rear shock

[The General]

Heh heh, where else, but on our FJ forum can you lather up the best ...
Discussion is good. Different view points are good. It's all good.

[Pat Conlon]

Ross won't make them with lower compression? I thought they would make pistons to your spec's. And why are you going to long skirts?

Ross will custom make pistons to any specifications. These are off the shelf from Curt Andrews with an advertised compression of 12:1
http://andrewsmotorsports.mybigcommerce.com/yamaha-fj-fj1100-fj1200-xjr1300-1380cc-ross-piston-yamaha-cylinder-kit-83mm/

12:1 compression may be fine for racers but not for an aircooled/carburetted street bike, in the toasty desert where we get piss water Calif 91 octane E10 fuel.
10:1-10.5:1 is much safer, power output will be reduced, but so be it.

I want an engine that is oil tight. I ride my bike on 3-5k mile tours, typically 300 to 600 miles a day.. Regardless of the wonderful power output of the 82mm Pro Lite pistons, I dislike having to carry and frequently add oil on these tours.
 
A fresh engine with the new design oil ring in the  Pro Lite pistons that still uses 1 quart in 3k miles is not what I want.

[FJmonkey]

Monkey Mark when are you going to make the upper shock bracket. So the early owners can adjust the rear ride height via dog bones and use the RPM shock.

I have the design roughed out for the upper shock mount. I planned on finishing the hole location when I had the time and funds to start the '86 rebuild, I wanted the upper mount hole located to keep the stock rear height with the RPM '89/'90 shock and OEM dog bones. Then fine tune with custom dog bones for my 17" rear set up. I can ask a few vendors for the cost of a short run of 10 pieces or so, it won't be cheep. Here is what I have modeled so far. The upper hole is just a guess, if I made some up I would remove the hole and add it after mocking it up on the rolling chassis.

[giantkiller]

I would for sure take 2. I'm going to use them to put the r1 swingarms(braced and 2 1/2 " longer) on the 1350 and the Turbo bike. I will need the upper mount as high as possible. So no hole would be great. As soon as you get it going let me know. If you need me to buy a third I will. If you don't get enough interest from others.
Thanks Mark

[Capn Ron]

Ross won't make them with lower compression? I thought they would make pistons to your spec's. And why are you going to long skirts?

Because anything above the knee is considered provocative?   

[Mike Ramos]

Good discussion gentlemen!

If I may add my experience with the RPM shock......

I have at least one hundred thousand miles on the RPM shock over the past several years.  I would like to address a different aspect of adjustments as they pertains to the real world....

Although Mr. Conlon's comments are no doubt altruistic in nature, the logic as it pertains to the street riding is questionable.  It is a fact that a multitude of adjustments are beneficial within the confines and the known variables of an individual race track.

However, when away from the controlled environment of a race track, all the numerous adjustments are of limited use when encountering the UNKNOWN variables commonly encountered while riding on the road. The road conditions are constantly in flux and often unexpected; at times they are dangerous.  If the veracity of such a broad statement is in question, please review any of the several videos that have been posted which validate the ability of the RPM suspension to adapt to these variables instantly and effortlessly.

The importance of the suspension (both the forks and shock) being able to adapt instantly, without rider input, is of the utmost importance.  When the front and rear are adjusted properly, the all around ride is excellent; both over-the- highway cruising AND back road sport riding situations are addressed with competence; it is an experience in which the rider enjoys the best of both worlds.

There is also the advantage of the extended mileage of the RPM shock between servicing which is perhaps twice as long as most other units.

Concerning the height adjustments to the rear:  As a general rule, raising the rear compromises high speed stability and maneuvers.  In addition, the increased fork angle under hard braking makes for a too-quick steering situation, complicating the moment when the brakes are at maximum and then gradually released throughout the turn.

Unless the issue of counter steering is addressed, discussions of the claimed advantage of raising the rear height are not complete.  On the street, the advantage of counter steering will often negate the perceived advantage of raising the rear to an exaggerated height.  Practicing proper counter steering techniques will enhance the rider's ability to "flick" the motorcycle from side to side rapidly in a smooth & controlled fashion.  This is one aspect of motorcycle riding that is not often addressed yet one that is important and, just as with braking drills, should be conscientiously practiced.

Ride safe everyone.

[giantkiller]

Mike I have followed you through the mountains at the East coast. You are an excellent rider and smooth transitions, good lines. I have great respect for you. Your ability to cover unbelievable distances. Is impossible for me to wrap my head around.. I guess I forget that some riders don't know about counter steering. That's kinda hard to understand too.

[Country Joe]

Mike I have followed you through the mountains at the East coast. You are an excellent rider and smooth transitions, good lines. I have great respect for you. Your ability to cover unbelievable distances. Is impossible for me to wrap my head around.. I guess I forget that some riders don't know about counter steering. That's kinda hard to understand too.

You ought to check out a couple of the counter steering threads over at ADVRider.com if you want to be truly amazed.

[movenon]

Nice read. All I can add is that I have played a lot with adjusting the rear end height. Probably have 6 or 7 sets of dogs bones out on the shelf. As Mike covered

"Concerning the height adjustments to the rear:  As a general rule, raising the rear compromises high speed stability and maneuvers.  In addition, the increased fork angle under hard braking makes for a too-quick steering situation, complicating the moment when the brakes are at maximum and then gradually released throughout the turn."

At my highest setting I was on the freeway with no particular problem other than being slightly more sensitive, then on a off ramp doing some firm braking the front end went into a BAD shimmy, got off the brakes and it stabilized, back on to stop and again shaking. Got my attention........ Since then I have concluded that staying close to the stock height is a better place for me.  At present I am around 5/8 inch higher than stock.  The front and rear seem to be in good balance now. Just relaying my experience in reference to raising the rear end height.
George

[Flynt]

Randy to Pat - "As far as I know you have never ridden an FJ with a RPM shock, early or late design or fork valves, maybe I am wrong. But, I have no doubt based on the directions of this topic each & every time, your preconceptions would never offer any of the RPM suspension components a fair assessment..."

I'd like to weigh in on this after having RPM suspension on my '84 for a few weeks now...

I had the fork valves and the rear shock installed by RPM.  It wasn't plug and play exactly in that some preload tuning was required, but it was pretty darned close.  I made my final 1/4 turn adjustment on rear preload yesterday and just rode for ~2 hours on the local goat trails (Ramos and Rick will remember some of them).  The bike is transformed...  turns in easier and is MUCH more planted, even heavy breaking on turn in with broken pavement is totally solid.  I could get around pretty quickly on the '84 with what turned out to be pretty f'd up stock suspension and the A/D didn't bother me except for the annoying 2-step front brake engagement as the A/D piston moved before the brakes went to full power.  I'm completely sold on this being a huge improvement based on cornering speeds being up significantly on this common route for me... and the brakes are now predictable and 1-finger.

Comparisons to Wizard are difficult...  With Diane and me on the bike, it is similar to the RPM setup on the '84 I think.  For me solo it is a bit harsh feeling.  You could likely get it to ride similar to the '84, but it would take some work and involve changes to more than preload on both ends.  I still love Wiz for sure, but it is mostly my 2-up ride now.

If you're looking for the quick path to making your stock FJ into a modern feeling bike, at least from quality of ride POV, you'd be a fool to get into the heavily adjustable end of the pool when Randy has solved the puzzle for you.

Frank