Sticking Throttle Grip

[F16Viper68]

Dear Collective - I've recently purchased a 2020 BMW R1250RT with around 17,000 miles on it.  One thing I noticed right away was the throttle was sticking and the force required to twist the throttle was much more than my 2015 GS or 2019 GS.  A thought I've confirmed with a nearly identical 2020 R1250RT.  

 

As a quick test, I took off the bar weight and hit the throttle tube with some silicon spray. The throttle smoothed out but the excessive (IMHO) force was still present.  As I expected, the notchy throttle is starting to come back.  

 

Based on my research, I think I'm going to find rust under the throttle tube.  Since I'm about to install Ilium bar backs, I figured this will be a good time to address the situation.  I'll be able to strip off the throttle assembly and remove the handlebar tube for repair.  

 

Does anyone know if the tube (black metal part) is painted or power coated?  

 

Most of my research led me to the link below which is why I'm expecting to find rust or bare metal. 

 

https://forums.bmwmoa.org/threads/2016-r1200rt-throttle-tube-sticky-notchy.95179/

 

Determining if the tube is paint or powder coat will help me figure out the best course of action. 

 

Dave...

 

 

 

[Boxflyer]

Between Cap and jstacey203, you have all the guidance from either the Repair Manual, or the photos included in the thread to take it apart and reassemble.

 

I've done this on each of my RT's...2016 and 2017, but with a different decision about doing paint, power coat, or some epoxy paint.

I removed the paint completely from the areas where the sand/dust had already worn away what I believe is just paint, not powder coat...it's not as thick as I would expect if it was powder coat.

 

Then I sprayed the bare metal with Dupont Non-Stick DRY Lubricant. https://a.co/d/ehADYGE

 

Reasoning behind this is that there is already sand/dirt embedded in the plastic tube that will be rubbing on whatever kind of paint you apply, so I went with NO paint vs expecting to have to do this repair again.

Secondly, any lubricant that you use that is wet/damp/liquid/paste...whatever will keep trapping whatever dirt/sand normally flies around the throttle when riding...so I opted for the DRY film.

It turns out that the dry film is also an excellent protection for the bare metal and I didn't have to deal with rust in the tube again.

 

...Just the approach I took, you may decide that you want to repaint and use some grease, so I am offering up my course of action, not the absolute definitive way to proceede.

Brad 

[F16Viper68]

@Boxflyer thanks for the detailed feedback.  I'm curious, what led you down this road?  Did you notice an issue?  How long did you run it bare metal? 

 

Dave... 

[hunter41]

I have a 2022 1250 RS and occasionally notice slight stiction in the throttle.  Started noticing at about 5,000 miles (bought new earlier this year).  It's just the initial movement...once the twist action starts the movement is butter.  Right now it's not enough to worry about and it is still the best bike ever, but I'll keep an eye on this thread for possible future needs.  Good info on the MOA link.  Good luck with your fix!

[F16Viper68]

@hunter41 I'll be sure to post up what I find once I take it apart this weekend.  

 

Dave...

[Boxflyer]

@F16Viper68

Dave, on the 2016RT, I felt the slight catching of the roll on/off of the throttle after about 20k, and investigated it shortly after that.  I had ridden that bike in every imaginable weather and even some chemically treated roads in light snow...that bike was showing several areas of concern that I now see on a regular basis when doing many, many 12k services.

These large contact areas between the handle bar and the twist grip are too inviting for dirt/sand/dust to pass through, so sticky/wet lubes did not look like they would work for me.

 

Mainly, the lower on the bike, the worse the effects of riding in the rain/crappy roads. 

For an example...

If the rear caliper pin does not get cleaned and extra attention with Silaramic or something similar (don't know what is better though) it will almost certainly wear the alloy caliper itself and then the binding of the pin in the caliper will cause the rear brakes to drag, overheat the rotor, make quick wear of the pads and the only real solution is to ultimately replace the caliper/bracket assembly.

 

There are several areas of concern that I will go over on your bike when we are at FART.

Brad

[Cap]

11 hours ago, F16Viper68 said:

Does anyone know if the tube (black metal part) is painted or power coated?

 

It is painted.  To expand on what @Boxflyer said, when you pull the throttle assembly off the bike, you will see that the paint on the handlebar has worn through in certain places.  This suggests that the plastic tube is sometimes rubbing on the handlebar.  The tube has a large enough diameter to clear the bar without touching, but the forces imparted by the rider's hand are enough to deflect the tube.  So, yes, there may be some additional friction caused by that rubbing, but I do not think that is the major source of the stick-slip phenomenon that many of us find annoying.

 

You can do an experiment to determine if the friction you feel is imparted by rubbing of the throttle tube on the handlebar.  Go for a ride, and move your right hand off the grip and place your palm on the tip of the bar-end weight.  Then, use your fingers to grab the end of the throttle tube.  While holding the throttle tube centered on the handlebar so it is not rubbing, give it a twist.  Do you feel less resistance? 

 

When I do this experiment, I feel no change in resistance, but the stick-slip seems to be mitigated.  And I think this implies that the stick-slip is caused by axial misalignment of the throttle tube, and the location of the sticking parts is in the left side of the throttle assembly near the return spring.  In that area you will find some loosely fitting plastic parts that capture the rotating throttle tube in the non-rotating switchgear assembly.  I find that I need to periodically clean that area, and then apply some very light grease to the contact areas where the rotating parts of the throttle tube are captured in the non-rotating assembly.  I do not recommend spray lubricants because they are impossible to apply to small precise locations, and overspray will just collect dirt and eventually make things worse.  Similarly, liquid form lubricants will not stay in the location where they are applied.  I use a toothpick to apply small dabs of light grease where the plastic parts rub.

 

Finally, with respect to the amount of force required to twist the throttle: yes, this seems higher to me than my previous motorcycles.  I think this is partially due to the small diameter of the throttle tube.  On that previous post on the MOA forum linked above, I mentioned that I increased the grip diameter by installing some foam grip covers.  Since then, I tried a solution suggested by @Boxflyer where I stacked 30+ rubber O-rings across the grip.  And I like that solution even better because it works better than foam grips in the rain. 

 

Cap

[F16Viper68]

Thanks everyone for the feedback.  I've ordered a push/pull gauge to baseline the force required to twist the throttle to see if my efforts to smooth out the throttle also reduce the amount of force required. Waiting for my bar backs and puller to arrive.  

 

Dave...

[F16Viper68]

Well as expected the paint has been work away and it was dirty with a black grime but no rust or sand.  I did find it interesting there are ridges inside the throttle tube but only on the upper left side of the tube.  The ridges are worn away and they have rubbed the paint off the bar.  Cleaning it up the bar and tube certainly helped with the sticking throttle.  There's a lot more play in this throttle than my 2019 GS.  

 

Waiting on some dry lube spray from Amazon to see how it help.  

 

 

 

 

[JCtx]

Man, that looks like metal to metal contact, and pretty heavy wear at that. Is it plastic inside the throttle tube? RTs have a chair-like riding position, so there should be basically no force exerted on the bars when riding, to cause that kind of wear. That's very strange to me. Do RTs have a unique throttle tube, or is it the same my R bike has? Never heard of throttle tube wear before. Or sticking either. Now I'm curious about the cause.

[F16Viper68]

4 hours ago, JCtx said:

Man, that looks like metal to metal contact, and pretty heavy wear at that. Is it plastic inside the throttle tube? RTs have a chair-like riding position, so there should be basically no force exerted on the bars when riding, to cause that kind of wear. That's very strange to me. Do RTs have a unique throttle tube, or is it the same my R bike has? Never heard of throttle tube wear before. Or sticking either. Now I'm curious about the cause.

Yep, you have the same throttle grip as the 2020 RT.  This type of wear is not unusual from what I've been able to figure out. It's simply the paint being rubbed off the handlebars which leads to sticking throttles.  Now why is it being rubbed off?  Obviously a bad design because this shouldn't be possible imho.  

 

Dave...

[JCtx]

That's what I figured (same parts); thanks. But you know, now that I think of it, my bike has a powder-coated (steel) handlebar, so probably wouldn't have that issue. But yes, seems bizarre.

[F16Viper68]

Well today ranked up there with one of the more frustrating days I've had working on bikes.  Trying to install bar risers and discovered the bars were pressed into the handlebars by the Hulk.  The Illium press/puller I rented stripped out after moving the left one about 1/2".  After a lot of trips to the hardware store, welding, and yelling I was able to get the left one out via my Harbor Freight bearing puller.  Of course, the Harbor Freight one stripped out halfway through removing the right side.  

 

I think the Illium press was damaged before arrival but I can't say I'm surprised it stripped.  These things are stupidly hard to remove.  

 

This one lasted about five minutes.  

 

Hours later I was able to get the left side removed.  The right will have to wait until tomorrow.  

 

[Hati]

5 hours ago, F16Viper68 said:

Trying to install bar risers and discovered the bars were pressed into the handlebars by the Hulk.

 

Yep, that's public knowledge. It can be done however using heating and freezing. Hot air gun on the outside (silver part) as you use the bearing remover and freeze the part for a few hours before installing it when ready to put them back together. I couldn't get their puller due to my location, so a decent bearing puller and the above mentioned hot/cold approach worked.

[F16Viper68]

Well I'm happy to report I was able to get them both off the bike.  The third puller was the charm.  :)  

 

I ended using a combination of the two pullers. The left portion is Harbor Freight, welded nut to ensure press screw didn't slip (also drilled out the nut threads), and the Illium puller on the right side.  I think, if necessary, I could have solely used the HF puller but it was better to use the Illium portion to minimize damage.  

 

Seriously hoping the next phase (installation) goes smoother than this part.  

 

[Cap]

I use the same risers on my wethead RTs.  And I found that I needed to play around with the final positioning of the bars before I was satisfied.  Given your struggle to remove the bars from their tapered mounts, you may wish to delay full installation until you gently try some different orientations of the bars.

 

The instructions tell you to orient the extenders in line with the factory angle.  I found that recommended orientation made the bars too tall for my preference.  I wanted the bars more rearward, and not quite as tall.  And unfortunately the Illium bar extenders are configured in a way that when you roll them back, they force the brake and clutch reservoirs to take on an unfavorable angle.  As I recall this is especially awkward for the brake reservoir.  There is a non-critical web of aluminum along the bottom edge of the brake reservoir that you can grind off without harming anything -- and doing that will gain you just a bit more clearance.  I found that I could orient the bar extenders somewhat rearward while keeping the brake reservoir mostly level.

 

The second issue that you will discover if you pull the handlebars slightly rearward is that while riding you will feel a difference in the rotational axis with which you apply pressure to the bars.  It starts to feel like you are driving a toy wagon.  So, there is a trade-off between the best ergonomics for hand position, and the best feel for steering input.

 

Have fun,  Cap

[F16Viper68]

@Cap your post is very timely since I've been out in the shop for over an hour working on the ergonomics. :).  Even more so since I was just eyeballing the bottom of the brake reservoir for the exact reasons you outlined above.  I agree, the suggested angle doe not feel quite right to me but I am curious how it will affect the handling.  I had no issues with the risers on my GS but I'm not sure that's comparing apples to apples since the geometry of these risers are so different.  

 

I'd be done if it wasn't for the fact I'm trying to deconflict the GS style mirrors from hitting the windscreen when moving lock to lock, ensure they feel good, and everything is equal left to right.  

 

Dave...

[F16Viper68]

Well I took the bike for a ride and it's fine!  Luckily it doesn't ride like a toy wagon.  :)

 

Dave...

[F16Viper68]

Well the bikes all back together which I didn't think was going to happen anytime soon.  The throttle is now smooth and snaps back quickly. I removed the paint from the areas where it was rubbing, blended the paint to smooth it all over, and applied dry-lube.  The bar risers are set up and torqued down.  Now to see how it rides on long distances.

 

  

 

 

Also, added cylinder head protection from MachineArtMoto which went considerably easier than the bar risers. :)