help needed on 1992 XR250R

hey guys, i'm new here and recently bought a 1992 XR250R for $250 dollars. the motor had just had new piston and rings put in but needed to be put back together and put in time, so i put it together and put it in time. the engine was missing quite a few bolts so i ordered them from bikebandit and put them on. the motor is now on the bike turning over smoothly... but it won't start. i tried pushing it while in gear and letting out on the clutch to try roll starting it, and it sounds kind of weird sort of like the spark plug is out or something. the spark plug is tightened up good and tight and it has spark as i have already checked. i've been reading alot on here and decided it's time to join and get some help. i am really hoping you guys can help me out. is this normal? do all xr250r's do this after they've been rebuilt? thanks in advance for any help you may give!

Edited by caseywoods5

The problem could be so many things, it's mindboggling.

Check the simple stuff first. Air, fuel, spark, compression.

Next, you didn't say anything about checking/setting the valve clearances.

You have to start your kick from TDC, that hard spot you come to when kicking the engine over slowly.

Did you have a manual to go by when putting it together?

is there a way to set the idling on these bikes? i'm not familiar with these types of carbs.

i am going to check today to see if it's getting fuel (going to take out the plug and check).

i never messed with the valve clearances as i don't have any of the tools for the valves, all i did was rebuild the top end and put it in time.

yes i have been kicking from TDC as everybody has told me that is the only way to start these bikes.

no i don't have a manual i am getting one soon though.

alright i checked and it is getting gas, and plenty of it.

i tried pulling it with a fourwheeler while it was in gear to start it today, it acted like it was trying to run but if i touched the throttle any at all it would bog, so thinking it probably needs a new plug. also it is pouring gas out of the back of the carb around the airbox boot so thinking either it isn't wanting to take the gas, it is putting out too much gas, or it was flooded. and yes the airbox boot is all the way on and tightened.

also does anybody have any pics of how the wiring goes on these bikes? i had to guess on it so i hope it is right.

and does anybody have pics of where all the hoses go like the breather hoses and other hoses coming off the carb? thanks in advance!

Edited by caseywoods5

i looked on denniskirk and by the looks of it i have the wrong plug for this bike, could this be the problem?

starting to wonder why every other thread gets lots of replies and fast but mine hasn't got very many in the past day or 2.

i looked on denniskirk and by the looks of it i have the wrong plug for this bike, could this be the problem?

starting to wonder why every other thread gets lots of replies and fast but mine hasn't got very many in the past day or 2.

Even with the wrong plug an engine will run.

As for the response time to you post... Dude it's only 24 hours old and some of us work... even on weekends. :smirk:

^^^^ well thanks for the reply i really appreciate it haha, and i think the plug in it is done for, my other bikes won't even run with it in so i guess a new plug is a necessity. do you have any ideas about what might be wrong?

i had to edit one of my posts because i said gas was pouring out of the overflow but i meant to say it was coming out of the back of the carb around the airbox boot.

Your first post makes it sound as if you don't have any compression. :smirk:

Are your valves adjusted correctly?

Perc

Gas pouring out of the carb overflow vent line means that there's a piece of crud between the needle and seat, that the needle needs replaced or that the float level is out of spec..

Response has been poor because no one feels like writing a troubleshooting book today.

the bike has plenty of compression, and not sure on valve adjustment i don't have a tool for them yet. i just put new piston and rings in it so they can't be a problem.

@trailryder42 it's not coming out the overflow it is coming out around the airbox boot that connects the airbox to the carb.

Try turning your gas off while there is some gas in the carb and try to start it so it doesn't keep flooding and a new plug definitely would b good. If it still doesn't start check ur valves sounds to me like its flooding and the plug is fouled

as far as tools for the valves you really only need a feeler gauge and an 10mm or 8mm(can not remember)for the lock nut and in a pinch use pliers to hold the square tappet. I agree it sounds like the intake valves are not open, your sure your in time, and cam lobes were down at tdc

^^^^ you just revealed the problem, i wasn't sure on which way the cam should be turned and i decided to turn the lobes up since it was at TDC. and i am going to put a new plug in anyways. thanks!

this is also where you want to adjust your valves at as well

intake .03-.07mm (.001-.003 in)

exhaust .06-.10mm(.002-.004in)

also at tdc check your decompression cable if you have one 1-2mm free play(1/32-1/16in) do this after your valves though.

Dude ,you need to buy a manual ,sit on the shitter and do some reading.

Then go and get the basic tools ,it doesn't take much to work on a bike like yours.

The guys here would be more than happy to help you with a few questions but you can't expect to get it running with a hammer and a screw driver and very limited knowledge. No body here wants to rewrite the manual and teach motorcycle mechanics in print.

You can read alot of threads on here that I think would help you ,theres a huge amount of information but a manual is a good starting point.

When I buy a used bike ,I buy a manual before a spark plug.

Sorry ,but thats just my 2 cents ,good luck !

this is the first xr bike i've ever worked on. i have worked on honda crf/r models, crf/f models, and crf/x models but never any xr bikes. i rebuild alot of the crf/r bikes for my friends and a few 2 strokes for the ones that have them. but i can't wait to learn more about the xr's! and i put the bike in time (the right way, with cam lobes pointing down at TDC) and after it was back together i gave it a few kicks and it gained a TON of compression i can't even kick it now (and i don't have the compression release hooked up). could i push the bike or do i absolutely need compression release? and i ordered a spark plug and a Haynes manual for it yesterday.

pull the head release with your hand and give it a shot, if not, pull the plug, kick it a bunch with throttle open and choke off. plug back in, if your lucky 2 kicks and she should fire. But check your plug is it wet? these bikes are known bears to start sometimes

was working on putting a rear end on my fourwheeler today and didn't get to mess with the xr any, i'll try what you said tomorrow if i finish my fourwheeler in time.

EDIT: also my spark plug and Haynes manual came in today, Denniskirk always gets it to me in 1-2 days!

well i thought it was just alot of compression but i took out the plug and it is not turning over at all now. i'm not blaming you guys but it seems weird to me that it only did that AFTER i went back in and turned the cam lobes down at TDC. got any ideas? i would like to be riding this thing soon haha.

Someone correct me if I'm wrong, but I'm pretty sure it wouldn't matter which way you put the cam in. The 'T' mark is going to align on both the compression stroke (lobes down) and the exhaust stroke (lobes up).

In other words, if you installed the cam with the lobes up, you could rotate the engine one revolution so the T lined up again (the cam would rotate 180 degrees) and the lobes would be down with everything aligned again.

If it won't turn over you need to take everything back apart and going through it again now that you have a manual. My opinion.

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