Engine Miss - Under 2,000 RPM

[Lotsokids]

My bike has developed a "chugging" or miss under 2,000 RPM with a slow roll-on with the throttle. I took it out yesterday and refueled, but it was VERY hard to start, and almost didn't. I reached 145 MPH (I don't do that very often) and it pulled really strong.

Any thoughts?

[Flying Scotsman]

I think I would look at the carbs...
High speed circuit is ok
Mid range ok
Low speed circuit or choke not so good.
Pilots or idle air fuel mixture.

[RichBaker]

If it started this AFTER the refuel, I'd be looking at the new gas..... Water in it, maybe?

[Lotsokids]

If it started this AFTER the refuel, I'd be looking at the new gas..... Water in it, maybe?

I thought of that also. I'm running some complete fuel system cleaner through it now.

[mr blackstock]

G'day,

mine was missing badly at low revs, I suspected electrical, so just for a try I put on some spare spark plug caps off another bike and the problem seemed much better.  So I bought 4 new NGK and the problem has all but disappeared.  I will get some new plugs soon and that might solve the issue completely.

Anything to avoid pulling the carbs apart!

Cheers, Gareth