Rear tire hopping around when applying brakes

[jjs1234]

Hey everyone!!


I wanted to get your opinion on an issue I am having. Not 100% sure as to what is the problem... unless its the mono-shock.


Problem:


The rear wheel hops/skips around when the rear brake is applied (medium strength), not enough to lock the wheel up. This also seems to happen only when I did not dis-engage the clutch. I was curious as to why this is happening. My guess is the mono-shock is the issue, but perhaps its the way I am riding?


Thanks!

[BrickMW]

Mine does this also, not with rear brake application, (which I rarely use...) but with aggressive downshifting / engine braking. The back tire in a state of half skidding / half turning -- skipping.


Never really thought much about it nor tried to eliminate it, maybe a new shock would help, or maybe it's reverse jacking??  :dunno


Whatever it is, I'm pretty sure it's not good for the rear rubber, so I try to avoid it. Planning to have my shock rebuilt this fall, unless I find a cheap "fill in" before then. Till then I can only wonder if it would help or not.

[Chaos]

check your back brake closely, cracked rotor or warped maybe.  A bad shock would cause problems in other situations too.  Bushings on shock, swing arm play, that's an old bike plenty of possibilities.

[Motorhobo]

Never really thought much about it nor tried to eliminate it...

Really? Something like that would freak me out.


Are you sure it's the rear tire and not something further up the drivetrain? How long has it been going on?

[BrickMW]

Really? Something like that would freak me out.


Are you sure it's the rear tire and not something further up the drivetrain? How long has it been going on?

It is a little unnerving I guess, if its a "new" sensation.. I come from a off road moto background and did this all the time during quick slow downs or downhill portions of a ride, where the hill overcomes the engine and starts skipping the rear.. On the brick, I just tell myself "that downshift was too early--rear tires aren't cheap!" whenever it happens.


Wind out 4th gear to 6K, pull clutch and let the revs settle, then drop to 3rd and dump the clutch... rear end skips for 1.5 sec while the engine tries to catch up the revs.. nothing weird to me. Or maybe I'm weird.. :dunno2:

[Martin]

Engine speed not synchronised with wheel speed try using more front brake. Aggressive downshifting can also cause this.  Could also be suspension related.
Regards Martin.

[jjs1234]

only seems to happen when the engine is engaged and the rear brake is applied. During quick stops I almost get pretty nervous on how much front brake I should apply.


The shock is old and I think it does have a tendency to bounce.


I can imagine a loss of control if this happened while cornering.

[Martin]

Replace the shock and do a motorcycle riders course, you can only benefit. A good course will teach you heaps of valuable skills. The front brake should be doing most of your braking.
Regards Martin.

[Motorhobo]

Replace the shock and do a motorcycle riders course, you can only benefit. A good course will teach you heaps of valuable skills. The front brake should be doing most of your braking.
Regards Martin.

+1 on front brake and safety course.


I think Rear brake dependency is a cage-driver mindset thing - it's a high side waiting to happen. Most riders I know use front brake primarily. I myself have tried to train myself to use the rear only in controlled situations when it's beneficial, like rolling out of tight curves, in order to condition myself not to ever hit it hard enough to have it lock up.


Interestingly, the people I've known who use a lot of rear brake are owners of big-ass Harleys that spend most of their existence in the garage.

[Filmcamera]

I use the rear brake primarily for low speed control, 5mph and less. Other that I use at least 70% front brake, often as much as 90%.  The rear disc brake on Ks are terrible anyway so for normal slowing I often don`t use the rear brake at all.

[boostd4]

It is a little unnerving I guess, if its a "new" sensation.. I come from a off road moto background and did this all the time during quick slow downs or downhill portions of a ride, where the hill overcomes the engine and starts skipping the rear.. On the brick, I just tell myself "that downshift was too early--rear tires aren't cheap!" whenever it happens.


Wind out 4th gear to 6K, pull clutch and let the revs settle, then drop to 3rd and dump the clutch... rear end skips for 1.5 sec while the engine tries to catch up the revs.. nothing weird to me. Or maybe I'm weird.. :dunno2:

This is normal (I'm guessing) if you're not rev matching.   My new (to me) brick has a good 25 degrees of slop in the throttle grip (I haven't adjusted yet - partially scared of all this throttle-sync'ing I'm hearing about ), but it makes it very difficult to accurately blip the revs up to match the previous gear.  If I don't get it right (revs too low for expected engine speed in lower gear), the rear tire hops and skips around.

[Laitch]

My new (to me) brick has a good 25 degrees of slop in the throttle grip (I haven't adjusted yet - partially scared of all this throttle-sync'ing I'm hearing about ), but it makes it very difficult to accurately blip the revs up to match the previous gear. 

Have you removed the cover from the throttle actuating cam housing to determine if the arrows on the cam and the throttle gear are aligned? Throttle body synching is a different animal. It's part of the tuneup procedure. Fear it some other time. :giggles

A hair-trigger throttle is unnecessary for most of us. What is really important is that the speed drops off quickly when the throttle is released. Blipping the throttle accurately comes with enough practice but first, see if it is aligned correctly.

[boostd4]

No I haven't.  Is this cam housing on the engine side or the handlebar side?

[Laitch]

No I haven't.  Is this cam housing on the engine side or the handlebar side?

It's part of the front brake master cylinder housing assembly. Remove a couple of screws and there it is.

Throttle cam:gear marks from K75-K100 2V manual.jpg (23.55 kB . 768x260 - viewed 262 times)

There's a K75-K100 workshop manual pdf in the Repair Guidance Section Master List that could help orient you to adjust this. The most time consuming part of the process is finding the kill switch assembly screw after you drop it in the tall grass or gravel driveway.

There also should be a few threads here explaining it.

[boostd4]

^^  This was exactly it!


Very simple fix (I hope).  Mine was about 2 teeth off.  I lined up the lines and put the cover back on and now there is maybe 1mm or less play.  I can still hear the "click" from the throttle switch when I slightly crack it open so I'm hoping it's where it should be (and not too tight).  It's raining cats and dogs here now (and is supposed to until tomorrow night).  Can't wait to ride her on Saturday.


Thanks!