1500RPM + on overun? Hot start?

[Tav]

Issue:  When I lift off throttle at say 3000rpm and put cluch in the revs don't return to 900-1000rpm idle position.  They will instead drop to 1500rpm and hold there for about 10 seconds (clutch still in at this point to test) before finally going back to 900-1000rpm idle.  Issue only seems to be apparent once car is warm.  Once it starts happening it'll do it almost evey time.  I don't coast but I notice it when dipping cluch for speed bumps where I'll stay in second but ride it a little on other side.

Solutions:  I thought it might be throttle closed switch on TB.  Will need to check this tonight.  I tried rulling it out by waiting for revs to get to idle with clutch in doing say 30mph downhill.  Then popping it into second and letting revs rise to 3000rpm but not using throttle.  Finally dip clutch again and see if they fall to idle or 1500rpm.  It was almost 50/50 as to whether they stuck or dropped.  Not very conclusive...

New blue temp sensor in.  Checked c02 pot.  Earth straps good.  It's over fuelling a little but not 100% sure why yet. 

Issue: Sometimes struggles to turn over when hot but battery has plenty juice.  Clock will go off and it'll sound like a dying battery.  Try it later and boom straight on.

Solutions: Prob. wiring issue? 

[PeteG40]

Sticking throttle?

[samg40]

Have you got a 51mm throttle?

[hayesey]

as above or check the throttle switch with a multimeter

[Tav]

Just a regular thottle I'd assume...will whip it all off and give it a good clean tonight and see what like.

[Andy]

Sticking throttle plate, sticking throttle cable, incorrect ignition timing, incorrect idle speed, air leak. Worth checking them all!

Hot start issue is worth checking the starter and associated wiring. Cable resistance increases with temperature, but not significantly - so I'd bet on a dodgy connection or knackered starter/solenoid. Cold start requires more torque from the starter and thus draws worst-case current from the battery, so a weak battery usually shows up as a cold start issue.

[z3i]

The incorrect idle speed adjustment is what caused mine to do the exact symptoms youve described

[Tav]

Idle speed...into service mode and then adjust screw.  Car warm?  What speed recommended?  Currently idles 975-1000 when warm.