January 06, 2010 05:32 PM Hey,
I'm working on rebuilding a 98 250 trail boss.I bought the 250 for $100 and for the most part its all here.I took the cylinder off and it look like it ran hot.There are some scarring below the intake & exhaust ports on the cylinder and scarring below the rings on the piston. The crank to rod bearing was also shot.I bought a used 93 crank off of ebay, plus a full gasket kit. Would you just hone the cylinder and put new rings in it? Also what is this number on top of the piston, I know the (F) is for the flywheel side but what is (5W)?
Any info on this thing would be great. I'm on a very tight budget so please be nice.
Thanks

 

Have the cylinder measured as to what size piston is needed!! Dont just assume a standard piston can be installed. Clearance between piston and cyl should be around .002 after honing! Have a shop measure the cylinder and have it bored and honed to proper over size.
If the cylinder is scored,it WILL have to be bored Sizing is the key to proper piston and rings. The 5w you mentioned is a stock piston,it probably needs just first over size piston. OPT

 

Thank you very much for the info. One more question ,what brand piston would you go with? Thanks again for the help.

 

I'd say wiseco is about the best aftermarket piston.

 

Ok just bought a wiseco 536M07250 with rings,clip,pin,and top end bearing for $60 off Ebay. Local lawnmower shop said they could bore it for $50. Thank you very much for the help. With any luck maybe this thing will be running next week for the kids.

 

Ok, got parts in today and was going to start to put the crank seals in but my kit has 3 seals. I have 2 that are the same and 1 thats different. All looks to be the same size. Which goes where? The manual I have is a joke it don't tell you anything. Thanks for any info.

 

Never mind ,looks like the 87 - 92 trail boss 250 both seals are the same and the 93 - up has different seals on each side. Thanks.