I recently bought a 2019 800 bout 1500 miles on it, that running along and when I get to around 45mph it makes a little noise and stops pulling. I can briefly let up on the acellerator and  reaccellerate and it drives on, but I've never tried going any faster.

Any ideas?

Thanks

[2015 Z Force 800 53/Trail EPS]

Can you describe this "little noise"? The things that can stop it from increasing speed and/or RPM are the limiters such as 4wd, reverse, seat belt..ect. The main limiter is around 7700 RPM and that's well past 45 in high range..normally. Other things are low fuel pressure or volume which can be a bad pump, stuck tank check valve, plugged fuel filter..water in the tank. Low coil power of low system power from a bad connection battery.. ect. The clutches can limit some speed if binding but won't stop the RPMs from increasing to the upper limiter. Of course there is the old valve timing problem some have but if that were the case it would run like hell all the way down and NOT correct by playing with the throttle.   

Ok, let me explain this different.
I'm 70 yrs old and I've been a mechanic all my life and pretty familiar with engines and transmissions and all.
I just bought this ride.
The belt has been replaced, less than 100 miles on it, as I'm told. The secondary clutch has not been removed , the paint marks on the nut and clutch are still aligned. When I started driving it, I was just puttering around in the yard and field with the grand kids. It starts great and idles smooth, with snappy acceleration. I filled it up when I got it with non alcohol non ethanol gas.  Then when I headed down the road and about 45 mph it made a clattering sound and acted like I shifted gears in a manual transmission a missed the gear. I didn't accelerate any more because I didn't want to cause any more damage. But, as I let off the accelerator, it was like it dropped back into gear and I went on. Just keeping my speed around 35 - 40 mph. The rpm's never got even close to limiters max cutout. The seat belt was not latched the first time but was latched the second time it happened. Like I said, it's as if it jumped out of gear and ground the gears trying to get into another gear. As soon as I get a project cleared out of my sho I'm going to go back in and take both primary and secondary out and inspect them closer.
This is the first cfmoto I've had, but I've got a Polaris four wheeler and side by side. 

[2015 Z Force 800 53/Trail EPS]

In my mind I am visualizing it jumping out of gear, making a grinding noise as it starts skipping, then with power-off it jumps back in. Better check the shifter alignment..right now. Otherwise if the detents are aligned, and is may be what's happening, it indicates a bent shifter fork...but lets not jump to there yet. Also check the engine mounts for loose or rubber coming out of the mounts.

Although mine is a 2023, when shifting into low, I need to pull it firmly all the way down. If I just casually pull it into low, I will often get that horrible grinding gear sound. I had it to the dealer a couple months ago to have oil change and inspection done. Originally they said there was nothing wrong as it wouldnt do it for them. I found that I could make it do that on command by lightly shifting into low gear and demonstrated it for them. They mentioned like NMKawierider did that the linkage probably needs to be adjusted. They also mentioned that if I adjust the linkage so it doesnt happen in low, it may affect shifting in other gears as well. I call BS on that and think that if properly adjusted, it could only help. It only would occasionally do it in low but not any other gear. So my solution for now is just to firmly pull it into low and it works fine. Eventually I am going to try adjusting the linkage myself and see how that goes.

Ok I'll check it.

I've got my boat off of its trailer on my 2 post lift.
It will be out of the way in a couple days then I'll get my 800 on it and see what I can find wrong.
I'll get back when I figure it out.

Thank you for all the info, it has help me understand more how they work.

Thanks
You're a Gentleman and a Scholar

I'll be back, this is a good fourm.

Ok, I'm back. On my 2019 800 CF Moto.

I haven't taken it apart as of yet. But, I've looked into it more and what I've found is that it is jumping out of High gear and it will drop back right back in gear when I let up on gas pedal just a little.  It does this only at speed above 42 mph, and it is at random speeds above 42. Also it seems to not be getting a good detent when selecting High gear. It also has started being a little hard to change to any selection most especially fwd and rev gears. It has a new mfg belt.
In low gear it will stay in gear even as rev limiter degrades it.
I'm thinking it is in the wet clutch and/or high shifting operation.

This one has the primary side in rear standard right hand threads. So will the secondary which is in the front be left hand threads.
The primary was rubbing the shield behind it and squalling. Was no washer between main case and primary pulley, wearing a slight groove in the case, so I put a thin machinest washer to stop the squalling.

Thanks for your input, it's really appreciated.

[2015 Z Force 800 53/Trail EPS]

First, on all with wet clutches and single nut retainers on primary, both are right-hand threaded so "lefty-loosie" applies. Second, if in fact that it is able to move gears at any speed out of their seated position means the shift fork is being flexed or has bent already and that the dogs are becoming tapered which means they may never be able to seat correctly. However..let's check the detent alignment first as so many came mis-aligned. Start in neutral and go either way. Adjust so that the shifter gate's detents exactly align with the transmission's in both direction. Ok, next, if it shifts into each gear easily shut off but not running, there is pressure being applied through the clutches and you are correct, the first place to look is the wet clutch...but not always for a problem with the shoes. There could be an alignment problem with the shaft that causing some contact with the shoes like with warn bearings...either the case or the shaft inner. You said there was an issue with it rubbing so I suspect there is a bearing issue.

Ok, thanks, good info, I'm going to check into each of these items. I'll post what I find. It will be a few days, but I'll post results.

Oki aligned the shifter and trans detent and it's not any better on coming out of gear but it shifts better.
My next question, can I get to the shifting fork and gears without pulling the motor and/or transmission. And if I must pull it out, how difficult is that going to be?
Thanks

[2015 Z Force 800 53/Trail EPS]

Oki aligned the shifter and trans detent and it's not any better on coming out of gear but it shifts better.
My next question, can I get to the shifting fork and gears without pulling the motor and/or transmission. And if I must pull it out, how difficult is that going to be?
Thanks

Far as I know there is no way to replace any part within the transmission without a complete engine tear-down...and that means a full rebuild. Lets check a couple of other things first. Check the engine mounts first for loose bolts or lost rubber mounts by placing it in the open area, starting it, applying the brakes and placing the shifter in low and reverse and giving it gas while holding the brakes on and watching the engine move. If it moves more then a couple of millimeters, there is a mount problem. If not let's go to step #2 which is removing the shifter shaft between the shifter and the transmission, by hand putting it into H or L..whichever it pops-out of, and taking it for a run down the road. Do whatever it usually takes to make it pop out of gear. If it does, then the problem is internal. Sorry. If it doesn't then there is something happening with the frame somewhere...IMO.