o rev but it wont
Sport & Outdoor – Others

Experienced athletes share their insights in answering this question:
Http://www.smallengineadvisor.com/memberdetails.htm

A great DIY motor troubleshooting

http://videos.wittysparks.com/id/3648715610

Above is a service and repair manual, in Video format.

http://www.scribd.com/doc/19783206/1998-Polaris-Sportsman-500A-Parts-Manual

Above is the parts manual, below is a service manual in PDF format. I am sure with all this you will be able to troubleshoot and repair your motor.

Some tips, Check, Battery, Check EARTH, Check, Spark plug lead, (Replace on spec usual) Spark plug (Again replace on spec) Check any “Points” system, be they mechanical, or electronic, Check the capacitor, if there is one. Now, make sure you are getting a good hot spark. Now when you are sure you have a good electrical side, we troubleshoot the “Gas” side of things, now, check, the Carburettor, check, the Float, and Float Bowl, check the Float Valve as well, check Choke is OK, check, Butterfly Valve is OK, Set the Mixture, make sure you have good fuel flow to carburettor. Hopefully between this advice and the links provided you should be able to remedy your problem.
http://www.freepdfmanual.com/2009/02/06/polaris-sportsman-400-atv-parts-catalog-2005

How to Identify and Resolve Common Issues ?

We offer a diverse range of insights on identifying and resolving common problems in sports. Our sources encompass academic articles, blog posts, and personal essays shared by seasoned athletes. :

There are many reasons why an ATV sputters. The most common reason has to do with a carburetor problem like a tuning issue, vacuum leak, or gas leak. Other sputtering issues can be caused by an ignition issue. For the combustion chamber to work on an ATV, it needs air, gas, and a spark.
ATVs commonly backfire due to the imbalance of air and fuel sparked outside of the combustion chamber. This minor explosion takes place in the engine`s intake or exhaust and can cause the vehicle to shut off. Common reasons include issues with the fuel/air mixture, carburetor, ignition, or fuel pump.
Carburetor Assembly Fits Polaris Sportsman 500 2001-2013 OEM 3131742, 3131712.
The Ignition Coil

A faulty ignition coil will not be able to transfer a spark powerful enough to the spark plugs, which will ultimately cause the ATV to bog down and struggle.

One of the most common causes of a sputtering engine is an issue with the vehicle`s fuel system—the filter, pump, and injectors. These three critical components work together to ensure fuel flows smoothly from the fuel tank to your engine`s fuel injectors, and then pumps into the engine evenly.
Just because you hear the fuel pump run does not mean it is pumping the correct pressure to the injection system. If the pressure is real low or the filter is plugged solid, then the pump may not get enough fuel to the fuel rail. The only way to know is to test the fuel pressure at the fuel rail test port.
A weak fuel pump or insufficient fuel pressure are two reasons that prevent the combustion chamber from receiving fuel in the required amount, and as a result, your ATV backfiring. Letting the fuel sit in the fuel tank for a long period makes it thick and capable of clogging the jets of the carburetor.
Your pilot jet (or slow jet) controls the idle circuit, or from zero to one-quarter throttle opening. The pilot jet and airscrew control the amount of fuel and air going into the engine at slow engine speeds.
To arrive at the most appropriate carburetor choice, there`s a basic formula: engine displacement multiplied by maximum rpm divided by 3,456. For example: a typical 355ci small-block—a 0.030-over rebuild—with a 6,000-rpm max engine speed would work well with a 616-cfm carb ((355 x 6,000) 3,456 = 616.32).
If the engine is low on power, it will bog down when you try to accelerate. This could be caused by a number of different issues, including low compression, a bad timing belt, sucking too much air, or even a head gasket leak.
A spark plug fouled with fuel, carbon, dirt and oil on the electrodes will result in an inconsistent spark and loss of power.
Check the Air Filter: The most common reason why an engine bogs out under acceleration is because the air/fuel mixture is `dirty` or inefficient. If the air filter is clogged or has a lot of dirt in it, it could be bogging down the engine. Clean the air filter and see if the problem goes away.
The carb float works to regulate the flow of fuel into the carb bowl through a simple mechanism. But if it gets stuck in an open position, fuel will keep pouring into the bowl to the point it overflows through the fuel overflow.
To check fuel delivery, remove the fuel line where it enters the carburetor and use a length of rubber hose to direct the flow into bottle or similar container. Fuel should pulse out in strong spurts if your engine is equipped with a mechanical fuel pump (electric fuel pumps are more of a steady stream).
The symptoms you typically experience when your pump is failing are poor upper RPM performance, a loss of top speed and poor acceleration. This definitely makes your Polaris much less fun to drive, but even more importantly, a fuel pump problem can cause your engine devastating damage by not supplying enough fuel.
Irregular resistance within the fuel pump motor can lead to your car slowing down and being unable to accelerate. Failing to accelerate is a good sign that your vehicle`s fuel pump needs inspection.
If there is still no pressure, then replace the fuel filter and retest. If nothing after that, then the fuel pressure regulator is not working and needs replacing. If you get pressure to the rail, then there could be a problem with the injectors; they may be either dirty or plugged up.
Fuel pump failures can be caused by electrical faults, old age (wear) or fuel contaminants (dirt, moisture or bad gas). Fuel pump failures often occur without warning. Fuel pumps, injectors and pressure regulators are the three most commonly replaced fuel system components.
Another possible cause of your backfire is a spark plug refusing to “spark” when the exhaust valve opens. If the air/fuel mixture has become too rich, unburned fuel is left in the exhaust system. The misfired spark plug ignites the rich air/fuel mixture, causing a loud “bang” in the tail pipe.
Find the adjustment screws on the front of the carburetor.

There should be two screws on the front of the carburetor, which are used to adjust the air and fuel mixture. These often look like flat-head screws, and you can use a screwdriver to turn them, adjusting the amount of fuel and air mixing in the carb.

Backfires are caused by an incorrect fuel to air ratio. These small explosions result in a loss of power when accelerating and a loud pop or bang. In some cases, this may even be accompanied by a burst of flames.
Blown gasket may be cause of backfire.
On the other end of the spectrum, a bad fuel pump, vacuum leak, or clogged fuel injectors could cause an air-fuel ratio that`s too lean; that is, it has too much air and not enough fuel. Though this is the opposite problem, it can also cause a backfire as vapor escapes into the exhaust and combusts there.
1 – Engine acceleration is flat, uneven, not crisp. 2 – The throttle needs to be opened continuously to maintain consistent acceleration. 3 – The engine performs poorly when the weather gets warmer, or the engine works better in cold conditions. 4 – Black smoke coming out of the exhaust.

Discover Relevant Questions and Answers for Your Specific Issue

the most relevant questions and answers related to your specific issue

I have a 99 yamaha f100 four stroke outboard. Problem I have is boat will acclereate fine get up on plane and after running for about a mob at wot will decell and only run around 4500 rpm. Then after coming back to idle will have a slight miss then run smooth and repeat every run. Changed the plugs and fuel filters alll oe yamaha has fresh oil timing belt is good any ideas will help or fuel psi spec. I am an ase master automotive tech so I know alot about engs. To me it feels like it’s running out of gas. Like the carb bows are full when I take off but then runs out after running wot. Any info will help
ANSWER : I have exactly the same problem with my Yamaha F100, have you got any solutions yet?

Read Full Q/A … : Sport & Outdoor – Others

I have a 1996 yamaha wave venture 1100….ran greatsat for 2 yrs..started but only ran for spray into carbs….drained fuel started and ran good. Started about month later and would only run as long as primed with starter fluids…checked fuel filter(ok)…fuel flow to fuel pump ok…output of fuel pump appears ok….but engine will only run as long as starter fluid/gas is sprayed into carbs. I don’t think it’s the carbs as it ran great a month ago…now it’s starving for gas flow….so it appears to be a fuel delivery problem…what would be the sequence of tests up to tearing into the carbs? is there a fuel filter inside the carbs? remember it fires off great when primed…until the fuel spray is consumed…
ANSWER : Check the on/off/reserve valve

Read Full Q/A … : Sport & Outdoor – Others

My engine revs on high by itself and runs rough
ANSWER : We had the same problem with our snowblower. we tried everything. ponits, adjustments. even converted points to electronics. we ened up putting on a brand new carborater and it runs great now. save youself the headaches and buy a new carborator. we spent $87. so much better

Read Full Q/A … : Sport & Outdoor – Others

I have a 2008 polaris sportsman 500HD the damb thing has been nothing but problems ever since i got it, right now the damb thing won’t even run, here’s what its doing, when you start it and put it in drive and start to go it bogs down, it also leaks fuel out the bottom of the carborator; heres what i have done; i’v taken the air filter out that didn’t help, took the inline fuel filter out and by passed it that didnt help, i’v put fresh gas in it still nothing, please help
ANSWER : It sounds like your carburetor is gummed up. This is a common problem if the engine has not been run in a while or if has been stored for the winter without fuel stabilizer. You may also have gotten some bad gas, or a fuel treatment that wasn’t compatible, (if you ran one).

If you are familiar with your machines carb; dismantle, clean, inspect components, replaced damaged items and reassemble.

If you are not familiar I suggest taking it to your local service center.

Let me know if this helps. Good luck.

Read Full Q/A … : Sport & Outdoor – Others

I have a 2001 Yamaha XL700Z Waverunner. The compression on both cylinders is about 120, it starts and runs fine – dry. Won’t quite idle, but I can start it and rev it up fine (for a short period, of course). However, as soon as it gets in the water, it will barely run – it will start and sputter and you cannot get it to run more than a few seconds or rev up. Take it back out, let it dry, starts & revs fine. It is not getting any water in the casing that I can tell, its almost as if water is getting something wet through the cooling system that I cannot see?
ANSWER : Try cleaning the carbs and the fuel lines, filter

Read Full Q/A … : Sport & Outdoor – Others

Scag SMT61A Mower with Kawasaki 27KA engine. 200
ANSWER : Look on the bottom of the fuel bowl. See if it has an electric fuel shut off solenoid. If it does unscrew the solenoid clean with Carburator cleaner and work the needle up and down until free. When you have it off of the carb plug it back in ground it to a metal surface and turn the key on and off. Watch the needle move up and down. Install back on Carburator bowl and start it up.

Read Full Q/A … : Sport & Outdoor – Others

Mule 610 will not start. Was running fine, plowing snow and it starting acting like it was running out of gas and stalled. Put gas in put it won’t start and acts like it is not getting gas. Could the gas line have frozen due to the depth of the snow?
ANSWER : Did you ever find the fix for your mule?

Read Full Q/A … : Sport & Outdoor – Others