Two-stroke experts, I have a tricky problem...

[Latte]

If I was evil I could suggest that perhaps the seal was sucking air from the top of it quite some time before it started opening up enough to suck oil & when the seal was replaced the mixture was rich. But that might make your head explode so pretend I didn't suggest that.

+1 - I was going to post this as well but thought I better check if someone had beaten me to it.

... time to start a pool ? $1 on this

[noobi]

REEDS, easy enough to check if your pulling the carb off every 15minutes
Carbs dont go bad suddenly from wear, it takes years to oval out the needle orifice. Unless the mainjet was sitting in the bowl it doesnt really account for whats happening.
A gummed open PV doesnt account for the smoke, it would run like crap until pv opening rpm then it would be fine, which it is, but it wouldnt smoke like the choke was on.
Could be electrical, but loose connections give the opposite symptom, ok low rpm, crap high rpm.

[oldskool]

When you've triple checked the fuel symptoms and all else fails look at the electrics. Somewhere I've read 99% of carburettion problems are electrical. In my experience that's been so.

[B0000M]

problem solved.

i re-set the float level.


the question is why did this occur suddenly given that until yesterday i had not had the carb apart in at least a year.


also the reeds are fine,

as for the top half of the seal idea - getting bloody far fetched, but still possible i suppose lol

[Pornstar]

years ago i put my rmx back together with a stepped coller that went into the crank seal the wrong way around, talk about HOLY SMOKESCREEN BATMAN.

[F5 Dave]

Hey, awesome you've fixed the issue. Why did it suddenly go off? Well it could have been the gradual degradation of the float jet surface raise the level it needed to be to seal? Keep an eye on it & if it starts to get worse then consider replacing it.

Actually it could also have had some fluff or hair under it that couldn't get out & created a part mis seal. This stuff manages to travel through filters but stays put where it will be a pain.

I'd also play with the airjet screw & see if it still needs to be a ways out. They only work in a narrow range & if it is at the end of its adjustment the next size pilot jet will put you back in.


Just a point Noobi, yes it takes years for carbs to wear, but a 250 will wear one quicker than anything else. A leaking airfilter could get some grit in & this bike is a 06 yeah? Not new. Sure I was grasping at straws a bit, but I've seen slides wear deep grooves in them on dirtbikes in the idle position. the needle is also bouncing around when idling. Who knows if another issue was happening during the time the seal was leaking (not sure how long that was going on for). Actually as it turned out something else was happening in that time as a nice double act.

[sugilite:Me]

Thanks for the informative posts guys, I learned a bit with this thread

[kezzafish]

As booms solved his problem... i'll chuck mine in here... It's a KTM 300EXC

The bike is running now but on the weekend in karapoti i went into a deep puddle and tried to ride out. It sucked a huge gulp of water and died. I flipped it upside down and drained all the water i could out of it (tank off, plug out etc etc (in the pouring rain lol)). I kicked it for a very long time and have quite a sore right foot arch but it wouldn't go. Have drowned bikes before and not had this much trouble getting em started. I kicked it for aaaages. My question is... why did it have zero compression? I figured I had rooted the ring and that's why it wouldn't start. But after i pushed it out of this track for half an hour it fired when i tried to kick start it (I didn't try to bump start it at all)... then all of a sudden it had compression again and started and i rode it home? WTF? why did it have no compression and then it all came back?

[ktm84mxc]

How much water was still in the crank cases sloushing around & in the exhaust pipe If there's little air to compress it may give u an answer.

[F5 Dave]

That's queer. so you imply that it was super easy to kick over? Perhaps some grit stopping the rings sealing?

Often you have to turn a bike upside down to get the water out of the pipe & cases or it just won't start. Some Euro bikes have a bolt in the cases to drain them. When I drowned my Gaser (first ride Kairapoti by myself -dickhead) I kicked & kicked. Didn't have the tools on my to open the drain. Didn't think to turn the bike upside down. Took ages.

In your case I'd want to pop the top off & have a looksee if the compression did go. That sounds weird & you'd want to see no damage has occurred. Also gear oil & muffler packing will need replacing.

[kezzafish]

yeah it was easy as to kick and then it was normal again after it finally fired. the ring gap thing is all i can think of too but doesn't seem feasible really? due to how big the gap would have to be

[kezzafish]

How much water was still in the crank cases sloushing around & in the exhaust pipe If there's little air to compress it may give u an answer.

not quite sure what you mean? i had it upside down and pumped all the water out... drained it out of the pipe. do you recon if there was a blockage in the carb it might cause the symptoms i described?

[F5 Dave]

No that makes no sense at all. Water is not compressable, (well not really in practical terms).