Rough throttle pull action

[keelerb]

I've got it, on an 84 R100RT.

It's not the carb springs, nor the throttle cables, nor the throttle twist grip, nor, as far as I can tell, the cogs that mesh between the throttle twist grip and the chain that pulls the throttle cable.

Rather, as far as I can tell, it seems that the little "carrier" at the end of that chain is rubbing against the housing it rides in.

Thus, I feel the roughness when I pull the throttle open, and it doesn't snap closed - rather, it will rather leisurely close over the course of a second or so.

Anyone ever run into this? I am wondering if I could relieve the carrier and/or the housing with a dremel to cure the interference, if such it be, but I'm not 100% sure of my diagnosis. Seems a bit odd for a BMW - precision fit parts and all that.

Thanks folks - BrianK

 

[moose738]

Delay the Dremel

Hello Kellerb - I wouldn't be in a hurry to dremel the hardware. Things should work just fine if nothing is cracked, broken, lacking grease, kinked throttle cable etc.

From your posting I was unsure whether you had actually disassembled all the items you described. I'd suggest disconnecting the cables from the carbs and cleaning, greasing, and reassembling the throttle assembly at the handle bar. Then rotate the throttle grip back and forth while maintaining a slight tension on the bare cables with your hand. With the cables disconnected from the carbs, you will have plenty of bare cable to grab up at the handle bar.

That should tell you if your throttle assembly is OK.

Good luck....John

 

[keelerb]

Thanks John.

I can physically feel the roughness originating from within the throttle pull assembly. I can't reproduce the effect with the cover off, so not 100% sure but it sure does seem like the carrier is rubbing.

I'll keep at it....

 

[pglaves]

I've got it, on an 84 R100RT.

It's not the carb springs, nor the throttle cables, nor the throttle twist grip, nor, as far as I can tell, the cogs that mesh between the throttle twist grip and the chain that pulls the throttle cable.

Rather, as far as I can tell, it seems that the little "carrier" at the end of that chain is rubbing against the housing it rides in.

Thus, I feel the roughness when I pull the throttle open, and it doesn't snap closed - rather, it will rather leisurely close over the course of a second or so.

Anyone ever run into this? I am wondering if I could relieve the carrier and/or the housing with a dremel to cure the interference, if such it be, but I'm not 100% sure of my diagnosis. Seems a bit odd for a BMW - precision fit parts and all that.

Thanks folks - BrianK

No grinding should be needed. As you surmise something is wrong.

Your post rules out all the common causes. So - recheck all of that. Then carefully examine the gear on the chain. Examine the underneath side for roughness, and inside the bore on which it pivots. Also verify that you have the correct part for your bike installed. Two cable model? Single cable with the wrong part?? Sticky splitter?? Missing spring washer from on top of the gear??

I don't know what else to say. It isn't supposed to happen. If the parts are correct, are properly lubricated, are properly installed, and not worn it won't happen.

 

[James.A]

I agree with Paul, especially on the hand set thing. These things are more often neglected than an under-the-tank master cylinder. Hard to believe, but true. And once they get hinkey, they go from O.K. to impossible almost immediately.

 

[keelerb]

Thanks guys. You're right, time to dissassemble and find the root cause. Will do! - Brian

 

[paulfinney2]

Is the throttle screw engaged?

 

[keelerb]

No throttle screw on my bike. There's a hole for it but it (or its plug) must have fallen out.

I have to plug that hole to keep moisture out. Anybody know what the thread size is?

Thanks - B

 

[keelerb]

PS, I did dissassemble, lube the splitter, check cable routing, re-lube throttle gears and tube and reassemble - still some roughness but much improved.

Thanks for all your help folks.