a 300 express and a 400 sport a 1995 & 1996 they started out of the blue just acting like they were choking out or flooding out. (boggin down) a few back fires and then they quit. The plugs are new the air filters new, the fuel filter is new, have no clue. The gas is going in the plug is fireing a bit of gas in the cylinder head does not fire either. Both are 2 strokes this occured with 3 days of each other. The gas came from 2 different states. Help????[img]i/expressions/face-icon-small-confused.gif[/img]

 

What was the temp outside when they started acting up

 

On the 300 it was very cold. The 400 happened today and it was 60 outside.

 

How old is the gas?

 

ftwflh,
Sorry for slow response. Gas is new a week maybe. Just now took carb off and cleaned (not much of anything found there). Air box nozzle was cracked temp fixed and now have good suction but still just cranks with out firing. The plug is new and is firing when grounded on the frame. So at this point the gas is going in and the plug is firing but no explosion. The compression guadge read about 30 psi on the head just cranking it. I used the running 400 to compare and got 55 psi. Of course now the 400 is doing the same thing. I changed out for a new plug new air and pre air filters. It also just cranks and won't even try to fire just like the 300. I must have upset the polaris gods or something. I have checked that the flywheel is tight. I am not good with electric diagnostics. But I am sure that I am getting fire through the plugs (ngk's). So got gas got fire still no run. I am on the verge of a dealership breakdown. I hate those.
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If you did a compression check and comp was les than 100psi you need a new topend(rings,piston,bore job)

 

Thanks!

The sad part is my 400 turned around and did the exact same thing they are both 96's . Ruined a good weekend for riding. Oh well maybe it is saving my son or myself from getting hospitalized. Heck I will be well versed in the polaris engine by the time I get them both rebuilt. Do you need to replace the rod bearings when you drop them or do you pull the cylinder off of the piston and leave the rod connections alone?

 

The head comes off first then the cylinder comes off the piston it isnt like a car motor.It is fun to work on these but you DO need a manual.

 

THANKS AGAIN FTWFLH

So does the new piston slide through enough to get the wrist pin in? I will get a manual. Suggest dealer or will the haynes do? You have obviously done this before so I ask to avoid all the mistakes you may or may not have made when you started working bikes. I have done most of the work on my 65 mustang so I relate most of this to cars. Again thanks for your insight and patience. I have learned alot on this site in a short amount of time.


You guys are great. No offense to any gals that may be out there and do their own work.

 

The piston stays on the rod when you take the cylinder off.You take the wrist pin out to take the piston off the rod.When you go back be sure to use a Weisco piston instad of a stock one.You will find that the factory manuals are the best but I use both factory and a Clymer the clymer has better pictures to go by.But the factory ones give better directions. I see you are from St Joe MO we are wanting to go ther ethis summer and check out the park.How is it?