Id say the cover for the ultramatic has got to come off, and looked over. Most likely the weights on the drive pulley, need to come out and be cleaned and relubed. Your best bet is to get a service manual, and if you are somewhat mechanically inclined, you should be able to do it yourself. The only tough parts is removeing the big nut.
go here
texmudder
and scroll down to the "changing clutch weights on the grizzly", and itll explain what needs doing. Keep things clean, and you can use marine grease instead of the ultramatic grease.
If you arent comfortable doing this, then youll probably have to have someone else do it. It wont go back to normal until its been regreased.

 

Did you say 21 MPH? That's the key to the whole problem. Mine was doing the same thing. When it hits 21 mph the REV limter kicks in. What happened to mine was a stick grabed the plug in to the front differental and pulled it out a little. On the left side down on the pumkin or the differental case you will see a black plug-in. I'll bet you if you check it your problem will be solved. After reading your post you have describe my problem exactly. 21 MPH is the key word when I brought mine into the dealer. The mechenic looked down and said here's your problem and pluged it in real good and everything was perfect I'm sure it's your problem either with the plug in or some where with the rev limiter. let us know

 

well i checked the differential and it appeared both plug ins were in as far as they would go. i guess its time to take it back to the dealer. man is this frusterating. i figured it would go through alot more then what i took it through. after hearing all the good talk of these things and getting such high hopes, what a let down. hear i was going to add a plow and have it part of my snowplow business but this is showing that after a month and it breaks down. man who knows whats next.

 

Before you take it back to the dealer...remove those plugs, by the differential, and make sure they are dry, then clean them up, if they are dirty and reassemble them with dieelectric grease in the connectors.

Lets face it, sometimes our quads fail because of us, and what we do to them. Thats why i have hondabuster for a nickname, Ive been known to trash a honda or two, but i still buy them. I really doubt a dinili or mercat , or other tiawan quad,would last long with me riding it.

I believe, in the owners manual, it says something like 9 inch water is the deepest, it was designed to go thru...yet we all know itll go deeper, but then realize, the deeper it goes, the higher the risk that something bad is gonna happen. If 9 inches of water is all we would go thru..it wouldnt be much fun. Its one of those things...its a hobby, and you gotta pay to play.
I wouldnt let this one event sour me on a quad or manufacturer, id learn from it.

 

If it hit 21 mph and then cuts out it's has somethinng to do with the rev limiter. Does the 03 have a override rev limiter on the left handlebar like the 05's. If it does push it in and see what happens when you get up 21 mph. I'm dying to hear what is wrong, but if it runs fine until 21mph then it's got to have something to do with it. Good luck!

 

Wow the frustration, my jeep my phone and my KOdiak all are dieing , i think i am cursed or am to hard on my toys. to me it sounds like the rev limiter as well as for it makes the same sound in reverse. I haveto go out and disconnect them then reconnect and see what we got. my kodiak 05, does have the rev limiter overide on the left handlebar but when i do 21 mph and hit it i still am unable to go faster.

you guys are giving me hope please let me fix this it is such a fun toy.

 

I got yours confused with the original post who's got an 03. Your is no problem to fix. It's only a month old. Take it back to the dealer say nothing about getting stuck and trying to make a Submurine out of it.
It's there problem, just let us know what it was. I'm sure it has something to do with the rev limiter. Mine did the same about 7 miles from home. I had to limp back at 20 mph when I hit 21 it cut out.[img]i/expressions/face-icon-small-disgusted.gif[/img]

 

wish me luck, i am on the wy to the dealer and he didn't sound to promising..... stated " well it only does 21 mph, we haven't had anything like that come through yet". oh boy....

 

A friend of mine had the same problem on his rhino. What he found out is the rev limiter switch had gone bad(it was telling the system that it was in reverse) so all he did was ground the line right in front of transmission. Which by-passed the switch. Now he says he can almost go as fast in reverse as he can forward. If this doesn't make sense then let me know and I can get him to explain exactly what he did verbatem.

 

makes perfect sence just didn't want to start tampering with anything whileit's still under warrant. scary i took it to the deaer mechanic and he was likte " wow i have never seen this before" oh man i almost did'nt leave it there. i figure man i should just take it apart myself and try and fix it. i have no confidence in him and i hope the warranty covers it. plus they want $172 for the initial check up. grrrr. think i mines well get the check list ad do that myself.