How do i fix the compression release

What exactly are you trying to do? I'm assuming you meant 'Compression'.
Are you refering to the compression in the cylinder? I don't think the early Grizzlys had fuel injection so that won't be the issue. Engine compression isn't usually that high and is released when you remove the spark plugs.

Remember it is only a 250 but a couple things will cause that problem I have found that 2 stroke engines tend to stop up the exhaust pipe try taking it off replace it with a shorty pipe to test it if it runs like a striped ape the pipe is probably stopped up take out the baffle and clean pipe and muffler good reassemble
then there is the chance that it is low on compression this would constatute a top end rebuild

When you check on top of your carburetor ,while the engine is running, you will see fuel being sprayed from one of the jets.That fuel goes to the inlets,so if there is no fuel being sprayed that means there is a blockage on the jets where there is a float.Remove the upper part of your carburetor by taking off the screws.Becafull

Spark timing or valve timing.

Spark time is fixed and controlled by the crank trigger. There is only two things that can change spark timing. a twisted crank ( very rare ) a sheared flywheel key (Also very rare)

Valve timing, remove the timing inspection plug and the the pull start housing, you will use the nut on the crankshaft under the pull start to turn the crank to bring the timing mark TDC-COMPRESSION STROKE - into the timing inspection hole. remove the spark plug so your not fighting engine compression to turn the motor.

Now remove the the valve cover and check the alignment line on the cam. the alignment line should be level with the top of the edges of the cylinder. if not you have a problem

Hey Brighette
Its time to check a few things.. First - remove the air filter and see if it runs ok then... if not... have the carburetor professionally cleaned and set... does it run ok now? .. have you installed a new spark plug? .. do that.. if it is still not running ok.. time to check the compression using a compression gauge that screws into the spark plug hole...

Innova Compression Tester

Your engine should pump at LEAST 120PSI. Once you have screwed the gauge in and lightly seated the o-ring.. turn the engine over for at least 5-8 seconds with the throttle WIDE OPEN... 120psi. minimum... if you are not getting very very close to this.... its time to find out why??... it might be that the valves are too tight... but find out why?... this is probably the reason it won't run..

A cylinder efficiency test would be the quick answer. Set the engine to top dead centre on the compression stroke if it is a 4-stroke or any top dead centre if it is two stroke. Lock the crankshaft or engage high gear and apply the brakes to prevent the engine rotating during the test (locking the crank is better). Jam the throttle open and remove the air filter.
Remove the spark plug and fit a commercially available adapter or a modified spark plug which allows compressed air to be fed into the cylinder without leaking.

Once the cylinder is fed with compressed air, leaks through the induction indicates a faulty inlet valve or seat, air escaping through the exhaust indicates similar problems with the exhaust valve or seat and more than the usual dribble of air escaping through the piston ring gaps indicates problems with the piston, rings or cylinder bore.

This type of test is quick and reliable and far superior to wet-and-dry compression testing but the diagnosis is slightly different for a 2-stroke as there are no valves but the process is quite intuitive and a valuable aid to fault finding but stick to low pressure on these engines..

3 things you need to check
1. spark (blue or white good) (orang or yellow bad)
2. fuel
3. compression

It sounds like the camshaft is going flat. The exhaust lobe on the camshaft is the first to wear. Basically the exhaust isn't opening the entire duration it needs to expel the exhaust. This will cause the bogging issue. Polaris uses an overhead camshaft, which fortunately, makes it easier to replace. To check the camshaft:
1. Remove spark plug
2. Remove the large bolt on top of the recoil starter
3. Rotate the engine with the pull rope until the "T" mark on the flywheel is visible through the hole the bolt was removed from
4. Remove 8 screws on valve cover, fuel tank removal is not necessary but gives you more room
5. Remove 4 bolts from rocker arms, lift rocker arms off camshaft
6. Rotate engine again with pull rope to inspect camshaft. The center of the camshaft is the exhaust lobe, intake lobes are on the outsides of cam. The exhaust lobe should be about the same height as the intake lobes, and will be noticeably flat
To replace the camshaft:
1. Remove camshaft gear access cover on right side of engine
2. Rotate engine again until the "T" mark on flywheel is visible, 2 dots on the camshaft gear should be at the top of the gear and will be parallel to the mating surface of the valve cover
3. Locate the chain tensioner, 2 small bolts holding tensioner to cylinder and 1 large bolt in the center. Remove the large center bolt to remove tension. There will be a spring and pin inside tensioner so be careful not to let it fly out.
4. Remove screws holding gear to camshaft, leave the gear on the chain
5. On the left side of the engine, clamp the coolant hose going into the thermostat cover
6. Remove thermostat cover, some coolant will come out but is ok
7. There will be a round cover on left side of engine with 3 screws, remove that cover and pull the camshaft out through that hole.
8. Install new camshaft, make sure the automatic decompression lever does not come out while handling. Keep pressure on decompression lever and hold cam so that the little ball inside the cam is facing downwards, this will help to keep the lever inside the cam
9. Install cover on the left side
10. Install cam gear on camshaft
11. Remove exhaust rocker arm from the shaft and replace with a new exhaust rocker arm
12. Install spring, pin, and bolt in tensioner once the gear is in place
13. Install rocker arms, set valve clearance to .006 in for intake and exhaust
14. Reinstall covers and thermostat cover
15. Option B is to take it to a Polaris dealer to avoid the hassle of trying to do it yourself!
Hope this helps, if you need any more assistance let me know, Daniel