I have received numerous e-mails about what can be done to increase the performance of the SP500. Most people seem to want to do the usual... jet, K&N and Pipe.

This is my opinion on the subject, and maybe this will help some of you.

The SP500 exhaust flows plenty of air, and probably more than most of you will ever need. The restriction of airflow is in the head and airbox. You may disagree, and if you do try this... remove your airbox lid and run your bike with a k&N around the block. The bike will lean out so much, it will not run. This tells you that the airbox is restricting airflow. If you intend on increasing the performance of your bike, you have to solve this problem first. Once you have increased airflow, the bike may lean out a little. At this point, you have to increase your jet size. Once you have increase the air flow into the carb as much as possible, and jetted up accordingly, then you should look to the head/cam and exhaust. If you do decide to go with the 40mm carb and scrambler cam, you will not get the full effect without increasing the air flow into the carb. Once all this is done, the last thing I would do is change the exhaust.

This does not go for all bikes. Most Hondas are restricted by the exhaust, and even more by the design of the head. That is why you hear people comment on the difference thay experience by adding a pipe. You can do the same airbox test with most Honda 4-strokes and the bike will run fine. The airbox is not the problem with the Hondas.

Anyway, for you people think about dishing out $200 for a pipe to increase performance, I would save my money unless you just want the bike to sound faster.

Greg

 

Explain to me how you increase air flow? If you cut holes in the air box, water becomes a big problem!!! My 00 sp500 has a kn and has been jetted down-it still is a slug. I like the bike, but it is slow!!! I think there is more performance to be had with some carefull carb & clutch setup. The problem with clutching changes, is found with the lack of knowledge around. If you talk to most dealers, they don't have any idea how to set these things up.

 

I also have a 99 SP500 and am not impressed with its performance. Seems I have one of the slower ons 45mph Max!!!!!!!! with a tail wind downhill. Can almost out run my sons trailboss 325. On long streatchs he catches me. Any pointers would be helpful. I would like to retain the submarine capabilities but if I have to give them up I will. I know how to jet an engine just havnt messed with it yet.Is there a mod for the airbox lid? or just toss it? BY the way dont email me the address in the profile is not good anymore. New address is hlhacker@optonline.net

 

Are you talking about a Sportsman 500 or the new and improved 500 HO?
I have excelant power with my HO and have no mods as of now because all Sportsman mods on the market are for the 1999 and older machines.
My quad is still being broke in and only has 67 miles on it so it is still a little tight but I have reached 65 mph and can't understand why some guys say there quads are slow and will only do 45 mph.



2001 Sportsman 500 HO Yellow-stock for now
1998 Sport 400-to many mods to list and scary fast
2001 Scrambler 90

 

i think hes refering to non ho`s..another thing you can try is taking all the slack out of the throttle cable..there is an adj on the cable up by the pod,i noticed a big difference after doing that on my exp. and have had to 52 m.p.h. with the throttle just a bit past half way so adjusting the slack out might help..and i cant take credit,i got this idea as well other good ones from greg as well he seems to know his stuff

 

My SP500 would only do around 52MPH the day I got it. It will now do 60+, ride a wheelie down the rode even with a winch on the front, and I regularly outrun SP500HOs in the sand drag. The first thing to do is adjust the thottle cable. Let the bike idle and adjust the cable until you hear the bike rev slightly, then back it off a little. Of course, install a K&N, and then modify the airbox to increase airflow. I closed off my stock intake, and ran a 2"snorkel to allow for the increased airflow. My plug went from dark balck to light brown as it should be. You will need to make sure the bike does not lean out too much, and if it does go to a larger jet. Also keep in mind that the bike will run leaner in extreme cold conditions than it will in warm conditions. Also, I live in East Texas barely above Sea Level. Depending on where you live, you may need to jet accordingly. I hate giving advise like this because I do not know where and how you guys ride. The only way to properly jet a bike is to actually be there and do it yourself.

If you want to see my set-up, here are pics. There are close ups of the Tranny snorkels also.

http://photos.yahoo.com/bc/gregsims01

Hope this helps.

Greg

 

Greg, Are you serious? These are the only mods to your quad? No spring or anything else? I may look into the snorkled airbox with that kind of gains in power. Did you experiment with 2 and a half inch tubing? You said you blocked off the existing intake and how did you make a good connection with the pipe at the airbox? I am very interested in this.

Thanks,

Dave

 

Dave,
Look at my pics. I cut a 2" hole the bottom right had side of the airbox uder the fender. I sealed off the original intake with black duct tape. I can remove the entire snorkel system, plug the airbox is a threaded cap, remove the tape, and be basically stock in 30 minutes or less. Anything bigger than 2" ABS is overkill. My 98SP500 leaned out so much with 2", I have to go back with 1.5" ABS. I have not changed the spring, but I am considering the white spring. I do some very serious rock climbing in Arkansas, and that is why I have not done this already. I like the smooth power I get right now.

Greg

 

Checked the cable slack first day I had the quad. There is no slack. Also checked float level, valves and all the oviouse things. Basicly it runs perfect but is a slug. In low range standing start there is no way It will lift the front wheels off the ground. Go over a log or something it will lift right up and stay there. Obviosously theres something not right with it. I do mostly trail riding and short bursts at full throttle. In NY there isnt many places to go over 50mph so it doesnt bother me much. It would be nice to lift the front off the ground at will though. Im 265lbs and can gun it from a stand still and pull with all my might and might get it 6-8 inches off the ground. I will take the lid off and check the jetting and take it from there. Only have about 1k miles on it.Been back to the dealer 10x because it so slow. I even wrote Polaris and their respose was they do not guarentee any max speed.

 

Checked the cable slack first day I had the quad. There is no slack. Also checked float level, valves and all the oviouse things. Basicly it runs perfect but is a slug. In low range standing start there is no way It will lift the front wheels off the ground. Go over a log or something it will lift right up and stay there. Obviosously theres something not right with it. I do mostly trail riding and short bursts at full throttle. In NY there isnt many places to go over 50mph so it doesnt bother me much. It would be nice to lift the front off the ground at will though. Im 265lbs and can gun it from a stand still and pull with all my might and might get it 6-8 inches off the ground. I will take the lid off and check the jetting and take it from there. Only have about 1k miles on it.Been back to the dealer 10x because it so slow. I even wrote Polaris and their respose was they do not guarentee any max speed.