Hi again, I'm asking my question on the forum yet again since I'm not an acomplished mechanic yet (and I will never be). My friends don't really trust the net but anyway, 90% of my knowledge is from this site and I've solved a lot of problems with the help of the forum people. Anyway, I'm gonna ask those questions for my friend and when they ask me how I sold it, I will tell them that it's from people online [img]i/expressions/face-icon-small-happy.gif[/img]

One on my friend have a 87 250X. It won't start. He said that last time he rode it, it stalled like it was short on gas and never restarted. Compression is good. Good Spark. It Seems to get gas. When we check the plug after cranking, it seems to smell gas and it's full of oil on the thread so I think maybe the ring are worn. What do you think about it?

I know this forum is not about dirtbike but anyway, An engine is an engine.... This friend have a 91 RM 250. When it's really really cold (haven't ran for a couple of hours), it starts right up like a new engine on the choke. Then , at a given moment,when it's getting warmer, it's just stall like if the piston was dying or the engine was dying like pressing the kill switch. Then it never restart and the carb flood itself. Then the gas is coming out from the hole on the bottom of the carb (sorry I don't know what it is in english [img]i/expressions/face-icon-small-sad.gif[/img] (LET ME KNOW ) ) Any ideas on that one?


Anyway, thanks a lot

 

Hi Quadsport. I'll give it a shot. The 250x has compression, spark and gas? That thing should fire! The only thing that could keep it from running is that the ignition, or valve timing is off. Is it trying to run at all? No popping, backfiring. Try a squirt of stating fluid, if it fires, it's a gas problem. On the RM 250, sounds like a needle valve problem, resulting in the flooding/overflowing of the carb. It may just have a piece of dirt holding it open, it's worth a shot to check it out, clean the carb. Good luck!

 

Thanks Custom. We're gonna check for the RM carb. But for the 250x, it doesn't even start when we put gas in the plug hole. I don't know why the valve timing would be off. He didn't touched about that. It just stalled.

 

have you even tryed a new plug for the 250X? i kno they rarly foul but sometimes they do... it would defintly foul a couple plugs here and there if it needed new rings because it would burn oil. Other than that it is probably an eletrical problem.

With the RM. Probably a carb problem. take it apart and blow everything out and make sure everything works right. Also make sure there isnt an air leak around the motor (gaskets and stuff) It will cause the piston to heat up and expand to much (possibly melt if bad enough) That happend to my blaster and ran just liek you explained.

 

Put a new plug in the 250X. I've seen a couple four strokes with old plugs get spark at the plug but still not run.

 

We tried it MachWon. We were thinking it could be the carb for both machines

 

If you change the plug and put gas or starting fluid in the combustion chamber, and it still does not run, then it cannot be the carb. Sometimes, if the timing chain tensioner is broken, or not working properly, it can jump time. I suggest you check that, if you can't get it fired up.

 

Ok, How can I check than custom? With the HONDA's case big allen bolt?

 

I don't know about your particular model, your book should tell you, if you've got one. Look for an inspection plug on one of the side case, whichever one has the magneto in it. When you find it, take it off, then look inside the hole while turning over the engine by hand. You will see two marks on the flywheel, one marked "T", and the other one "F". The "T" is the one you want. Line it up on the fixed mark on the case, inside the inspection hole. When this is lined up, you have to remove the inspection cover for the camshaft, on the side of the head, if there is no inspection cover, then you will have to remove the valve/cam cover. When you remove this, you will see the camshaft sprocket. Usually, there are marks on the camshaft sprocket spaced exactly 180 degrees apart, a straight line. These marks will line up with either marks on the head, or they will line up with the mating surface between the head and valve cover. Another thing you could check, is if the spark is timed with the "F" mark. Get a timing light, hook it up, remove the spark plug, so it turns over easily. Then, point the timing light inside the inspection hole, have a friend kick the engine over. While the engine is turning, if the Ignition timing is correct, the timing light will light up at the precise moment the "F" mark is coming into view in the inspection cover. If it doesn't, then Ignition timing is off, and I think it is non-ajustable. Let me know what you find out! Good luck!

 

On the 250x there is 2 covers on top of the rocker cover yoy will need to pull aleast one of those. Take that big allen screw out of the left side case and also the 6mm one above it. Turn the crank until you line the "T" up with the mark in the small hole, there is 3 letters so make sure it is the T . Once there the rockers should have play if the timing is right, about .004 or .005 . If they are tight you lost time if they are loose its a good time to adjust them. GOOD-LUCK