03 Yz259f Major issue water

As stated it is a 03 yz250f.

Back ground info on the issue that caused the breakdown. I went dirt riding with my buddy that claimed he had a sweet spot to ride. I show up to find they are riding 4x4 farmer john 4 wheelers. We go out it is nothing but over grown weeds with logs under the weeds. It is all wet so no traction, also no way to get any speed to hop the logs. After getting through all this crap we get to the open area. Turns out to be nothing more then a power line strip. Best part is it has 3- 4ft tractor ruts all over it, plus standing water every where. After a colorful conversation with said friend we go to head back, as I was not going to run this place. We start to leave my friend just up and stop for no reason as I am skipping across the ruts and mud holes. I am left with no other choice but to go to the side of him so that I don't wreck into the back of him. That bought me a 3 ft rut full of water. Needless to say the bike slide out and the water splashed the filter there by killing the bike. I can't get it to start back up for the life of me. So we have to tow it back to the truck. No way to go the way we came as it was a crooked as a snakes back. That leaves us with going down this power road. To make this shorter. This road ended up being a damn pound. Needless to say the bike was at it's bars in water. Get back load it up go home.

Now I know that I can't run this thing with out taking the top half off and cleaning it and the carb down. I do so, as well as clean and lube the whole bike. I get the bike back together and not it will not start. I have kicked it till my foot hurt. The only thing that has happened is two back fires. So I rip the cams back off to make sure that I have the timing right. I think I do. Put it back together and same thing nothing, then after a few kicks with the hot start pulled in back fire. I have read a lot of threads on this site trying to get answers. Sad to say I am not getting the info that best fits my needs. I did take the filter off and shoot some starter fluid in there. Same thing single backfire then nothing not even another backfire.

I have been working this thing for a few months. I am at my wits end. I have not done a valve check or adjustment. But that should not keep it from at least starting. Also I have not done a bump start as the damn clutch lever cable holder is busted. I will order ASV after I get it started.

I gave you all this info including the story to help get a whole picture. Please help me get this thing up and running. Maybe someone has a start up procedure. I am new to dirt biking but not motorcycles. This is my first carb bike.

As stated it is a 03 yz250f.

Back ground info on the issue that caused the breakdown. I went dirt riding with my buddy that claimed he had a sweet spot to ride. I show up to find they are riding 4x4 farmer john 4 wheelers. We go out it is nothing but over grown weeds with logs under the weeds. It is all wet so no traction, also no way to get any speed to hop the logs. After getting through all this crap we get to the open area. Turns out to be nothing more then a power line strip. Best part is it has 3- 4ft tractor ruts all over it, plus standing water every where. After a colorful conversation with said friend we go to head back, as I was not going to run this place. We start to leave my friend just up and stop for no reason as I am skipping across the ruts and mud holes. I am left with no other choice but to go to the side of him so that I don't wreck into the back of him. That bought me a 3 ft rut full of water. Needless to say the bike slide out and the water splashed the filter there by killing the bike. I can't get it to start back up for the life of me. So we have to tow it back to the truck. No way to go the way we came as it was a crooked as a snakes back. That leaves us with going down this power road. To make this shorter. This road ended up being a damn pound. Needless to say the bike was at it's bars in water. Get back load it up go home.

Now I know that I can't run this thing with out taking the top half off and cleaning it and the carb down. I do so, as well as clean and lube the whole bike. I get the bike back together and not it will not start. I have kicked it till my foot hurt. The only thing that has happened is two back fires. So I rip the cams back off to make sure that I have the timing right. I think I do. Put it back together and same thing nothing, then after a few kicks with the hot start pulled in back fire. I have read a lot of threads on this site trying to get answers. Sad to say I am not getting the info that best fits my needs. I did take the filter off and shoot some starter fluid in there. Same thing single backfire then nothing not even another backfire.

I have been working this thing for a few months. I am at my wits end. I have not done a valve check or adjustment. But that should not keep it from at least starting. Also I have not done a bump start as the damn clutch lever cable holder is busted. I will order ASV after I get it started.

I gave you all this info including the story to help get a whole picture. Please help me get this thing up and running. Maybe someone has a start up procedure. I am new to dirt biking but not motorcycles. This is my first carb bike.

Iv heard of a couple of guys having the valve shims move out of place slightly, id check that along with all your clearances! You had the head off, did you check all the valves to make sure you didn't bend any slightly? Are you 100% sure your timing is right. There is threads on here that have GREAT photos for YZ timing!

Is the plug wet? I the plug new? Is it flooded? Do you have a strong spark? Is there water in the plug lead or any electrical connectors or around the coil? Is there water in your fuel? Are you kicking it from just pass top dead center and giving it a full kick through? Are you using the De-comp lever or not? Assuming you drained the fuel out of the carb?

Matty's got some good tips there. I just found this post after I answered your pm. Sounds like two things. Read my PM, then apply this....

Could just be lean or no gas coming thru the petcock. Pull the fuel line and turn on the petcock to verify. Then re attach to carb and loosen the bowl drain screw and turn the gas on again to verify. All the time, draining it will help get water out.

Now for a totally different tact. Could be a sheared woodruf key on the flywheel. Get a puller and verify the flywheel is still in time. All you need to run is air, fuel, spark, and timing. Get those and IT HAS TO RUN !!! Oh, and if you unscrewed the idle adjustment, that would also do it. It has to have a certain amount of throttle opening to idle. Startup drill on my bike is 5 twists of the throttle while push the kickstart thru slowly, then kick to start with choke.

Iv heard of a couple of guys having the valve shims move out of place slightly, id check that along with all your clearances!

I will double check the shims, as well as the clearances.

You had the head off, did you check all the valves to make sure you didn't bend any slightly?

I didn't take the valves out. So I guess that means I don't know if they are bent.

Are you 100% sure your timing is right. There is threads on here that have GREAT photos for YZ timing!

Is the plug wet?

No

I the plug new?

Yes

Is it flooded?

Should not be. I cleaned ever inch of this thing.

Do you have a strong spark?

I think so.

Is there water in the plug lead or any electrical connectors or around the coil?

No blown out with aire then used a connector cleaner, followed by die grease.

Is there water in your fuel?

No I cleaned it and put new gas in.

Are you kicking it from just pass top dead center and giving it a full kick through?

I think the answer is yes, I am kicking it the same way I did when it was running.

Are you using the De-comp lever or not?

If you are talking about the little black lever that I was told is called hot start. Then yes I have tried both holding it in and not holding it in. the only time I get a back fire is while holding it in.

Assuming you drained the fuel out of the carb?

Yes it was drained, cleaned in a immersion carb cleaner. Then wiped down afterwards followed by carb cleaner spary.

Could just be lean or no gas coming thru the petcock. Pull the fuel line and turn on the petcock to verify. Then re attach to carb and loosen the bowl drain screw and turn the gas on again to verify. All the time, draining it will help get water out.

Check going to go do this right now.

Now for a totally different tact. Could be a sheared woodruf key on the flywheel. Get a puller and verify the flywheel is still in time.

This sounds like I am going to need a little more info. As I have no idea what or where that is. I will do some thread searches to see if I can find a how to.

All you need to run is air, fuel, spark, and timing. Get those and IT HAS TO RUN !!!

I hear you.

Oh, and if you unscrewed the idle adjustment, that would also do it. It has to have a certain amount of throttle opening to idle.

I am sure that I did do this as I toke the engine apart as well as the carb. I think I have it set back to factory setting. If I am thinking of the right thing. Do you have a pic lol.

Start up drill on my bike is 5 twists of the throttle while push the kick start thru slowly, then kick to start with choke.

I will try this start up after I do the fuel check.

Thank you all for your help to this point. I think with your help i can get this thing back together and running like a champ.

Ok I did the fuel trick. All ways as it should be soild flow both places.

I also did the start up trick no go.

I just bought some 45 degree feel gauges to check the valves.

I still haven't heard you say you verified that you saw spark at the spark plug. I'm assuming that since it did backfire, it is sparking. To pull the flywheel, you need a flywheel puller. It takes 27mm left hand inside thread. Its same puller for KDX200 220 and Honda Z50 for reference. Looks somethiing like this:

http://cgi.ebay.com/ebaymotors/Flywheel-Puller-YZ250F-YZ400F-YZ426F-YZ-250F-400F-450F_W0QQcmdZViewItemQQhashZitem3353e98887QQitemZ220451145863QQptZMotorsQ5fATVQ5fPartsQ5fAccessories

For the moment let's assume the key is not sheared you have timing and spark.

You need to pull the plug and see if its wet with gas. I've seen new plugs gas foul, so if its wet, it could be fouled, don't rule out fouled plug. If it is wet and not fouled out, then clear the cylinder by kicking it over 15-20 times While plugs out.

With auto decomp, the only to clear cylinder it to hold the throttle wide open and kick it. Sometimes they will start while clearing which is fine. Don't forget, this carb has accelerator pump so wicking the throttle is not what you want to do if its flooded. Once cleared, try it with and without hot start to see it it will fire. If not, assume it needs gas and so use the throttle with 3 twists and see it it hits. If it hits but doesn't crank, try 2-3 more twists.

This is why I like pushing it off, saves the foot and frustrations.

Find a shallow hill, driveway, dip place and line it up to roll off, you need about 30 ft straight space to be safe. Get it rolling and jump on and jam it down into first gear. Have the choke on and be ready to clutch it when it fires up. We do this all the time on any bike that gets mean to start. It's an old 70's thing we used to do at the track with 125s. I even did it yesterday when my clutch cable broke on the trail. Just cranked it up, pushed off and jamed into gear and motored off. Keep after it.

I will check the spark plug. I would love to bump start it but I have a busted clutch holder and other crap. I swear when it rans it pours.

having just overhauled one of my bikes I lent to someone that thought it was funny to submerge it over the seat....I had to do the carb twice...first time I didnt remove the hot start and choke plunger...there was a fair bit of crud in the passages....

I needed new rings after it was drowned .....the oil rings for some reason went from .003 gap to .065...so the bike smoked bad...

If you are getting a back fire thats a good thing...you are getting spark, and some gas....

so now tha issue is is it sparking at the right time...if the bike was killed by water while it was running then there is a chance the key got sheared as mentioned....pop out the timing / crank plugs...pull the spark plug...and turn the engine with a long wire or stick in the plug hole.....you want to feel the piston when it reaches top dead center.....by turning the crank find TDC....now look at the timming mark...it should line up with the marks...if it is way off then there is where your problem lays...

If that is good then do a leak test....pressure up through the spark plug and confirm the rings and valves are sealin....

If you have cleaned the carb, and pulled the fuel screw out ( which you should have ) recheck the setting....

get 2 more new spark plugs and try again,

This is after you have cleaned and installed your air filter, and inspected in the boot for water....rechecked all your vent hoses ( blow through them)......had rechecked the carb...Pull out every jet and blow through...

There is no shortcutting these checks....a very small amount of water can cause huge problems like you have...keep in mind as the water was probably dirty ti would have brought debris into places you would never otherwise get it into...( see my experience with the choke plunger)...

Good luck!

having just overhauled one of my bikes I lent to someone that thought it was funny to submerge it over the seat....I had to do the carb twice...first time I didnt remove the hot start and choke plunger...there was a fair bit of crud in the passages....

I removed everything and did a immersion carb clean then sprayed with carb cleaner and then air.

I needed new rings after it was drowned .....the oil rings for some reason went from .003 gap to .065...so the bike smoked bad...

Have no clue on that part as i didn't take the engine that far down.

If you are getting a back fire thats a good thing...you are getting spark, and some gas....

Yes it does backfire now and a agian.

so now tha issue is is it sparking at the right time...if the bike was killed by water while it was running then there is a chance the key got sheared as mentioned....pop out the timing / crank plugs...pull the spark plug...and turn the engine with a long wire or stick in the plug hole.....you want to feel the piston when it reaches top dead center.....by turning the crank find TDC....now look at the timming mark...it should line up with the marks...if it is way off then there is where your problem lays...

I can give this a try. TDC the way I think it means is. When said stick that is in the plug hole rises to it's highest point just before it starts to go down again right?

If that is good then do a leak test....pressure up through the spark plug and confirm the rings and valves are sealin....

Ok will need to look into how to go about doing this.

If you have cleaned the carb, and pulled the fuel screw out ( which you should have ) recheck the setting....

Yes I am 100% sure that I pulled this screw. I think it is the screw that the manual says to count how many turns you out it is, as it is set at the factory for each bike right?

get 2 more new spark plugs and try again,

Ok I have spare plugs.

This is after you have cleaned and installed your air filter, and inspected in the boot for water....rechecked all your vent hoses ( blow through them)......had rechecked the carb...Pull out every jet and blow through...

I will do this after I do the others.

There is no shortcutting these checks....a very small amount of water can cause huge problems like you have...keep in mind as the water was probably dirty ti would have brought debris into places you would never otherwise get it into...( see my experience with the choke plunger)...

There should not be any water any where as it was cleaned and is I a hot garage all summer.

Good luck!

Again thank you all for all the help so far. My friend might live to see x-mas after all.

ok so here is a little more info for you guys. I did the feeler test. All but the first intake is with in spec. I will double check to make sure a shim didn't slip monday.

valve-2.jpg

Edited by streetjester

OK, when you get the center valve spec'd, let us know. Put the shims on top of the valves, making sure they are seated all the way down in the pocket. Then put the buckets in. Sometimes a shim will wedge sideways and close up the clearance.

BTW, I'd make sure the intake ports are absolutely clean since it sucked dirt in and hydraulics locked on you.

street, I would put my money on the flywheel/key/timing thing. You've cleaned everything and are getting gas & spark. The backfire makes me believe you're getting spark during the exhaust stroke.

Thanks Kmac. I need to also get my shim right, as well as double check my fuel screw.

put a brand new plug in it and check to see if you have spark.... Don't use the plug that is in it, don't pick one up that you previously picked up....Put a new one from the store in it..

And your valves are tight...but they are not zeroed out (meaning you can still get a gauge under the lobe).... Find out what your middle valve is... The bike was running before you drown it and took it apart, so as long as everything went back together right I would bet spark, from the sounds of it....Make sure you have a new plug and check for a good blue spark..

Since we talked yesterday I thought of some things:

One to be aware of is if it was running when it sucked water in, besides shearing the key, is that the ring lands can get mashed, which will keep the rings from sealing properly.

And the rod can get bent. You will never verify those items unless you remove the cylinder and inspect. I know you didn't want to hear that.... but.... .

The middle intake cam is in spec Ron.

Did you do the timing check?....when you pulled out the fuel screw did you notice the tiny o ring, spring, and perhaps a small washer....After reviewing your post other than the keyway being sheared....the only other things I can think that are giving you issues are something never went back together right....if it was running fine before the dunk, you did a disassembly and put everything back then it should be as it was...The fact you get a backfire means most of the components needed to make it run are there...it just isnt right...so only the amount of gas/air mix or the timing of the spark can be causing the problems....its hard to figure out exactly based on how you explain...lots gets lost in the interpetation...so I have to guess if I were trouble shooting I would look at the carb, and spark at this point...If the carb isnt set to exactly where it was or every part put back perfectly the bike wont start easily or run...

Pull the carb but leave the cables and try not to spill any fuel.....look in the bore and open the throttle and see if it squirts....and see if the needle is going into the carb...then tip it over and pull the fuel screw and make sure all the parts are in it...if its missing the o ring then that alone can cause the bike not to start....I would also pull the bowl and recheck the pilot...

Ok thanks for the info Dirt. I am with you 100%.

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