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Discussion Starter #1
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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I think you’re doing all the right things there sofar except maybe the getting hot bit.
Check the service manual to see how the cooling system sposda work—it doesn’t have a cooling fan and likely not an overheat protection system but should have a hot light.

Test the oil temp sensor to see if it works

What carb number is it? QB01A? Does the choke work on the carb? If it sputters when warm then maybe not or pilot screw too far out.

Did you assemble the pilot screw in the right order? Tiny oring on top, tiny washer, tiny spring
 

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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.
 

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Discussion Starter #4
So I tore down the carburetor again to tinker around before the new parts came in, everything's there like it should be from reading the manual. I lowered the clip on notch on the throttle needle I noticed that the guide on the other side of the carburetor has threads and an adjustable nut on it. How do I go about knowing if that is at the proper height?
I rebuilt the carb slaped it on and it fired up first kick, it runs smooth until you get on it. It acts like the reve limiter is engaging! Is that to much fuel being dumped at once? Can I fix that problem? Or does that mean theres not enough fuel to catch up with the acceleration?
 

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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.
 

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Discussion Starter #10
Well I adjusted it as far as it would go which was not further than where it was at in the picture. It drives better, when I hit the gas it still has a delay but it pheesable until the rebuild kit comes in.
 

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Discussion Starter #11
Also I after I adjusted the valves its smokes pretty good now, is that improper adjustment or maybe wear and tear?
 

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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.
 

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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?
 

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is that mineral buildup i see, in the picture, #6 post. above the float in this picture?
what color is the smoke?
 

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Discussion Starter #15
I adjusted the brass piece in the last photo up towards the seat as if the carb was on the quad and I also brought the needle up towards the seat, moving the C clip down on it to the 4th notch I believe it was. I have a 02 300ex an I compared carbs, they look identical, on the 300 the needle is on the 3rd notch and the brass piece up towards the seat as well and she runs strong. So maybe since they are identical could I set the 250 carb up like the 300?
 

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Discussion Starter #16
The smoke it strong when first cranked and strong when on the gas, it doesn't have an oil smell but it's kinda gray. I couldn't really tell it was real humid (sticky) today and kinda dark due to implement weather
 

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Discussion Starter #17
Soo. I bought a new carb, a japan built carburetor. I installed it and the quad cranks first kick. But still Boggs down when throttle is applied aggressively. Maybe the needle with the C clip needs adjustment? I adjusted the fuel mixture needle too 2.5 turns out and went in an out still nothing changed.?
 

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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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Discussion Starter #19
I have not tried the cdi. I am getting a new coil and plug tomorrow if honda is open if anything maybe a uto parts store. I adjusted valves to what the repair manual states. .004
I have not done a compression test yet. I dont have a gauge in my possession yet.
I was thinking in my head maybe the petcock or fuel screen in the gas tank(if there was one?) Could be clogged up and when the gas is applied the pressure draws the trash together clogging the flow? The gas cap is free of debris.
 
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tylerjones
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