Throttle Stuck Open 1998 M600 DARK CARB

[dr chris]

Hello, I was coming home last week in the pouring rain and when coming to a stop at the lights found the engine just kept screaming at full revs with the clutch in.

The only explanation would seem to me to be that the throttle was stuck open, meaning that the return cable had snapped and, simultaneously the mechanism was too stiff for the spring to close it down.

I've had it all in bits today and can't see anything wrong at all. The open and return cables are fine (i've tried putting my finger in the throttle body to obstruct the butterfly as it closes and pushed against it via the handle bar grip and there is no stretch or play). The mechanism doesn't appear to be stiff at all, nor is the return spring damaged or corroded.

I'm at a loss as to what could have caused this to happen? I can see others on the forum that have had the same problem but there doesn't seem to be any good explanations out there.

Any ideas?

[He11cat]

Mine did this the other week .then it seemed to be ok . I rode on and it did it again in traffic the exact symptoms your describing.
I called out recovery at it was getting so so hot.
Bike didn't do it again recovery bloke said nothing wrong with it!!!
I tried one more time and with in 3 miles it did it again!

The next day it got really bad.
It wS screaming it's nuts off poor bike. Went from imtermitant to all the time!
My throttle seemed to work but has always been a bit tacky.

It turned out there was a very slight kink in my return cable nothing really noticable either but enough to upset things. Wear and tear I'd say as my bikes the same age and a carbie like yours!

Replace the cables and all should be good again.
It's a faff as you hVe to take off the airbox and the lock to get the airbox out so you can get in at the carbs.

Cables are not expensive and I'd replace both the throttle and return at same time.

It scared me when it did it! I was in a traffic jam at one point and my leg was getting a tad hot!
Hope that helps

[gary tompkins]

Could be early onset of carb icing - I had it happen several times in the rain on my 600. The main jets ice up holding needles in emusion tubes, and stopping CV piston slides from dropping.

Once I exited a motorway at 70mph and couldn't slow down. Had to pull clutch in an coast to hard shoulder with engine screaming before hitting kill switch. Left it standing for a few minutes and it was running fine again.

Try running silkolene pro FST in fuel

[Blufoot]

Try running silkolene pro FST in fuel

i second this

[He11cat]

Mine had it in already . I had that in the petrol anyhow as matter of course after last winter!!
My bike at first was being very intermitant and got worse as it got hotter and seemed to be ok for a few mins or a few miles when it had cooled down. Soon

Is the bike doing it as soon as you start up or after a short while of riding ?
Mine got worse over 2 days.

I'd taken it out for a 40 mile ride and it was fine 2 days later all wAs not well!
Worst of all was my bike was loaded up with camping gear in the rain ick!!!

After the return cable was detached the screaming stopped.
Now it has fresh cables I took it for a ride on a parky day for an hour and all is well touch wood!!!

[Scott1]

I've had two M600's and they have both done this, it seems to be completely random as it was winter with one and this summer with the other, both times it went away after adding Pro FST and cleaning the air filter and air box out, the air box had a bit of residue in it both times.

The only thing different after it went is that my bike now has a slightly higher tickover.

[He11cat]

Mine was def cable as the airbox and airfilter was very clean and when the return cable was disconected the problem stopped.
It's quite alarming when it happens.

The first time mine was fine until 3miles down the road.
Then it did it.

At first intimitantly day 2 from the moment I started it it screamed like a banshee!

Try all the other things first I guess pro FST and all that.
Then if it does it again look at cables.
Mine was cable as when it was taken off it stopped.

When the new cables where put back on it has been ok since

These bikes like to scare you don't they!!

Saw Gingers
brake calliper prob and my rear did the same and left me stuck in the fast lane!!! DUcati's gotta love them even when they try to maim and kill you lol!

[dr chris]

I'll replace the cables tomorrow and will let you all know if it does it again. They are most likely over 12 years old!!

It's only done it once for me and I've not run the bike since as the battery went flat when trying to restart it (difficult with the throttle wide open!).

Has anyone here had their engine cover's repainted by theway? All the origional powercoat on mine is blistered and peeling off !

[dr chris]

Replaced the cables yesterday, lubed up everything, and it ran today no problems .... finger's crossed that's the end of it.