I am having major hesitation problems with my '86 fourtax 250 and am wondering if I need a new carb or if I should just rejet it. If you try to accelerate hard or just burp the throttle, it stalls out. If you bring it up slow, it revs up fine. It is bone stock and other than setting valves has had nothing done to the engine. Just wondering if the 17 year old carb has packed it in finally or if it just needs to be rejetted? Where in Canada can I find a carb for a fair price?

 

Swampdonkeykiller, that is a good carb on that machine and there's no need to replace it unless you see pieces. Get a new pilot jet, main jet and maybe a gasket kit from your dealer. Pull the carb and the four screws on the bottem and replace those parts. Clean it out with some carb cleaner. The mixture screw on the bottem turn out three turns from bottem. If the airbox manifold or other rubber is getting old and stiff, a bit of heat ala hair dryer and a can of spray silicon lube works wonders. There is a possibility that the needle jet set could be getting wore too (that's the slide needle and the little jet that sits atop the main jet stack). If spark plug fouling hasn't been a problem, I would let that go for now.

 

It is very possible that is it just due for a good cleaning. If you haven't cleaned it out in a few years it is probably full of dirt. Most of the time you can take a pin and unclog the jets and slap it all back together. Use some carb cleaner and compressed air and get everything good and clean. If you have never done it then a manual would not be a bad purchase. They are pretty simple to work on though.

 

No pin I've ever seen will fit through a #35 pilot jet, if it does your machine will run rich and crappy. One strand of a small gauge wire would be more like it. Anyway, those jets are too precise to be sticking things in them. It is possible to clean them and sometimes carb cleaner and compressed air is adequate, but often not. At work we use this soak solution that works very good called Hydrosolv II. Takes about 6 to 48 hours of soaking and they come out looking new. But that stuff isn't cheap, and for the occasional carb cleaner it's more economical to just buy new jets, and then you are certain. Swampdonkeykiller, If you know some guys in a local shop and they have similar soak solution, you could ask them if they would just throw the jets in there for a day or so instead of buying new.

 

The carb has been apart in the last year and the float and needle assembly were replaced last year. It got cleaned very well. Is it possible for the mixture screw seat and needle to be damaged and causing this problem? Or does it sound more like a jetting problem? I would like to know before I get carried away tearing this thing apart.

 

It sounds like your pilot jet is clogged or partially clogged. The hole is so fine that it can happen in only a few months of storeage or infrequent use. If this were the case it would idle poorly , and have a bad off idle hesitation, and run ok at quarter throttle and above.

 

It idle's fine, and rev's up slowly fine but is hard to start and you can't give it quick throttle burps without it stalling.

 

SDK , have you tried opening the choke slightly when it is reving slowy? If that helps it's a sure case your lean somewhere. If it makes it worse maybe you should have a good close look at the airbox, snorkel , air filter, the air intake. If it's not leaking gas on the ground or back in your airbox the needle and seat should be ok. A mix screw problem would show up more at idle.