Crf450r 2003 cutting out top end?

Hey guys was wondering if you could help me, I have bought a 2003 450r supermoto converted. It had been garaged for a few years and when I got it it would run all lumpy. So I put a crab cleaner through it a new filter fresh fuel and a spark plug. It has started to run better but On a short motorway run at 70mph after a minute or so it will start spluttering as if I'm on and off the throttle, even when you drop it down a gear and when you pull over it just cuts out. Was wondering if it would be a carb issue or maybe a bad ignition coil or something? Thanks.

I would pull the pilot and main jet ...just get new ones and see how it runs. I would bet gas was left in it at some point.

Stator is dying

Thanks guys for the replies, sorry about the late reply been trying out a few things, as to now it's had a full carb strip and clean, new stator and pickup a new ignition coil and even tried a new cdi that I knew was working. But I still have the same issue its been on the dyno and when you hold mid throttle it's as if it has a slight misfire but on the road it's fine any suggestions? Thanks

Hmm....sounds dumb.... But I might check to make sure your kill switch isn't bad or shorting. Take it back to the simple things first.

Could be a good idea as it has been changed to a pull cord switch but it happens at nearly the exact same distance every time as if something is getting hot and overheating.

That's been checked and there's nothing wrong there so I'm assuming last thing is the wiring loom??

Hmmm......ya know....did ya check the fuel filter in the the petcock? I had a YZ 80 when I was a kid that had some dirt in the tank. After bout 5 min it would just bog and die...due to clocked fuel filter (petcock). Wait a few min, it would start back up and repeat the cycle. This was when it was new from dealer! Once I got tank clean....end of prob. Might be worth a look....

Not sure...I'm just throwing that out there as a previous experience......

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