As some of you know, I have been in the process of upgrading my wife's '98 SP500 to HO - I bought an HO camshaft, HO carburetor (ebay), and the intake boot.

Before putting the HO carb stuff on, I wanted to see the performance difference with just the camshaft - but I could not get it to run worth crap with the stock carb. I can put the HO carb on and it will run like a dream.

This was bugging the crap out of me, so after scratching my butt for several days, trying this, checking that, adjusting this...... I finally realized that the '96-98 500's run a 142.5 main jet in the carb vs. the '99 up's use a 155 (or 152.5) main jet. I stuck a 155 main jet in the carb and it now runs great with the stock carb.

As far as the performance differences - my buddy has a '99 SP500 and an '01 SP500 HO, and we have not been able to get our schedules together yet to try them out. I'll make a post as soon as I have a verdict.

 

I have a 2000 and was thinking about doing the same thing. So make sure you let us know how it compares. I really wanna know how much difference there is.

 

You may or may not know that the exhaust head pipe is larger on an HO. I found this out the hard way, I bought a HO exhaust (Big Gun) off of eBay and it will not fit my 98 because the head pipe was too small. Might get it to breath alittle better with a HO "complete" system. Good luck.

 

Just to put in my 2 cents... My uncle took his 500 in when the HO's came out in 2002 wanting to upgrade to the HO motor. Polaris and the dealer specifically said that there is no way to simply upgrade the motor with just a simple camshaft or other small parts. They basically said you would have to buy an entire new motor. They never offered an upgrade kit either. Not sure what the differences in the motors are, but maybe there's more differences, such as bore, valve lift, etc. Ask the dealer if there is a Technical information release about this.
Just my 2 cents.

 

The HO has a stronger bottom end. Bigger big end etc. The other mods can be made as many have already but you run a higher risk of bottom end failure. Maybe people that have made the conversion can comment on the longevity.

 

Before I started this project, I had looked at everything - except the bottom end. Everything is the same on the top end, except for the camshaft - never even crossed my mind to check the bottom end - and talk about price differences - example connecting rod 500 $170, HO $40 - crankshaft assy 500 $550, HO $440 ......... hmmmm

I had seen the post about the exhaust difference, we'll see what happens - may have to put the HO exhaust on just to get it to breath right.

Although this quad doesn't get ridden hard very often, we put a lot of daily miles on it, so we will see what the longevity of the engine turns out to be. My wife is just happy her ride is back moving on its own again (I don't think she cares a hoot that I'm trying to make it HO).

 

Just my 2 bits, if your not riding hard very often you might want to stay with the none HO. I say this because the gas mileage for the HO is a good 25% less than the none HO. 15 mpg compared to 22 mpg none HO. I know I've had both.

 

Wow, i never knew you can upgrade a pre-99 sp500 to an HO? now i might just have to Upgrade my 97 to HO spec, thatd be nice [img]i/expressions/face-icon-small-happy.gif[/img] . how much does all the stuff cost in total?? granted i like the power it has now, its plenty for me, but more is good too, as always lol.