Adjustable knob on the Mikuni BS26 Carburettor. Please advise what it is for.

Most times this is caused by to much fuel. You can clean the carburetor (disassemble it). I just buy rebuild kits and rebuild them.

TRY THE KNOB LOCATED ON THE CARBURETTOR TOP WHICH INCREASE OR REDUCE THE ENGINE RPM.OR CHECK FOR ECCELATOR WIRE THAT MIGHT HAVE GONE STUCK. ALSO SEE THE HALF ROUND ROCKER WHICH IS TURNED WITH THE ECCELATOR LOCATED ON THE ENGINE TOP (CARBURETTOR) HOPE IT DID NOT GOT STUCK CHECK IT MOVEMENT. OTHER REASON COULD BE THE CHOKE THAT GOT ENGAGED AND COT COMING BACK IF IT IS AUTO CHOKE OR IF THE CHOLE IS MANUAL SEE THE PULL KNOB NEAR THE STEERING IF IT IS PULLED OUT HAS TO BE PUSHED IN. ENGINE EXCEED ITS RPM WITH THE CHOKE APPLIED. I DO NOT KNOW WHICH TYPE OF CHOKE YOUR TOYOTA IS USING.


JUST FOUND ENGINE MANUAL/REPAIR PDF FILE THAT MAY HELP YOU PLEASE SAVE A COPY FROM THE SITE.
http://celica.nfv.ee/manuals/2ZZ-GE_repair_manual.pdf

yes it is,contact the original bajaj spare dealers.

See below. Please rate my answer. thanks.

its a fixed jet carb no tuning possible unless re-jetting and this is not to be advised ,only the mixture on idle is adjustable on earlier models

YAMAHA ROYAL STAR Engine Type: 1294cc liquid cooled 70 degree DOHC V-four, four valves per cylinder
Bore and Stroke: 79 x 66mm
Compression Ratio: 10.1:1
Carburetor: 4 x 28mm Mikuni CV
Transmission: 5-speed
Wheelbase: 66.7 in.
Dry Weight: 701 lbs.
Tires: Front; 150/80V16 Rear; 150/90V15
Forks: 43mm Kayaba
Rear Suspension: Kayaba mono-shock with adjustable preload
Brakes: 298mm dual front discs with dual-piston calipers; 320mm rear disc with dual-piston calipers
Seat Height: 28.3 in.
Fuel Capacity: 4.8 gallons