After 320 very happy miles since picking up my 996s I rode it to the pub last night with a mate and all was good, getting back on to ride back and the throttle won't twist more than about 1-2cm. I could get it home with very slow acceleration. So any ideas, common problem, diy fix, where do I start investigating ?
sounds like either the cable has jammed/fraid or the twist grip has, also check the actual rubber grip i had one move up the thottle and stuck against the cable housing. failling that check the throttle body end, there quite a simple system shouldnt be to hard to find.
More likely to be a cable jam, as has been mentioned it is a very simple single cable operation but if you get slack in the cable it can jam in the housing. You can take off the top off the throttle assembly and also the angled piece to check for fraying or jamming. Simple enough job to replace the cable if need be. If you are using the fast idle button under the housing check to make sure you have the cable properly adjusted or it won't raise the idle speed.
Thanks gents appreciate the replies and sounds like it could be a simple fix. It's interesting you mention the fast idle button as when in use it barely fast idles so maybe needs adjusting. Is there a bit of an idiots guide to adjusting the cable or taking bits apart around that area. I'm ok at these type of things if they are simple but any upfront knowledge is always useful !
The cable needs to have virtually no play to get the fast idle button to work properly. If you take the throttle housing apart it's quite self evident. Cable play is adjusted at both the injector end and also at the handlebars make sure you have either way adjustment on both to make life easier. It's possible you may need a new cable especially if there is any sign of fraying. Look carefully around where the throttle bends and also at the adjuster where the injectors are as they go there sometimes.
Thanks for all the advise so far, took the throttle housing apart at the top today and all looks ok, traced it down to the right hand side (with panel off) and released the cable from it's housing and it all looks ok and pulls very smoothly through and back top to bottom. The twist grip is as expected also. I'm sure it has a more technical name but I assume the "gold widget" that the throttle cable plugs into should turn freely ? Mine will pivot but with a lot of effort and is not fluid in it's motion, it snaps up with the force (using fingers) and then has to be snapped back down again. So what next do we all think ? Gold widget
The gold 'widget' is the throttle cam, it opens the butterfly valve in that throttle and using the link arm the one in the rear and it should snap shut when released, it is not shut now without the cable on it so is not returning properly. Could be a broken spring? but I have also seen the screws that hold the 'butterfly' onto the shaft come loose - they shouldn't fall out (and get sucked into the engine) because they are peened over to prevent this but if they are loose the plate can move and get stuck in the throttle, alternatively it is not unknown for the bolts in the front bracket under the tank to fall out (if tank is still secure then at least one must be still in place). If this happened it could (hopefully) jam in the throttle mechanism, I say hopefully because if it passes through and gets into the intake valves then you are looking at a big repair bill! You need to take the tank off to investigate and don't run the engine until you know what it is, hopefully it's something simple...
Agree with the above advice. Something could have got stuck in a throttle butterfly to jam it. It could only be one of the bolts mentioned or maybe a small animal sucked in. Good luck with finding the cause.
Ok thanks guys, is taking the tank off tricky, does it need to be drained out first or anything, and will I have a clear view of the throttle butterfly when it comes off ? The throttle cam will open and shut but as I mentioned it takes some pressure and is not a smooth motion so it's not completely jammed or anything.
One bolt to the rear then lift the tank slightly and remove the two fuel quick connectors, you will see all you need then. No need to drain the tank. Steve
Just to add to the above, do you know if you've got an ITG one-piece aftermarket air filter and have you experienced any coughing/misfiring lately?
Tank removal is easy, remove the bolt at the rear of the tank (need to take the seat off first) then lift the rear of the tank slightly and unplug the pump connector and release the fuel lines - there is a small button on the side of the fittings and they slide out, the tank will then slide slightly rearwards to release the pin at the front from the hole in the airbox (this is the bracket that could have lost a bolt). You may need/want new 'O' rings for the fittings once out as they can get damaged and leak. You don't need to drain the tank but it is much if you do at least that it's not full, because 17l of petrol doesn't make it any easier. Once off you can look straight down the throttles into the intake valves Also just thinking now that you if your bike has an (aftermarket) undertank air filter this could have been sucked into the throttles causing the jam, if so be grateful it didn't jam at full throttle...
From your description another thing could simply be the pivot shaft jammed in the throttle body. I had that happen on a Triumph TR6 car. The throttle got slowly stiffer. I say this because the spring looks a bit rusty. It's two dissimilar metals. Make sure you check all the points Duke Desmo said though
You also need to remove the fuel tank vent hose when removing the tank, disconnect the long pipe that runs down the nearside of the engine. The rest is noted above.
Ok so next installment and again thanks for the help so far......... Tank off and I was kind of pleased to find the ITG filter thinking that could be the issue as described but the filter seemed well connected to the bodies and was actually quite tricky to remove. But having removed it the action on the throttle cam is exactly the same, I have taken a pic of the bodies open and closed, but the cam's action has not changed in it's sticky feel..... So where do I go next ? Tried to pic the bodies open and shut
Worth spraying all pivots and both ends of butterfly internally with penetrating spray etc for starters just to see if it improves matters. If either of the ball end joints at each end of the rod linkage between butterflies become partially seized then the symptoms are similar.
In your first picture it looks like the linkage has come off . It goes from one throttle body to the other and yours dosent seem to be attached properly . Maybe not though.
I'd be taking the airbox off to investigate properly, that way you can see everything in it's working state. Not a big job but in itself if you're confident enough.
