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Throttle tube sluggish to return to idle

Salishmoto

Just got it firing!
Joined
Aug 17, 2021
Messages
21
Location
Olympia
Been working on it all morning and now throw up my hands. I've spent the entire morning trying to eliminate friction in my throttle assembly and though it seems I have done so, when I put it all back together the throttle sticks and at best is sluggish to return to idle. Let me list what I have done and see if any of you have any insights. I'm installed Oxford Heaterz though that seems less of an issue.

The cables themselves move very freely in their sleeves. I took the housing apart and freed the cables from their connection and they move very easily by hand, with no evident sticking. I move the throttle body and the springs seem strong and there seems plenty of pull.

On the bars, I found a little roughness and used 400 wet dry to lightly polish the bar to smooth. The throttle tube itself is cleaned and smooth. I've lightly lubed the bar and throttle tube with dry graphite spray. I've lubed the housing lightly where the throttle tube revolves within, and there is no sign of wear there.

I've adjusted the cables to seem right, with the pull cable adjusted to have idle right at 1100 and not more. The return cable is slack, and here is a strange thing. If the return cable is slackened all the way, and the Heaterz are not slid onto the throttle tube, then the tube itself will snap back to idle seemingly fine. But if the return cable is tightened at all, even a few turns from dead slack, the whole assembly binds and won't return if the throttle is opened. Ok, fine, I cannot for the life of me figure out why that return cable being tight causes the whole assembly to bind, but it does.

So I go ahead and put on the Heaterz and for whatever reason, though it is touching absolutely nothing!, it causes some friction in the system and the throttle tube is sluggish to return.

I cannot figure out what is happening. The throttle springs are untouched and seem strong when you open the throttle by hand at the pivot wheel. There is no friction in the cables. There is no friction on the bar. There should be no added friction with the Heaterz, and no it isn't the cable binding or anything as I checked that 100 times and ways.

I'm more or less cutting and pasting this from the advrider forum to see if there are folks here with any other ideas and can't get rid of the black background, sorry.

I'm at a loss. Any insights?
 
One thing that sticks out is that you say you adjusted the throttle cable for idle speed. That's not right, there should be idle adjusting screws on the throttle bodies.
Another thing I can think of in case you have grips with a closed end, is that the grip could rub on the handle bar when pushed on too far. Check if your handle bar is not sticking out further than the throttle. Or if you have bar ends, could the grip be rubbing on that? See what the throttle does with the return cable eliminated?
 
I wasn't adjusting idle with the cables, only making sure the pull cable was not too tight, which causes elevated idle. T'hat cable is just a hair slack at idle. And I thought the same thing about rubbing somewhere with the grips everything is fitted just fine. The throttle tube is flush with the end of the bar, per normal, and there is no rubbing whatsoever between the throttle tube, grip, or bar ends. I checked that 100 times. It's either something in the housing, or I don't know what. And I can't see anything in the housing being the cause since it is all properly assembled and lubed.
 
Update: After fine tuning the cable adjustment tension and after everything else I've done today, it is now snapping back just great with only the Heaterz grips on. Snaps back with that nice solid "clank" of the throttle bodies closing firmly. However, I've learned that when I put my cramp buster onto the grip, that alone causes too much friction somehow and makes the system stick. So, at least part of my problem is that the OEM throttle tube, which I've found is quite thin, and especially after sanding down the ridges a bit to get the Heaterz grip on, lacks the rigidity to resist the compression forces of the cramp buster, and this causes enough friction with the bars despite everything being polished and smooth, to prevent the throttle from closing. So now I am wondering if there are aftermarket throttle tubes that might be firmer and resist this compressing force. I love solving problems and appreciate your questions and suggestions as I've worked through this.
 
Thanks for the info. I'm installing Oxfords on mine pretty soon. Any additional tips for the removal of the OEM grips and installation of the Oxfords? Did you get the adventure-style grips?
 
I did indeed get the adventure style, and don't make my mistake and trim them. They do not need to be trimmed as I mistakenly thought they needed to be flush with the bar ends but our bar weights have a good portion that sticks out from the end of the bar before there is a lip. Getting the old ones off was easy with a flat blade screwdriver worked under the rubber bit by bit and squirting liquid like Windex under there until you can begin to rotate the grips and pull them off. The wiring was easy, and you do NOT need to remove the tank or anything hard. Just route the wires along the frame tube and out under the tank up by the triple clamp area. And I squirt ACF50 into all those wire connections to prevent corrosion.
 
I did indeed get the adventure style, and don't make my mistake and trim them. They do not need to be trimmed as I mistakenly thought they needed to be flush with the bar ends but our bar weights have a good portion that sticks out from the end of the bar before there is a lip. Getting the old ones off was easy with a flat blade screwdriver worked under the rubber bit by bit and squirting liquid like Windex under there until you can begin to rotate the grips and pull them off. The wiring was easy, and you do NOT need to remove the tank or anything hard. Just route the wires along the frame tube and out under the tank up by the triple clamp area. And I squirt ACF50 into all those wire connections to prevent corrosion.
Awesome thank you!
 
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