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Cables / Bowden Box replacement


Rocer

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I've just installed new throttle / fast idle cables including Bowden Box on my 2000 R1100RT. I'm at the stage of adjusting the cables at the throttle bodies and trying to arrive at the "one click" balanced point. The clicking I'm hearing is from the Bowden box itself and not the throttle bodies as I was expecting. Does this mean I have over tightened the cables at the throttle bodies and so they aren't closing at all (ergo no clicking coming from the throttle bodies) or have I missed something? I adjusted the cables at both the handle bar ends and throttle body ends first to get 1mm slack.

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My questions on sync'ing the throttle cables went unanswered over the Easter weekend so needless to say I carried on. I was anxious that I had introduced tension on the throttle cables and once Humpty was back together again I would experience a fast idle. Well, as it turns out things seem sync'd okay cable tension wist (still have to fine tune with the manometer) but I have lost the range that the fast idle lever had before I started this project. There is no change in idle speed until the lever reaches the detent at the 3/4 point and so only a modest up idle after that. It suggests I've got slack but I don't know why as I'm pretty sure I matched what I was seeing as far as the connection in the original Bowden box.

 

Does anyone have experience with this situation that can shed some light on how to correct this? I'm praying to several deities that I don't have to take Humpty apart again to get to the Bowden box.

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Morning Rocer

 

IF, you are sure you have the cables installed correctly, & have FULL throttle cam travel from solidly hitting the idle screws to firmly hitting the WOT stops.

Have a bit of slack in the lower cables & a bit of slack at the twist grip (choke off).

 

Then-- just slide the rubber boot back on the fast idle cable (up near the fast idle lever end) & lengthen the cable a bit so you have the fast idle you need.

 

If you can't get the fast idle you need with a simple fast idle cable adjustment then you will need to go by the BMW service manual & properly re-set up ALL the main throttle cables.

 

The usual cause of what you are seeing (it seems to happen a lot) is starting the adjustment of the newly installed cables with not enough slack in the upper cable near the twist grip so the threaded ferrules at the TB's end up screwed too far in.

 

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I lost my fast idle when replacing throttle cables. Turned out that I had too much free play on the idle stops. The fast idle advances the throttle from the Bowden box, so if you have too much free play between the idle stops and your throttle cable, fast idle will not work. I ended up adjusting the throttle cable barrels at the throttle bodies.

 

This would mean that you would have to re balance your throttle bodies off idle. I like having the fast idle for when the engine is cold.

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Thanks Rich and Dirtrider. Too late home and too tired to go back at it this evening but will tackle it again in the light of tomorrow. I'll let you know how it goes.

 

When I was trying to synchronize the throttle bodies to click at the same time when the throttle was closed I was only hearing what I perceive to be clicking from the Bowden box itself. The adjusters at the throttle bodies are screwed in + 1/2 of their range so I gather that is too much and that's where I should start the readjustments.

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The clicking I'm hearing is from the Bowden box itself and not the throttle bodies as I was expecting. Does this mean I have over tightened the cables at the throttle bodies and so they aren't closing at all (ergo no clicking coming from the throttle bodies) ...

 

You can check this by simply getting under the bike and seeing if the stop screw is resting against the plate on the throttle body at idle. If there's a gap, your cable is too tight.

 

That said, it sounds like your problem is actually the opposite of that. You have too much slack in your lower throttle cables. Your fast idle is simply taking up the slack instead of opening the throttle bodies.

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Morning Rocer

 

If you are happy with your present cable travel & balance then why not start with adjusting the choke cable itself (slide rubber boot back up near choke lever).

 

Basically, once the boot is pulled back lightly pull on cable housing to see how much cable play you have. Then turn adjuster until you have less cable play & the fast idle you want.

 

IF, adjusting the choke cable itself doesn't give you enough fast idle only then re-adjust your main cables.

 

When setting the main cables start with the cable adjuster up near the twist grip (under rubber boot) I believe .5mm but check your manual. That will set your boden box cable spool position, then set the cable adjusters on the TB's. Make sure your choke cable isn't interfering with the main cables pre-adjustment.

 

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Morning Rocer

 

If you are happy with your present cable travel & balance then why not start with adjusting the choke cable itself (slide rubber boot back up near choke lever).

 

Basically, once the boot is pulled back lightly pull on cable housing to see how much cable play you have. Then turn adjuster until you have less cable play & the fast idle you want.

 

IF, adjusting the choke cable itself doesn't give you enough fast idle only then re-adjust your main cables.

 

When setting the main cables start with the cable adjuster up near the twist grip (under rubber boot) I believe .5mm but check your manual. That will set your boden box cable spool position, then set the cable adjusters on the TB's. Make sure your choke cable isn't interfering with the main cables pre-adjustment.

 

EUREKA!!! Had to take a couple of days off to recover from some "poorlies" after my first off road rally on the weekend but finally got back to the RT's lack of fast idle throttle range. Armed with Mitch's "Official - Unofficial R-Bike Tech Daze Manual", Keith's reference to "Baravian Workshop - Throttle Cable Seminar", responses to my HELP ME, HELP ME posts from Dirt Rider, Rich T and Jim Moore with added support and guidance from my neighbour I went back at this project.

 

Long story short (we spent a lot of time examining the old Bowden Box trying to determine if I had done something incorrect in hooking up cables to the new one) I had the two cables at the throttle bodies turned too far in. Once we backed them out we were able to re-adjust the other cables and now have normal fast idle cable range.

 

I was polite about it all the time 'cause I knew all you guys were looking over my shoulder. ;)

 

Thanks lots. I was so pleased to finish that project I replaced the side stand switch too. :clap:

 

 

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