Hot Pamp
 

Sunday during a ride at CATRA (Fishouse, NY), a rocky challenging set of single track trails in the southern Adirondacks, my '04 Pamp 280 began running very hot, blackening and partially melting the plastic behind the exhaust. The engine was low on power and could not be be "cleared out" by holding the throttle open. Cooling fan was operating and coolant level was high. Changing plug, running without air filter or muffler offered no improvement.
I later found mud on the lower two or so inches of the radiator. Could a hot running engine cause the problem?

C'mon, 31 views and no ideas. I know this bike, (and rider) first hand and I am personally stumped by this prob. Any insight would be very much appreciated.

perhaps the vent hoses for the float bowl are plugged? If the float does not operate at atmospheric pressure the consumtopn of fuel will reduce pressure in the float bowl, making the mixture leaner.

Take half an hour and reroute those vents to inside the air box.

Running hot: Is the water pump working correctly, the impeller might need replacing.
Also check your float, I had the hinge plate on the float crack on one side. Easy to weld up using TIG. Check the hoses on the carburetor and make sure they are clean and not blocked.

Blocked rad fins
 

Having done cooling systems on trucks & cars lower part of rad is where your coolant should be at it's coolest before heading back in to engine to do the rounds again,ring damage or piston is not uncommon you didn't say what it ran like after it cooled down, so unable to be sure of long term damage but it will not have done the motor any good.SORRY:(

At one time the factory told me to check the impellers on '03-'04 EC's as some of them were not fastened properly. Also, the cheap plastic factory impeller (bakelite like plastic) would melt and all you would have is a bolt spinning in your overheating coolant. Check the impeller first.

Seemingly unrelated, but the EC50boy also has an airflow issue that can cause it to overheat. The rad is too small and located right behind the fender and frame. It has major airflow restriction at any speed.

I haven't seen a pamp up close for a while, but check your airflow behind the fender and around the shrouds. The fan on the pamp should help, but it won't do much if there is restricted airflow over the rad.

Don't know if any of that will help... just sharing my experiences since 2001.

Good luck.

I have an '02 Pampera 250 that my wife rides. The rad is small and depends a great deal on the fan for cooling, even when the bike is moving. If the fan is jammed by debri the bike will immediately overheat and blow coolant, it has happened, no mystery. We never had any other running problems though, but the bike does not get ridden a lot and when it does its just casual trail riding. I personally wrecked the rear brakes getting too aggressive on it and overheating the caliper. Had to rebuild everything. If I rode this bike regularly I would have to modify it or it would be destroyed. Two things I would do is adapt an EC airbox and radiators. Maybe drop the compression a bit as there is more than enough low end and it has a stiff kick. Its a fun, light little bike great for my wife but its no EC, thats for sure.

Partially blocked rad might do it, but I'm surprised you didn't blow half your coolant. Actually sounds like the motor had a partial seizure.