when you rebuild a 2-stroke what all has to be done

 

That would be way too lenghty a reply and it would need to be quad specific. The best thing to do if you've never done it is buy a clymer book or something similar and definetely talk to someone who has rebuilt that particular motor. Ask them about any quirks or tips. ie: lt250r the head gasket will go on more than one way but you gotta be sure that you have the big cut outs in the water jacket on the exhaust side or your motor won't last very long. Use 2stroke oil for assembly lube. NEVER EVER USE GREASE LOL I know of someone who did that, what a moron!! Get a ring compressor, they're fairly cheap. Make sure you lube that up too.

Now by rebuilding, do you mean just a top end? That's fairly easy, although I wouldn't recommend doing it all by yourself the first time. Have a friend there that's done it before. If you need to split the cases and remove crank to have a new rod installed, I'd just bring it to the shop. Well, I wouldn't but I think if you've never done it then you should.

 

im rebuilding a 1986 honda 250r

 

Just top end? I haven't personally rebuilt one of these myself. I do know that most people I know use a cr head gasket. Sorry I can't help more, but at least I'm keeping your post up top!!LOL I've also heard that mototassinari's v-force reed cage is awesome on them. Some people shave the head stay, but I heard that's not a good idea.

Fairly simple in general. Put clip in one side of piston, put needle bearing in rod, line piston and bearing up, slide wrist pin through, install other clip. BE SURE TO WRAP A RAG AROUND ROD AND LAY ON TOP OF CRANK You need t do this in case you drop the clip. It flies pretty easy and will probably take a few tries anyway.

Wrap the ring compressor around piston and slide jug down over. Pull ring compressor out, remove rag tourque down base bolts. You may want to just hold jug down first and make sure the piston moves properly.

Install cr head gasket, head and tourque down in thirds (If it's 30 lbs do 10 then 20 then 30) in a criss cross pattern. In other words, you'll make three trips around the top of the head tourquing. I believe there's 6 studs so it would go like 12o'clock, 4o'clock, 8o'clock, 1o'clock, 5o'clock, 9o'clock (approx. positions)

Anyways, I'll let your Honda brother's give you the specifics.




Come on Honda guys I know a ton of you have got some tips and things to watch out for.

 

Are you planning on splitting the cases? or just a top end? I would start by buy a manual for your machine and read it before you head out into the garage. I have a manaul for everything I own except for the yamoto. And I do all of my own work. The manual will have pictures for different steps along the rebuilding process.

 

well, at least 2-strokes are easier to rebuild than 4-strokes for the most part.

Here's a list of what you should have done:

Cylinder bored and honed (job for a small engine shop), buy new piston w/rings and wrist pin (wiseco sells them as a piston kit)
Split the cases and install new main crank bearings, new crank seals (seals are important to avoid air-leaks)
With the crank out, send it to an engine shop to have a new rod bearing installed. The crank has to be pressed apart, better to let somebody who has the equipment do it. In fact, you could just take the crank out, remove the old piston, and send it out to have the rod bearing and both main bearings done, then you could concentrate on cleaning the cases. Just use starting fluid to clean the aluminum cases.

 

thanks guys i was just planing on doin the top end but should i the top and bottom at the same time

 

I wouldn't mess with it if there's no problem. "If it aint broke, don't fix it." I would, however, replace the crank seals as quicksilver said. (I just wouldn't ever use starting fluid to clean out parts, I use a fast evaporating brake clean and blow it off with air gun.) Make sure you get them in there straight, my brother trusted a shop to do this then his motor blew up again. We found a crank seal cocked sideways in there. Must have sucked wind and got lean.

So just replace top end, and remember it's more important to not pussyfoot a new motor than it is to not beat it. Don't keep the rpm at same point for too long, but go ahead and use full rpm range. Don't be afraid to let the engine brake the quad (slow it down) when the throttle is closed and your high in the rpms, it creates a lot more vacume in the cylinder (and out the exhaust) which helps get rid of those little filings of metal from break in. There's aa awesome link on this forum somewhere about break in procedure and the myth of pussyfooting the things. I'm just paraphrasing here.