rebuild top end?

[300rman]

ok, i have a top end on a 2 stroke i need to rebuild.
i know what all needs to be addressed, i am just not sure in what order to address it.

i would think:

Bore cylinder/hone cylinder
order matching piston kit
get gasket kit
re-assemble


or, would i order a piston kit, then have it bored/honed to the piston kit?
either way, i cant grind the rings myself, unless someone has a tip on doing so?


The cylinder has some amazingly horrible gouges and wear marks, i mean absolutely horrible. i cant believe it runs, let alone how well it runs, but it wont last, its piston-slapping.
i guess, my question would be: should it be ran at a denser oil ratio, like 20:1? its at 32:1, and this damage was done with supposedly low hours.

[84honda200s]

if its that bad id get it bored. as long as you know what size bore you want (i would go 2 or 3 sizes up if its that bad) it wouldnt be too bad to order the piston kit and get it over with. i use to and still do order my piston kits threw dennis kirk. they have free shipping and i usually get them in a few days. ive redone many of sled motors and never had any problems. just make sure you know what bore size you want before you go ordering the kit.


as for grinding your rings ...the kit comes with a paper that tells you how to do it. or it should anyway.

rebuilding a top end isnt all that bad really. its pretty self explanatory for the most part. a 2 stroke is probably the easiest motor ive ever worked on. no valves no or very little timing to worry about setting..... i love the 2 stroke motor for that reason. i just hate buying the danm 2 stroke oil for the danm things.

good luck and im sure someone else with more knowledge of the 2 stroke motor (250R?) will chime in.

[Danold]

You should get the piston before you have it bored so they can match the piston to bore. Better than the person boring it to big and ending up with a piston to small.

[Erics350x]

It prolly wasn't broke-in properly

[masonryman13]

I order my pistons first. I then take both to the machinist so he can check the piston to cylinder wall clearance while he has it. Catch is, u gotta know the size u r at b-4 bore so u can order the right plus size piston. My last time dong this i ended up 0.80 over stock, so thats it on this jug. New sleeve next time.......

[money89tractors]

Sometimes the problem is the bore is egg shaped...like mine was. Wasnt sure if it was going to true up. I dropped my cylinder off and the mechine shop, told him the stock bore size and what the max bore would be before resleeving, and he called me when her got it done with the new bore. He left enough for honing and so on.

-Phil

[300rman]

ok, thats all i needed to know, weather to buy the piston first or to bore it first.

so, when i measure the cylinder, i would like to go 2 bore sizes greater, its pretty well beaten up, may have to go three.

so how many thousandths would each "overbore size" be?
like, overbore 1 is 10 thou, overbore 2 is 20, and so on.

[300rman]

Bump, questions in above post are still unanswered.

[Danold]

overbore 1 is 10 thou, overbore 2 is 20, and so on.

thats correct. I wouldnt bore it out more than you have to so there will be room the bore later.

[OldSchoolin86]

Take it to your machinist and have him mic the cylinder and he'll tell you what size you need. You only need 1 size bigger then your widest spot unless it's right on the edge then 2.

[The Goat]

most shops give a pretty good discount on a piston when you order it from them and get them to bore it.

[OldSchoolin86]

most shops give a pretty good discount on a piston when you order it from them and get them to bore it.

I've never had a shop give me a good price on a piston. Always shop around.

[300rman]

i always shop around lol.

im thinking, just take the cylinder to a shop, and say, i need a piston kit, and need it bored. that way i can take it home and assemble it.

that bout cover it?