Advice Needed. My RC26 is Scary Around the Corners.

Your tawking semantics. If I point my gun at a paper target and I hit the bulls-eye, I dont think about windage and wind drift and yada yada yada. You said it your self in the above post, short wheel base bikes steer quicker, plain and simple. Get the bike slowed down, (front end compressed-weight on the front tyre.) Turn it at its shortest wheel base, get on the GAS! and go around the turn, beat your friends/competitors on the race track.

I am sure there are concert piano players that cant tune a piano but can play the shit out of it. Some people know how a bike should operate and can get it to go how they like, is there a correct "set-up" formula? NOPE.

There are countless articles on bike set up, you could also go to Compu-Track to further deplete your bank account. I go by static sag and some other black sciences. Thats aboot it...Zip Ties around your fork legs work ok too. Nuff Sed :vtr2:

 

Agreed. Sounds to me like everything: worn out chassis components on an old bike +/- rider experience.

Don't forget fuelling - flat spots or surging can make it hard to enter & exit a corner smoothly.

If I only had $50 to spend I'd fix the steering head bearings too. To some degree the other stuff can be ridden around by slowing down. Not ideal though.

 

I don't think I am. For instance, increasing rebound on the rear shock or increasing preload can reduce the rear suspension from extending so much under braking. There is no change in wheelbase, yet the geometry and handling during braking has changed. If you thought wheelbase changes were the only reason a bike felt twitchy under braking, you would be scratching your head wondering what happened.

Maybe to you it's not important to know the real reason for things, but for me, I want to know all the little specifics and how they interreact with each other. Also, since this is a forum where people come to learn stuff, I want to get good info out there and counter any bad info I see. I think the wheelbase shrinking under braking making the bike feel twitchy is just nonsense.

 

So lets assess the bike, RC26, last produced 1989 ish ? so 40K not a lot of miles for one of those, but probably got 24year old oil in the forks & shock, so basically water with NO damping, so fine on smooth roads, but NOT on any kind of rough surface ! The 41mm forks on those usnits are fine, they only moved to 43mm on later units that were much heavier. I believe the forks are damper rod on those, so get front springs suitable for your weight & either a heavier oil &/or a set of RaceTech Goldcartridge emulators & a new or fully serviced rear shock. You will be amazed.

You can try a simple bump test of the shock, set bike on wheels, have a helper hold the bars to keep it upwrite, then bounce the rear via the grab rail or rear seat, use a lot of your body weight. the rear should squat underload & recover with some damping, if it springs back immediately & ties to ossolate then the shocks damping is shot. Refurb or replace.

 

That drop sensation is the rear not working properly. Are the shock linkages greased & free moving, they are known to seize !
The falling sensation is from underinflated tyres ! Put some air in them.

I see you did the front fork oil/preload, so narrows the fault to the rear !

 

Just because Honda recommends high tire pressures does not mean that is the end all, be all answer. The higher the pressure, the smaller the contact patch. Some tires run pressures lower than 30 psig.

As for the suspension, it is shot. Forks and shocks should be serviced once a year. My guess is that the fluid is mud, contaminated by the consummable bushings being worn out and you should pull your fork and shock springs and measure the free length, they are probably sacked, not to mention that they are probably not matched to your weight. Sag is the single most important adjustment after correct spring rate, however, to determine if the spring rates are correct, you must first attempt to set the sag......rebuild your suspension, get the right springs and get the sag right. When the components are being rebuilt, disassemble, clean and inspect all of the linkage components, replace any bad bearings and seals and put fresh water proof grease on everything. Replace the headstock bearings and races and grease them too. Get a decent set of tires mounted

Then, and only then, can you start working on the chassis geometry.

 

Mohawk and Norcalboy, did you see my recent posts or just the 8 month old one? A lot has changed, I did a front end swap. It's no longer scary around corners. In fact it's fun, I speed up through the sweepers now. :wink:

The rear of the bike was not causing the scary feeling, but it's still too stiff. It makes my back hurt after a long ride. I'm in the process of swapping a softer riding 170 or 180 radial into the back. After that I'll see what my ride heights are and I'll have Jamie D rebuild and revalve the shock as well as alter it's length if need be.

Then this old antique is gonna be a real beauty.

 

Hi JasonWW,

Apologies for the last post - I was responding to your 2012 message. I didn't check the date before opening my mouth.

I agree with your assessment on how the new forks might be helping your bike's handling with regards to front end dive affecting rake and trail. The same thing goes with a crappy rear shock. If the back end bottoms out on acceleration you'll increase front end rake and trail, leading to understeer and a bike refusing to turn a corner. Then you back off the throttle and the front end dives, sharpening up the rake/trail and making it really twitchy. This phenomenon is why such a big deal is made over 'funny front ends' like the BMW telelever/paralevers and Bimota Tesi, which to some degree avoid this geometry change.

Throw in a set of worn out steering head and/or swingarm bearings and you're riding a piece of spaghetti.

Tyre profiles will also influence handling. Touring rubber tends to have a flatter profile than sports rubber, making it more stable but requiring more effort in corners. Old tyres will just feel rubbish.

I went through a similar experience with my Ducati Monster this year - the thing just refused to turn corners predictably until I had both ends of the suspension resprung to my weight and had the damping revalved.