Yamaha Engine breaking up at 25 mph

[asutoad]

I am having an issue with the engine breaking up at 25 mph. I have gone through the carb and changed the coil. With a stock cdi I get 25 mph and with an aftermarket cdi I get 31 mph. What do you suggest I do next. The thing fires up great it is almost like it is hitting the rev limiter. The belt seems fine also. It is very consestant so it make me feel like it is electrical. Thanks for any help or ideas. It is a 2007 660 rhino.

Dave

 

[Glamisfan]

Fuel filter /pump?

 

[asutoad]

Gravity fed right to carb no change. Sorry I should have listed it.

 

[Glamisfan]

Does it sound like the motor is revving out to 8000 rpm or 4000 rpm?

 

[poflo]

Put a new plug in it....easy check.....Gravity feed fuel may not open the needle on high demand...it works on start-up & idle,but not if the bowl is full due to spring on needle( needs 3 to 4 psi)

 

[Glamisfan]

If it revves to 8000, then probably one of the rollers in the primary cvt clutch fell sideways. Time for a cvt rebuild. And if you've never put in a modified primary, then now is the time to do it. I'd suggest the Hunterworks greaseless wedge one's.

 

[the stripping shop]

ground the rev switch out first.

 

[Slowpoke Rodriguez]

Im with Glamisfan, check your sheave, maybe a weight flopped and wont let it shift.

 

[prerunner rhino]

+1 check the reverse switch

 

[c&c rhino]

if it revs up to 7k ish then its probably a roller weight issue in the primary clutch. if its breaking up under say 4k there could be a few things. make sure your plug cap is good, there is a wire that snaps onto the plug inside the cap that can break, especially if the rubber plug isnt correctly seated in the valve cover. if thats broken and the rubber plug isnt keeping it in place it can bounce around causing misfires. a stuck reverse limiter switch usually causes it to hit the rev limiter pretty low in the rpm range but its a possibility. gravity fed fuel will still fill the float bowl and it has a regular float with needle and seat so that should be fine for testing. you already tried the stock cdi so that should take it off the list.
are you sure the cable is pulling the butterfly all the way open in the carb? ill try and think of other possibilities.