so it's super easy to pull it and split the cases to clean out all the piston shards that have fallen into the crank area.  After restoring dozens of vintage two-strokes, I've learned not to scrimp on anything during engine assembly and always opt for new rods & crank main bearings, as well as new top ends.  Seems like no matter how clean the bike appears and no matter how much the previous owner professes to have "gone through it completely", I seldom find it to be the case.  You've got a wonderful collectible there that'll be well worth the time and trouble to do a proper rebuild on.  Have at it, have fun, and enjoy the restoration.  Once done, those bikes are incredibly reliable and a ton of fun.  Keep us posted.

Classic bike man...be good for everyday use.

Quote from: mxwinky on June 15, 2008, 07:57:22 PM
The wonderful thing about the old R5 and RD engines is how easy they are to work on.  The engine is horizontally split so it's super easy to pull it and split the cases to clean out all the piston shards that have fallen into the crank area.  After restoring dozens of vintage two-strokes, I've learned not to scrimp on anything during engine assembly and always opt for new rods & crank main bearings, as well as new top ends.  Seems like no matter how clean the bike appears and no matter how much the previous owner professes to have "gone through it completely", I seldom find it to be the case.  You've got a wonderful collectible there that'll be well worth the time and trouble to do a proper rebuild on.  Have at it, have fun, and enjoy the restoration.  Once done, those bikes are incredibly reliable and a ton of fun.  Keep us posted.

Yeah, once I got the gas tank drained (every always breaks w/ a full tank of gas...) it only took be about 15 - 20 minutes to get the entire cylinder off. At that point it was obvious that I needed to split the cases and it didn't take long at all to get the engine all the way out of the frame. I haven't split the case yet, but I figured sometime this week I'll get that done and come up with my shopping list of parts.

I didn't measure yet but I'm pretty sure this is the standard piston. So I will probably go ahead and get the bore for the 1st oversize on the good side. The cylinder has a little gouge in it from the piston coming apart. I'm hopeing that it isn't so deep that I can just bore it out and fit an oversize in that one. If not I'll just get a new cylinder for that side.

I did find something weird though. The crank has been modified. It has got some sort of metal filler in the hole at the bottom. I'm the third owner of this bike. The 2nd one only had it for two months. So I'm trying to get in contact with the original owner to see if he has done any internal modification on it.

That is one sweet 'vintage' bike.  Have fun working on it   

Nice ride!  I'm in the middle of putting an RD350 back together so I can relate a little. Great little bikes.
Not sure if you've seen these guys yet, but they're worth checking out: http://www.hvccycle.com/
They really know their way around those bikes. Plus it's one of the only places i've found that actually carry replacements for all the dry-rotted little bits on them. Also have some nice performance parts, and since the thing's already opened up.... 

Quote from: Scheffy.G on June 16, 2008, 07:09:54 AM
Nice ride!  I'm in the middle of putting an RD350 back together so I can relate a little. Great little bikes.
Not sure if you've seen these guys yet, but they're worth checking out: http://www.hvccycle.com/
They really know their way around those bikes. Plus it's one of the only places i've found that actually carry replacements for all the dry-rotted little bits on them. Also have some nice performance parts, and since the thing's already opened up.... 

Thanks for the link! Looks like they have pistons -- which is what I was worrying about.

I'm thinking about opening up the ports a little. Thought about evening going as far as the TZ conversion. Not sure yet. Trying not to get too far into destroying this... I move in 3 weeks.

Sweeet ride
The piston thing sucks, but you'll have a lot more confidence in it when you're done [moto]

Pretty slick little ride, here's to getting it running again soon.

Nice ride man, I just picked up an 81 cb750 three weeks ago and found myself a nice carb leak, gas tank leak, petcock leack, as well as what appears to be a head gasket leak.  I'm feelin your pain.

That looks pretty cool.

[TJ]
Did you ever sell that sweet squareback?
[/TJ]

Nice bike! Did the AutoLube quit working? You did have 2 stroke oil in the Autolube tank, didn't you?