Quote Originally Posted by GezTheHealer View Post
Not ridden my bike in a while, perhaps its getting back used to it, but under 4000rpm there's a noticeable delay/lag/stuttering even if I give it a decent amount of throttle. Upshot is I can't pull away as quick as I'm used to unless I slip the clutch and rev a bit higher. Over 4000rpm it seems fine. I have had about half a tank of fuel in it, probably some as old as November, the rest around January, so it has been over a month or so. I'm thinking it might be stale fuel doing this. Seemed Ok this morning, only noticed it in the afternoon after getting a minor service (oil). But the tank wasn't off, so unlikely a pinched fuel line.

I only get the stuttering under load, it rev's freely if in neutral. Maybe the cold weather and mix with old fuel?

Anyway I've put some Redex in the tank for the time being and will fill it up to full with newer fuel to see if that helps.

Thinking otherwise could be sparkplugs maybe. Looking online someones suggests IACV hoses, though IDLE seems smooth and fine.

Any thoughts welcome.

Thanks.
Id say it sounds like old petrol.
When I park a bike up I fill the tank to full to avoid condensation/rust inside tank, then when I start using it again I drain 2/3rds of the petrol out and refill with fresh then use the old petrol mixed with new each time I fill up.
Try topping of the tank with fresh petrol then going for a lively ride (whilst remembering your likely to be abit rusty yourself from not riding for a while).
The injectors could be gummed up but I'd say it's unlikely after just a few months parked up.
Personally though I wouldn't expect petrol to go stale to the point of being noticeable after just a couple of months, yes it'd be past it's best but should still be useable.
Dunno where you fuel up and Iv no evidence of this but iv been told/read that the reason supermarket garages can sell petrol cheaper than Esso etc who they buy it from them in the 1st place is they buy it at knock down prices as they buy older/stale petrol, if that's a fact and you fuelled up with it then the petrol in your tank could be older than you think.