Why won’t my bike start without throttle?
If your motorcycle refuses to start unless you crack the throttle open, it’s a strong sign of carburettor problems. Normally, a well-set carb should allow the bike to start from cold with the choke and from warm without any throttle at all. When it doesn’t, the issue is almost always a blocked pilot circuit, misadjusted mixture screws, or incorrect float heights.
The pilot jet supplies the fuel your engine needs for starting and idling. If that jet is partially clogged with varnish or dirt, the engine won’t receive enough fuel to fire up unless you open the throttle, which pulls fuel from the main circuit instead. Over time, this also leads to hard starting when hot, rough idle, and stalling.
DIY fixes like spraying carb cleaner into the airbox or using fuel additives don’t reach the internal passages where the blockage sits. The only reliable solution is to strip the carbs, clean them ultrasonically, and reset all fuel and air circuits to specification.
At The Carb Shack, we handle this problem on a daily basis for bikes ranging from Honda CBs to Yamaha R1s and Suzuki Bandits. Our process ensures the pilot jets are clear, float heights are set, and mixture screws adjusted so your bike starts first time, every time.
If you’re tired of fighting with the throttle just to start your bike, book in for a carb cleaning and rebuild. It’s the professional solution that guarantees proper starting and smooth running.
