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.