ATV Florida Forum

What should the compression be on a 2 stroke Predator 90 ?  Mine has 90-95 psi cold,It recently started bogging really bad and will barely accelerate at all,Has new fuel filter,Spark Plug,Recent Coil & CDI + AirFilter Fuel is ok,how would it act if there was a Reed Valve Problem?

thats not bad its a little low but you need to check you exhaust screen its in the muffler on the rear remove the retaining screw and pull the screen out see if its plugged up with carbon and dirt seen this problem in this model several times

Steve

I will look at that if it has one it has a FMF Turbine Core Pipe on it.

alot of times a clogged up exhaust screen will make them run like crap, iv seen it 100 times. if its a reed problem the motor would be very difficult to start, it would be like starting a flooded engine, would probably smoke alot and run rich, ect. it would accelerate slow too as you describe.

If it has a lot of hours on it sometimes the exhaust port will clog enough to cause poor running.

It starts up easy & idles great,My son rode it for about 20 minutes it was running great then all of a sudden it stated bogging & it's still doing it,I kinda thought it may have been a carb problem so I pulled it off & cleaned it out but it seemed pretty clean but that didn't help the bogging,checked the fuel for water but it looks fine & is only a few weeks old + has Stabil in it

id be wiling to bet the problem is in your exhaust being clogged. check that first thing and then post your results.

I dropped the exhaust pipe down at the cylinder it looked ok from what I could tell stuck my finger up in there it seemed ok started it up with the pipe off it still boggs just the same as before? what now?

the blockage would be at the tip not at the exhaust port. there should be a screen in the exhaust tip at the end of the muffler. check that. but if it still bogs with no pipe, there still may be something up.

 although 90psi may be ok, maybe that particular motor doesnt run its best at 90psi, who knows. do this, take the spark plug out and squirt motor oil in, if it runs better with the motor oil its because the oil is sealing up the piston rings giving you higher compression temporarily. you can use 4 stroke motor oil, or 2 stroke oil, whatever, it will burn off in no time. this should help further narrow down your problem. try it out and let us know what it does.

your clutch rollers are flat spotted...guarntee it.....95 psi is as good as it gets on a stock predator,even new the bike didnt have any more compression..call me 352.303.5122   i can help you if you need it........

It wont even rev in neutral with out bogging,If I don't let off the throttle when it starts to bog it will stall out

call me i work on hundreds of minis a year,i can help you....its easier over the phone i can ask a series of questions and get you on the right track....rollers can still make it bog on the stand if the trans is stuck in high gear....

My DRR which has the same motor as the predators had a jet that was clogged and did the same thing, it would run great at idle, as soon as you gave it gas it would fall on its face, if you let off the throttle it would idle fine but if you stayed on the throttle it would just die. I pulled the carb and cleaned it all out and ran no problem, don't know if that is your problem but it only takes an hr to take off, clean and put back on!!

Thanks I am going to pull the carb tomorrow & clean/check it if that doesn't fix it I will call you

Good call Miniquad. :Fp

I would also remove you new fuel filter and see how well the fuel flows. Some of those small filters are junk. It is also very common for owners to "loop" the fuel line causing an air bubble to get trapped in the line.

Many Thanks To miniquad8! I called him & with his help it's running great now,My son was grinning ear to ear when he rode it,Most of the problem was I had not put the Air Box back on after cleaning the carb

always glad to help, sometimes the obvious is over looked due to frustration...call me anytime........