Time for a new throttle cable?

[billington92]

I checked my throttle synchronisation and noted that it was a little out of synchronisation on my R1150R (2004). Hence I began the procedure to adjust it; however I was unable to achieve the 2 mm of freeplay in the cable at the throttle bodies. It was always much greater than 2 mm, ranging from 4mm to about 7 mm of free play.

Is the simple answer to this problem change the throttle cables?

Do I need all three cables accelerator cable, bowden cable throttle valve left and bowden cable, throttle valve, right?

Also do I have to change the choke cable?

My bike has done 23,000 miles, Haynes manual suggests the throttle cables should be changed at 18,000 miles.

To view the online Fiche for the R1150R follow the link:

http://www.maxbmwmotorcycles.com/fiche/ ... d=04302013

[CycleRob]

A throttle cable is not going to wear out in 23,000 miles!! "Haynes manual suggests the throttle cables should be changed at 18,000 miles". I think it should have read "adjusted" instead.

There are 3 separate freeplay adjusters between the twistgrip and TB throttle butterfly shafts and that should allow you to eliminate all freeplay. Just remember, do NOT OVERTIGHTEN the TB cable adjuster locknuts, or you WILL break the threaded adjuster, requiring a very creative workaround repair -OR- an annoyingly difficult replacement of that cable assembly. If you hit another roadblock, resist the temptation to "wing-it" with trial-n-error and seek the help of someone nearby with mechanical motorcycle experience. That person should be able to preset a very close visual/tactile on-throttle synch (off the idle stops) with the right freeplay, before starting the engine. From there a water manometer will dial it in very close to perfect for under $5 in materials.


EDIT: To update to a better, faster photo host.

[billington92]

Thank you for your response, it is helpful.

To make sure that I have explained my situation correctly. I’m seeing between 4 mm and 7 mm freeplay at the throttle body, as a result of screwing my throttle body adjuster either fully in or out. Before undoing the lock on the throttle body adjuster there was no freeplay a the throttle body. This was after setting a gap of 1 mm between the lockwheel and adjuster head on both the choke and throttle at the handlebars.

So do I still need to change or the cables?

[Arbreacames]

As Rob stated, you do not need to change cables at 23k miles. And if you did, that would not be the easiest route that you are seeking.
What I can't understand is how the freeplay increased from zero to 4-7 mm by "undoing the lock on the TB adjuster". You are only using the cable adjusters rather than the throttle stops,right? Did you adjust the left or the right cable adjuster?

[billington92]

Hi Carlos, I now that my history of how the freeplay changed from 0 mm when the lock nut was tight to 4 mm -7 mm after moving the thread adjuster is strange, but this is how it seemed to me.

Please remember this is the first time I’ve performed this task on my R1150R, I’m prone to error like us all, I may not have been pulling hard enough when the lock nut was done up tight. I have only changed the right hand throttle body.

The left hand throttle body was also tight but I have not changed the lock nut position on this side yet, but I have taken a picture for reference. At first I thought there was 0 mm free play but then I managed to get 2 mm of free play with a strong pull.

I’m finding it a little difficult because there is an after market crash bar very close which means I can only get two fingers on the cable, which I have sprayed with WD40 to remove road soil.

However I’ve decided that tomorrow I’m not going to worry about what the Haynes manual suggests is the optimum free play at the throttle body. I’m just going to warm the engine up then simple have a go at changing the throttle body cable adjuster until I get an nice balance at about 3500 rpm then set the idle balance using the screw. This should be possible because before I made any changes I checked the balance at idle and 3500 rpm and they where only a little out.

[CycleRob]

billington92, It seems you do not have a clear understanding of the 3 adjusters as far as which one to turn which way to get a desired result. It is very rare that more than 1 turn will be required at the TB adjuster for a perfect synch unless the PO was a novice wrench, but up at the upper end of the throttle cable, 2 or more turns can be OK after a period of neglect. You do not say if you are using a water manometer, mercury carb styx or a TwinMax for the TB synch. If it was a water manometer, the wide variations in TB cable freeplay adjustments made will definitely suck the water completely out of the tubes before you can react with the kill switch.

[billington92]

CycleRob, I will be using a Morgan Carbtune, which has metal sliders. However I will turn the Carbtune upside down which is recommended for a general guide, rather than an accurate value. I think this is because BMW boxer engines create a vacuum which is outside the normal range of this gauge.

While I have been changing the right side throttle body freeplay I have not yet attempted to run the engine after the change to synchronise it. I have a general idea which side air screw or throttle body needs to change to make a gauge balance.

Thank you again for your help.

[CycleRob]

These words in my Aug 26th post above were carefully chosen:

"If you hit another roadblock, resist the temptation to "wing-it" with trial-n-error and seek the help of someone nearby with mechanical motorcycle experience. That person should be able to preset a very close visual/tactile on-throttle synch (off the idle stops) with the right freeplay, before starting the engine. From there a water manometer will dial it in very close to perfect for under $5 in materials".

Here is how you get the on-throttle synch very very close without starting the engine.
--Set the proper freeplay on the Left TB throttle cable.
--Stand on the left side of the bike.
--Place your left index finger on the left TB cable pulley and hold it there.
--Place your right hand on the throttle grip.
--Lean over the seat and look down at the right side TB cable pulley.
--Begin slightly rocking the throttle off it's TB idle stops.
--Notice the difference between what you feel in your left finger and what you see with your eyes.
--Adjust only the Right side cable adjuster until your finger and eyesight tell you it is the exact same part. You are done!

BTW, that differential water manometer (DWM) absolutely blows away the almost ballpark accuracy and high costs of ALL the other synch devices. This was demonstrated live-and-in-person to the few attendees of my last tech session AFTER the bike was perfectly set using a TwinMax. Started up immediately after that with that handsome white painted wood DWM with green tinted water it showed a 2 inch+ (51mm+) error at idle and an even greater error "on throttle". The most satisfying attribute of the DWM besides it's very low cost is that it is ALWAYS in ABSOLUTELY PERFECT calibration and "zero" setting, by virtue of gravity acting on water. No battery. Change the internal liquid color at your desire. It's only flaw is that sometimes it's hyper sensitivity requires another very low cost homemade device using 2 airtight glass bottles hose connected and 40% filled with plain or tinted water to get the idle and on-throttle adjustments close enough to use the DWM. Here is what I'm talking about, using 2 screw top wine bottles:


WARNING: Every OilHead/HexHead/CamHead rider should know that you should NEVER tamper with or adjust the blue painted throttle shaft stop screws to adjust the idle synch, or for any other reason. Doing so will FUBAR the factory set calibration that will require a savvy, trained (BMW?) mechanic using an accurate digital Voltmeter to set it right again.

EDIT: To update to a better, faster photo host and add water bottle picture.

[billington92]

Thank you CycleRob I’m glad God loaned you the talent to help me and thank you all for your kind advice. My bike is now fully balanced at idle 1100 rpm and 3500 rpm.

As a result of your help I have avoided the expense of purchasing new cables (circa £120 British pounds). So I have decided to use this money to replace the front tyre which is near to the end of it life.

What have I learnt from this? Well … you do not have to achieve all the Haynes manuals suggested levels of freeplay to synchronise your throttle bodies. “Going by the book.” Is a good axiom for life but you need to be discerning when to use your own rationale (or the collective knowledge of this forum) to achieve a solution.