2000 YZ250 died when riding now wont start

Alright guys I need some help on this.  While riding down a dirt road the bike died, I pulled the clutch in and coasted to a stop.  Tried to kick it over again, no go, changed plug still nothing.  Got it home and started into it but can't get it to fire.  So far I've:

 

disconnected the kill switch

checked compression (a little low, see below)

changed plug(again)

pulled the flywheel cover(everything looks correct, but i dont have a flywheel puller)

grounded plug to head(get blue spark)

cleaned the carb(looked pretty clean actually, jetting below)

Reeds look new

piston and clyinder look fine from intake and exhaust ports

 

And of course I had just filled the tank full. 32:1 yamalube R & 92 oct.

 

 

Compression: 160

Needle:  N3CW 3rd clip

Pilot: 50

Main: 180

Power: 55

 

 

Any and all ideas welcome, thanks in advance

Edited by Carcinogen

Alright guys I need some help on this.  While riding down a dirt road the bike died, I pulled the clutch in and coasted to a stop.  Tried to kick it over again, no go, changed plug still nothing.  Got it home and started into it but can't get it to fire.  So far I've:

 

disconnected the kill switch

checked compression (a little low, see below)

changed plug(again)

pulled the flywheel cover(everything looks correct, but i dont have a flywheel puller)

grounded plug to head(get blue spark)

cleaned the carb(looked pretty clean actually, jetting below)

Reeds look new

piston and clyinder look fine from intake and exhaust ports

 

 

Compression: 180ish (going to go check again to make sure WOT)

Needle:  N3CW 3rd clip

Pilot: 50

Main: 180

Power: 55

 

 

Any and all ideas welcome, thanks in advance

Hey man, so obviously, it hasnt seized, which is good. Okay so you have checked everything for spark. We know it needs three things to fire up. Compression/spark/fuel. You have compression and spark. Take apart the carb. Give it a good clean. Obviously check for clogged lines. Also check that your gas tank has a little tube on the cap. It has to be a fuel flow problem!

Hey man, so obviously, it hasnt seized, which is good. Okay so you have checked everything for spark. We know it needs three things to fire up. Compression/spark/fuel. You have compression and spark. Take apart the carb. Give it a good clean. Obviously check for clogged lines. Also check that your gas tank has a little tube on the cap. It has to be a fuel flow problem!

I completely skipped over that you cleaned the carb. My bad mate:/ How is the ring on the piston? i had this problem once where everything checked out, but the ring welded itself to the piston..

Spray some starting fluid in and then kick it over. That is the only piece of the puzzle that you havnt verified while kicking over. If it fires then you know you have a fuel supply issue to the carb.

Try a new plug? Could have fouled it

Could be a sheared FW key. Do you get any type of abrupt backfire ? Tell tale sign the key sheared and the FW is out of time.

I completely skipped over that you cleaned the carb. My bad mate:/ How is the ring on the piston? i had this problem once where everything checked out, but the ring welded itself to the piston..

 

I'm trying to avoid tearing into the engine right now if possible, dont have the money for a rebuild but they seemed fine through the exhaust port.  Is there an easy way to check?

 

Spray some starting fluid in and then kick it over. That is the only piece of the puzzle that you havnt verified while kicking over. If it fires then you know you have a fuel supply issue to the carb.

Try a new plug? Could have fouled it

 

I dont have any starting fluid, I'll have to get some and try that.

 

Could be a sheared FW key. Do you get any type of abrupt backfire ? Tell tale sign the key sheared and the FW is out of time.

 

I dont think its the woodruff key, flywheel mark is still TDC when the piston is.

Edited by Carcinogen

I'm trying to avoid tearing into the engine right now if possible, dont have the money for a rebuild but they seemed fine through the exhaust port.  Is there an easy way to check?

 

 

I dont have any starting fluid, I'll have to get some and try that.

 

 

I dont think its the woodruff key, flywheel mark is still TDC when the piston is.

The exhaust port doesn't really cut it man. If you want peace of mind, you're going to have to open her up! 

Don't forget a fresh plug! Mine did the same thing when it fouled last time

I tried a brand new plug when it first died and another after I cleaned the carb

You didnt mention a new plug, just wanted to make sure it wasnt over looked :)

Have you pulled your fuel line and made sure the petcock is flowing good?

Yeah, petcock checks out ok.  Drained a full tank back into a gas can.  I do need new fuel line though , its old and stiff.

When it died traveling down the road, what did it do? I'm still thinking it's in need of a new piston & rings. Check the compression again.

2 strokes need fuel, compression and ignition. You're missing one of these elements. You should at least be getting an exhaust fart or something.... i'm at a loss with this one.

When it died traveling down the road, what did it do? I'm still thinking it's in need of a new piston & rings. Check the compression again.

 

Just cut out as I was getting off the throttle.  And yes I'm sure it needs a top end, the power just wasn't there.

 

Oh yeah, checked the compression again last night and got about the same(but I dont have another gauge to compare against...) :(

 

2 strokes need fuel, compression and ignition. You're missing one of these elements. You should at least be getting an exhaust fart or something.... i'm at a loss with this one.

 

Yeah man, me too.  It just kicks over without a sputter, which leads me to think its not getting fuel(or enough fuel).  I need to try the starter fluid suggestion.  What about squirting some gas into the plug hole and putting the plug back in, would that work?

Edited by Carcinogen

Just cut out as I was getting off the throttle.  And yes I'm sure it needs a top end, the power just wasn't there.

 

Oh yeah, checked the compression again last night and got about the same(but I dont have another gauge to compare against...) :(

 

 

Yeah man, me too.  It just kicks over without a sputter, which leads me to think its not getting fuel(or enough fuel).  I need to try the starter fluid suggestion.  What about squirting some gas into the plug hole and putting the plug back in, would that work?

No, if you do the fuel doesn't atomize with air correctly. Just yank the air filter, and give a good blast of starting fluid down the intake boot, and kick, you should get the engine to fire after like 3-4 kicks. Simple and conclusive test. I do it all the time to "isolate" fuel or ignition issues.

It doesn't want to start with starter fluid and it doesn't want to compression start either.  When I try to compression start it, it just locks up the rear tire.

 

Pulled the plug again and verified spark. I have not double checked the kill switch since the first day I tore it apart, but I figured it wouldn't spark to the head if the kill switch was bad anyway.

Edited by Carcinogen

Does it even sputter or nothing at all?

nothin'

May be time to pull the top end...

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