Forum

[Zululima]

Greetings all from the antipodes.
I have a 2016 B500 Bullet I have had from new. Done just over 25,000 km. Recently it has started hesitating but only on accelerating after closing the throttle to slow down. It will cruise perfectly at 100km/hr but as soon as I throttle back to slow down - viz approach a sharp corner or come up behind another vehicle - and then open the throttle to get back to 100 km/hr it noticeably hesitates briefly. Most unnerving. I'm a bit baffled. Anyone throw any ideas on this one? Anyone else struck it? Thanks. William.

[Chris [Stockport]]

Just a thought before delving any deeper, how's the action of the throttle cable?
I'm not sure if it's a single or a double on your bike?
Hope something a bit deeper will appear for you on the forum soon...
Good luck!

[Zululima]

Thanks Chris.
An old timer out this end has just suggested to me it sounds like water in the fuel. Which may have some validity. In retrospect it seemed to happen half way through a two week trip - and thinking back the bike got thoroughly soaked prior to this. So maybe water is getting in past the fuel cap. Next step is to have a close look at this. But it certainly shouldn't happen; I thought there was a drain to avoid this. Cheers.

[Daiwiskers]

Not sure if you are getting the same rubbish that they call petrol here, but the alcohol added to the petrol absorbs water from the atmosphere then separates from the petrol leaving you with a very low octane petrol floating on top of the alcohol and water mix beneath
Could this be the problem you are suffering from?
If so perhaps draining the tank and refilling with fresh fuel may be the fix

Hope this makes sense Dai

[stinkwheel]

I don't know much about FI but if it was an old diesel engine, those would be similar symptoms you'd get if fuel was leaking back from the injectors (like with a faulty non-return valve) or the pump wasn't maintaining adequate fuel pressure. Does it start well or do you have to crank it for a while before it fires up?

[Zululima]

Fuel here is pretty good. Not adulterated with methanol. 91 or 95 octane. Starts easily and runs fine - except for the missing after deceleration. I guess the sudden slowing is causing a bit of sloshing down below and a few molecules of water are getting pushed through - if that's the problem, which seems likely given the feedback.
Next step is to drain and refill the tank - and find out why water is getting past the filler cap. I note there is a drain hole and a rubber hose connected to carry any water away so must check if that's all working as well.
Will report back after the drain/refill exercise.

[Vince2]

Hi, Check fuel filters. I had a similar problem and it turned out to be restricted fuel flow. Also check you plug gap has not got to big , this can cause hesitation. Vince

[Wheaters]

Do these bikes have a throttle position sensor? If so, it might be faulty.

[Zululima]

They do and have been known to fail. It will be my next port of call after the tank drain, fuel filter task if that proves fruitless.

[Duke of Wybourne.]

Greetings all from the antipodes.
I have a 2016 B500 Bullet I have had from new. Done just over 25,000 km. Recently it has started hesitating but only on accelerating after closing the throttle to slow down. It will cruise perfectly at 100km/hr but as soon as I throttle back to slow down - viz approach a sharp corner or come up behind another vehicle - and then open the throttle to get back to 100 km/hr it noticeably hesitates briefly. Most unnerving. I'm a bit baffled. Anyone throw any ideas on this one? Anyone else struck it? Thanks. William.

I have experienced this on several occasions with different bikes and the cause has always been the same. If your bike is still doing it, try this before you start ripping it apart. Take it up to cruising speed on a straight road, then before you throttle off, pull in the clutch and throttle off so the engine is not being driven on the over run. When you get down to around 30-35 mph let the clutch out and throttle on again. If the symptoms are not there under this method, then you've most likely got a bad spark plug. I have had these same symptoms on Enfields, Kawasaki singles, and Ducati Twins. A further check is to fire up the bike in a totally darkened room, rev it and watch the plug, and the chances are you'll see the spark tracking down the side of the plug, only on the over run. Bosch and Denso plugs seem to suffer more from this than others.

Good luck.