Bandit fueling issue

[Moxey]

Evening all, bought my first big bike about 3 weeks ago a 98 Bandit 600 N, before I bought it I knew the previous owner had some issues with the carbs and was paying £150 to have them rebalanced by the shop I saw the bike in.

Wasn't in any doubt for a second that the shop mechanic had just done f*ck all to the carbs and pocketed £150 of the money I paid to the original owner through him for the bike when I got it, though it does have a new fuel tap. Bike ran fine when had it in garage last week working on other things but now after doing about 300 miles since getting it on the road saturday the carbs seem to be playing up again.

Symptoms are as follows (though not consistent), In 5/6th gear the bike starts to lose power then surges again suggesting not enough fuel getting through, also when dropping down the gears to a stop the bike suddenly just cuts out completely even with clutch disengaged, starts up again after full choke and setting to prime on fuel tap for a second.

Strangely though the bike runs fine for quite a while in between each little incident of what seems like fuel starvation.

So am I right in thinking that the carbs need rebalancing or cleaning?
____________________
Current: 02 FZS 1000 & 91 Royal Enfield Bullet 350 Some Bike Pics...
'I was too busy paying attention to pay attention'

[nowhere.elysium]

[Pete.]

Sounds like fuel delivery problems. Possibly pulling a vacuum in the tank. Try running it with the fuel cap loose. Make sure the tank isn't near full when you do it.
____________________
a.k.a 'Geri'

132.9mph off and walked away. Gear is good, gear is good, gear is very very good

[Moxey]

Thanks for the help guys help is highly appreciated, going to try both suggestions tomorrow.

Should also mention that the engine idle rev does vary a little, normally its at 1100 or so but sometimes it climbs to about 2000 with hand completely off throttle when I pull up after normal riding. Also after an 'incident' i.e. the bike cutting out when brought to stop at junction etc when I start it up again (with use of choke+prime then turning them off) it idles at 900 ish but again this isnt consistent and the bike has only done this twice, once on sunday and again today but sat, mon and tues it ran absolutely fine idling at 1000-1100 at every junction/stop, confuses me how the problem suddenly disappears then recurs without warning
____________________
Current: 02 FZS 1000 & 91 Royal Enfield Bullet 350 Some Bike Pics...
'I was too busy paying attention to pay attention'

[Moxey]

Little update here, problems still persisting but have found that I can run the bike fine on prime so long as i remember to switch it to on/res to avoid damaging carb needles on full tank of petrol. Though again today the bike died as I came to roundabout from about 75ish and managed to start it up again with choke on but pisses me off that I ran the bike fine for nearly two days without so much as a hitch.

Very much drawn to the idea that a loss of vacuum is creating the problem as it seems the revs vary like air is finding a way in somehow where it shouldnt be (tried wd40 on carbs but not difference and no pressurisation or anything when I open petrol cap). I have a rough idea that something mechanical in the carbs is prventing the vacuum from chaning at certain times as tonight when I got back the engine was ticking over fine at 1100 then I blipped the throttle to get the bike in the garage and heard a strange click as if something has stuck and the revs climbed to 2k at idle which would explain the inconsistency of the problem, going to have a look tonight.
____________________
Current: 02 FZS 1000 & 91 Royal Enfield Bullet 350 Some Bike Pics...
'I was too busy paying attention to pay attention'