But I could do with a second opinion before I start taking it to bits.
Having spent the best part of the last 6 months laid up in the shed (used occasionally) I changed the fluids bank hols and got the thing out properly yesterday (Saturday). In gears 3 4 5 & 6 at 4500/5000 revs or higher, my CB500 (parallel twin) looses power and backfires, tries to chuck me over the bars as it looses power then gets it back again. I think it’s the spark plugs that have corroded so I’ll have a look and clean them up/replace them next week. I don’t think the fuel’s combusting properly - it’s almost missing a beat, so it hits the hot exhaust and that makes it go pop 
. Can anyone confirm my suspicions/ suggest an alternative?
Thanks
Ian.
Ian
When you say you changed the fluids! did you drain the tank?
If you left it full when you laid it up Im wrong but:
Unleaded fuel goes off, it solidifies over time.
I think if you clean the fuel tap / float chamber and carb it will be fine.
Change the plugs anyway but that sounds like the problem,
The fuel turns to jelly after a couple of months.
Another warning from a friends experience! Dont use that carburettor cleaner from halfords, etc, it rots gaskets.
Rossi is a god 
numerous possibilities with this but wheelnut may have hit it on the head.
i think its a blocked jet as it happens after a certain rpm.
because of this i also doubt its the plugs.
drain the tank, fill up with fresh fuel and use a cleaner as per wheelnuts suggestion.
Ahhhh, that may well be it. Mr Haynes is also heading in that direction. I’ll see if my dealer’s got some kind of carb cleaner I can use on it . I was thinking plugs because it sounds like it’s not igniting the fuel, then I get a backfire. I’ll have them out next week and see what happens.
I think with poor fuel it wouldn’t start and if it did it would run rough at any revs. If the fuel system was partially blocked then it would ride like it was running out of fuel. I’d replace the fuel and check the plugs as they are cheap options, but if the problems continue it might be an ECU or coils.
Big one!
What motorbike dealers are there in Loughborough?
I know Arnolds have a place. I was there yesterday but didnt see any others.
I went to Melton Mowbray at warp factor 9
There has ben a lot about fuel going off whilst in the tank in the vintage motor cycle club magazine of late & its down to bactaria, its one heck of a problem to get rid of & if I remember rightly it stinks.
I’v just had, (& solved ) a similar problem on my wifes run around, check for pressure at the end of the exhust & check the air filter as something could have got blocked & then check the jets, these are the three easiest & most logical causes.
Wheelnut, Twiggers Motorcycles are ■■■■ good if a bit pricey and usually booked up because they’re half decent , the best one I can think of near you is SDH motorcycles at Swadlincote. Does a good service (service/mechanical and bolt on bits bits only) and he’s reliatvley cheap, although he’ll probably have to order you parts. This is only a personal thing but I wouldn’t touch Arnolds with a great big barge pole, I don’t like his mechanics. If you want I’ll PM SDH’s phone No to you.
I see the devine being won first time out on his Yamaha 
.
Cheers mate,you can pm the no for SDH, but Im going to take my bike back to supplying dealer in Leamington for some warranty work. may as well try to get a service at same time.
Im just finding new and other dealers in the area to get free coffee from. 
The problem is sorted.(Famous last words). Took half the ruddy fairing off today and cleaned the carbond deposits and oil off my plugs. Then went for £3.00 of Motorex carb cleaner from my dealer this a fternoon. This has seemed to do the trick. Not a peep so far today. Lets see what the A6006/6057 does to it tomorrow. (Wheelnut should know what I’m talking about .