Z1000st won't idle below 2500rpm

[Mrg]

Bike has been standing for 20 years so Striped and cleaned out the carbs reset siders at 0.7mm if I lower the revs below 2500rpm the engine cuts out like the ignition has been turned off it doesn't struggle or flutter just cuts out can anyone help me with this ?

[zed9]

20 years is a long time to have been standing.

Does adding choke make any difference.
Some idle fuel/airways could have been gummed up by stale evoparated fuel. Were the carbs ultra sonic cleaned with all jets and air screws out.

[kev edwards]

Pilot circuit.

[Philippe]

Hi Mrg

after 20 years of standing a bike needs a complete tune up.
It's not enough to pour new fuel in the tank and to put a new battery in...you have to do a "little bit more effort" to get it running in good order.
Take the carbs off, clean them ultrasonic, replace the inside parts with new ones (Keyster), replace the seals with new fuel resistant ones.
Replace the old fuel lines, clean out the fuel tap and replace the vacuum valve
Change the oil and the filters (oil, air)
Replace the spark plugs with new ones
Check all the electrical connections, moisture can cause oxidation resulting in bad electrical connections.
When the engine is running, you have to listen to suspect noises, rattling of the camchain ; you might consider changing the camchain and the whole system (sprockets, guides,...).
When you replace the camchain with an endless one you have to open up the crankcases and take the cylinders off...you might as well hone the cylinders and put new piston rings on the pistons and replace all the oil seals.
I know, it's a lot of work but if you want a reliable bike, that's what you'll have to do.
Time has its effects on us, it also has its effects on engines...the parts deteriorate, seals become dry and they start to leak when the engine is running again.
Good luck !
GrtZ
Philippe

[Mrg]

Sorry should have said everything has been checked, cleaned and where needed replaced cam chain was replaced 5000 miles ago with a 0.5 over rebore.
Any recommendations on ultrasonic cleaners don't what a massive one just big enough to do one carb at a time.

[kev edwards]

Just a cheapie if it's just for one time use, I have always used laundry liquid without any problems at all, once clean squirt wd40 or brake cleaner through all the little holes in jets air fuel passages and choke lift not forgetting the little jet in the float bowls for the choke lift.