Newbie with a 250sx that won't run

[84specialed]

Thanks for the add fellas! I'll be doing allot of searching, my 85 250 won't stay running, after a carb bowl clean and cleaning the petcock. Here's a pic, it's been setting for a few years.

[ps2fixer]

Looks like a nice clean machine, hopefully you didn't pay too much for it with it having problems.

I never really had the problem myself, but a friend of mine has had it on 2 of 3 3 wheelers he has owned (both were 250es). Try to take the gas tank cap off and let it idle for a while. If it seems better, your gas cap might not be venting (make sure it is turned to on btw).

You cleaned the carb bowl, how bad was it? It is really common for machines that sit to have rust at the bottom of the tank, and the very top, that rust could be the source of your problems. An inline fuel filter never hurts things and if you get one you can see though, it will give ya an idea how much crap is coming though.

If it isn't a fuel delivery issue like I'm assuming it is, then the carb might be way out of wack. Does it only die when you try to give it gas basically every time? Does the choke help or make it worse or no change? Never hurts to take the spark plug out and see what color it is. White powder is too lean, light brown is just right, black and/or wet is rich. It is generally best to test with a new plug, but it should give some idea on what is going on.

Just a few things to get ya started, report back anything you find.

[84specialed]

Ps2fixr, the bowl wasn't all that bad, there was some gummed up fuel but I've seen much worse in other bikes I've owned. I've tried the gas cap thing as well, didn't make a difference, the choke also doesn't seem to affect it. The tank is clean, I've looked it over on the inside pretty well. The carb is getting plenty of fuel from the petcock. It runs great when it does run, doesn't seem to be lacking power at all, but then it just dies.

[gimmeamidget]

Is the float and needle free to let fuel in or is it just running until the bowl is empty and float sticking and not allowing fuel to refill bowl? If it only runs for a minute and dies I would try opening the bowl drain on the bottom and see if fuel comes out.

[84specialed]

I'll try that tomorrow, thanks!

[ps2fixer]

Is the float and needle free to let fuel in or is it just running until the bowl is empty and float sticking and not allowing fuel to refill bowl? If it only runs for a minute and dies I would try opening the bowl drain on the bottom and see if fuel comes out.

That's a good diag on fuel delivery .

Does it seemly die at complete random times, like sometimes it will run fine for a few mins, while other times you can go 10+ mins? I'd hate to say it, but a bad connection or bad section of harness could do similar things. Are the wires stiff around the engine/cdi area? There are a couple of wires that run up to the handle bar switches too that are for killing the engine, but the hot side has to ground to give you problems, so unlikely there. CDI isn't all that common to get a bad internal solder joint, but I rarely heat about the larger machines having the problem, it seemed to be more around the 200cc engines.

Since I'm kind of targeting wiring now, when it dies, check if you have spark, also just to confirm, check for fuel like gimmeamidget suggested. This hopefully will get us in the correct direction to narrow down what is going on.

[84specialed]

Update: should've left it alone. Tried tearing the carb all the way down to clean it better to rule that out, broke it when trying to remove a screw and it is now un repairable. Anyone know where to find one? A usable core or a good one?

[DohcBikes]

post a pic of the damage

[84specialed]

Here it is, broken tab off the top cover.

[NETRA3]

You might get away with JB Welding that part.

[ps2fixer]

Yea, JB weld the ear back on (with the top off till it sets), and/or use RTV silicone to seal it up and hold it down. Good thing about the silicone is that it holds pretty well on a prepaired surface, but is still removable with out damage. Using it on engines requires more careful application since it can plug oil passages, but on the top of the carb there is little risk.

[Georgiabii]

I third the JBweld

JBweld the ear back on. Then file it down smooth with the carb and carry on. I would run a tap down the hole to avoid any more issues.