Piston at TDC, inside flywheel cover you will find the stator with a raised line on it on lower left side, a raised mark on case, and a line on flywheel. Lined up like the stars, earth, and moon, the piston should be at TDC. With a dial gauge, make sure piston is at TDC, and rotate stator plate .002 clockwise.
250 The 1999 YZ250
- Thread starter Trfsrfr
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Thanks Gary,
I figured it had to be something like that, but wasn't able to locate that particular section in the manuals I have. Doesn't save time that I have to page through 3 other languages that the manuals are written in either, but hey, they we're free.
I just got home from work and am gonna rip into it again.
@Andy - the main jet is a 172s. Not sure what the s means. I will find out what needle it has in it too. BTW - is this the junk carb you were thinking of?
Also - just for my own knowledge, doesn't there need to be a timing advance as the rpms increase? Or does the power valve facilitate that?
I figured it had to be something like that, but wasn't able to locate that particular section in the manuals I have. Doesn't save time that I have to page through 3 other languages that the manuals are written in either, but hey, they we're free.
I just got home from work and am gonna rip into it again.
@Andy - the main jet is a 172s. Not sure what the s means. I will find out what needle it has in it too. BTW - is this the junk carb you were thinking of?
Also - just for my own knowledge, doesn't there need to be a timing advance as the rpms increase? Or does the power valve facilitate that?
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@ossagp - Yes, it has an electrical solenoid.
So quick update -
The needle is an N3VF.
I just removed the carb and did some more cleaning, and reset the float. This float is tricky to set for me, but I put it at what I believe is 6.5ish mm, but its hard to tell cuz the tang holds it a set distance from the float valve plunger. Hard to see exactly where its resting. I might have leaned it out too much.
Also removed the solenoid and hooked it up to a 12v source and it moves/actuates, about 1/8 to 3/16 of inch. Also carb cleanered and blew out those passages, it appears that the rubber tip on the solenoid has seen better days, but maybe? not completely unusable, so it went back in. Also carb cleanered and blew out the passages for the air idle screw.
Set the air screw at 0 turns, per temp, altitude rec's.
Put the needle clip back at 2nd position.
Approx 1100 ft MSL in my area, give or take a couple hundred feet.
Started on 2nd kick.
Took it out for a quick rip - runs like shit. Mostly wouldn't rev.
Only went around the block once, but it intermittently hit the power band. Gonna park it for the night and try again tomorrow.
Did not check timing.
4 strokes are much easier to diagnose...
So quick update -
The needle is an N3VF.
I just removed the carb and did some more cleaning, and reset the float. This float is tricky to set for me, but I put it at what I believe is 6.5ish mm, but its hard to tell cuz the tang holds it a set distance from the float valve plunger. Hard to see exactly where its resting. I might have leaned it out too much.
Also removed the solenoid and hooked it up to a 12v source and it moves/actuates, about 1/8 to 3/16 of inch. Also carb cleanered and blew out those passages, it appears that the rubber tip on the solenoid has seen better days, but maybe? not completely unusable, so it went back in. Also carb cleanered and blew out the passages for the air idle screw.
Set the air screw at 0 turns, per temp, altitude rec's.
Put the needle clip back at 2nd position.
Approx 1100 ft MSL in my area, give or take a couple hundred feet.
Started on 2nd kick.
Took it out for a quick rip - runs like shit. Mostly wouldn't rev.
Only went around the block once, but it intermittently hit the power band. Gonna park it for the night and try again tomorrow.
Did not check timing.
4 strokes are much easier to diagnose...
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Initially when it was leaking from the carb you said it wasn't from the overflow where was it leaking from?
I would reset the float again and go in the other direction and see what you get. Ive set my float to where I'd swear it was perfect, and it hit a wall on overev just like yours is doing. It sounds to me like it's underfueled.
I would reset the float again and go in the other direction and see what you get. Ive set my float to where I'd swear it was perfect, and it hit a wall on overev just like yours is doing. It sounds to me like it's underfueled.
It looked like it was leaking from around the float bowl gasket area, but it's hard to be sure anymore, that was so long ago. It could have been leaking from the petcock and running down the hose. All I know is that it wasn't leaking out the overflow tube.
I will try the float reset again, it definitely ran better yesterday before I touched it.
Main bigger? I'm minimum 1100 feet above sea level, shouldn't it be smaller?
I was thinking that maybe the PJ should be smaller though.
Premix is 32:1...
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Stock: 178 50 2nd from top and 1.5 is where I start on all my rebuilds. They run fantastic when I am done. but this is 2001 up to 2004.
Okay,
After reading all of the recommendations given, I have another question:
Assuming this thing is running lean on both jets, and since it is running worse since I reset the float yesterday;
Is there some overlap on jet size vs float height?
I'm gonna order 5-6 new pilot & main jets, but can the same objective be achieved by raising the float height?
Just kind of wondering where the nuances in this lie...
After reading all of the recommendations given, I have another question:
Assuming this thing is running lean on both jets, and since it is running worse since I reset the float yesterday;
Is there some overlap on jet size vs float height?
I'm gonna order 5-6 new pilot & main jets, but can the same objective be achieved by raising the float height?
Just kind of wondering where the nuances in this lie...
I have only seen one photo of the plug, and that one still looks way dark and rich for most of where it is living. the 172 would tell me that somewhere along the line that one was leaned out probably like most people do, to try to cure the sloppy float setting.
you say it wont rev: OK, is it sputtering and trying to catch, or is it just going going on it's face like the tank went dry? Show a plug again please.
In the mean time, run your tests with the choke knob screwed down snug, not just pushed down, and NO, it won't idle.
On the float level, other models yamaha settings are using a fuel hose type meter to set the actual fuel level. that is done with the float bowl full and you take your measurement with the carburetor mounted and as i said full of fuel. what does your manual show? does it actually show the process?
elaborate on air screw set at "0". does that mean you have it turned all the way in, snug against it's seat?
you say it wont rev: OK, is it sputtering and trying to catch, or is it just going going on it's face like the tank went dry? Show a plug again please.
In the mean time, run your tests with the choke knob screwed down snug, not just pushed down, and NO, it won't idle.
On the float level, other models yamaha settings are using a fuel hose type meter to set the actual fuel level. that is done with the float bowl full and you take your measurement with the carburetor mounted and as i said full of fuel. what does your manual show? does it actually show the process?
elaborate on air screw set at "0". does that mean you have it turned all the way in, snug against it's seat?
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