Throttle is initially stuck.

[Henchman]

Hi all - Weird scenario here and a bit hard to explain....but my throttle is initially lightly stuck, it gives resistance when I first twist it. So I have to "break it loose" with the initial twist and then it's much better, but hardly perfect. So after i break it loose, it's much better but it still does not come on smoothly.   I don't like hoe the power comes on abruptly and I want this problem sorted out.  

 

I the throttle body apart and lubed the cables as best as I could, which wasn't great bc it's super hard to get lube inside and that didn't accomplish anything. The inside of the throttle tube itself is clean and feels very smooth when i twisted it around with the cables off. 

 

I also loosened up the cables where the attach to the throttle body and squirted some lube on return spring, but the problem persists. 

 

I'm thinking I'll need to do a proper lube job and/OR replace the cables themselves as this is the only other thing I think I can do.  

 

Any other ideas...I'm all ears.

 

Thanks!

[winddown]

Have you tried simply disconnecting the cables at the throttle and seeing if it rotates freely?  We often start by pulling apart something unrelated but it's easier to check the simpler subsystems first.  I did this one when I had a starting fault in a car.  Began by replacing the alternator, then the battery, it turned out to be clutch dust on the little shaft on the solenoid of the starter motor, preventing the gear from engaging the toothed ring on the flywheel.

 

Perhaps try loosening the housing up top where the cables go over the handlebar?  Give it a wriggle, see if it makes a difference.  Keep us posted ok.

Edited September 28, 2023 by winddown

[DT675]

I would also suggest as @winddown has mentioned.  I had a similar but opposite issue on my Yama Fj09- it would stick at WOT as you describe.  I checked over everything and found nothing wrong.  I then disassembled the throttle tube assembly (still found nothing wrong!) and reassembled it and it is now resolved.  I'm not sure what, but something had to be binding with the cables at the throttle tube assembly.

[random1781]

The glue from my aftermarket grips had broken loose at one point and the grip was rubbing against the switch assembly. Took me an embarrassing amount of time to realize that was the problem.

 

Aside from that, my cable seemed really sensitive to routing near the bars. Slightly different positions would cause it to stick a bit.

[Dougie]

Agree with the others. Might just be some shite in the grip if you’ve not changed them for heated, or re routed the cables after a service. 

[winddown]

Pro Tip:

Own two bikes, that way when one plays up you can sideline it and take your time diagnosing a problem.

[Simmons1]

My WR250R has been doing this for several years. A new throttle cable did not fix the problem. However, I started putting roughly an ounce per 5 gallons of marine two stroke oil in the gas periodically and the throttle hasn't stuck since I started doing this. 

Edited October 2, 2023 by Simmons1

[Henchman]

Ok guys thanks for all the input!..I'll take the throttle assembly apart AGAIN and perhaps also squirt some lube in there.

YES, @Windblown and @DT675these cables can be finicky so maybe I can loosen things up and reroute them for some good results.  

I  love the PRO TIP windblown!..I own 3 bikes with at least one of them always having this same damm problem! 

1 of them is a WR250r @Simmons1 but I don't see how adding oil to the gas would affect the throttle play? This bike also has a slightly sticky throttle but nothing like the problem here with my T7 that's need to be broken loose. It also came with a throttle tamer which is nice to have on that bike.  

I also just put new throttle cables on my ktm500 awhile back and that helped alot, but the throttle play on that bike is not what I'd call perfect, but at least it doesn't stick!:)

I do have Heat Demon heated grips @Dougie , new grips w/ NO glue...but they're not rubbing anyhwere.

[winddown]

Mods can always lead to issues, the heated grips are probably the cause, perhaps it's bearing down on the handlebar at a certain point.  I don't suppose you can revert and see if that solves it?  A lot easier than pulling out the throttle bodies I'd suspect.

[Henchman]

Yes understood @winddown...I took it the throttle housing apart again this AM. I manually pulled on the cable w/ my hand and still got the initial stick. So i pulled off the curved end of the cable so i could get more lube down there and was successful, but I bent the cable/housing where it inserts back into the curved part...so gonna need a new cable which i got on order... ARGH!

Then I played with the intake body where the cable attaches and also felt the STICK down there when i manually rotated the housing like the cable would do. SO...I'm convinced I have some sort of problem at the intake housing where the cable attaches at the far end of the cable.  

So my next step is to take the tank off so I can route my new cables.

To be continued....:)

[winddown]

Well you seem to be on top of it.  Keep us posted hey

[Henchman]

I'm happy to report that my sticky throttle is largely fixed with the install of a new throttle cable. I say largely bc there still a bit of resistance when I open the throttle but I believe this is coming from the throttle housing itself as I could feel this when I'd manually opened the throttle when the cables where removed.   I'm thinking this could could be normal with all T7s and perhaps why people complain about the power coming on too abruptly?

But it's a night and day difference so I'm good:)  

 

The new cable install was a bit of a challenge tho, so I removed the tank and also tied a pull line onto the old cable when I removed it, so I could easily pull the new cable through. But both removal and install was difficult as there is very room mid cable where it passes over the head of the engine. But I was able to get a screw driver in there and manipulate some of the soft parts in that area to create more space and a path to free the cables so I could pull them through in both directions.

 

Anyhow, it's great to have the bike back so thank you everyone for your help!:)

[DT675]

Great news! So do you know happened to the original cable? Splinters inside?

[Henchman]

@dt675...Well I thought it was fixed:(....the new cable made it feel as tho it was fixed but it still gets stuck after it sits for a bit. 

But like I said, it's just the initial twist that is sticky.

So, I'm gonna live with it as I can simply unstick it and ride!!!

[Hollybrook]

@Henchman did you ever investinvestigate what was causing the bond with the throttle body? 

[Henchman]

No @Hollybrook...i could kind of tell that the throttle body was the culprit. When I had the cable removed from it, I'd twist it and it felt sticky. 

I didn't know how to address this so I simply sprayed some lube on it and then installed the new cables.  

Strange problem that I don't have an answer for

[Hollybrook]

I think you would have to investigate the throttle body further. It could be something as simple as the shaft has bad lube on it, or there could be something worse going on. 

 

I would want to know what the problem was before riding the bike.  What it the throttle sticks when accelerating? 

[Canzvt]

1 hour ago, Henchman said:

No @Hollybrook...i could kind of tell that the throttle body was the culprit.

You have a sticking butterfly valve in the throttle body. It is probably gummed up with evaporated fuel deposits or possibly carbon - depending upon how many miles are on the bike, and how it has been used/stored. This was SUPER COMMON on the older bikes with butterfly carbs where the butterfly would stick, causing a very stiff initial throttle application, resulting in abrupt acceleration. The butterfly valve is a thin brass plate that rotates within the throttle body housing and controls the air flow entering your engine when you twist the throttle grip. Its position is monitors by the throttle position sensor which is attached to the butterfly valve shaft and is fitted to the right side of the throttle body assembly.

 

Pages 7-5 through 7-12 of the service manual (if you need a copy, dm me) explains how to remove, clean, reinstall and calibrate it if necessary.

 

Here's how you diagnose it... Remove the mounting plate, then remove the cables from the left side of the throttle body. This is the round wheel like device where the inner cable end is attach to. See arrow in image. It is behind this mounting plate. Once the cables are removed, gently try to rotate the wheel in a clockwise direction (when looking at the left side of the bike). If you feel the 'stickiness', you have confirmed the problem. If you do not, then your problem is in the cable/throttle grip assembly.

[Henchman]

Yes @Canzvt this is my problem...I didn't have to remove the mounting plate (Black triangular thing right?) when I installed new cables, but I did rotate the wheel (where the cables attach) before I installed the NEW cables and I could tell it was indeed STICKY.

I have the manual so will check out the cleaning process.   

My bike only has 6k on it but I use it somewhat regularly like 5x/week.

I'll get into it!

Thanks

[john_aero]

If there has been mods to the throttle I would do the following as other said

 

1 - go back to stock, original throttle tube and grips if have them

2 - clean the throttle tube and lightly oil to ensure no crap stuck inside there

3 - check throttle body lower down to make sure cables are free and also not getting caught there

 

Just re read topic and see its at the lower end where "sticking is"

 

4 - Check for a fuel additive to clean any gunk or ethanol that has built up around throttle vale.

 

A note on the "oil" in fuel. This would help free up a sticking throttle body valve 

Edited October 24, 2023 by john_aero