1971 R5 350

[CABilly]

My dad has been on a retirement kick fixing up old Japanese bikes from his youth. Today he handed down to me this sick 1971 Yamaha R5 350. It’s pretty much stock except for the front disc brake and I guess the pipes aren’t OG. It just needs a final tune to be 100% and since I’m not skilled enough to get it there I’ll be calling shops this week to try to get it finished. She starts on the first kick and runs great but was acting wonky with maybe a stuck float and a bad petcock on the ride home. I’m looking forward to bombing around on this sweet classic ride.

The only things I feel like doing to it is maybe a lighter front rotor, sprocket, and some (period correct) expansion chamber pipes. I absolutely love the purple and white color scheme so that’s not going anywhere.

Anyway, I’ll use this thread to post the new life and times of this bike. And probably asking for help along the way. I’ve never had a 2 stroke and I’m excited for this new chapter in riding. I gave my ‘96 M900 to my brother and it’s a big change going from that to this. The power comes on much later but it’s fun when it hits. It’s so light I feel like I can make most turns just by weighting the pegs.

I’m open to any tips and suggestions for making it run the best it can while keeping it mostly stock.

 

[Butch]

Nice. I had one of those in college.

 

[bmwbob51]

My first bike was a 1975 R5. Sadly the learning curve was steep and I lost count how many times I crashed it. Now I'm mortal, so rubber side stays down!

 

[Seizer]

With 50 years of race development, the sky’s the limit on the venerable Yamaha 2T twin. Basically everything is upgradeable but sometimes they’re best when left stock. You’ve got a sweet bike there as it sits imo. They’re fairly simple machines to work on and not difficult to tune if you go slowly and methodically. What are your plans for the bike?

 

[CABilly]

With 50 years of race development, the sky’s the limit on the venerable Yamaha 2T twin. Basically everything is upgradeable but sometimes they’re best when left stock. You’ve got a sweet bike there as it sits imo. They’re fairly simple machines to work on and not difficult to tune if you go slowly and methodically. What are your plans for the bike?

My only plans are to ride it and keep it in good shape. I’d like to reduce rotational mass where I can and maybe add some expansion pipes for some more oomf and a more aggressive 2-stroke sound. That’s about it I don’t want to make it too radical.

 

[bmwbob51]

My only plans are to ride it and keep it in good shape. I’d like to reduce rotational mass where I can and maybe add some expansion pipes for some more oomf and a more aggressive 2-stroke sound. That’s about it I don’t want to make it too radical.

I'd keep it stock and ride it Sundays. It's a wayback machine to many

 

[1962siia]

SCORE! Congrats!! Bike looks awesome!

 

[Lonster]

Good electronic ignition (Penton) is about $800, but worth every penny.
Get some expansion chambers.
Ride it whenever you can.

 

[Seizer]

As with anything, modifying one thing usually leads to the need to modify something else. If it were me, I’d put a Dyna-S ignition in it (they’re like 300 bucks and basically replace the points), a 520 chain swap, and ride it. Of course some RD350 cylinders, chambers and an RD gear set (6 speed and direct swap) would be fun too haha.

 

[CABilly]

Well today was fun. The bike and I are now bonded. The petcock issue I thought we had was the result of a mixup of my dad having a side yard full of Nortons, Kawasakis, Hondas, Yamahas, Triumphs and so forth. He had it backward so i ran the carbs dry thinking I was on reserve and it’s caused some issues. I fired it up today and noticed it seemed like only one cylinder was firing. I hovered a hand over one header to feel for warmth and when I moved to feel the other I lost my balance and wound up grabbing a handful of hot header.

I rode it to the gas station and by the time I got home both were firing but later when I started it back up it was back to one cylinder at idle. Maybe I’ll replace the spark plugs? Would it be bad to replace the plugs and just take it on a long country road and open her up?

I’ve got some good blisters to take care of but at least she still starts on one kick and rides well. And it gave me an excuse to hold a cold beer the rest of the day!

Also, my dad told me the bike had a six speed but he sold it and swapped it for a 5 speed. Same final gear but...banging gears is fun. Maybe I’ll look for a six speed in the future.

 

[Seizer]

If it were me...
Verify timing is set correctly. If it’s off, you can hole a piston pretty quickly. Ask me how I know ha.
Make sure the points are within spec.
Do a leak down test. This checks the integrity of the crank seals. R5 seals don’t require you to pull the crank to change them like an RD.
New plugs and pull them and check after a short time. They should be a light mocha color. Dark brown=too rich. White/gray=too lean.
Check your jet sizes. Modern fuels (ethanol) require different jetting than the original specs.
Make sure your oil pump is functioning correctly.
Check air filter.
Once you get it sorted out, it’s just minor maintenance.
Fun bikes and they turn a lot of heads these days.

 

[bobl]

And, carry a set of spark plugs in your tool kit. An occasional fouled plug is a fact of life with a point controlled 2 stroke. Riding along and suddenly finding yourself on a 175 single is not all that uncommon. Plugs changes take only a couple of minutes along the side of the road. Sure wish my 4 strokes were that easy to access. :laughing