RPM drop at idle and throttle closure when hot

[rainycoastguy]

A problem has shown up on my 2002 Tiger.  At 56,000 KMs it has always run well, but now it is giving me a headache.  

From cold the bike starts with no problem and runs with no problem.  If I shut it off and start it again before it has cooled off, it fires up and runs up to the 1200 RPM idle speed then drops to 500 RPM and below before recovering.  Sometimes it doesn't recover and dies.  If I rev the engine and let go of the throttle the same thing happens.  However, if I control the idle with the throttle the problem disappears after a minute or so.

It has had less than a thousand kms put on it since a major service at a dealers, but that was about 18 months ago and I haven't been able to ride it until recently.  It was stored in a heated garage and started up monthly during that period of time.

Any problem solving suggestions will be more than welcome.

[Timbox2]

very similar issue to what I was getting, mine was a dodgy idle control valve stepper motor

[rainycoastguy]

I have replaced the stepper motor, the hoses, and the throttle body gasket.

[Bixxer Bob]

Dying when hot, running fine when cold, sounds like crankshaft sensor,  do a search, here's just one of many posts on the subject:

http://tigertriple.com/forum/viewtopic. ... aft+sensor (http://tigertriple.com/forum/index.php/topic,7767&highlight=crankshaft+sensor)

[blacktiger]

Mine does exactly the same. Most often after stopping for fuel but not every time so I'm not particularly bothered. Should I be?

[Bixxer Bob]

If it's the sensor, it'll leave you stranded when it finally gives up.  I don't know of a way to check the sensor at the moment - probably would need a scope.  I'm still away from home so can't be more help for now.

Just arrived home and read this again over a cup of tea.  Ignore what I said earlier.  The crankshaft sensor symptoms are starts and runs fine when cold, dies on the road and then won't start when hot until it's cooled down, then starts again normally.