Scrambler 400 Question

[Fear-Nuttin]

My son's '99 Scrambler 400 4x4 - 2 stroke seems to be lacking in power and throttle response. Top end is in the mid 50's, but when he nails it from stop, it hesitates a bit. Shouldn't this quad stand on back 2's when punched?

[4TraxRider]

Have you done a compression check? Might need a new top-end if it hasn't since you bought it. The clutch components wear out on them as well as they get older. The helix's or even the belt could be worn.

[Fear-Nuttin]

I haven't done a compression check. How much is it to have the top end re-built? Should I start checking at the engine first, then move to the clutch? Honestly, I'm not familiar with working on these. But thanks for the information...I'll start with a compression check.

[matthoyda]

check the carb first, check the secondary jet and the needle jet, then move to compression..but i doubt thats it, its rare for the polaris 400 to loose compresion....but if it does it wouldnt be any more then 150 dollars to rebuilt it. It could also be the secondary shive. the clutch buttons could be worn down on the inside of it...its a ***** to get it apart and back together but the buttons are only 15 dollars if i remember right.... thats really all it could be...ive had one and ran it as hard as you can and had about everything go wrong with it.

[yfz450les]

it is 100% your buttons because i have a polaris 400 sport and it done same thing it had a hesitation on bottom but mid-topend was ok but you can still fill a powerloss and if u have enuff $$$ i would prefer to buy a new belt along with new buttons.

[Fear-Nuttin]

Thanks guys, this helps a ton! This forum rocks!

[bradley300]

it could just be because its apolaris. my dad had one that was stock and wouldnt ever stand on the back whel without a brake start, but the one he had with a pipe and clutch kit was much much better. its the fact that the motor needs to pull the slack out of the drive belt by hitting a certain rpm, the clutch kit changed all that

[Honda#4]

Look into Hotseat performance they cover polaris quads.

[Fear-Nuttin]

So- U guys are recommending rebuilding the clutch? I've never attempted this. How difficult is it? Do you need special tools? Do I simply take the entire clutch apart and replace the Buttons and whatever else is needed? Is there any good book, manual or website that shows how to rebuild a Polaris clutch? Hey - that "hotseat" website is awesome!!

[yfz450les]

all u need to do take secondary clutch off take helix out and replace buttons shuld be three of them its not that hard its a do urself job. its not diffucult to put clutch together and u dont really need any special tools.

[Fear-Nuttin]

Thanks for the tip!

[bradley300]

what i suggest is a clutch kit, your not rebuilding it as much as you are re-working it. gives a higher engagement speed, but once it engages, it GOES. it might be the same thing the other guys are talking about, but i'm not sure, maybe someone can clarify

[yfz450les]

that is exatly right soon as u hit throttle its there thats wat the springs are for.

[Fear-Nuttin]

Are there any good books or websites to show me how to work on the Polaris clutch?

[Honda#4]

Try offroad.com they have a clutch setup topic somewher on that site.