So I've been having a bit of bother when riding at higher gears. From 4th onwards if specifically. When doing around 60mph in any of these gears and I open the throttle she doesn't go anywhere. I have to drop down 1 or 2 gears then accelerate. She'll get to around 80-85mph and will not go any faster but will struggle when I up gear. Revs stick to 4000-4500 in top gear with wide open throttle, the clutch isnt slipping.
I've cleaned the carbs completely, disassembled and run wire through every hole. Floats are in spec, everything I can think of with the carbs has been done. All rubbers have been replaced too, I've checked for vaccum leaks and have none. I even replaced the rubber seals on the choke plungers. They've been balanced too. Fuel mixture screws adjusted suitably.
Spark plugs are new and gaps are correct.
Fuel tank is clean and nice new fuel, filter has been changed, air filter too. New Polaris fuel pump as my last one died. Petcock replaced, vacuum ports plugged as it's not a vacumm operated one.
I've done the valve shims and they are in spec.
Sprocket and chain is in good condition and has stock teeth. Gas cap is venting correctly.
She starts on choke but doesn't seem to like it, so I have to knock the choke off and hold the revs myself till she's warmed up. I've been trying to get this thing working as it should but, I'm starting to lose interest now because I can narrow down the problem.
I even checked the timing just in case today and it's spot on. Though my cam chain seem to go tight and then loose depending where the cams are rotated.
My exhaust isn't leaking, but isn't stock neither.
The only thing I can think of doing next is a compression test but I'm dreading the results. I don't get any smoke or backfiring, she'll idle at 1200 no prob and the revs drop fine when hot.
Any ideas guys? I'm at the end of my tether.
