1991 CR250. Its got a Keihin PJ carb on it, and what looks to be a UNI filter. AS far as I know reeds are stock. Do not know what is stock for the bike or not, its my brothers bike.

Anyways I rode it to go get gas for him. Bike seemed pretty low on fuel. Ran like a damn top the whole way there. If I drop 250mL into 7.5L of gas then I got 32:1, which is what he runs at. It only took about 4.5L of gas but I put the oil in first (I know, shouldnt have) so its a litle oil rich. Bike fires up and runs great till I get a block from the station and it dies, just quit all of a sudden. Im driving along and it just bogs. Not even trying to run whether I let of or gas it. I put a hole in the bottom of my shoe trying to kick it and it didnt even try. After I got it home I made sure gas was getting to the carb, which it is. Checked spark and its good. Seems as if no fuel is getting into the cylinder. Plug seemed pretty dry. I sprayed a little fuel into the plug hole and bang, fires right up, and dies after a second. If you hand choke the carb (completely cover the end with your hand) it will fire up, and die just like the dribble of gas in the cylinder.

So it seems to me that I've got a fuel delivery problem. What would cause it to happen all of a sudden? Is it the oil rich fuel that is screwing me up here, because it willl run on that fuel if its shot directly in the cylinder. I intend to clean the carb thoroughly. Would that be the problem here?

 

sounds like dirt in the carb. I would definitely start by cleaning it. I wouldn't go crazy and take it completely apart though. Take it apart enough to spray out the jets and needles. I wouldn't disassemble the carb body if you can avoid it.

Make sure you change out the spark plug before doing anything. Personally, 32:1 always seemed to rich a mixture. I stuck with 40:1 unless using Amsoil then I would go to about 60:1. I would probably ditch the current gas and put a fresh "known" mixture in.

/Jon

 

The problem isn't that you are running "oil rich", you are running the engine GAS LEAN. You are running way too lean. Drain the tank and PREMIX the gas in a container BEFORE you put it in the tank. This way you will always have the right mix. When you run too lean you are running way too hot and stand the chance of frying your engine.

32:1 is not a richer mixture than 40:1. It is the exact opposite. Richness in a mix is determined by the amount of GAS in the mix, not the amount of oil. So 32:1 means there is less GAS in the mix than 40:1 (32 ounces of gas to one ounce of oil & 40 ounces of gas to 1 ounce of oil)

Like I said before, drain the tank and always premix your gas.

 

Most likely, the jets or passages are blocked by dirt or rust. Is the tank rusty? When you pull off the float bowl, is there crud in the bottom of it? If you find particles in the float bowl, then thats the problem. Clean out the jets, and install an inline filter to the gas line.

 

The carb is pretty dirty inside so Ill start with a thorough cleaning. Thanks for all the replies fellas!

As for the oil rich, gas lean stuff. Thats a good way of looking at things. It was a fluke mistake though. First time I had ever put fuel in that bike and the tank is shaped wierd. It seemed like it was almost empty! Ive never had a problem like this on my LT. As long as 7.5 Litres of gas fits in the tank, then the oil goes in after. I should have put the fuel in first. The fact that I bumped into my grandfather there likely threw me out of whack when I went to talk to him...

I thought that 32:1 was a pretty good mix considering my quad calls for 20:1. That would be farting out blue clouds wherever I go! But its likely a good idea I go to 40:1, I may do that.