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Gotta new bike...

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So yesterday I picked up a 07 polaris sportsman 800efi stealth edition for 3k.  Will lead a pic ltr.  In good shape.  Here's what's wrong with it:

The rpm needle doesn't work just like my other sportsman... not too worried ab that.

The motor doesn't sound like it's running quite right and doesn't feel like it has much more power than my 500.  I'm thinking it needs a tune up and some fresh oil..  but also it feels like it's running rich.  It's a little buggy when you goose the throttle and sometimes farts when you let off (like I little backfire out the exhuast). I'm gonna check timing and valave clearence on the motor first but thinking of putting a tuner on it? Anybody got a suggestion?  Mainly looking for more power.

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What’s up Jacob, congrats on the bike. I would start by going through all the basic stuff first. 

Check the air intake for blockages or obstructions. Throw a new plug in, check the exhaust for anting blocking it. 

Take a look at the ecu for any moisture past or present. 

Check you throttle position sensor also.  It could be out of spec.   There is a tool to calibrate it. Just check the specs on the number.  This is a big item that could be the culprit of your problems.  

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Yea sorry I havnt been on the forum lately..  been working 14 hour days.  So it's running a lot better now that I drilled holes in the exhaust to open that up...  turns out factory these bikes are tuned rich so now it's really responsive and spunky.  Still want a tuner for more power but I'll get to that ltr.  So ima do the usual run down... valve and timing check, new spark plugs, and front in alignment as it has a fair amount of tow out.

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Nice looking bike. I like the radiator mount. I’m a little leery of drilling holes in the exhaust. Should not have to do that, I disagree with ya having to do that, the amount of back pressure allotted for the engine is a design/performance thing.  If there is an issue like that it’s a tuning thing.   Do some research on the TPS for your bike. Look on YouTube. I’m sure it will open your eyes to some tuning tricks.  

Im sure your very excited!!  It’s a bad as* bike. Be careful with that power. 


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Ok.  So I drilled a hole a while back on my 500 and couldn't believe how much more power it had..  the stock exhaust on almost everything nowadays coups up the power in my opinion.  No I wouldn't go cut the pipe off at the manifold, but this is a 1/2inch hole in the end of the exhaust.  I'll check the TPS as well.  Not really concerned with the stock tune as I plan to put a tuner on it anyway.

But yes, yall can hurt you engine by allowing too much backflow into the manifold.

Edited by JacobSlabach
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So to me it sounds good low end but seems to race high end and sounds like it's about to fly apart...  looked online and turns out this is an ohv engine, not a ohc, so no timing or valve adjustments... 

also can anyone point me to a yt video on how to test the speed magneto on polaris bikes? This one and the one on the 500 are dead I believe, but this has also been partly rewired for the rad relocate... 

also it seems to be continually losing starting power to the starter as time goes on..  the battery reads 12v and 14.3v when running. But the starter struggles on the first stroke to turn the engine over..

Gonna be a learning curve to figure out the tps.. but I think your right ab it not being right as every once in a while it seems to not have power.  Also noticed it seems to lose power at high rpm.

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Voltage rectifier/ regulator .  There  may be a blown diode in the rectifier allowing the battery to  bleed back.  You  could  disconnect the  battery  and  charge it  fully..  Then  use   you  meter   set  on 10  amps  and connect the battery through it to the system and see if  it reads any  draw..  Don't  turn anythnig on  while doing that test . Leave the battery  disconnected overnight to  see if the battery itself is  discharging through a [possible internal  short.

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So turns out the k&n filter had some dirt in it, flushed it with gas, blew it out with compressed air.

One of the intake snorkel hoses was kinked, cut that out, will replace ltr.

Now bike is running better and idles around 1200-1400 rpm which feels too high.  It idled at 800-1200 rpm before.  

Gained noticable power tho! I cant seem to find the spec for the tps idle voltage, but I'll check as far as increasing voltage smoothly.

I'm gonna have to do a fair amount of snorkel work.  The air box is missing the gasket, and several hoses for the clutches and that intake need to be replaced.

Also, I think the screaming that I'm hearing is the belt topping out on the secondary clutch.  No problem, just louder cause the intake and output are snorkeled right up to the handlebars rather than under the gas tank.  I topped out the engine going up the driveway and its sounding like normal.  Had a backfire fart after letting off, but didnt lean out or anything..

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  • 3 weeks later...

Update on the 800- so I'm thinking a crack in the exhaust pipe is causing the screaming noise..  havnt taken the time to find the tps specs yet.  I think the belt is almost shot, gonna order a new one. 

I'm trying to find the best way to fix the exhaust?  I was thinking put one slip on coupling and cut out the welded part..  also put on a 4in lift, starting to look for 29-30in wheels for it without having to pay 1k lol also tryna find a clutch kit for it..  any input from those murders out there would be greatly appreciated!!!

Gotta rebuild the snorkel, had some holes in it.  What sealant should I use?  What hose should I use?

Here's some pics of the exhaust and lift






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  • 1 year later...

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