Throttle issues after Motobox install

I did search on the issue but didn't find anything. Admittedly my search skills suck so I apologize if this is a common question. So I installed a Motohooligan Airbox and removed the SAS plumbing yesterday. Everything went as planned except my throttle now stays in the open position unless I manually return it to closed. When I manually open the throttle at the throttle body it automatically springs back to the closed position per normal operation. There's noticeable slack in the cable but I couldn't tell you if that's normal or not. Just to be clear...it opens fine, but will not return unless I manually close the throttle. Before I go and create more problems for myself I'd like to know if this is typical after removing the throttle bodies for maintenance, etc. Does the bike just need to reset or do I actually need to adjust the cable tension? I don't have a TuneECU at the moment so I wouldn't be able to set throttle stepper motor to the basic position.

I had zero problems prior to the Motobox install.

Can you take a pic of how you have the cables installed in the linkage on the throttle bodies?

The throttle tube has two cables to operate. Open and close.

It sounds to me like there is some problem with the cable routing not with the throttle itself. Did you remove the cables from the throttle body when installing? I didn't, I just lifted them clear of the frame to work and then put them back. Maybe you inadvertently twisted them as you put them back and so there is too much friction for the return spring to pull the cable and shut the throttle grip?

Good luck in finding the solution. Must be frustrating not to go out to test the new set up. Remember, you really need to remap the air/fuel mix to get the best out of the free breathing set up or risk running too weak and damaging engine. Either with a Power Commander and custom map or with the Tune ECU and do it yourself.

If you used the instructions that you can down load from the MH site then you looked at the pictures of my bike when I was doing the install all those years ago. I was so impressed with what Aaron was doing at Motohooligan that I offered to photo my experience when I fitted the box and I took those pictures and wrote the instructions and put together that PDF document for him.

I think it helped a lot of people fit that box! Hope so.

Glad to see that people are still using it!

Yeah man, I used the hell out of those instructions. I literally went step by step using your pictures. Thanks for putting that together for us mouth breathers.

You may have snapped the return cable or pulled it out of the mounting at the twist grip - pull on it at the TB end to see if there's any resistance.

So what happens when you pull on the return wire (not outer tube)?

When I pull on the return cable at the TB it eventually closes the TB. It's hard to do because of the weird angle I have to pull the cable from.

When I do it from the throttle end (handlebars) the cable still tracks as if it were functioning. It just won't do it without manual help.

looking at the TB end you're almost at the end of the adjustment - it MAY have partially snapped inside the tube, because steel cables are twisted strands, if some are snapped, the remaining ones will straighten out and as a result the cable *will* get longer.


It's a possibility anyway, i went through loads of clutch cables on my old blandit and they showed the same signs prior to snapping all the way through

Talking at cross purposes - fully open throttle at twist grip and let go - you're saying throttle doesn't close and stays open - if so, then pull on return cable at TB - does it return twist grip to fully closed position?

I just double checked for my own sanity. Throttle stays open and I return to the closed position by pulling on the throttle cable at the TB.

What happens when you open the TB flies by turning by hand the cam to which the throttle cables are attached?

It's no bit deal to remove the cables from the TB - unscrew the nuts either side of the slotted TB brackets, pull cables out and unhook cables barrel ends from TB cam - without cables attached, turning TB cable cam by hand will show you how strong the two TB closing springs are (or not....), mechanism should snap shut when released.

Looking at your photos, both open and close cables are way too slack but don't understand how/why it was OK before but not after - are you sure that you haven't bent the link bar or interfered with something else when you 'suspended' the TB?

So when I open the TB cam without using the cables it snaps shut right away. It works fine without using the throttle/cables. The spring tension is good.

I didn't mess with anything else prior to installing the airbox. The bike has less that 5000 miles on her so everything was still in tip top shape. I must have fooked something up when I pulled the TB off. I'll remove the cables and then reinstall to see if anything changes. At this point I'm thinking it needs to go to the shop.

I'll go ahead and start stretching now. Might as well limber up for the ass pounding I'm about to take.

So when you fully open the throttle at the twist grip, flies fully open - you let go twist grip and it stays in fully open position - do the flies stay in fully open position or do they snap shut when you let go of twist grip?

When I open the throttle at the twist grip the flies open and remains open until I manually close them with the twist grip. The secondary flies don't move but I'm sure that normal....right?

The bottom of the original box is pretty big so I give you permission to punch me in the face if I ever miss something like that. I reassembled the box and its already sitting in storage. I'm going to remove the Motobox tomorrow to see if there's anything glaring that I missed. I'll let you guys know if I happen to resolve the problem. I can't tell you how much I appreciate your time and insight, especially No. 47. Thanks gents.

Fixed it! I basically tore everything down in an attempt to recreate the "crime scene." I even hung the throttle bodies again to see if I accidentally put excessive strain on the throttle cables. Nope...if anything I only created slack in the line. There's no way I pulled on those cables.

I then decided to completely remove the throttle tube and then reassemble. As soon as I slid the throttle tube back over the bars and up against the on/off switch the throttle snapped back like it should . I have NO idea how this happened during the install process. I'm currently on crutches so maybe I grabbed the throttle to support myself and yanked the shit out of it in the process. Who knows...its fixed now and I'll be able to sleep tonight. Thanks again for the help.

Hurray!