Loss of power

[rumbleguts]

Advice neede please, I rode to work this morning and everything was fine.Stopped at tescos to fill up and rode last half a mile within the 30mph limit. Coming home I stuck to the speed limits through Lincoln and once clear of town opened it up and found it wouldn't rev over about 5 grand!! It runs and sounds fine if taken gently through the gears but will top out at 70ish mph and if I wack open the throttle it just won't have it and feels breathless, no popping back or loud misfires. Iv'e got a haynes manual and know a bit about mechanics but I'm asking if anyone out there can advise on the best sequence of checks as ther seems to be quite a lot of possible reasons for this problem??? Cheers mike

[benny hedges]

did you run it almost dry>>> was it raining when you filled up?
wondering if you got a bit of crap in a jet or got some water in the tank?
try running it with the filler open (you may need a spare key!)

you could try undoing the drain screws and see if any jelly crap comes out.
i think its a bit coincidental it happened just after filling up.
also may be worth going back to the tescos and complain.... maybe loads of others have had problems... water ingress is not uncommon in petrol stations

[rumbleguts]

It wasn't raining when I filled up but It's persisting down outside now so i'll try the drain idea tommorow and nip into Tesco on the way to the lincoln bike fest on sunday if its not sorted, thanks Benny. PS do you mean the carb drain screws?

[benny hedges]

yes the big brass flathead screws at the bottom of the bowls.
there should be a drain tube on them but it may have been removed.
if ots there try & catch the fuel and see if its shitty.
may just be a blocked or partially blocked jet.

running a modded airbox on mine with no insides and no snorkel, i had a similar episode the other night coming home in the rain, lots of mway spray.... the airfilter was piss wet & the bike was popping and misfiring like hell but was ok the day after