Engine Surge issue

Hi all,

My first post and my first bike! HURRAY

I have a 53 650s, 8000 miles on the clock.
The bike belonged to a friend who could not afford to keep it insured or to run it, as a result its been sat in the garage for about 6-9 months doing nothing.

I agreed to buy it if they got an MOT, the battery was flat so we had to bump start it and so I took it for a spin to get it clean and to charge the battery a little.... I noticed as the ride went on that the bike started to surge a fair bit, not during acceleration but mainly when holding speed, for example at 4-8RPM doing any speed. The guys suggested that the battery needs replacing so they did this and got it through the MOT.

Ive now brought the bike and in the main I am over the moon with it, however the surging is still there. No most people have said to me to give it a good thrashing, it appears that no only the petrol has been in the bike but also the petrol and I assume the petrol has gone bad and its this that has effected the engine, so I have filled it with Super unleaded and put in a fair amount of fuel addative to help clear out any rubbish that may be in the engine.

Am I doing the right thing... should I continue to rev it high and do some nice motorway rides to try and clear it out?

Most people have suggested something to do with the fuel injectors being dirty and that it may resolve itself or I might need to get it cleaned out?

I am going to give it another 5 days of driving and then I will follow the mighty haynes manual and replace the air filter, spark plugs.

Thanks for any advice

[yorkie_chris]

What is it, injected or carbed?

If it's carbed then I'd say the carbs need cleaning out.

Injected, thanks for the reply

I am not a mechanic, my natural reaction is to treat it like a battle of wills and try and force the bike to give in and behave itself ..... hehe

[yorkie_chris]

TPS adjustment possibly.

Also just to point out that the bike seems fine when pulling off, when its cold it starts fine and sits there idle at 1.2k rpm and there is no bubbling on the revs if thats makes sense, so from my limited knowledge it does not seem to be vastly out of tune or anything.