Alright here is the situation: Bought a used 1998 Scrambler 400 2-stroke. Piston and Cylinder were scortched pretty bad. Got cylinder bored and top end kit purchased along with all neccessary gaskets. The question is why did is scortch?

I noticed the cylinder base seal was pulled into the cylinder, so obviously it was pulling air, running lean; however what would cause this? Crank Seals is my only thought. Carb boots look good and cylinder base is flat.

I ordered new crank seals; are they hard to install? I have to take off the covers on each side then what?

Any advice would help thanks!

 

drill a lil hole in the old seal and put a sheet metal screw in and you should be able to pull the seal out by pulling on the screw. you may want to check the crank by lifting and pulling on it to see if you have any end-play and up & down play, if it's noticeable then it's time for bearings.
give the carb. a good cleaning on the inside, you may also want to look at your radiator and fan to make sure that they are working properly

 

Yeah thanks for the advice 4getful2! I just had the carb completely rebuilt so it should be good to go! I will check on the crank shaft play tomorrow when I get it all torn apart.

I am getting all the parts in tomorrow so hopefully I can get the bike to run!