other than HPD which other exhaust company makes a full system(header
back) that also comes with jetting suggestions and or jetting kits?

after doing the exhaust/jetting what is a standard clutch upgrade?

can i get away with doing a spring only since this is a trail machine,not mud?

if so what color spring(s) would i want?

the last 500 i bought was already pretty much done so and the new one is bone stock.

 

Pro Circut is a great full system that requires jetting.If it were me I would find a used White Bros and repack it.No jetting would be required.Clutching is endless depending on what you want out of your machine.Let me know what you want out of it and I will set you up on what you will need.

 

I just replaced the primary spring from stock to the orange and seems to have some "stall" better than stock but not aggressive . don't recall the #'s but think it's 145lb vs the 95lb stock if memory serves me correctly. This is on a 400 sport application but I'm sure they are similar. The price was $20 and was 10 minutes to install

 

Clutching on a 400 is a very critical due to if you get the rpms over the power range of the pipe you will loose power.Going to a spring that is more aggressive than a Polaris green or Dalton blk/white can get you too much rpm.(40-120 range).Like I said let me know what you are running and I can set up up.
A 500 has endless combination to run depending on what you want out of it.Just have to keep the top rpms safe and have a controllable engagement speed.You dont have to hold a set rpm on 4strokes

 

Yeah,he's probably right. The spring I just installed works for me but that's just me lol. I probably should stick to making Gen 1 Ford Lightnings fast. I haven't fooled with atvs in 8 to 10 yrs. My 400 sport was est. 60hp before I sold it . bought it back 8 yrs later and it's still pretty fast for a 94 model. Not alot of $ invested and think it ran 9.40 @66-7mph in 1/8th . I remember it's .30 over with a weisco,boyesen power reeds,DG nickel header and +2 from stock jet size.
I am considering making the 97 400 sport I got from my dad FAST , so any suggestions you may have ftwflh send me a PM sometime...you seem to be very knowledgeable in the atv area as I an just a beginner

 

I got a complete IDS2 for my 500 off ebay and a Comet HPQ 103 complete clutch also off ebay. The comet came already set up for a 400 so I changed the weights and spring with the recomended parts off their data sheet.