Followup: Edson's R5

Following up on the A Question of Time post from a few weeks back, here are some images of Edson's R5. Enjoy!

Reader Electrical Gremlins

Mike writes in with an electrical question:

I recently purchased a not-quite-running Yamaha R5B, and first off I'd like to thank you for compounding all the information you have! your site has been a major help while I'm working on the bike, and for just learning all I can about it since it is my first motorcycle. I have two questions for you, the first is that the bike didn't come with front turn signals installed, but luckily I was able to get ahold of the correct pair from my uncle. Unfortunately my wiring knowledge is limited to replacing wires where the old ones were, but with your site's help I was able to hook up the brown and green wire clusters to their respective bulbs, but I am not sure where/how to ground them. Both have the eye terminal wires coming off of the bolts on the signals, but I am unsure of where exactly to plug them into. The second is that the bike has a short somewhere and keeps blowing the main fuse off the positive battery terminal. All lights/signals/horn work as they should it seems (except the ones I haven't grounded/hooked up). The bike starts, will run for a minute or so before either dying of a spent battery or the main fuse going. I started checking for continuity, and sure enough there was continuity between the positive and negative battery hook-ups with the key on, started following it back and it lead me to the red wire entering the rectifier. I'm not sure where to go/what to do from there, or even if there is supposed to be continuity through there! Do you have any insight/ideas for tracing the fault? Thanks again for the site, and any thoughts you may have!

Any feedback or suggestions greatly appreciated.

Gearing Questions

Geoff writes in with a few questions on gearing:

I recently purchased my first 1972 Yamaha R5C from a coworker for $100!! (The bike has 11,000 miles on it) When searching for restoration info I came across your amazing site. I am anxious to start riding this beauty ASAP and was looking for a little advice. I am finding that most people start with handling and engine issues. The engine appears to be running well, but I feel I need to replace a few key components (sprockets, chain, brake shoes, etc.) I am having trouble finding concise info on how to gear the bike. Do you have any suggestions on what size front and rear sprockets to use and what type of chain? This is my first street 2 stroke and I will be using it mostly for occasional pleasure riding. Any help or referrals to info would be greatly appreciated!

Neil writes in

Neil wrote in to share:

Just picked up my R5 yesterday. 4418 miles. Shined her up today & took a short test drive. All good. Might change the handle bars in the near future. Your site has a wealth of info... Thanks. Neil

R5 Rat Bike

Check out this thread about a sweet hardtail R5 rat bike project.

Insane custom R5 chop

Came across this insanely beautiful and meticulously hand-crafted R5 chop on Motorhugger. Interestingly, there's a small inset pic of my very own R5 in the writeup as an example of what "regular" R5s look like. Thanks! I'm grateful to have my bike shown alongside work like this!

A Question of Time

Edson writes in with a question:

Hello Lawrence,

First, thank you for putting together this website. It is very helpful.

I recently (yesterday) bought a R5 350 with a small history - the father used it in college back in the 70's then gave it to his son when he was 10, the bike was stored for 35 years, the son took it to college, a bunch of friends told him they "knew" how to work on bikes and put the whole thing apart and were never able to bring it back to life. Now, the son is finishing college in 2 weeks and needed to get rid of it (in boxes) The bike is in outstanding condition with 3100 miles on it BUT completely apart. I plan on restoring it S-L-O-W-L-Y. I know the engine 'turned' but did not run.

My question to you is, how much do you think (estimate) to have the engine done over? And how long do you think it will take to assemble this bike? I could not pass it on since I always wanted this bike since back home.

I appreciate your advice.

Cheers,
Edson

Edson - I bought my bike off eBay, with no prior knowledge of two-strokes (or motorcycles in general for that matter). I took it to a licensed H-D mechanic, who had recently hired a Japanese bike specialist. It took about $500 worth of sorting, cleaning and replacement of worn parts to get her going again. This price did include things like lightbulbs, tires, etc, so depending on the state of the engine assembly, this figure could be less.

Hope that helps. Keep us posted on your progress!

Racer Change of Ownership

Ricky writes in with an update to the Slick R5 Racer post a few weeks back:

Hello, I bought this bike from Michel who posted pics on your site. I have changed it up a little and had my first two races on it. Headed to California to race it at Willow Springs AHRMA April 22-24. Cheers Ricky

Reader Mail and Questions

Mike wrote in yesterday with some nice things to say about the site, as well as an interesting question:

How are ya? I'm a new R5 owner (as of Saturday) and found the site in my research travels! Very cool stuff. I've wanted an RD forever and lucked into an R5 basket case for $40, so I couldn't say no. I currently have several 70s era Honda projects, including a 1968 CL175 sloper (only year made) cafe racer project and a 1972 CB350 custom hardtail chopper. Anyhow, you don't want to hear about the old Hondas cluttering up my garage!

I'm actually writing because I found an article online awhile back that had some interesting modifications that racers used in the 70s on their R5s. One of which was a swingarm swap from a Yamaha enduro (I believe) of the same era that extended the wheelbase by 1.25" thereby helping to keep the front end down under hard acceleration. I am building vintage race replica for the street with my R5, plan on some basic power upgrades, and would love to do this swinger swap. I cannot for the life of me find the site again though.

That said, would you know what bike the swinger needs to come from? The DT360s of the era look similar, but I cant seem to find anyone that will take proper measurements for me. I could always lengthen the stock piece (as I've done before for bobber and racer projects) but would prefer not to.

Thanks for your time, and I look forward to seeing more of the R5 site!

Thanks for the kind words Mike, and congratulations on the find! $40 sure is a deal!

There's of a lot of interchangeability between the R5 and the early RDs, and had heard of brake and transmission swaps most commonly. Makes sense that you could swap in a longer swingarm from within the Yamaha family and have things line up pretty well.

It also makes sense that a longer swingarm would help keep the R5 from pointing it's nose to the sky so much. I couldn't find much on swapping with an Enduro, but I did find mentions on a swap with an RD400 (assuming a 1973 model year or close). As with any swap of this nature, I'm not sure how it might mess with the suspension geometry...

I also noticed in my research that Spec II offers a racing swingarm with an adjustment for stock axle position or 1.5" rearward. Check with them to see which application would fit, as well as what other adjustments might be necessary in terms of suspension setup. Might be worth looking into, especially if you're looking to go for more of a racer look.

Does anyone know of any particular enduro swingarm swaps? Anyone willing to forward some measurements?

Thanks again Mike, and congratulations. Send pics of your progress and I'll be sure to post them here.

Triple Engine R5 Drag Racer

I've seen this insane bike posted all around the internet. Unfortunately there's little information to go with it, other than it was photographed during "Suzukijoe's visit to Willow Springs"...









Found these images via 2 Stroke Biker Blog. Anyone have any more information on it?