Arctic Cat Bearcat 454 "Backfiring"

[swedishpimple]

I have been getting the old "Moth-balled" 1998 Bearcat 454 ready to continue its service life on an island. I put a new battery in it, changed the fluids, new spark plug...all the good stuff.

The machine has sat unused for 3 or 4 years. One of the gas lines on the primer bulb from the gas tank was leaking. Fixed that and fired it up.

She runs great, idles nice...good power in first gear.

When I run it in second or third...or fourth gear she backfires towards the end of the powerband.

It was backfiring in neutral, but that cleared. I thought there may be water in the gas so I added some icopropyl. After I did that the motor did not back fire in neutral and had great power.

Any Ideas on the backfiring in the higher gears but not the lower or neutral ??

[Dave S]

if you're on the gas when it happens, you're running lean. Check your pilot jet in the carb to make sure it's not gummed up.

If it happens when letting off the gas, it's an indication you're running rich and fuel is igniting in the exhaust. Check in your air box after sitting that long. I hate to use the "mouse" excuse again, but in this case, it's a good possibility. It could also be a valve adjustment issue.

Keep an eye on your spark plug as that will be the best indicator as to what your problem is (rich or lean).

[Scott K]

Valve timing would be another thing to check if back firing on decel.

[swedishpimple]

Pretty sure it is not a mouse....went through that little issue with my sled all fall and winter.

It is not backfiring on the deceleration.....only on the acceleration.

I was leaning towards a timing issue. Any quick/simple fixes??

[Scott K]

If only on accel ,most likely dirty carb, or old gas.

[jltimm]

Dump in the magic "seafoam"!

[Dave S]

 Originally Posted By: swedishpimple

I was leaning towards a timing issue. Any quick/simple fixes??

If it ran ok before it was put into storage, the likelyhood of the timing going off is pretty slim but not impossible.

But on that note, my old DS 650 started acting up one day where it would only run to about 1200 RPM and cut out beyond that. I also needed to keep the lights on (are Can Am and Polaris related? j/k). Turns the lights off, and it would kill the machine. I could run it through the gears fine, but just couldn't get more than 1200 R's. It would idle fine as well. Eventually it quit running and wouldn't start. The problem was a pick-up coil that went bad. $200 later, I was back in action.

[swedishpimple]

I don't know how she ran before it was parked. It is not anyones choice ride when we have a Kingquad 700, Grizzly 660, Sportsman 500 H.O. and 2 Sportsman 500's. That old 2wd 454 just does not cut the mustard in todays market.

The tank is not full....I had some leaks so I di dnot dare to fill it. I was actually thinking some magical SeaFoam and a full tank may help.

[Dave S]

I hear ya on the choice ride thing when you have newer machines in the stable.

But the older machines can be fun just for old times sake or work around the house.

[swedishpimple]

Yeah...it is a fast machine..should still have years to go

[SlamNFish]

I have a bearcat 454 4x4 97-98 i had a similar issue as yours i brought it in to jjsports in winsted. Jason cleaned the carb which was green and gummed up,and he added a new fuel line all that stuff plus there was a small leak in the bottom of the tank seal which was allowing air in the line which would cause cutting out , after the repairs it has run like a top! Hope this helps steer ya in the right direction.

[swedishpimple]

SlamNFish,

Yeah..sounds a lot alike. There could be another gas leak at the tank.

There are some weird "breather" tubes that come out of the tank and drain below the seat. The tank was bone dry when I started working on the machine. When I added 1 gallon of fresh gas it all drained through these tubes out on the floor. After I got the machine running/primed gas quit running out of these tubes. I thought it may have something to do with some air in the primer system.