The 250x dosnt have any sort of cooling help. It is an air cooled only. Dosnt even have an oil cooler. Just fins on the side of the motor. That being said at idle it will get very very hot. Not so hot it seizes but way hotter than most other engines. Black plug means your running rich. Which is what you want. Could also be a very very old worn out spark plug tho aswell. I would start by getting it to ride fast enough to get the air cooling fins working to your advantage before getting to worried about the hot motor. Unless its glowing red or seizing that is lol.
1987 250x
I bought my first semi-vintage bike, when I went to test ride the bike he had the idle turnt up pretty high. I test drove it bought it went home, opened my new toy before I got home (as every kid does lol) parked it. Last night I cleaned the carb and diaphragm out. I put the setting ton the carb back to where they was before I tore it does except for the throttle speed. I turnt it down so ots not high revving. I cranked her up, she would idle but not move, so I removed the side cover on the right side of the bike covering the throttle cable and pumped on the diaphragm because when I hit the gas it did not move well. So I got the bike to drive after that, she hesitates when I give it gas but it will slowly get up to speed if I dont hit the gas hard. After the test ride she cut off and wouldnt crank. She was really hot as well, hotter than normal. I pulled the spark plug and it was black. Cleaned it, installed it back and she cranked up. But yet she is running hot still. I know cleaning the plug wont cool it down. So I ordered a carb rebuild kit, that will be here sunday. Is there anything else that I should do to help cool this thing down or maybe is it my fault for inproper carb adjustment? I'm going to adjust the valves today as well and tinker with the carb until the new parts get here
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The reason that is like that is so the fuel pulls from the bottom of the bowl. The reason they do that is for going up or down hills so it wont starve the main jet for fuel unless its completely upside down. Now that being said if that was adjusted down so far its touching the bottom it wouldnt get any fuel from the main jet. Which could be your problem. The best thing to do to set it right is to put the bowl back on and remove the bottom 17mm round cover. You will be able to see where the tip of the main jet sits and it should be about 1/4 inch down in. Not flush or sticking out at all. If its either of those its adjusted wrong.
Yeah i would adjust it down alittle more.
Which way did you adjust it? We will talk from the point of view that the carb is on the quad. Did you move the main jet up into the carb? Or down closer to the bowl? When we were talking before i said down which was down further in the hole. Which would be up from the point of view carb in quad. Lets just use that as our point of view for now on so i dont get confused anymore lol.
Adjusting valves wrong wont make it smoke anymore or less. Starting will be tough and it may be down on power a good bit. When does it smoke? Just when it starts or all the time? And does it get better or worse as it warms up?
I will say aftermarket carbs are generally a no go. They usually dont run well if it all. But since the original carb and this carb are doing the samething i would suspect something else is the culprit here. Could be a bad cdi box maybe? Have you changed the plug? Could be a weak coil. I would change the plug first in hopes that solves it if you havent already. I would also suggest a compression test since its smoking just to be sure that aspect is good to go. Whens the last time you checked valve adjustement? Alot of times people will do the its not ticking they are fine method. But valves over many years will beat themselves into the seats and actually tighten the valve lash. Valves to tight 100% could cause your problem.
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