[UPDATE: ISSUE RESOLVED. See this post for more info: https://cfmoto-forum.com/800ex800/power-issues-on-800-trail/msg52158/#msg52158]

Desperate for some advice here...

During my last few trips my 2021 800 Trail (625 miles and 50 hours of use on it total) has been acting weird at higher RPMs. Would not get above 4600ish RPM in high gear. Almost like a governor was on it. Low gear seemed normal. And no, it's NOT the seat belt or air filter.

Dropped it off my my local shop last month. They said valve clearance was slightly out of spec and they resolved that. $300 later = issue remains. Then they said my "rollers and CVT in drive pulley were flat spotted and needed to be replaced". + $350 later = issue remains.

Now I'm being told that the "drive shaft is misaligned" and it needs new everything CVT (drive shaft, clutch housing, clutch assembly, gaskets, etc). First time any clutch work has been done on it so no idea how this happens and they aren't able to tell me how either. All this to the tune of +$800 more. Parts are ordered but they have no clue how long it will take to get them (weeks or months they claim). And ask me how optimistic I am that will fix the issue...

Of course, none of this is going to be covered by my useless extended warranty. So ~ $2k in parts and labor later I'm quickly loosing faith my CFMOTO!!!

Does any of these make sense to you guys? Are all of those CVT/clutch parts required to be replaced just to do the drive shaft?

Does it sound like a "misaligned" (whatever that means) drive shaft could be causing this power issue? To my knowledge they haven't even hooked it up to a scanner to see if it's some engine/software/tune issue before throwing all of these parts at it.

UPDATE: ISSUE RESOLVED. See this post for more info: https://cfmoto-forum.com/800ex800/power-issues-on-800-trail/msg52158/#msg52158

[2015 Z Force 800 53/Trail EPS]

Don't loose faith in CFM..loose faith in that dealer. They have no idea and just milking you for everything they can get. Get it away from them and then run a few tests yourself.. or find another dealer with a certified service department. Sounds like a low fuel pressure issue or low system voltage. Get a service manual and review the trouble-shooting section.  You could just have some water in the tank or filter but it needs tested...pressure and volume.

Would water in the fuel or low voltage cause such a consistent power loss? Always in high gear and always at higher RPM?

[2015 Z Force 800 53/Trail EPS]

Would water in the fuel or low voltage cause such a consistent power loss? Always in high gear and always at higher RPM?

Yes, it's two of the most common things that can cause it. That's why I mentioned them. Low compression is also one but let's hope that's not it. Have you been running the CFM air filter in dusty conditions? If so it is on the table. Hopefully you switched to the Unifilter at or near purchase. Otherwise the average engine lifespan in dusty conditions has been less then 1200 miles.

Yes, it's two of the most common things that can cause it. That's why I mentioned them. Low compression is also one but let's hope that's not it.

So I need to tell them to do a "fuel pressure and volume test"? And a "voltage test" (I assume you mean battery voltage)? Is that the correct terminology?

Hopefully you switched to the Unifilter at or near purchase. Otherwise the average engine lifespan in dusty conditions has been less then 1200 miles.

Yes, installed the 2 layered Uni filter right away. Along with the Outerwears prefilter on the actual intake between the seats.


Another complication: When I went to test drive it last week at the shop after they did the new belt and rollers, it's now making a horrible rattling sound. Like marbles in a tin can. Assume it's coming from CVT. Seems to be worst when you left off the gas and are coasting to a stop. They claimed that the new belt and rollers was causing the "misaligned drive shaft" to act up more (making contact with something, I guess??) with the added tension of the new/non-stretched out drive belt. Does that make sense to you?

[2015 Z Force 800 53/Trail EPS]

Yes, it's two of the most common things that can cause it. That's why I mentioned them. Low compression is also one but let's hope that's not it.

So I need to tell them to do a "fuel pressure and volume test"? And a "voltage test" (I assume you mean battery voltage)? Is that the correct terminology?

Hopefully you switched to the Unifilter at or near purchase. Otherwise the average engine lifespan in dusty conditions has been less then 1200 miles.

Yes, installed the 2 layered Uni filter right away. Along with the Outerwears prefilter on the actual intake between the seats.


Another complication: When I went to test drive it last week at the shop after they did the new belt and rollers, it's now making a horrible rattling sound. Like marbles in a tin can. Assume it's coming from CVT. Seems to be worst when you left off the gas and are coasting to a stop. They claimed that the new belt and rollers was causing the "misaligned drive shaft" to act up more (making contact with something, I guess??) with the added tension of the new/non-stretched out drive belt. Does that make sense to you?

It's more likely this shop didn't set the cam plate on the splines correctly when reassembling the primary and torqued it...or maybe not even torqued it. Who knows. But something was incorrectly assembled is a given. Telling ya..need to get it away from those guys...now.

Problem is I don't have another shop that works on CFMOTOs for hours. And I don't currently have a truck or trailer even if I did. So I've got to figure some way to get it running again with them.

So I need to tell them to do a "fuel pressure and volume test"? And a "voltage test" (I assume you mean battery voltage)? Is that the correct terminology?

[2015 Z Force 800 53/Trail EPS]

Problem is I don't have another shop that works on CFMOTOs for hours. And I don't currently have a truck or trailer even if I did. So I've got to figure some way to get it running again with them.

So I need to tell them to do a "fuel pressure and volume test"? And a "voltage test" (I assume you mean battery voltage)? Is that the correct terminology?

These guys should have already done that...but yes, fuel pressure and volume test and a system's voltage test, not just at the battery. And have them do a compression test and check the valve timing as well. Doesn't mean they will understand. Looks like they are just screwing-up your machine and you are paying them to do it. You would be better off doing this yourself but you would need some tools and equipment...so I guess you are stuck. Good luck...and I mean it. They have already ripped you off so bad on this other useless other stuff.

These guys should have already done that...but yes, fuel pressure and volume test and a system's voltage test, not just at the battery. And have them do a compression test and check the valve timing as well. Doesn't mean they will understand. Looks like they are just screwing-up your machine and you are paying them to do it. You would be better off doing this yourself but you would need some tools and equipment...so I guess you are stuck. Good luck...and I mean it. They have already ripped you off so bad on this other useless other stuff.

Ok, updates on this one from the shop!

On the loss of power issue:
• They tested fuel pressure and volume = was fine.
• Check battery and system voltage = was fine.
• Compression test and valve clearance = was fine.
• Check fuel for water/bad gas = in progress/TBD.

On new rattle noise in CVT since belt/roller replacement:
• Didn't set the cam plate on the splines correctly when reassembling the primary and torqued it...or maybe not even torqued it = said they checked and even called CFMOTO and all seems installed correctly.
• Since they said the new noise may be due to new/tighter belt; they are reinstalling old belt to test and see if still make noise to test that theory = in progress/TBD.

What are you thoughts?

[2015 Z Force 800 53/Trail EPS]

My thoughts? After what they have already done(or not done) I find it difficult to believe anything they say. That's just me. Have them give you the print-out of the actual numbers on fuel pressure and flow rate, compression, valve lash and running system (not just battery) voltage. Then post them. I do believe them on the re-assembly of the clutch because it's happened before to others.. and now the splines are likely damaged which means the cam plate and possibly the shaft will need replaced. Maybe not...hope not but if so it's on them. Sorry if it sounds like I have attitude but I'm so tired of people being taken to the cleaners because of outfits like these guys. I might be dead wrong about this dealer and if so I am sorry. It's just I hear about so many getting the "short end of the stick" every day and over time it gets to you. Even me...I just got the shaft "again" from my Ford dealer. 5K to replace a 1900-dollar turbo that only had 3800 miles on it...and the impeller-to-housing noise is still there...bs I say. Make them prove it by giving you the actual data. OK, rant over.. Carry-on     

My thoughts? After what they have already done(or not done) I find it difficult to believe anything they say. That's just me. Have them give you the print-out of the actual numbers on fuel pressure and flow rate, compression, valve lash and running system (not just battery) voltage. Then post them. I do believe them on the re-assembly of the clutch because it's happened before to others.. and now the splines are likely damaged which means the cam plate and possibly the shaft will need replaced. Maybe not...hope not but if so it's on them. Sorry if it sounds like I have attitude but I'm so tired of people being taken to the cleaners because of outfits like these guys. I might be dead wrong about this dealer and if so I am sorry. It's just I hear about so many getting the "short end of the stick" every day and over time it gets to you. Even me...I just got the shaft "again" from my Ford dealer. 5K to replace a 1900-dollar turbo that only had 3800 miles on it...and the impeller-to-housing noise is still there...bs I say. Make them prove it by giving you the actual data. OK, rant over.. Carry-on 

Latest update from last week:

• Again, all the tests you mentioned (fuel pressure, voltage, compression, etc) checked out fine - so they say. I am going to request actual numbers like you mentioned though and will post when I get them.
• New drive belt and rollers on = no difference.
• New drive shaft, clutch housing, clutch assembly, gaskets, etc parts all finally came in stock and have been installed = no difference.
• The rattle noise that popped up after they installed new belt/rollers a few weeks ago did go away with these new parts... so either something with these old parts OR they figured out how to reassemble correctly this time. That's one positive thing so far!

So 3 months and $1500 later, the problem is the same! I test drove it in their parking lot again last week and same result. Simply will not go above 35-40 MPH in high gear (flat road, pedal to the metal, just me the driver with little to no gear on board).

I starting to feel like I'm going crazy now...these things DO go faster right?! Surely would have noticed this when it was new. I swear I remember getting it up to 50-60 MPH previously. How fast do they usually go??

The only other thing I can think of is the new tires. I upgraded them to 28" ITP Blackwater Evolution Mud Terrains last year. I'm sure this effects gearing/top speed/weight/etc...but SURELY not that much! Right?! What kind of difference in power/top speed would be normal with slightly larger tires? I asked them to temp install some stock wheels/tires from another 2021 they have in the shop to test this theory this week.

What else could it be?!?

[2015 Z Force 800 53/Trail EPS]

Mine stock when new without anything else would do about 65 on the flat at 5200 feet. Adding the 27" tires alone took it down to 56(speedometer had to be re-calibrated) but re-clutching took it back up to about 59. Then I added wind shields. That dropped it to about 52. With that much added wind resistance the 800 just can't overcome it and get anywhere close to the RPM limiter. I can take the windshields off and it get pretty close...but still not hit it. Keeping in mine that for every 1000 feet in elevation off seal level you loose about 3% power. For me here at the house that's a little over 15%. That means my little 60HP engine is putting out less then 51HP. You can imagine the loss when I get where I ride mostly...above 8500 feet. So..yeah depending on your elevation those 28s with no clutch mods will have a dramatic effect on speed on any engine. Also, if you are running the Unifilter or any other foam filter, make sure it's not over-oiled as it will restrict the air flow...and if you are running a prefilter such as an outerwears, take it off and try it. They are restrictive even clean above 4K. 

Mine stock when new without anything else would do about 65 on the flat at 5200 feet. Adding the 27" tires alone took it down to 56(speedometer had to be re-calibrated) but re-clutching took it back up to about 59. Then I added wind shields. That dropped it to about 52. With that much added wind resistance the 800 just can't overcome it and get anywhere close to the RPM limiter. I can take the windshields off and it get pretty close...but still not hit it. Keeping in mine that for every 1000 feet in elevation off seal level you loose about 3% power. For me here at the house that's a little over 15%. That means my little 60HP engine is putting out less then 51HP. You can imagine the loss when I get where I ride mostly...above 8500 feet. So..yeah depending on your elevation those 28s with no clutch mods will have a dramatic effect on speed on any engine. Also, if you are running the Unifilter or any other foam filter, make sure it's not over-oiled as it will restrict the air flow...and if you are running a prefilter such as an outerwears, take it off and try it. They are restrictive even clean above 4K.

I do have the Unifilter as well as the Outerwears pre-filter. Once I hear back from them about how it did with stock tires on it again, I will make sure the Uni is a bit dry and remove the prefilter and do a test run.

I get that the tires would make a difference...but a 25-30 MPH difference?!? I'm going to feel like a totally idiot if that's all this issue was the whole time!!!

[2015 Z Force 800 53/Trail EPS]

Mine stock when new without anything else would do about 65 on the flat at 5200 feet. Adding the 27" tires alone took it down to 56(speedometer had to be re-calibrated) but re-clutching took it back up to about 59. Then I added wind shields. That dropped it to about 52. With that much added wind resistance the 800 just can't overcome it and get anywhere close to the RPM limiter. I can take the windshields off and it get pretty close...but still not hit it. Keeping in mine that for every 1000 feet in elevation off seal level you loose about 3% power. For me here at the house that's a little over 15%. That means my little 60HP engine is putting out less then 51HP. You can imagine the loss when I get where I ride mostly...above 8500 feet. So..yeah depending on your elevation those 28s with no clutch mods will have a dramatic effect on speed on any engine. Also, if you are running the Unifilter or any other foam filter, make sure it's not over-oiled as it will restrict the air flow...and if you are running a prefilter such as an outerwears, take it off and try it. They are restrictive even clean above 4K.

I do have the Unifilter as well as the Outerwears pre-filter. Once I hear back from them about how it did with stock tires on it again, I will make sure the Uni is a bit dry and remove the prefilter and do a test run.

I get that the tires would make a difference...but a 25-30 MPH difference?!? I'm going to feel like a totally idiot if that's all this issue was the whole time!!!

Also if you didn't re-cal the speedometer it will show much slower then it really is.

Also if you didn't re-cal the speedometer it will show much slower then it really is.

Tested and ruled out that theory last week when I test drove it. Used GPS app on my phone and it was within 1 MPH the whole time. So speedometer shouldn't been the issue.

Not to mention the first time I really noticed this issue was on the mountain highway roads (pavement) in West Virginia back in Oct. The inclines slowed me down so much could have literally walked faster. My group of other riders on ATVs and RZRs left me in the dust like a joke...it was insane how slow it was going...like 10-20 MPH was all it could do on those hills. I was speechless how under powered it was. Totally embarrassing lol.