Hi all:
Are stock front springs an issue? 
I have a front end mild hop at 60kmph.
New tire balanced (twice) still mild hop, above and below this speed silk smooth.
Springs are all I can think of it do the ks have this issue?

are you sure its not coming from the back ? not a problem i have had from the front

I'll try that. The rear shock is On its softest position, I'll move it one notch up for a firmer ride.
Roads are full of potholes here.

If that's the original shock, it needs changing because it will be fubar by now.

Rear shock is rubbish, if its working it WILL fail. 

Try a YSS budget one I have used them and found them quite good. I have one on my RS has about 25k miles on it and before that it did about 40-45k miles on my K100RT. Still going strong.

The rear shock now on was given to me, the chap replaced it years ago said it was okay seems fine so far. Will adjust up today and ride it tonight when cooler, heat wave here. Let you know.

Rode last evening. Made no difference with rear shock adjusted furmer. Didn't think it was.
Thinking perhaps it is rubber in new tire breaking in, only 400km on new tire. Inflated it a little more today; off to races today so 100km run.

Tire ppressures at 38psi front and 40-42psi rear?

Tire pressure okay. Just got in from 70km ride, no difference still hop at 60know silk smooth under and over this speed. I can't believe I have to live with this!
Has to be something with front shocks, springs, oil viscosity or?

lucki wrote:July 06 2023
The rear shock now on was given to me, the chap replaced it years ago said it was okay seems fine so far.
Has to be something with front shocks, springs, oil viscosity or?

When you wrote above "seems fine so far," how much riding had you done on it and how fast had you ridden? Was the new tire involved in all that riding? After all, the chap replaced the shock you now have with something better so it's probably not in good condition by now.

Your Brick has136,000km. It was in rugged condition when you bought it. It's likely the front fork assembly didn't see much attention. Take it for a ride to warm up the suspension fluid then drain it and replace It. Heat up the drain bolts on the tubes, spray Liquid Wrench on them, tap on them then try removing them after twenty minutes passes. Replace the fluid with 7.5 grade to start. If you're lucky, the bushings aren't damaged and the valves aren't clogged, but someday the tubes should be stripped and inspected. This might not cure your current complaint but should be done anyway.

You could have a factory-defective tire; it happens occasionally however, you're lucki. You've got that on your side!

Just under 500km since I got the bike, all with new tire. This is third rear shock. Going to put it on centre stand, Jack front off ground and look for play. Tire took one and three quarter oz both balances. Do this tomorrow, still recovering from surgery.

There is a proper sequence to tightening all the clamp bolts of the front suspension.  You must loosen everything, bounce the front end and tighten the bolts in a sequence starting at the top and working down.  Bounce the front end after tightening each set of bolts. Don't forget the fork brace bolts.

The reason for this is to remove any stiction or binding in the fork travel that will make the front end bounce at speed.  I had this problem in one of my bikes and corrected it by proper tightening.

Another suggestion is to get the front wheel off the ground and spin it slowly looking for any uneveness in the rim.  BMW wheels are cast from a soft alloy that deforms easily in order to prevent them from cracking on hard impacts.  You would not be the first to have a deformed rim.  Check the rear wheel as well.  Fortunately, the sort alloy will allow you the hammer out any dents you might find.

Will put bike on centre stand today and check for play in triple tree and wheel run out. More little bugs in this critter than I figured!

Steering tree has no play and side to side is smooth though I am sure could benefit from new grease no noticable notch.
Put dial gauge on the front rim, rim true, just a few thou out.I

Then spun tire against solid surface, got one quarter inch difference, hmmmm.
This is my third set of new shinko s , this is my first issue. Will drive to about 1000km see if tire seats, if not into the dumpster it goes. I wondered about that tire when I balanced it twice the previous two sets of shinkos took half oz to balance. Get what you pay for.

if you think its the front tyre throw it away , to much of a risk

If you haven't done it already, I would stronglyy suggest re-tightening the front fork fasteners.  Proper alignment and zero twist in the front end is importannt for smooth running over small suspension inputs.

Also, on the tire.  Is it uniformly seated on the rim all the way around?  If not, reduce the pressure to about 20psi and with the wheel off the ground beat it at the spot where it isn't seated fully.  A little glass cleaner spritzed on the tire/rim joint will help get it to seat.

Another tip: When installing new tires, check the rim balance BEFORE installing the tire and put the tire's balance dot there instead of at the valve.  I have found that my wheels all have heavy spots as much as 6" from the valve location.  This will make static balance a lot easier.

Point:
Great tips on balancing, will use them for sure.
Did check fork clamps for tightness, okay.
Found one engine to frame mount bolt a little loose, half turn.
Looked very close at bead around tire for uneven mounting didn't look too bad but will look again.
Was thinking of breaking bead and remounting, will try the 20psi trick!
Don't get me wrong, I love this bike so far; did nothing to the engine drvetrain runs amazing!

You aren't looking for loose fasteners.  What you are trying to accomplish is the removal of any twist in the front forks that can cause them to stick with small inputs.  You have to loosen everything and bounce the front end while going down the legs tightening everything in sequence until you reach the bottom.  Of special importance is the fork brace. 

At the starting point the only tight bolts will be the ones at the top triple clamp.  Everything else will be loose enough that you can easily wiggle the front wheel from side to side in the forks.

Bounce the wheel, tighten the lower triple clamp pinch bolts.  Bounce again and do the fork brace.  Bounce again and tighten the axle screw.  One more bounce and tighten the pinch bolts at the bottom of the fork legs.  Now your fork legs will be parallel and fork action will be as free as possible.

Just came in from shop. Took another look at tire bead . Took a piece of three quarter steel and rotated tire against it had one quarter inch gap in spots. Let air out to 20psi as suggested beat on high spots with two pound club hammer. Lots of soap.reduced distance to about one sixteenth. Inflated tire almost true now. Will road test tomorrow.
Cheers

Point-Seven-five wrote:You aren't looking for loose fasteners.  What you are trying to accomplish is the removal of any twist in the front forks that can cause them to stick with small inputs.  You have to loosen everything and bounce the front end while going down the legs tightening everything in sequence until you reach the bottom.  Of special importance is the fork brace. 

At the starting point the only tight bolts will be the ones at the top triple clamp.  Everything else will be loose enough that you can easily wiggle the front wheel from side to side in the forks.

Bounce the wheel, tighten the lower triple clamp pinch bolts.  Bounce again and do the fork brace.  Bounce again and tighten the axle screw.  One more bounce and tighten the pinch bolts at the bottom of the fork legs.  Now your fork legs will be parallel and fork action will be as free as possible.

This is really important. I have seen a few threads in different groups about issues after tyre changes arising from not doing this.

Just got back from 100km run. Slight improvement, still not great. It is a tire issue. Next rainy day will take tire off rim balance rim put tire back on balance again. After that if not better will throw tire on campfire!

Did you do the bounce and tighten on the front end?

Not yet. Got wheel off now spent last hour trying to balance it. I have balanced tires in the past, a five minute job. Not this one. Get it as close as I can reinstall and bounce.

You don't want to balance the wheel, just note where the heavy spot is and put the tire's dot there.  Then balance the tire and wheel as normal.  I just make a small dot where the heavy spot is on the rim with a Sharpie pen so I know where the heavy spot is when I install the tire.

fit a steering damp asap , this problem could result in a tank slapper , you really need the front wheel balance and tyre seating 100% , have you tried over inflating to seat the tyre .

Things advancing! Got tire off, wheel balanced, tire back on, balanced. Took 5 minutes to balance, what a difference!
Picture shows how far off the heaviest point was from the valve stem.
On bumping; the lower tree bolts are as you know a very shallow Allen head. For me this is a winter job , the fairing has to come off to use heat to get that bolt out. Aluminium and steel bolts always bad if they used anti seize at the factory it would help. So did the rest of the suggested bump thing and with the wheel now well balanced will hope for the best. May test ride it before the rains let you know.
Cheers

Yeah, that's what I found with my wheels.  Chasing two different heavy spots can make static balancing a royal pain.

Took the bike for a little test ride. I am 70 percent there on the 60 kmph flutter. Tried a little test. Holding a steady 60 kmph on smooth road I lightly applied back brake no difference. Then the front brake giving it throttle to maintain 60, flutter went away. Thinking now maybe one or both front brake calipers not fully releasing? Or maybe no oil or low oil in front shocks.
Thoughts.
Overall an improvement from 65 to 120kmph you could not ask for a smoother ride.

Fork tubes are dry, no leaks unlikely both shocks dry. Based on handling symptoms, 5 or 7weight? Will change oil.

lucki wrote:Just got back from 100km run. Slight improvement, still not great. It is a tire issue. Next rainy day will take tire off rim balance rim  put tire back on balance again. After that if not better will throw tire on campfire!

Not sure about balancing the rim without the tyre. The only thing I think is to put the valve in and see where is the heaviest point in the rim before putting the tyre on. It should be at the valve but may not be, as pointed out. That heaviest spot is for the dot on the tyre but no weights go on at this point. After that its a case of fit the tyre and balance the wheel with the tyre on. Hopefully not too much weight needed at that point.

strip the forks and make sure all valve holes are clear , i bet they have never been apart and will have a build up of sludge .

Olaf, I don't know where the confusion is coming from, I thought that I was clear about checking for and MARKING the heavy spot on the wheel/rim, NOT balancing the rim before putting the tire on it.

The old steel rims that were made by forming a formed steel shape into a circle had much better balance than the cast metal wheels.  I started checking and marking wheel balance a few years ago when I had a tire that I just couldn't balance.  Since then, I check all my wheels, and nearly all of them have the heavy spot somewhere other than at the valve stem.  In one case the heavy spot was nearly a quarter of the way around the wheel from the valve stem.  Putting the tire's dot there made static balancing a lot easier.

My my I don't think the shock fill bolts were ever off. I put the 22mms wrench on the shock nut to hold it then using the Allen wrench tried to loosen the fill bolt. Had to use a pipe extension on the Allen wrench to loosen let go with a loud snap. Fork oil dark to black one side had way more oil than the other. Refilled with 280 ml of auto trans fluid, to flush, will drive 100 km then change to better stuff. Looks like seals when the snow flies.

Be careful tightening the the drain screws at the bottom of the forks.  It is very easy to strip the threads in the holes. 

Also, there is no good reason not to use automatic transmission fluid in your forks.  I have been using it for years in my forks and shocks.  The viscosity is around 7.5 which is about the middle of the range that works well.  ATF also has nice things in it for cleaning the internals and conditioning the seals.

Good to hear about atf, have lots here, will still change it in about 100km along with engine oil. Done just over 600km since the resurrection.
Cheers

Yes, you want to do a couple of flushes to clean up the internals.

I'd like to run something by you.
Whilst looking for answers on the front end issues I came across a video that had an interesting point.
Loosened the fork brace four bolts.
Put axel in twisted the lower fork tubes so the axel went in smooth.
Tightened fork brace now the axel was binding.
He then enlarged the holes in the lower fork tubes slightly.
Now with larger holes the fork lowers could twist a tad so that when fork brace bolts tightened the axel was now free to slide in and out.

When I was fiddling with mine the same thing occured the axel was free but when the fork brace tightened the axel became hard to move.

Thoughts

I am going to guess that the forks in the video were twisted in the triple clamps.  That binding is the reason you do the bounce and tighten.  Because  the guy in the video didn't get the triple clamps right he had to ream out the fork brace holes so he could untwist the fork legs to get the axle in.  Crazy...

I guess grinding out the fork brace holes is easier than loosening the lower triple clamp bolts.  I'm done with posting on this thread.

Try using less fork oil. What forks do you have and how much oil per leg are you using?

I had a K100RS4V once that would "jackhammer" the front end when I got up to speed on the freeway. Reduced the oil in each fork by about 10 ml and the issue went away.

I also had weird front end action on a K75RT every time I got up to 40 MPH or so. That one was cured by replacing the front tire.

Point-Seven-five wrote:I am going to guess that the forks in the video were twisted in the triple clamps.  That binding is the reason you do the bounce and tighten.  Because  the guy in the video didn't get the triple clamps right he had to ream out the fork brace holes so he could untwist the fork legs to get the axle in.  Crazy...

I guess grinding out the fork brace holes is easier than loosening the lower triple clamp bolts.  I'm done with posting on this thread.

From my experience fixing pranged bikes the triple clamp is twisted and nothing short of a big press and plenty of time will make the axle go in easily.  I have fixed quite a few that were returned to the original repairer because they thought a quick twist on the handlebars would do the job when it was bent in a 40mph T Bone.  Make sure the fork tubes are parallel in both planes.

I suspect my bike had an accident. When I put new tires on it inside the front rim was written "92 krt" so this was a replacement wheel.
My bike is as good as I can get it I can live with the way it is now.
Thanks to all for the help and patience shown me.
Cheers

put the axel in first then tighten whilst working the forks , if you think something is bent or damaged change it .

Update
Just turned 2200 km since getting the bike resurrected.
The front end flutter is still faintly present at 60 km better since I changed fork fluid again, this time tried 15 weight up from atf. Considering fork springs from motobin. If I was passing through the 60km point it wouldn't.matter that much but when going into small village's the speed limit is 60km.
Question:
Can I change the fork springs with the forks still in the bike?
I love this bike at 100 to 120 through corners on twisty roads!

firstie wrote:Can I change the fork springs with the forks still in the bike?

Here's a thread containing a pictorial from a member who accomplished that feat—post #9. There are relevant observations throughout the thread. If you have a Sport fork, it might be slightly more challenging depending upon your intentions.

Yes, you can change the springs with the forks on the bike.  You need to move the bars out of the way and remove the caps.  Pull the old springs and drop in the new ones. 

You might want to look into Race Tech Gold Seal Cartridge Emulators and single rate springs.  They made a night and day difference in the front end of my K75RT.  Smoother over bumps, way less brake dive, and a much more confidence inspiring feel in corners.  Best thing I did for that old war horse.

https://racetech.com/

Always found those Emulator things interesting...useful to hear a positive review, I think I'll upgrade in due course. Slight issue is that I have aftermarket Ceriani forks on my K100. These were supposedly a K100-specific upgrade years ago and cost a lot. Always thought they were rubbish - they are damper forks, crudely made, and the 'adjustable rebound' was a joke, as was the anti-dive. Time to sort them out...maybe have to buy some standard-fit Emulators and set to in the lathe.

Back on topic, if aligning the forks properly is your thing, then I found that a salvaged mirror of the right(ish) size makes a great flat surface for laying against the fork stanchions, after removing the sliders, so's you can check for skew (and reach for a scaffolding pipe if a corrective twist is felt to be in order)

The idea with the Race Tech retrofit is that a single rate spring will stiffen the static sag in the front end, reducing the brake dive and pitching when the throttle is changed. 

The cartridge emulators have a poppet valve that opens a big hole when you hit a bump eliminating most of the compression damping, allowing the fork to easily move upward absorbing the shock.  As soon as the fork begins extending the poppet closes and the rebound damping takes over.  

Because of the single rate spring, the spring rate is higher at small deflections so a higher rate of rebound damping is possible over small bumps and when changing throttle settings in curves.  The greatly reduced compression damping allows the stiffer initial rate of the single rate spring to actually allow the wheel to deflect more easily over bumps, but reduces deflection when braking or changing throttle settings.

Hope this made sense.

Update
Now up to 3050km since resurrection. Just installed progressive springs in front forks this morning. Will ride it tomorrow. Also sucked it up and loosened the shallow cap screws on the shocks to allow me to loosen all fasteners and bounce the front wheel and retighten. I did one trip last week 480km it was a warm day that bounce at 60km now faint, still present. The spring replacement job was simple. Got them from motobin, parcel post about 10 days.

Did 100k on new springs, great. Over familiar road over known bumps a big difference, less nose dive during hard braking. Would buy again.