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Posted by: Pechmial
Do some searching on "Sportsman 90" and you should find some threads that will help. Searching on Mini ATV's in this forum will help too.
This topic has been covered several times.
Basically, though, in answer to your questions, there are modifications you can do to your engine, exhaust, transmission and suspension that will greatly improve your mini's performance. I've heard of mini's that can go 60mph so it's not out of the question. I'd consider some suspension mod's along with it, however, to be sure the machine can handle the speed.
Posted by: Pechmial
There are kits you can buy for the tranny that change it's engagement points and such. I won't pretend to understand it all.
Performance links for Kid sized ATVs....
Rhino accessories from Keen Perception (I ordered the oversized cylinder from them)
Mini Quad Racing
Mini ATV parts
Trinity Racing
Hetrick Racing
WRH racing
These are probably only scratching the surface, but they'll get you started. Be prepared to spend, though. Making a race ready mini cost almost as much, if not more than the mini cost originally!
Posted by: Pechmial
Overkill has a very good point, too. No matter how much you modify a 90cc, it's unlikely to ever match a blaster in terms of suspension and potential (particularly with the Blaster's aftermarket).
I may do a few more mods to my 90, but then I have a few kids that can grow into it yet.
Posted by: Pechmial
Wheel spacers will improve the WIDTH, not the Wheelbase (that's the distance front to back). You'd need an extended swingarm to improve the wheelbase.
With the oversized cylindar my kids report an increase in power, but the top speed has been unaffected. Adding a pipe will probably further increase the power. Speed, I believe, is limited more by the transmission than the engine.
Posted by: Pechmial
Tommy's right. The cylindar upgrade on mine did produce some noticable power, the kids can get up hills better, etc, but there was no change in top end speed.
Tommy, my 90cc is a 2001, does it have a CDI? And where would such a thing be? Also, before I tear the carb out and dig around in it, is there a restrictor in the carb? There was NOT one in the exhaust intake or on the muffler. I'm not yet ready to drop any real money into this thing, but keep thinking there are some smaller things I might be missing.
Posted by: Pechmial
Foneguy, those are older pictures where we didn't know any better. There was no snorkle on at that time, but I did open the airbox after a few trips like that and everything seemed ok. Not that those puddles were only inches deep, though. In later runs they went through a puddle about a half a foot to a foot deep and managed to introduce enough crud to badly score the piston and cylinder (hence the current oversized set). Until I find a perminant solution they are restricted from puddles. Since the kid who liked to splash the most is big enough to ride the adult sized ATV's the little one rarely sees mud anymore anyway.
Posted by: foneguy
hey prechmial, i looked at your pics of your son raelly splashing through the mud and water, did you build a sort of snorkle for the 90? i was working on ours and the 2 breathers, ( air intake and crank case) are so low im afraid to let my son even go near the water. if you did what size pipe did u use or was it just something like a large dia hose.
Posted by: foneguy
i built my son one just took some tubing up by the gas tank, ill let u know how it does
Posted by: foneguy
i cut off the 90 deg part on the ari intake tube, then put a ribbed 90 with 2 ft of 3/4 in clear tubing and flexed it up over the gas tank and under the plastic to concile it. looks olike it will work, runs fine with it on. also going to find a torn pair of tighties from my daughter to go over the inlet to act as a secondary filter. should do the trick ill find out next weekend after the rumble.
Posted by: foneguy
let me know how the tires work out,,thats next for Johnathon.....img src="i/expressions/face-icon-small-happy.gif" border="0">
Posted by: Overkill
If you want to go that fast, it would be cheaper to buy a Yamaha Blaster and have 2 quads. Just a thought. We have been very happy with our Sportsman, but when it's time for our son to go a little faster, we'll just buy him a bigger quad and pass the Sportsman on to our daughter.
Posted by: Muddog007
YO MR sportsman 90 that litle Quad is not ment for speed wait about 3 years then with all that money you saved you can buy a real bike!! Know what I am saying here!! AM 14
and I ride a SP 90 I might put bigger tires on it but thats IT!!!! DUDE I have broken my arm on mine!! IT hurt!!
Posted by: Muddog007
My dad and I were going to use a dryer vent tube.We think this should work.BR>I hope!!!!!!!!!!!!
Posted by: Muddog007
Oh ya Ibroke my front rack at a weld any one ese do this???Any brake an A-arm doing jumps??? wach out SP90 rider that is how I broke my arm!! Its now fixedand Iam back riding
Posted by: Muddog007
Yo bud thanks WE think we may go up by the handlebars to chanal it up with a ram air type thinge a bit above the rack. I am now going to get some big 22in tires on the back and 20 in front!!
Posted by: TRexTommy51
Here is what you can do to the 90. A pipe is the first thing along with a air filter. To make it run up over 60, you have to change the sprocket ratio to 19 front, 25 rear. Change teh CDI box to a digital cdi or a 9500 rpm cdi. To get to 60 fast, you need a new head, 24mm or 28mm carb, Some like 20mm but I recommend 24 or 28mm. A ported cylinder, transmission kit(have to have with pipe).
As far as suspension, +3 A-Arms, 2.5 wheels spacers, works shocks, Tomco rear swing-arm(+3), aluminum handlebars, (Have I spent enough of your money yet?), Double A-Arm kit if you want, douglas wheels and tires.
Posted by: TRexTommy51
You will not get anymore top speed out of this machine unless you allow the engine to rev higher or change the sprocket ratio. The 53mm cylinder kit will give you very limited power gain, but it is an excellent top end rebuild.
Posted by: TRexTommy51
Pechmial,
The sportsman doesn't have any physical restrictors that I am aware of. It is limited by the sprockets and CDI. THe CDI you have is a 8300rpm CDI.(Don't quote me on that but it is low.) The real solution for power is a pipe. the solution for speed is sprockets. Be careful about getting a unresticted CDI. This machine will not hold up to 10k rpm for very long. You can cut every other fan blade out of your fan. This will help the power some. Take off the oil injection and pre-mix with good oil (BelRay H1r) at 40:1 will help a little, plus it is better for your engine.
Posted by: TRexTommy51
For the most part, If you stay with the stock carburetor and get a Tomco exhaust system with Air Filter, then you will need to take the float bowl off the bottom of the carb and replace the main jet with a biogger one. WRH Pipe=.95mm Ex-Pipe=1.10mm PP=1.25mm main jet. THe needle will have to be moved up one notch.
The stock clutch springs are set up for the power of the stock engine. If you change the pipe, you have to change the clutch springs, variator roller weights, and teh torque driver spring to get the right power delivery out of the machine. That is were you need to buy performance parts from a minni quad performance dealer.
Posted by: TRexTommy51
Foneguy,
A air filter off of a DRR raps around and goes under the set. It is a great set up for trail riding in the mud and stuff.
Posted by: BigDaddy28
I am kinda new at this too. But I know that there are plenty of upgrade parts.
You might want to read through the other threads asking about mods.
Posted by: Sportmanrider90
I want my polaris sportman 90 to go 40 - 60 is that even posable? If so waht do i need to get that? Where can i find it and how much? My polaris is fully stocked no aftermarket Parts. Thanks
Posted by: Sportmanrider90
What would i do to the transmission that will help?
Posted by: Sportmanrider90
Thanks for the input. My friend has a blaster is fast!! im still no to great on shifting from nuturel to 1st. Its hard for me. i mean i just want a little more speed. I think im going to change the piston and put a new pipe on it. Im only 12. I dont think im ready for the blaster. I got to learn how to use clutch first
Posted by: Sportmanrider90
About how fast would it go if a put on 93 cc kit and a pipe and silencer and a trans kit? Mayeb wheel spacers for a little extra lengh it the wheel base?
Posted by: Sportmanrider90
Whats jetting and what do u do? I getting a filter and a pipe. And im going to premix do i need to jet? Or could i re jet to make it have power/speed?
Posted by: Sportmanrider90
Also do i need a trans kit with the pipe ? Or i could just get the pipe?
