Blew up the three wheeler

[ants84olds]

I finally got around to taking off the cylinder today and did not like what i saw. It ended up melting the piston on the exhaust side. It looks like it was recently rebuilt and i can still see the cross hatch. Can i hone the cylinder or should i get it bored. The cylinder is allready .050 over so there isnt that much left.

[quadracer87]

is it scratched?


if not hone it n slap a new topend in

[ants84olds]

This is a pic of the piston and number one reason that the jetting should be right.

[rm250dude]

just hone it and slap a new top end on u got plenty left i think u can go .080 over

[Diesel_Tech]

With the looks of that piston skirt, there is going to be definate cylinder scoring. If it were mine, I would have it machine, but thats just me.

[MADILL]

giver a hone...throw a new top end in ....if that shirt is in the exhaust side it might wen right out and didnt screw nething up....that bad in you cyl

[xxxbansheexxx]

nows a good time to stroke it
lol

[2twin350s]

Ok,first of all,I think I read in another post that you had a 150 main jet with a FMF pipe on your R.
That is too lean.
You should at least run a 48 pilot and a 162 main to start.Break the engine in and lean back from that 162,if it burrbles on the top or dont rev out.Keep leaning back until it revs out smooth on the top end.Almost all 3 of my 250R's with pipes and porting run 162-165 main jets in them.I am at about 300 ft seat level.

Next,make sure you let that bike warm up before you rip on it,and make sure it is broken in.If you do not,it will cold sieze a piston.

Your pic looks like the exhuast was too hot from running lean,OR someone did not relieve the ports during the bore job,and your rings were clipping the exhaust port.

I can just about bet that there is debris down around the crankshaft.Best bet is to turn the machine upside down,and flush it out with brake cleaner and compressed air blow gun,and then dump some 2 stroke oild down in there,and flush it again,while the jug is off.

Do not just hone that jug.Send it out and have it done right with a bore.Most boring jobs only run 50 bucks.Make sure whoever does the bore relieves the ports so the rings will not catch the sharp edges.
Make sure the crank spins free with no notchy or raspy feeling,and make sure the rod has no up and down play in the big bearing before you reassemble the top end.

One more tip.Dump that POS 85 roundslide carb,and get you a PWK 36-38 mil carb.
Those 85 carbs were junk,and a PITA to get jetted properly.
Do it all right,and you will avoid anymore problems.

[atomicsaladbowl]

honing would be a mistake, listen to 2twin350s he definitely knows what to do!!

[ants84olds]

I had it jetted with a 160 and it wouldnt run and fouled out a plug. The stock jet is a 140 with a 52 pilot. I ordered a 150, 148, 145, and a 55 pilot jet. I dont have the money to do what I want so I am going to hone it and put a new piston in it until this winter probably and then bore and port it. If I had the money I would do it all right now.