Changing fork oil

[SMF]

Anyone have a quick explanation of how to change the fork oil for an 87 K100rs. I have the Clymers manual but they show taking the whole fork apart. I'm thinking theres an easier way to just pull the drain plugs, let them drain a bit then take plug out from the top of the forks and replace with oil.

Simple enough?

Thanks for any help.

i installed the new rear shock this weekend and I'm going to order new tires this coming week and wrench them on myself. Any issues with mounting tires on these rims. I've been changing the tires on the F650 for a year now and I have no problem changing them but I'd like to know if the K rims will be more difficult. Once the forks and tires are done, I should have a smooth running mile eater.

[st3ryder]

Years ago I was advised to be really, really careful using the drain screws on my K75 as they will strip very, very easily, so, I do what I would normally do with any other bike I've owned, pull the tubes, remove the forks caps and thoroughly drain the oil.

I'm guessing the type of tire you are going to be mounting will make a difference, but I tired years ago to spoon some high mileage bias-ply Dunlops on my "snowflake" rims, and damaged them with the levers, even while being very careful. I take the wheels and new tires to a dealer and have them mounted.

[Beemer01]

First, I changed my fork oil using instructions from this great collection -
http://www.bmwmcnj.com/Technical/bmd%20k100%20how%20to%20tips%20for%20free..pdf.

Not difficult, and yes please be careful not to strip anything.

Second, assuming that you can mount the tire to the wheel without damaging either and are successful in inflating it - how do you plan to balance the assembly? For the speeds that these bikes like to run at, I'm most comfortable having it balanced using a computerized dynamic wheel balancer (single plane) - and I don't have one in my shop. I request that they balance it to 1/10 oz.

Let the dealer mount and balance... and don't forget to install a new valve stem.

[PGlaves]

Anyone have a quick explanation of how to change the fork oil for an 87 K100rs. I have the Clymers manual but they show taking the whole fork apart. I'm thinking theres an easier way to just pull the drain plugs, let them drain a bit then take plug out from the top of the forks and replace with oil.

Simple enough?

Thanks for any help.

i installed the new rear shock this weekend and I'm going to order new tires this coming week and wrench them on myself. Any issues with mounting tires on these rims. I've been changing the tires on the F650 for a year now and I have no problem changing them but I'd like to know if the K rims will be more difficult. Once the forks and tires are done, I should have a smooth running mile eater.

Those forks probably have a small (10mm head) capscrew on the back side of each slider about 1 inch above the bottom. Remove the capscrews in the top of the forks to let air in, and remove the small drain screws at the bottom. It will squirt a bit so be careful.

K100 wheels are easy to mount tires on my hand. As easy as any I've done.

I use a balancing stand with rollers for the axle. Pretty much like you see the race teams using at the track. I've not had any balance issues doing it this way.

Mark Parnes makes/sells a variety. Telefix makes one. I made my own.

The issue with the rear K100 wheel is having a flange that is true to bolt to the wheel or having the cone setup like the Parnes unit.

[SMF]

Thanks for the help.
I've been using Dyna Beads inside the tubes on my F. They work great! That was the route I was going to take on balancing the tire on the K. I'll have to see what my shop is going to charge me for tires and mounting. And yes, I'm going the get new stems.

[Beemer01]

Paul - are there really automotive racing teams using a bubble or mechanical balancing system? Where? Perhaps NASCAR or dirt track, but certainly not more sophisticated venues.

I worked Gasoline Alley at Indy for two years as an engineering advisor to the Mac Tools team - every tire/wheel assembly was balanced on a computerized two plane balancer. Without going into the physics, the wider the wheel - and wider motorcycle wheels like the popular 5.5" wide wheels qualify - then absolute requirement for a two plane balance. The European market lead and the US market followed with computerized spin balancers in the late 70's and early 80's. The difference in improved ride and handling at all speeds was dramatic - and in the case of Indy and F1 cars this technology made them safer and faster.

I dialed out a persistent 190MPH vibration the Kenny Bernstein team had been struggling to eliminate by rebalancing the wheel assemblies on a computerized spin balancer my guys had designed.

Anyhow computerized balancing costs $5 or so in most places - way cheaper to get it right in the first place.

Re the dyna beads - I dunno. Seems like you are increasing the total weight of the rotating mass, which is universally bad for handling. F1 and Indy cars use cast titamium wheels with very light tires - all aimed at improving handling and responsiveness. BMW uses cast aluminum wheels for the same reason. I'd expect the balance weight on a BMW wheel with a quality tire to never require more than 1/2 oz. in a balance weight.

End of lesson.

[PGlaves]

Paul - are there really automotive racing teams using a bubble or mechanical balancing system? Where? Perhaps NASCAR or dirt track, but certainly not more sophisticated venues.

I worked Gasoline Alley at Indy for two years as an engineering advisor to the Mac Tools team - every tire/wheel assembly was balanced on a computerized two plane balancer. Without going into the physics, the wider the wheel - and wider motorcycle wheels like the popular 5.5" wide wheels qualify - then absolute requirement for a two plane balance. The European market lead and the US market followed with computerized spin balancers in the late 70's and early 80's. The difference in improved ride and handling at all speeds was dramatic - and in the case of Indy and F1 cars this technology made them safer and faster.

I dialed out a persistent 190MPH vibration the Kenny Bernstein team had been struggling to eliminate by rebalancing the wheel assemblies on a computerized spin balancer my guys had designed.

Anyhow computerized balancing costs $5 or so in most places - way cheaper to get it right in the first place.

Re the dyna beads - I dunno. Seems like you are increasing the total weight of the rotating mass, which is universally bad for handling. F1 and Indy cars use cast titamium wheels with very light tires - all aimed at improving handling and responsiveness. BMW uses cast aluminum wheels for the same reason. I'd expect the balance weight on a BMW wheel with a quality tire to never require more than 1/2 oz. in a balance weight.

End of lesson.

I was referring to motorcycle race teams. Lots of them use balancing stands.

The issue with dynamic balancing for car tires is the width. Radial balance on wide car tires varies side-to-side. When a computerized dynamic balance machine is used on most car tires they wind up with weights at one location on one side of the wheel and weights at a completely different location on the other side of the wheel. You seldom see this with spin balanced motorcycle tires because compared to car tires they are so narrow. Certainly true of Beemer wheels if not somebody's wide-bodied chopper wheel.

Spin balancing might be "better." The question is does it need to be better. I don't think so. I have been stand balancing tires for 25 years and cannot say I have ever observed (on our bikes) any detectable vibration, any balance related abnormal wear, or any suspension component wear from balance except when I threw an improperly attached weight a time or two. Our widest wheel however is a 5.0 so I don't know about a 5.5 or wider. The '87 K100 in question here has a pretty narrow wheel - a 2.75 or 3.0 by my parts listing. Not wide enough to "need" offset weighting in my opinion.

[cayuse60]

Thanks for the help.
I've been using Dyna Beads inside the tubes on my F. They work great! That was the route I was going to take on balancing the tire on the K. I'll have to see what my shop is going to charge me for tires and mounting. And yes, I'm going the get new stems.


Replaced both tires on my K75 and used dyna beads. I have some low speed vertical bounce on the front tire between 30 and 40 mph, but after that everything is smooth.