Spitting flames!

Sounds like the ignition timing may not be on target. if the timing is adjustable, check it.

if this is happening only when you back off the throttle it could be an exhaust leak

If the bowl has to been in a particular position, because it is a non-symmetrical type, be sure it goes back in the proper position.

What I have on one of the carburetors on the engines I have is one with a bowl with an area that looks dented. It came with a notched area that is supposed to be where the hinge for the float and valve are inside the bowl.

If the bowl is completely round, and symmetrical you probably do not have to be concerned about this.

The fact that you made a replacement pin to hold the float and lever mechanism for the float valve is probably of no consequence, unless it binds.

The other thing, if the float as it connects is bent up or down, it will change the level for fuel flow for start and stop points. This may have an effect on how rich or lean a mixture you would get. If you feel that this did not happen, then leave it as is.

Maybe the leak was the o-ring or gasket for the bowl, or the bowl nut just was not tight enough. A washer if it supposed to have should be with the nut.

Something like this happened when just for a short while on my Briggs engine when I had not started the engine for a while. It was like oil or something is in the muffler and had to clear itself out like a self cleaning oven mode. Then it did not happen any more.

MT

I used to drill a couple tiny holes in my exhaust pipe on the motorcycle to get it to do that. A bit of fresh air in the pipe will make the unburned fuel pop nicely.

Deleted 'cause I'm an idiot!

GearNut said:

Exhaust leaks on 2 strokes lean out the fuel charge in the cylinder. If it is really bad, it can get so lean as to cause damage.

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this is the four stroke forum, hes not talking about a smoker.

and my thumper belches out 3-6 inch flames when i engine brake, mostly because my idle jet is one or two sizes too large, but then again, im running a CNS on a HS49. most four strokes will pop out small flames when decelerating, especially when running a straight pipe.

http://www.youtube.com/watch?v=z6W7SLpdNaU

"Riding Man," Flaming Bicyclist at Burning Man 2007

I suppose flames on non-motorized bikes, there are no issues needing to be resolved. That is if ridden where allowed.

I just had to add this post!

MT

moonerdizzle said:

this is the four stroke forum, hes not talking about a smoker.

Click to expand...

I fixed my post.

The flame you are seeing is gasoline that was not burned on the previous power stroke. In other words, you are too rich. Probably on the low speed setting. OR, because the float is the last thing you messed with after it was running well, it's probably allowing too mush fuel into the float bowl which will cause an over-rich condition. I know you already thought of that, but check the float to make sure it shuts off fuel flow when it is approximately level.

Probably a stupid question, but you didn't happen to lose the needle while you were losing other parts , did you?

On the other hand, if the bike runs well but has the added feature of cool looking fire shooting from the exhaust, then I guess I don't understand the problem. Those flames should psyche out the competition and send the moped boys running.

The valve that is like a square pin some times I see in bowl carbs, is that like what you have? The end of it is shaped like a cone.

The tip of the cone seals on a seat that maybe be a replaceable part as well as the valve. If the seat is like an o-ring as in one carb I had, it cab be pushed out of place and need to be re-installed straight.

The edges of the valve the square part fit in the round sleeve and should be smooth without burrs. Maybe a magnifying glass you could look at it and if needing replacement parts you would not why it is sticking.

I'm not sure if using any method to remove a burr could work, but if you can get parts that would be best if you do see where the problem really is. Very fine 1200 grit sand paper did come to thought. This though would not most likely be a fix for the tip of the valve or the seat, but maybe if it was the square edges that guide in the slot to the valve seat.

I have to say I'm not an expert at this as I once put a fuel nozzle in upside down. The manual I had for the engine/carb did not make it clear. I scratched it up a bit, but l was lucky it was not by the holes in it that are a metered drill size. It fit it all back in place and it worked.

Actually it worked only after another separate problem with a fuel valve that was gummed up inside and the fuel was not flowing, but only intermittently.

It just cleared itself up by running it a while. The valve would have been not easy to disassemble, and my cleaning the carb was a bit of a time worrying did I ruin it, so I know getting help from someone with the same type carb and problem would be best, if they have answers.

MT

you just have unburned fuel in the pipe somehow.. make sure your rocker arms are correctly spaced aka i think its .006-008 you could have overlap or have them loose which case gas is not compressing and pushing out the exhaust valve before it closes.. try that..