Bike is idling at very high rpm.

After driving home from a friend tonight, something weird has happened.

I accelerated hard and when it was time to slow down and turn, the bike kept up a high rpm.
The throttle feels the same, but I'm not sure if it drives right throughout the rpm range, as I was going through the city, and had to keep it in the lower gears and brake, to not go too fast.

It does about 80-90km/h in forth gear without touching the throttle.

When I got home I turned of the bike, and when starting it again it's the same high rpm.

I have the Cobra Fi controller and DIY TRE installed, but don't think these can do this. Unless the controller is throwing fuel into the engine.

Any ideas what I should check for tomorrow ?

The obvious is to check if the throttle inlet is stuck at part open, but anything else ?

Check the Throttle cables, in the housing too?

Yes check at the end of the cables. Could be a frayed cable possibly. Could be a dodgy TPS, unlikely. Probably a leaking vacuum issue though, are the lines on correctly try, not loose?

Thx guys, I'll check the cables.

I have removed the pair valve and blocked the ports, what other vacuum lines are there ?

Started the bike cold, still high rpm.

Checked both cables, they are fine.

Checked the PAIR valve block off plates in the heads, they are nice and tight.

Removed the tank and could see the primary throttle valve shaft did not return all the way to the idle position.

Removed the intake snorkel and...........  

This is what I found 



The greedy bastard had tried to suck in the piece of foam, I used behind to cone filter in my attempt to make it a snug fit.

Now I just need to find out if blocking the secondary throttle valve, did damage to the STVA (Secondary Throttle Valve Actuator)

DocSjulle wrote:

The greedy bastard had tried to suck in the piece of foam, 

  Glad you got it sorted Kim 

I decided to check the STVA for damage by pulling it from the throttle body, and taking it apart.

To do this I had to remove the secondary throttle position sensor, and that is a bitch to put back in, but more on that later.
REMEMBER to mark the position of the STPS on the STVA, otherwise you will have to calibrate it afterwards.




We are in luck with the STVA, as it is kept together with screws and not rivets.




Another lucky thing is that it used two metal gears instead of plastic, and it was in mint condition.



Now came the hard part, installing it back in.
It is not possible to install the STVA with the STPS in place, and there is not enough room to put the screw holding it in place, after the STVA has been installed.

After I spend about 30min on this, I decided to loosen the complete throttle body.
Success, it moved the whole assembly up, allowing room to put the screw in.

Everything is back together and the bike is perfect again.

Pleased to read, all is well. Must of been an extraordinary worry at first.

Nice one Kim, glad your sorted.

Excellent piece of work Kim, well done, and documented.

Someone I know bought a non running 1978 (I think) Kawasaki 750 Triple as a non runner, it had done 4500 miles from new and still had the original tyres. Started to take the carbs off and found the foam air filter had been sucked into the carbs (mind you I think the foam had turned into powder), he sorted that out and gave it a good service and it ran like new. When he took it for its MOT he got offered 20k for it


Its very often the stupid little things that catch us out, the vacuum from a carb is stronger than you think, when I was testing my vacuum gauges I connected them up to the wifes hoover and it did not read as much as the carbs were sucking!!

Nice one Kim .... glad you got it sorted & shared your findings !

Careful Andrew .... if your wife sees your test results she will be after a new 'Hoover' ......
..... or worse still borrowing your bike to do the hovering ! 


    Yam

Well done Kim, excellent result and great photos and description

Interesting, as much as I like the idea of playing with carbs again THIS makes me sooo glad I have Fi!