Mk 1 speed triple problem slow to return to idle

Hi all,
Looking for help with a problem with my Mk 1 speed triple, the bike is very slow to return to tick over and sometimes sticks at about 3k, the throttle action is ok, returns with a crack, so don't suspect the cable. Have checked for air leaks around Carbs, all ok.
Also have noticed that the rev-counter does not return to zero when turning off the engine, stays about 500 rpm, it only returns to stop once ignition is turned back on, have tried another rev-counter and it does exactly the same. Cant see how the two problems are linked but the chance of two tachos being faulty is strange.
Bike as done just over 10K, starts and idles ok and runs ok other than this, my next plan is to balance the carbs.
Any help or suggestions greatly appreciated.

Thanks Pat

 

Hi ram,
Thanks for the reply, don't know how I have done it but I seem to have started two threads. I will as you suggest check the balance of the carbs first along with the carb rubbers and vacuum caps. If all ok I will have to strip the carbs and check diaphragm, might renew throttle cable as well just to rule it out.
I have owned the bike for 12 yrs and its been ok till now.
Any thoughts on the rev-counter problem, I think its a separate issue.

 

Hi,
Have just tried your suggestions, if I turn the engine off with the key at any revs the needle stops at 500 rpm, only returns to stop when key is turned back on. If I stop the engine with the kill switch it returns straight down to stop ?

 

Thanks Steve,
Will have to find out were the diode is located, have tried another rev counter but it was same. Have not got round to stripping the carbs yet, but will do. Thanks also wardy for your reply.
Pat