PDA

View Full Version : another winter project



prairiedog14
03-19-2014, 10:36 PM
yeah, another winter project haha. This here is my 85 atc 250sx that me and my dad spent the winter on as a "father/son" project. it didn't run when we got it at the end of october, (it still doesn't run but i'll get to that later) and so after a compression test (that it obviously failed) we pulled the carb out, where it puked guts all over the "workbench." so we cleaned it up, stuck it back in, and still failed the test. so we tore the engine out, and the timing chain was wrecked, the piston wasn't in great shape, and needed a bit of tuning. so we fixed all that, stuck the engine back in, and it STILL didn't run! so we took the engine out again, and it would appear that the valves were not very clean. so in this last week we cleaned the valves, and are hoping to stick the engine back in this weekend and hear it purr like a kitty.

prairiedog14
03-20-2014, 07:40 PM
ok, so here's an update. we got the engine in today, and, you guessed it, it STILL DOESN'T RUN!! before we completely give up on the darn thing, what do you think is wrong with it? it's properly tuned, has fresh oil, good valves, new timing chain, clean carb, does some backfiring, might have too much fuel to air going in the engine, and also wonder if maybe there's too much backpressure. i also wonder, the choke cable is in good condition but for some reason doesn't work right. do you think that could be a problem?

coolpool
03-20-2014, 08:06 PM
You never mentioned the spark condition, weak and yellow or blue and snappy? Does it have consistent spark? If so can you squirt a little gas in the carb to se if it will give you a few revolutions? What's the compression like now? You mentioned backpressure, did you confirm the pipe is clear?

prairiedog14
03-20-2014, 11:30 PM
coolpool we narrowed it down to either the coil or the carb, and it does not have a consistent spark. (we used a timing light) I have a video from today if that'll help you and yes the pipe is clear. it runs at 140 psi. we tried squirting gas in the carb and it didn't run any better.

prairiedog14
03-22-2014, 08:40 PM
189752

so yesterday we called my uncle who is a small engine expert and he told us to dump the carb in vinegar for 24 hours, (that's what the picture is) and we also decided to take a look in the tank. boy was it rotten! not sure if it's rotted all the way through. the filter is also crap, so now we're on the hunt for a filter and maybe a new tank. (we will buy a plastic one if we do get a new tank.)

prairiedog14
03-31-2014, 09:18 PM
Engine problems are done with. It was a cdi module, or something around that area of the trike. All that's left is brakes and fenders and lights