Okay start this story off got my mother a sxs  used traded my late dad's quad and moms quad in for a zforce 800 question is builds good power to around 35 then slowly climbs in mph! I've watched videos of these doing alot better!! Then 50 mph  I know it has more guts then 50 I don't expect Wheelies at 50 but the low end is amazing till 35 im sure there's post on this but I'm being a new guy and going the short route! Thanks for any help!

[2015 Z Force 800 53/Trail EPS]

Welcome. Tells us a little more about the Z...like year, mileage, what air filter has it been running, when was the last time it had a new fuel filter, clutch serviced, got a new belt... and about where you are in elevation, ..ect.

2015 1300 miles I checked out the air filter it's paper wrapped with a foam to be up front I ordered a k&n and a outerwear coming! Other then that needs an oil change was owned by a farmer that checked the cows! I don't know more than that! I'll look into a fuel filter! We are at 1200 elevation!

Does it have a full windshield? Combine that with maybe a wearing belt and you might not get more than 50-55mph.  Stock no windshield with 100 miles I get 68-70. seems once the belt starts wearing guys are losing mph down to 60-65 then if you add a windshield there's another 5-10mph.

I would also ask the previous owner if they did any clutch work. someone could have clocked the secondary and put too much tension which would get it lots of low end but you wouldn't get full shift out and wouldn't be able to reach the true top speed.

It has a half windshield! Well it got me wondering she pulled some paperwork out of the glove box something about the belt drive was checked out but the sales rep took it from her !!! I've got no clue what was on it never looked at it! So there is an adjustment on that CVT I'm new to these only ones I've dealt with you change out some springs and Bam your ready to chit and get! Thanks for the help!

[2015 Z Force 800 53/Trail EPS]

It has a half windshield! Well it got me wondering she pulled some paperwork out of the glove box something about the belt drive was checked out but the sales rep took it from her !!! I've got no clue what was on it never looked at it! So there is an adjustment on that CVT I'm new to these only ones I've dealt with you change out some springs and Bam your ready to chit and get! Thanks for the help!

Probably the best thing is to grab the free service manual we have and start checking things out. These have an adjustable secondary spring setup so no new springs are necessary. We have How To videos on this as well. I will say in my current position on the secondary..A2..that it hits about 32 ..like right now, then it slows as it builds to it's max of 64. Where when I was on C1 or B2 the increase was more even but..less low end. So..someone may have your clocking wrong for your needs.

We also need to let you know that 1300 miles on the paper filters has cost some engine life if it's been in any dusty conditions. Might want to take a compression test. That's also one reason for low power.  There's also a writeup here on one that used a K&N that came apart because of the pulsing action when it became restrictive and destroyed his engine. Just making sure you are aware, and here is that post:   

http://cfmoto-forum.com/800ex800/warning-about-kn-air-filters/

We do recommend the Unifilter or the TwinAir foam filters with the proper foam filter oil over anything else. Proven protection.

Sounds like its just general belt wear. They should get you 1500-2000 miles with general riding conditions, but you don't know how the machine was used by the previous owner, so I'd recommend checking the belt. Could just be glazed.

Thank you for the great info I've already got the manual printed that is awesome you can adjust them! It was farmer owned I know that I checked the oil and it needs changed! It just so happens it uses the same oil filter as my ds650 did as well as the old man's outlander had 3 on the shelf so I scored on that! We got mom into this just cause it didn't make much sense to have to quads sitting she was having a hard time getting her leg over the outlander and kfx700! Besides I had to rebuild the carb old gas as well as my sister's kfx700 we all know you don't use them what happens I just don't want to rebuild carbs every yr! Still have to do my wife's kfx as it has sat as well! I do appreciate the help!

Thank you for the great info I've already got the manual printed that is awesome you can adjust them! It was farmer owned I know that I checked the oil and it needs changed! It just so happens it uses the same oil filter as my ds650 did as well as the old man's outlander had 3 on the shelf so I scored on that! We got mom into this just cause it didn't make much sense to have to quads sitting she was having a hard time getting her leg over the outlander and kfx700! Besides I had to rebuild the carb old gas as well as my sister's kfx700 we all know you don't use them what happens I just don't want to rebuild carbs every yr! Still have to do my wife's kfx as it has sat as well! I do appreciate the help!

I wouldn't use the 15/40 they recommend, especially if you have any cold weather. I use rotella T6 its full synthetic and good for wet clutchs and quite inexpensive for full synthetic oil, about $19 a gallon at walmart by me

Lucas makes a synthetic for motorcycle v twins I was thinking about going with it! They sell it here at AutoZone! T6 would be good as well!

Mine has under 600 miles on it and its a 2015 Z800 EX, full windshield on front and back. I finally broke 55mph.....to  56 lol. Im also in Pa, not sure the elevation, but Im not running 22 lbs of air pressure, 10.5 in front and 12 in rear so the "squishy" tires may be affecting the top speed as well. Again that is in about an 1/8 mile space. Never had it on the road to see if I can get it faster.

I'm on a flat road Kansas and that was no wind that day! Well the ride home was on a paved flat road as well I went 3/4 a mile!