So from the beginning of building this bike I knew I wanted a bike that handled like a brand new sport bike. Rd’s wernt know for their stellar rear suspension when new and the 40 years of sitting in upstate NY made these ones good paperweights. I had looked into a few different options like Progressive and Koni and was not siked on spending the $400+ on them.
My wife had been out of town for work a few weeks and I spent lot of nights laying in bed thinking of options. What better way to get modern sport bike handling than with sport bike parts. Did a bunch of research on spring rates using the Racetech.com site and settled on a 07 Honda CBR1000rr showa unit. Its a nice unit with adjustable dampening and rebound and spring preload, plus a healthy aftermarket of parts as well. The spring rate is 11.5kg per mm and with the rd’s feather weight and my 195 lb self this puts me a bit stiffer than stock with tons of adjustments. A quick search of ebay yielded one from a low mileage bike for $25 with free shipping. I find its better to let the big bike mfg’s spend millions on R&D for their new machines and I’ll reap the benefits for my old junk.
New jawn off a 07 CBR1000rr
The next problem was how to make a shock with only 1.75 inches travel work in an application that needs about 5″ total with sag and not use all the fancy linkages that honda uses on there bikes. After much thought my solution was to make second arm attached to the swingarm but shorter to reduce the radius. After a lot of math I hadn’t used in years on paper I settled on needing a 5.5 inch radius from the swingarm pivot to give the proper travel when the 15″ arm moves. I decided to draw it to scale on the welding table to check the math. It worked in practice too.
Drawn out to SCALE
Now was the easy part of tabbing up the mounts. The rear is made out of 1.5″ square stock and the front that I forgot to take pics of is a 660 bronze bush I made on the lathe pressed into some round steel stock with a shoulder on it for the shock mount to ride on.
The start of the rear mount
Tacked in place
I also bent some round stock to act as a gusset for the rear mount and brace the swingarm. This should help with the torsional stiffness af the old arm as well.
Ready for finish welding
Really cleans up the lines without the rear shocks on there
So final verdict is that it feels like a new bike when you sit on it, It only cost $25 and the rest of the stuff I had at the shop or could be had for short money and the fab work wasn’t crazy. Ill take it. Thanks Honda
A few days ago my pistons and cylinders came back from the machine shop. Here is how they went together. The only company making true rd350 pistons now is wiesco big $$. Banshee pistons on the other hand are a dime a dozen and are available in a wider range of oversizes. With a small mod you can use the more plentiful banshee piston in the rd motor. Most places are charging $12-25 to modify this piston for your air cooled. Here were going to do it with no more than a few sharp jewelers files and some patience. There is a small tang under the piston ports you must remove. In the banshee intake there is a bridge in the center to allows this tang to ride. The rd has an open area here and the tang will catch on the bottom of the intake runner, break off and cause all sorts of damage to the top end. I started by marking with a sharp pencil where I wanted to file off to. I CAREFULLY filed down to this mark just making contact with the scalloped areas to ensure it was flat. When you have it smooth all the way across, use a fine file to bevel the edge as not to catch on anything. As a side note I held this in my hand to do this NOT in a vise. It probably took me longer to write this post than modify both pistons. Make sure to thoroughly wash the pistons with hot soapy water to remove any contamination.
This is how the pistons come stock, notice the small tang on the bottom of the piston under the intake ports
Now with the tang removed
Now to install the rings, there are 2 pins in the ring lands to capture the rings and keep them from rotating into the ports. Look at the rings, notice that the end gaps have a section to correspond with the pins in the pistons. Install them this way. I should also mention you should check the end gaps by installing the rings only in the cylinders and checking the gaps according to the specs listed in your shop manual.
Notice the small pin in the ring land, this is to keep the rings from turning and catching the ports in the cylinders
Since I was working alone this night I decided to try something to install the jugs more easily. It can often be hard to hold the jug and try to compress the rings and assemble it all even with a helper. I know some of you know what I’m talking about. This time I put the pistons in the jugs while they rested on the bench. This allowed me to only have to push the wrist pin in while suspending the jug with one hand, worked pretty well I thought.
Piston in just past the rings.
Paper towel to keep the circlip from falling into the case when I drop it
All together and at TDC
Later that night I put the heads on and did some measuring of the squish band, and started on some major rear suspension upgrades. Come back later in the week for more on that, promise you’ll be impressed.
Went down to the shop on christmas day eve for some motor building fun. I have been collecting the parts and I needed over the last few weeks. Here it is to enjoy
Cases back and bare from getting the "treatment"
Trans in and endplays checked and set
Bearings on crank and seals installed
All together now
For a long time now Ive been wanting a Yamaha RD350-400 but just couldn’t justify the cost of buying one with all my there current projects. I bought a fancy app for my phone that searches craigslist for you under the search criteria you want. It cost the same as a good cup of coffee, best 2.99 I HAVE EVER SPENT! At work this past week this modern marvel of technology lets me know that there a pair of rd’s for sale in upstate NY for $100 with title. Called guy and he gave me the story, been sitting since 81′ was the fastest bike he has ever ridden etc. After getting off the phone I felt an immeadate call outta work sickness coming on. Me and Cleo Dog took the 10 hour ride there and back through the fall leaves and countryside.Lately Ive been rather disapointed in the amount of time I’ve been getting at the shop. This project will be done at my house only like old times. Get to put a few hours in after the kids go to bed.
So Simple and well designed, no wonder the brit's went out of business
This will be kind of a super bike build. Lots of fiberglass, the bike stock weighs in at 351 lbs dry, pretty light to begin with. Im going to try to shave at about 50 lbs off it. I split cases and crank the other night, The build sheet will include new bearings throughout, rods, pistons, banshee reed cages, yz125 reeds, boost bottle, updated brakes and shocks, and aluminum rims. Stay tuned.
An excerpt from a story about our Spring Opener trip in 2010 . . .
We met some new folks in Knoxville after suffering a mid-trip slump earlier in the day. Complete with a little bitching and tension from having spent the last so many days with five guys on the road. At a rest stop at dusk about 100mi from Knoxville, Vinny and I decided “Let’s ride as fast as we can right into the middle of the busiest place we can find in Knoxville, park right on the sidewalk, walk in like we own the place and talk to EVERYBODY we meet and buy them beer!”
Rather than entertain any further discussion, we were flying along at 90mph in the starry dusk with unseasonably warm winds ruffling our sweatshirts. We were there in no time and the plan was an irrefutable success.
Three people we met: Nathan, a young vet who now builds sick canyon bikes and rides it like he means it. His friend John, a musician and fellow rider, albeit of the gentler variety. Tony, plain fucking insane and builder of the Banshee-powered RD below. Fastest bike I’ve ever seen, and I’ve been around the block a few times.
Full story here: Spring Opener 2010