Hitchcocks Forum

My 2009 EFI had a short spell of misfiring last year and then cleared itself.Now it has started to do it again!It is worse when i try to give it a big handful at any engine speed when it won't respond at all.I have had to nurse it to work today and hope i can get back home tonight!Bizarrely it cut out at some traffic lights and the electric start which hasn't worked all this year began to work again so luckily i was able to get it going again!Does anyone know if they have a fuel filter which might need cleaning or replacing?I did put a new plug in last year when the first episode of misfiring occurred.

Mine was doing that, and I cured it by fitting a new spark plug. The old one was an NGK BPR6ES and looked fine, but just changing it for a new one was an instant cure.



I say "instant" - in fact I thought I detected some very slight misfiring and hesitation a couple of weeks later, so I changed it again for a BP5ES, which is a shade hotter. It's been perfect ever since. Apparently the iridium-electrode version of the NGK plug works brilliantly - it's getting good reports on the American forum. I might try one of those myself.

Thanks Thack.I'll get an iridium plug off our hosts.On looking at the parts books online i can't see a fuel filter.

I agree with Thack about plugs. But I think the laws of physics apply to the fuel injector system as much as to the carburettor system. Which may mean that snapping the throttle open with a fuel injector is just as much bad practice as doing it with a carburettor, especially on a big single. When the throttle is opened wide suddenly there is a rush of air and, as fuel has greater inertia than air, the petrol/air mixture strength suddenly drops. This causes the engine to falter until the fuel air mixture stabilises again. Some carbs are fitted with an ‘accelerator jet’, which sprays neat fuel into the induction tract to compensate. But I don’t think that the fuel injector is able to compensate in the same way. So you get the hesitancy and stuttering that you’ve reported.

Martin I believe the fuel filter will be in the tank before the fuel pump, never looked at one but this is what I assume

Martin, the fuel filter is an integral part of the fuel pump... and the fuel pump is expensive! What kind of symptoms do you have when mis-firing? My mis-firing EFI became unride-able recently so I have looked into a lot of potential issues. Give me some details of the symptoms and I may be able to help out. BTW I hope to test ride my bike tonight after finally getting it all back together

There is NO serviceable fuel filter on the Efi. It is integral to the fuel pump. And unless you want problems with fuel leaks, its best to leave the pump well alone.

You’re right – some of these problems do seem ‘bizarre’. There don’t seem connected at all to each other. Which makes me wonder about the overall condition of the bike (not wanting to be insulting!) What is in my mind is the possibility of poor electrical connections – corrosion or whatever in connectors. Might be worth spending some time with WD40 and going systematically through the connectors, to make sure they are all sound and clean.

What a wondefull idea the filter being an integral part of the pump, wait till a few of these tanks start rusting

Not the best design methinks... a 50 pence service item and a 2 minute job is now a much longer job costing over 200 pounds for the part!