Hi,

I'm new here and I recently purchased a new 2015 Zforce 800 Slim 53 (actually 51.5).  I've got a little over 200 miles on it now (fully broken in) and it runs perfect so far.  No leaks, all bolts tight, etc.  All I have done to it so far was to replace the stock air filter with a Twinair, and I wired in a plug for a battery tender since it's a pain to get to the battery.  Also I added a full front and rear windshield from Superatv.com.

Since brand new I've noticed some bouncing/shaking at speeds above about 20 mph.  Also I can hear the tranny whine in rhythm with the bouncing.  Up around 50+ mph it seems like the bouncing becomes much less noticeable.  I assumed (hoped) this was just flat spots on the tires from sitting at the dealer for several months and it would work out after some more miles.  No such luck- it is just as bad as before, and now that I can stretch it out more now that it's broken in, this is a real bummer.  I jacked it up and put it on blocks and ran it so I could study the rotating tires and shafts and everything.  Conclusion- both rear tires are out of round quite a bit.  There's at least a 1/2" or more deviation.  It's up and down, not side to side.   

Has anyone else had this problem with the stock Abuzz rear tires?  If so, how has Cfmoto been about repair/replacement of tires under warranty? 

Overall I'm extremely pleased with the machine, it's just that I don't think I should have to replace the tires so soon!  I bought this thing only about 2 weeks ago. 

Thanks in advance for any information you guys can offer.

Kory

[2015 Z Force 800 53/Trail EPS]

Welcome Kory. Mine has some of that noise but it was just flat spots from a Bias ply tire sitting. It went away after driving it. If you see actual run-out on the tires, just take it in asap and tell them. CFMoto has been great on fixing problems. Tires should be no issue. I did get rid of my stock tires within 200 miles because  well, I just like radials on my stuff and a hair larger didn't hurt either.

One thing you might try is to see if the beads are fully seated. If not, it will make that kind of run-out. Just jack it off the ground, pull the valve cores. Once all the sir is out push in on the tire all the way around on both sides and see if there is any gap between the tire bead and the wheel bead edge. If you find some, spray some silicone spray in there and air it up to about 30lbs. That should pop it out. Then put it back to between 7-12 lbs.

Thanks for the tip and info NMK! 

I'll give your tip a try this weekend when I get back up north to the lake place, which is where my machine resides now.  The machine is kept in northern Minnesota, and I live in the Twin Cities area during the week.  The dealer is down here in the Cities, and I'd prefer to not have to trailer it back and forth.  I wonder if they would have a problem warranty-wise if I were to just take the wheels off and bring only them into the dealer for service?

Hopefully it's just bad bead seating, but wouldn't that be odd if both rear tires have almost exactly the same problem?  And just the rears?

I'll be interested to see if anyone else here has experienced a similar problem. 

I personally would like a taller, skinnier or thinner tire for my 53" Z.  Any ideas guys? All thoughts are greatly appreciated!  I would most likely want to go with radials also.

I personally would like a taller, skinnier or thinner tire for my 53" Z.  Any ideas guys? All thoughts are greatly appreciated!  I would most likely want to go with radials also.

You could go with the same size wheels & tires as the fronts, then just add to the height (i.e. 27s, 28s, ect)

[2015 Z Force 800 53/Trail EPS]

I wend with 27x 9/11s GBC Grim Reapers and love then so far. Perfect for everything I do. As for skinner on back or using the same as on the front I would worry about the added weight these have in the rear with the engine and passengers seated so far back. What effect would it have on traction and handling and how would that effect the service life of the tire. Unknows for sure. Just thoughts for now.

I wend with 27x 9/11s GBC Grim Reapers and love then so far. Perfect for everything I do. As for skinner on back or using the same as on the front I would worry about the added weight these have in the rear with the engine and passengers seated so far back. What effect would it have on traction and handling and how would that effect the service life of the tire. Unknows for sure. Just thoughts for now.

The fronts use a narrower wheel and tire, so wouldnt we be SHEDDING weight not adding by using the same size wheel/tire for the rear (replacing the 14x8 wheel in the rear with a 14x7)

[2015 Z Force 800 53/Trail EPS]

I wend with 27x 9/11s GBC Grim Reapers and love then so far. Perfect for everything I do. As for skinner on back or using the same as on the front I would worry about the added weight these have in the rear with the engine and passengers seated so far back. What effect would it have on traction and handling and how would that effect the service life of the tire. Unknows for sure. Just thoughts for now.

The fronts use a narrower wheel and tire, so wouldnt we be SHEDDING weight not adding by using the same size wheel/tire for the rear (replacing the 14x8 wheel in the rear with a 14x7)

What about that actual weight on each axles on the back compared to the fronts? Isn't there actually more load per rear wheel then front? or no. Maybe over thinking this but say you want the same pressure per contact square inch (where the tire meets the trail) and you have less weight up front then in the rear. Wouldn't you need more contact patch to distribute that extra weight so it would be the same as the front? And for that you would need.. a larger or wider tire.

An update to this thread in case anyone is interested-

I sought warranty service for my out of round tires at my dealer while it was in for its break-in service and oil change and another minor warranty issue.  The dealer had a difficult time getting any response from CST Tires.  After a couple weeks at the dealer, finally CFMoto stepped up and agreed to replace the tires for me.  I'm very pleased that CFMoto decided to take care of this, even though it is the tire manufacturer's warranty that should have covered it.  Awesome job CFMoto! 

When it's time to replace, I will say that I will NEVER buy CST brand tires for anything I own.  I guess you get what you pay for...

I wend with 27x 9/11s GBC Grim Reapers and love then so far. Perfect for everything I do. As for skinner on back or using the same as on the front I would worry about the added weight these have in the rear with the engine and passengers seated so far back. What effect would it have on traction and handling and how would that effect the service life of the tire. Unknows for sure. Just thoughts for now.

The fronts use a narrower wheel and tire, so wouldnt we be SHEDDING weight not adding by using the same size wheel/tire for the rear (replacing the 14x8 wheel in the rear with a 14x7)

What about that actual weight on each axles on the back compared to the fronts? Isn't there actually more load per rear wheel then front? or no. Maybe over thinking this but say you want the same pressure per contact square inch (where the tire meets the trail) and you have less weight up front then in the rear. Wouldn't you need more contact patch to distribute that extra weight so it would be the same as the front? And for that you would need.. a larger or wider tire.

I'm such a bone head. I reread what you wrote today and realized what you meant.

But yes, you are right, with the added weight of the engine plus the riders I'm not sure I'd run with narrow fronts on the rear.