yamaha enduro 250 help


new here, greetings everyone.

so, i have an enduro 250, not sure of the year, that i've been trying to get running. i've gotten it started 4 or 5 times, but it stalls out. i'm relatively inexperienced with dirt bike engines, but i'm good with cars, and they don't seem terribly dissimilar. i was wondering if someone could give me a list of things to check for, including how i would figure out the year, i guess, and i could provide more information. or, if someone wanted to pm me, i would be totally down to give out my phone number and he/she could walk me through it while i'm looking at the bike.

any help would be fantastically appreciated. i'm actually up in ny to get clean and step back from life for a bit, and i'm just dying to ride this damn thing, i've always loved dirt bikes since i was a boy. riding would be the perfect thing to fill my days with.

thanks a ton,


ps, i hope this is in the correct section of the forum. if not, please excuse my ignorance

Hi there and welcome

Post a pic of the bike, that will make most people happy :thumbsup: If it stopps running test if it has a spark. Or if the plug is wet. How much time goes by till it starts again.

You have to open the engine, have a look at the piston and the cylinder. That would be a first thing I would do. If the bike stood a long time you are up for seal changes, bearing changes.

Good luck


yeah, dunno why i didn't do that. i will snap a shot tomorrow. after it starts and is warmed up a good kick or two will start it back up, but cold it takes a bit to get it running. i'm pretty sure it's running rich, on top of whatever else may be wrong. thanks much for the reply and info, will have news tomorrow

Where in PA are you (generally) I may be close enough to stop by and answer your questions. If it a gold '74 model, I have some leftovers you can have. Either way, I'll walk you through this as far as I can go.

If it has sat for a while, I would start with the carb, pull it and clean it. Next, be sure that the rubber spigot/reed valve cover/carb mount isn't dry rotted and cracked. Also be sure that the air filter boot is good, and sealing, and the air filter isn't falling apart. If it the original, it is falling apart. Last: timing: this will give all sorts of symptoms that you don't want. We'll go from there. These things aren't tough to work on, but you can't just go throwing things at it and hoping, it must be done in sequence.

Edited by Yamaguy55
Oops: didn't see the NY thing the first lap.

that would be awesome. i live in west chester and great valley, sometimes, about 30-40 min from philly. the problem is, i'm up in ny about 30 min north of syracuse right now ;/

it's not gold, though, but i'll upload a couple pics in a sec. gotta email them to myself real quick

ok, this dumbass phone is terrible sending emails for some reason. there's a delay. i'm gonna go clean a little of the house then i will come back up and hopefully the pictures will have arrived.

that would be awesome. i live in west chester and great valley, sometimes, about 30-40 min from philly. the problem is, i'm up in ny about 30 min north of syracuse right now ;/

it's not gold, though, but i'll upload a couple pics in a sec. gotta email them to myself real quick

Well, what color is it? It will have a sticker on the steering head that shows date of manufacture. "this vehicle conforms to all applicable motor vehicle laws at time of manufacture 6/75" or something like that. Twin shock? Monoshock?

blue, twin shock. the pictures refuse to be sent, for some reason. i'm gonna try to just post them with my phone. and i will go check the year in a little bit.

it's blue, yamaha sticker on the gas tank that is light blue, blue, then black from left to right. black "wings" on either side of the 250 under the seat

ok, so the only way to get photos onto photobucket from a phone is via email... so i borrowed a camera and just shot some photos. here they are. also, you can't really see it in the picture, but the area where the year of manufacture is printed on that sticker is plucked up. it looks like 77






looks like a fun project

alright, i guess i'll rip the carb out tomorrow and check the seals and filter, will reply with how that goes

'77 tank, '78 for the rest. Silver was 78, blue 77. I have it's big brother in the shed, a DT400 in yellow. There is no difference between the two years of 250s except color.

You don't have to remove the carb, but loosen up both clamps, and after unscrewing the cap on top, remove the slide and let it hang by the cable. Rotate the carb in the rubber until you can get at and unscrew the float bowl screws. Carefully remove the bowl.

The main jet is the one sticking out of the center. Just in front of that, towards the reed cage and the engine, is a small hole that houses the pilot jet. Use a small flat tip screwdriver and remove it. It is most likely partially plugged. There are two very small holes inside that the pilot feeds, one on the engine side of the slide, and one right at the area where the slide closes. These have to be clean. No metal or hard objects. Berkbile 2+2 or another carb and choke cleaner and compressed air only. Same for all the jets. In the event that all of the stuff in there is caked with corrosion and fuel residue, loosen up those clamps even more, slide them out of the way, and remove the entire carb. WD40 on the rubber makes it easy to get it back in. Cleans it up real nice as well.

You can carefully strip the carb and run the body part (zamac castings, not the jets or float, tiny parts) through the dishwasher, cleans it up really nice. Then you probably should check the dishwasher. It most likely won't come to that. If it is really bad, a new complete carb can be had from Dennis Kirk for about 100.00. Easier than fighting with a rotted one.

carb specs:

main jet 150 (accessed through that hex head cover thing on the float bowl)

needle in the slide should have the e-clip in the center position. needle lower= lean, needle higher=rich.

pilot jet should be a 50.

float level is 15.8mm/0.62" measured from the gasket surface to the arms. There is a small tab that contacts the flat needle that is carefully bent to achieve the correct level. Air screw, the one on the side towards the air filter boot, is turned in until lightly seated, then out two turns, then leave it at that.

If I didn't already mention it, pull the air filter and be sure that it is clean, oiled and not falling apart. There's all sorts of methods to clean these. I use stale pre-mix very far from buildings and nowhere near sparks and flames, and soak it, then rinse it again, then re-oil and grease the ends where it seals. they tend to fall apart with age. Dennis Kirk and others sell the K&N replacement if your is past use. Don't ride without an air filter, that's what the previous owner did to my Dt400, and now I need the crank rebuilt and a new piston and bore job.

Drain the tank and fill it with fresh 91 octane or higher. Don't use car oil in the clutch and transmission, and use 2 stroke oil in the autolube. I prefer Bel-Ray Si7 as it is clean burning and made for injectors, but any two stroke oil will work.

Good luck.

thank you very much man. i'm gonna go start right now. would 2 stroke outboard oil work?

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