84 250 No power & SMOKING

[d.fender]

OK, bear with me here. I'm a 2 stroke virgin. Recently picked up a very sweet 250r at a good price. When I went to check it out I did a test ride, of course. Motor was cold and it fired right up with 2-3 kicks. Wouldn't stay running without feathering the throttle & had no power. I figured it was carb related and I bought it.

I got it home and immediately cleaned the carb-it didn't look too junky. After putting it back on I still had no power-maybe bad gas. So I mixed some up at 20:1 and OMG did it every smoke. I know that 2-strokes will smoke but this is excessive. And still no power. I cut the mixture to 40:1 and got the same results.

So I called the guy I got it from to see what mixture he was using and he told me that HE WAS RUNNIING STRAIGHT GASOLINE-NO OIL IN THE MIX. When I asked him why he said 'cuz it smoked'.

I'm ready to get to work on it but don't know where to begin. I could just shotgun whatever I thought it could be but don't really want to do that.

If I could get some ideas from you good folks it would be very appreciated.

[atc500x]

Check crankshaft seal or a crack in the crankcase,the smoke is probably because it burn the gearbox oil....

[trikerooster]

What NO oil? You should check the piston and cylinder. Take the head off and slide the cylinder off of the piston. I allways put some 2-stroke oil on the piston first. Check for damage if there is none then it is a deeper problem in the gearbox=hopefully not!

[MonroeMike]

Welcome to 3ww.

[fabiodriven]

You're just going to have to tear into it and find out what it needs. These machines are all getting old now and if you're going to be in the hobby you have to fully expect a rebuild on just about any three wheeler you buy unless you happen to buy it from somebody who you know for a fact took care of their stuff.

The first problem it sounds like you have is a worn out top end. The fact that it starts when its cold but not so well when it's warmed up is a telltale sign on a two stroke. When the motor is cold, the clearances are tight enough to produce enough compression to start the engine. Once you warm it up and the everything expands, it won't start so easy. And obviously you have a power loss as well. That's another easy sign to read.

On any 20 year old two stroke you have to replace the crank seals. They wear out and then you'll be sucking air into the crankcase through the seal(s) and your engine will run lean. If you're going in to do the crank seals, you might as well do the crank bearings. No sense in doing it halfway.

The suggestion these guys are making about a crack in the case seems far fetched to me. Don't get me wrong, it is completely possible. It just seems very unlikely to me. That is why you have to tear into it.

[Saul]

Post some pics of the bike when you get a chance!

All the suggestions are spot on - however, your smoke & no power problems could be as simple as jetting being off, silencer clogged with premix-goop ... does the smoke diminish at all after 5 - 10 minutes of hard riding? Or have you even been able to get on it 'hard' yet?

Two-strokes do seem to 'load up' when just idling.

[trikerooster]

Fagio-the suggestion these guys are making about a crack in the case seems far fetched to me. Don't get me wrong, it is completely possible. It just seems very unlikely to me. That is why you have to tear into it.

Don't listen to this guy! He is clueless!

[300rman]

the fact that it started cold in 2-3 kicks makes me doubt it ruined the top end. it probably is using transmission gearbox oil is why its smoking.

what did you pay for it?

[SYKO]

I say put a new plug in.

[4cfed]

start with the simple stuff... take the silencer off and blast it out with carb cleaner to get all the crap out ( my old 84 250r was almost pluged tight when i got it from it never gettin rode 'hot enough' to clear out) than new plug, run it 32:1 with a good 2 stroke oil, i personnaly like pro honda hp2, but to each there own,
fire it up and let it idle for about 5 min or so tell the head/ jug are warm/ hot to the touch, than take it for a ride, ride it eacy in 1st and second tell the throttle starts to respond better, than once she seems to be responding good crack on it
take it threw the revs and see what happens, it its some what healthy it should respond good once warm and haul ass...

my old bone stock 84 R would power wheelie 1-2-3 gears when warmed up

[Russell 350X]

If he ran it with straight gas then you have some issues. Could have killed the crank bearings/seals, and cooked the topend.

[Defender]

Apologies for not responding. I can't seem to stay logged in with my original Username so I re-registered with this. I wanted to give some additional information and ask a question or two.

I've got an 82 & 83 185s, 87 200x X2, an 85 & 86 350x so I ain't scared to tear into this one. It's just it's my first 2 stroke & I wanna do it without tearing something else up.

Something I wanted to let everyone about was the oil in case. I went to check the level and what came out immediately made me think 'blown head gasket'. The oil looked like it was mixed with water-a creamy kind of grey/brown. I drained it and put fresh oil in. It returned out of the check hole looking like it went in. After running it for about 30 seconds I checked it and it was nasty again. Any ideas?

I'm picking up what those of you are laying down about the seals leaking the case oil and burning. Because I'm not as familiar with the 2 strokes I gotta ask if the crank case oil was making its way to where it would burn wouldn't the trike smoke with the unmixed gasoline too? Because it doesn't smoke with straight gasoline.

I've got a top end gasket kit coming. I want to wait until I pull the jug and spec it out before I order rings or anything like seals and bearings.

I'll get pics of it up as soon as I get the login issue resolved.

To all of you that have posted I give much thanks. Ya'll are more help than I could have asked for.

[Defender]

One more thing. A neighbor of mine suggested taking out the plug and hitting the hole with compressed air. Now if there was compression getting by the rings it should have sprayed oil out of the filler hole in the case, right?

Well I accidentally left it in gear and when I hit it with a short blast of air the thing lurched forward.

Dont' know if that means anything.

[fabiodriven]

Something is not right. You said it's an 84, but an 84 is air cooled. Yours is liquid cooled, no? If that's the case it's either an 85 or an 86. A blown head gasket wouldn't leak the water in the oil, but a blown water pump seal would. That is more likely the culprit. From the sounds of it you should take it all apart anyways.

If you've done all that work on all those 4 strokes than this one will be, to borrow a term, "chicken". It'll be easy for you.

Blowing the air in the cylinder is not going to help you figure out anything either. The crankcase on a two stroke is sealed off from the transmission so you won't get any air blowing out of the oil fill hole. The easiest way to check it out is with a compression gauge.

[d.fender]

It is air cooled. What I meant was when I've seen a blown head gasket on something that was water cooled.

I'm wondering what may cause fresh oil to look like its mixed with water on an air cooled trike.

Thank again.

[fabiodriven]

The only way that could happen on an air cooled engine is if somebody actually put water in the crankcase. Either they drowned it in a pond, or some meathead thought he was going to wash out the inside of the engine. Don't laugh, I've seen it. Just keep putting new oil in it and running it until it comes out clean.

[d.fender]

UPDATE:

Gotta give it up to sykolincoln-plug was too short & wasn't burning all the fuel/oil mix.

Damn! That was too easy.

As a result:

Piston 'galded' over both rings at the exhaust port. The bottom ring can't be removed. Got a cracked piston too.

Interesting results when I spec'd the cynlinder. Got bore measurements of 71.04 - 71.145mm (std bore = 70mm). My thinking was 'Oh Hell' but then I got to checking out new pistons and voila! 0.040in = 1mm. Its already been bored 0.040 over.

Wiseco piston kit coming. Already got the right plug.

Thanks everybody for your help.

[MudBug]

glad to hear you got it fixed :)

[fabiodriven]

Nice job man.YAMAHONDAMAN