ATV Connection Magazine

AC 90 go fast

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Posted by: Catterman

No, that one isn't made by Kymco.

Posted by: eiger0304

I too have have an '04 and would like to a few more MPH. Looking at changing out the rear sprocket. Any ideas where I could purchase one online?? I too get only about 23 MPH out of it. Does anybody know who makes this wheeler? Yes the electric choke sucks. 9 out 10 times I have to put my hand down in the air box and cover the intake, with my hand, then it usually starts right up.

Posted by: eiger0304

May I ask what you had to drill out, to get rid of the choke problem?

Posted by: eiger0304

Thank you. I gve the local dealer a call to find out the bit size.

Posted by: eiger0304

Getting back to my kids '04 AC 90 4 stroke doing about 23mph. What size rear sprocket should a guy get? I believe stock gear is about 50t. I'm looking to get about 28-30mph out of it. Are we talking about a 35t or a 40 tooth sprocket. Will there be a noticable change in low end if I do this. Do alot of trail riding, and its tough only going a little over 20mph with the kid.

Eveything is stock right now.

Posted by: AIRMOBILE101

Is that one made by Kymco?

Posted by: AIRMOBILE101

Well, look on the frame. Might be some info. I have an 07 kawasaki. The bike is actually made by Kymco. I found many parts with"Kymco" stamped on it before It dawned on me!!! "This bike is made by Kymco" !!!!!!. Regardless who makes it, You can add some top end with a sprocket change. Put a smaller tooth rear sprocket on it, that should give a few miles more an hour. Actually ,check your cdi box ,that should have Kymco stamped on it if its a Kymco.

Posted by: AIRMOBILE101

Check ebay for sprockets , I dropped my rear sprocket from a 32T to a 28T. You can also get them from Hetrick Racing. I think Rebel Gears makes them for Hetrick , but don't qoute me on that.

You will lose a little take-off power , but top end will be good. I didnt notice and lose in take-off since my son's bike has a high stall for take off.

Posted by: Sportsman2

Am looking for help on making my kids 2004 Arctic Cat 90 4 stroke to go faster it sounds like it is against the govener or something i have taken the spacer out of the clutch, it does not have a spacer in the carb and never has from new, i have pulled the tube or manifold off from the carb to the motor there is nothing in there hole is same all way through, of course the throttle limitter is unscrewed all the way, the dealer gave me the limiter intructions on this machine all it said was about the spacer in the clutch which i have done and also about the spacer in the carb but the picture in the instructions for the carb looked different than my carb you had 2 screws holding the top on to the slider, mine is like a regular carb you srew the top of and pull the slider out but there was nothing in there, i bought this brand new so i know no one has messesd with it exept me, oh ya who ever thought of that electric choke thing ought to be shot, if anyone is interested i pulled the choke apart and drilled out the carb with i think #7 drill bit and it starts much better now that was per AC service dept. please someone help me with this 90 cc motor i know it will go faster than 23 MPH it sounds like it is right up against the govener, and 23MPH is all i can get thats gageing it off my 500 Sportsman speedo.
PLEASE and THANK you!!!!!!!!!!!

Posted by: Sportsman2

I do not know how would i find out!!!!!!!!!

Posted by: Sportsman2

How do you know!!!!!!!! also what do you guys know about CDI boxes i have been reading alittle bit about them and i see them advertizing like for Honda 90 that if you get a bigger one that it would override some limiter or something does that sound right or not.

Posted by: Sportsman2

Thats wild we were just talking about the sproket thing this weekend and comparing it to a aftermarket ATV about the same size and it had a much smaller back sproket on it I think i will drop a tooth or two but i have not researched it yet to see were i can get one, but i know i have seen them out there some were i think you may want to try Hot Seat Performance, and the choke thing i had to do the same thing (put my hand over the carb to get it to start ever since it was new, had it back to dealer couple of times they did nothing, finally i got ahold of AC tech services and they told me to have my dealer call them cause they had a new fix, so i did and my dealer called me back with the info on drilling out the carb were the choke is and i have never had to take the seat off again to hand choke it.

Posted by: Sportsman2

you take the carb off and look down the throat and you can see the hole were the choke is located you can drill that hole out but they want you to take the choke assembly out so as not to drill into it or get shavings in it, it has been about a year since i did it so do not quote me exactly on this but i do remember after taking the carb off and pulling the choke assembly out it was pretty self explanitory, like i said AC tech services gave my dealer instructions on how to do this and they just read them to me over the phone they said they would fax them but after telling me how,it sounded pretty easy so i just went right home after that and did it while it was still fresh in my mind, I cannot remember what drill bit they said to use but what ever it was i think i went the next size larger just to make sure that it was getting enough gas to start. Good luck like i said i have not had to take the seat off and hold my hand over the carb to start since i did this.

Posted by: Sportsman2

i would like to know that same ansewr let me know if you find out.

Posted by: IHI

Howdy boyz, first post but reading this and the fact i have just went through the ringer today with daughers new chinquad today i am pleased with our results.

/without going into a bunch of muss and fuss and boring stories, we ended up rejetting-came stock with a 35 and we drilled to a 37, quad still ran like crap and did'nt perform like i thought is should with throttle stop out....buddy that is the bike god took the breather off so it was just sucking gobs of fresh air...quad no longer sounded like it had a rev chip in it and was revving to the moon, sounded great.

reinstalled breather and back to barely getting above half the usable rpm..and was sounding like it was on a rev chip again. This quad of ours has the foam element that we're all used to and has two steel mesh spark arrestors that the faom is sandwhiched between. Removing these in motor cross bikes is worth a few ponies, so buddy removed just the one on the back side of the filer-the one where fresh air first enter the air box. Reinstalled and the thing runs like i've never imagined a lil $300 chinaquad could. We had a blast ripping up and down the road testing it out and just had to giggle to ourselves each time we came back to swap riders...HUGE difference. I'm not so sure the jet did much, but the stock 35 was crudied up and we did'nt have anything that small to run through it, hence using the 37 drill bit to run through, and just happened to bore it as well.

VERY worth while mod to heck into and may be some of the problem with lack of power. only takes a minute to test, just pull breather off all together and see what happens-lift rear end off the ground and that will tell ya since it'll wind to the moon if ya let it

long as i have a book going, today when initally cleaning carb out the first time (we bought this used from a guy that purchased it at auction 2 yrs ago, and it still had the same gas since grandson did'nt want anything to do with it) but when i put carb back on i musta got overzealious and over tightem the carb bolts since one of the manifold ears broke off. Took it to a buddy i drag race with to have it TIG'd back on and figured as long as manifold is off, why not port and polish the lil thing. So the little pipe got hogged out a bit, i rasied the roof and blended n the radius so it should have a bit better air flow and at least a nice smooth pathway. Dont know if it did anything, but like i said, this thing runs out now...guessing based on our other toys it's in the 25-30mph range, but I'll throw my GPS on it tomorrow sometimes and wringe it out to see exactly what we're doing.

Josh