Throttle binding

when I twist the throttle it binds or feels like it is catching on something at the half way point.
I have taken off the housing on the handle bar and everything looks okay.
I have a 2008 WR250X

Any suggestions as to where the problem might be?

Determine whether it is caused by the parts on the handlebar or caused by the throttle cables.

Common causes are a damaged throttle tube (plastic part the grip slides on to), the grip rubbing on the handlebar (often caused by a damaged throttle tube), or the whole throttle assembly being mounted on the handlebar too far to the left (removing needed clearance between the parts).

Disconnect the throttle cables from the parts on the handlebar, put the parts back on the handlebar without the cables connected and twist, looking and feeling for any friction or hang-up.

Pull the cable that opens the throttle with your fingers.
Any binding?

It appears to be the throttle cables.
On my 250x the housing for the throttle assembly has a nib that fits into a hole in the handle bar which gives you proper alignment.

With the throttle cables out of the housing I can feel them bind when I pull on them.
I have the gas tank off and looking at the cables and everything appears to be okay.

To give you an idea of how bad it is, at 3/4 throttle I can take my hand off the throttle and it will stay there.

The bike only has 2100 miles, it is a real puzzle where it could be binding.

Try squirting some thin lube (WD40, Bel-Ray 6-in-1, etc.) down the cables.
One of those neat cable lube tools is what I've used for 30 years.

This is not looking good.
Is it possible that the actual throttle body butterfly is binding?
I have read some threads on ADV that talk about the TPS being so out that it causes binding in the TB shaft.

Is this possible?

The two cables attach to the throttle body wheel, I can turn the wheel with a screw driver (by pushing it) and at the half way point it will not return to the original position. You have to pull a cable to get it to return.

So...I cannot tell if it is a binding cable or a binding throttle body. Very frustrating

As mentioned by YZEtc, you will need to just keep isolating all the relevent components to find the source of the binding.

I'd say that your next step is to remove the cables at the actual throttle body to be able to move the TB on it's own - if there is still that tight spot, then you could then try removing the TPS. I have also read about this as a possible cause of "seizing up", but usually only after people have been mucking around with the TPS adjustment....

In any case the first step of isolating the cables from the TB should be easy enough to see if the "binding" is at the cables or TB.

Cheers.

I will try removing the cables...if that is possible without a major tear down.
It is a very tight space in there !
Getting them off is one thing....getting them back on may be tricky.

I have only found 1 real post where someone had a similar situation. Their throttle started binding at about half throttle, I think he solved it by adjusting the TPS.

Have you installed bar risers recently? Does it happen only with the wheel turned or all the time? The reason I ask is because if the cables get pulled tight they will bind.

The bike is bone stock, no risers etc.
I actually just bought it last week. I knew the throttle was sticking when I bought it but didn't think much of it. It had aftermarket hand guards so I thought that was probably the reason (or some other easy to fix reason)

It is rideable that way but it still must be fixed

PROBLEM SOLVED

It was the TPS that was causing the throttle to bind.
I first tapped from the top...it got worse, I then tapped the TPS from the bottom and voila..the throttle operates as smooth as normal now.

It must be kind of rare because I saw it only mentioned once in my searches...hopefully this helps others.

Hey mate that's great that you have been able to narrow it down to the TPS, but it may also be a good idea to check the TPS settings in DIAG MODE for fully open & closed positions. This may let you know if a previous owner has adjusted the TPS incorrectly and gone over the 99% WOT limit. ( As i've mentioned in my 1st post, i've also read about this possible "binding" problem due to an over adjusted TPS setting ).

On my bike the TPS was set at 16~96 from factory, it's now set at 19~99, and all good. ( 1st number is the closed throttle position & the 2nd number is the Wide Open Throttle position. Readings are refering to % open ).

Also are you convinced enough from your "tap repair" that it was actually the TPS causing the bind. By this i mean that it could have also been a possible sticky throttle shaft / butterfly, which became free when you were tapping at that area. Once again this is why i mention to check the actual readings of the TPS settings in DIAG MODE, as this may point to a possible adjustment problem. Again for this model it's not a "known issue", being from the 100's / 1000's of regular forum members, for the TPS to just suddenly jam up, let alone have any "common" problems.

Anyway best regards to you if it actually is all good with the "simple" fix, but i'm just suggesting to "tick the box" for correct TPS adjustment as well.

Cheers.

 

Good advice !
I will check the TPS settings, I did find a thread on how to get into diagnostic mode so I will give it a try.

Just so I have it straight...in diag mode it shows a readout with the throttle closed and another readout when you open it up? this can all be done with the engine off.

I gather you do not want a reading of 100 with throttle open.
Is the optimum 16-99 then? I do not have a full shop manual yet so I am relying on internet info.

I will try and check it out today.

Thanks for the help

Just checked my TPS setting and it is 15-97
Is this okay? Factory is apparently 16-96.
Anyone one else change their TPS with noticeable results?

After reading numerous posts some claim a big improvement others don't notice much difference at all.

I am still puzzled about why my TPS setting would go so far out as to cause throttle binding.