las october i bought a used kfx80 for my then 9 year old son. it was his first quad. we took it out to the local desert for him to get used to it. he had a great time on it. we went again a few more times along with some modest sand dunes and trails in the area. the quad got stuck once in a while in the dunes, but did mostly well. last week we took it, along with my 80's vintage honda 250r 3 wheeler to coral pink sand dune park in utah. very disapointing!! the little quad would get stuck ALL THE TIME! it worked ok on level or downhill streches, but would bog down and get stuck everywhere else. we ended up towing it about 3 miles back to camp. my question is, can the kfx80 be modified to work well in the dunes, or is it beyound its ability, and am i better off selling and replacing with the next step up (like a yamaha blaster or somthing??) the quad is mostly stock from what i can tell, with the exception of a fatty pipe, pull starter, led tail and maier head light kit. the bike starts up, and seems to run fine. i have yet to do any repairs, or modifications on it. can it be made to run on the dunes, and NOT get stuck, or even keep up with my 83 250r, or am i just "beating a dead horse". incidently, coral pink is a beutifull sand dune park in utah, with very fine sand, and is at 6,000 foot elevation. any advise most appriciated, best bang for the buck for mods, do sand tires make a BIG difference on a mostly stock kfx, what is stock horsepower, and expected horse power increases with mods. how does it compare to the current line of youth quads, and is thier such a thing as a "performance-youth quad". we would love to keep it, if it can be made to perform in places like dumont or coral pink. thanks, adrian

 

Welcome to the forums.

There are some things that could be done to the 80 to pep it up a little, or if you have the time and money, a lot. What I'd be looking at is how big your son is, and how fast he is growing. I'm guessing he's at the "like a weed" stage. So you may be right in looking for something a little bigger. Just be careful not to get him on something he is physically too small to handle. (can properly reach and use all controls)

Asking it to keep up with a 250r is a pretty tall order.

 

Welcome to the forums.
The KFX80 can be made into a dune screamer.

 

yes my son is growing fast, in the last year he went from a size 2 motocross boot to a size 5, he is about 75 pounds now, and still fits the kfx perfect. but in a year, who knows. i find it hard to believe that this quad is recomended for riders 12 years old or older. by the time he's 12, his knees would hit the handlebars. the recomendations seeem like a joke to me. thanks, adrian

 

my sons LT80 (same bike as a kfx80) is pretty peppy for a bike that's been beat on. mods, I hear there is a restritor in the carb, mine never had it so I can't comment. I had three weights in the front variator and it would pull wheelies with me on it just nailing the gas on the street and my kid is 60lbs and he had it nail a wheelie on grass when it hooked up good and he nailed it on a launch lol. it was awesome. anyway, mine has the midwest mini speed gearing, a UNI pod filter no airbox, FMF fatty pipe, and just this past week I put a milled head on it.

sand paddles make a big difference on ANY bike in the sand so long you can turn them imo. porting, clutch mods, better airflow, better reed setup/fuel flow and you've got a pretty nice little bike. my sons 80 keeps up with my 450 in 3rd gear or cruising 4th I suppose we don't have alot of wide open runs as we only trail and mild track, so I haven't had him behind me at high speeds too much to tell. but on a trail ride I was actually surprised in the smooth stuff to see him still behind me in 3rd lol

LT80 there can make that thing a screamer... I'd love to get a motor done by him but I don't see the point for our type of riding and I want to upgrade my kid asap to a bike with more suspension travel for track stuff. but if I was doing sand I'd LOVE to see just what these little bikes can do.

I'm gonna see if it can pull on hills and if it can I may up the front to a 14t or drop the rear to a smaller gear to get more top speed. it has wheel spinning power off the line already so more top speed would be more fun from what I see lol. but depends on if it can pull the hills.

maybe his throttle screw is limiting the amount the carb opens? I'd check that and look up the carb restrictor and see if it's in there... get some boyesen reeds would be a good start since they're only a little over $20... the bike is probably running pretty rich too, if you can, maybe do a plug test at the elevation you ride and see where you sit. I adjust my needle setting for quick changes to richen or lean the bike for elevations if it's needed. I also have ours setup for premix and I use motorex semi-synthetic I think it is... 428 pitch chain (less drag) make sure the brakes aren't dragging, I set ours up so there's a little play before the brakes are pulled both front and rear.

for me the jetting being rich sucked alot of power leaning it up made it alot more peppy and I'm running a pod filter so I'd imagine a stock bike would be pretty rich to the point it'd last forever but suck for power lol..

when I originally bought the bike, it was setup for MX with some odd looking grooved trailer tires or something and 16.5x6.5" snow hogs on the back. 3 rollers in the front variator, FMF pipe/midwest mini speed package, large 26mm mikuni round slide carb (I had to tune it ran like poop at 1st, and the throttle would stick at times and it leaked like the float height was wrong or the needle seat or something was bad I dunno, took it off as it was a pita at this point lol) but when I got it jetted right it screamed for what it was.. it had a v-force reed cage setup the block intake port was bored to fit it. I have no idea what it's off of, but the 26mm carb and v force worked out good for power.. here's a vid of when we 1st got it running... not tuned in this vid. don't recall making any with the big carb after tuning...

fastdoughnuts.flv video by hawaiianbasshead - Photobucket

it has wheel spacers front and back, so it's pretty hard to flip. this was like his 2nd day ever riding a quad lol. he still does alot of doughnuts but I can't say much I do stuff like that too lol. just alot worse lmfao... anyway, if built right, yeah, it'll scream, imo, you should have LT80 do some work on it for ya if you haven't already. I know this is a few months late but I don't come on here often and was actually searching kfx80 stuff and found this thread

 

Well the answer is simply its a kfx80 its not the biggest most powerful bike in the world but if you tune it right and make sure you have the throttle adjuster screw set to max....... it will help even more if you get new tires i have some red eagle tires that work pretty decently on the dunes but its also about the driver you really have to hit any dune going about 40mph just to try to get to the top you also have to full throttle it up the hill to and some times get off and start pushing...... remember climbing never let go of the throttle until the tires start digging a hole

 

At 10 years old 75lbs and experience riding i would put him on a stock blaster for a third of what its going to cost you to get an 80 up to snuff. Your 80 should bring atleast 500 used and you can find a nice blaster for 8 or 9 hundred.

 

I don't feel that's safe....
At 10 and 75 pounds no bigger machine is needed.

 

Do yourself a favor,keep him on the LT80 just send Jack Moore your motor! You and your son will be happy! My oldest son is 8 and about 80lbs and a well built LT80 pulls him around great!Power sliding and wheelies out of turns kind of amazing what an LT80 can do!Just don't have a good suspension.

 

I had a 2006 KFX 80 - stock - my son rode it at sand dunes (Glamis) for 4 years with no problems. small hauler paddles and stock front tires, it will go up any dune with a 60-75 lb kid on it. Air pressure in front and rear tires makes a big difference as well - with light kids you can run in the 2-3 lb range and get best floatation. Never needed a pipe, just be sure he has all the throttle and it is jetted properly and it is the best small quad you can buy for dune type riding.

Last year I sold the 80 and he upgraded to a Raptor 250, which is a great all around quad for bigger kids with some good riding experience. Then 4 months after I sold it my 9 year old daughter suddenly decided that she wanted to ride, when she was never interested before. But she wanted "blue" - so I bought her a 2009 Yamaha Raptor 90. It is a great little quad, but in the dunes it does not have the needed power to go up any real dunes - it will bog down or simply get stuck, even with tires aired down to 2 lbs and hauler paddles.

So I am looking for an LT 80 for her and selling the Raptor 90 after I find one for her.