YZ250 Lean pilot issue

pete24
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pete24 12/2/2018 10:18am
12/2/2018 10:18am
I doubt its the slide that one isnt really bad but I would replace it because of that skid mark on it
scraprecon
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scraprecon 12/2/2018 12:19pm
12/2/2018 12:19pm
pete24 wrote:
I doubt its the slide that one isnt really bad but I would replace it because of that skid mark on it
Doubt that's gonna hurt it. Any other ideas? Next steps? Thanks for the ideas so far
scraprecon
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scraprecon 12/2/2018 1:26pm
12/2/2018 1:26pm
Just now I went out and let the bike warm up to around 140-150 degrees. It fouled a spark plug idling(br9eg) so I replaced with the proper br8. Tried leaning out the airscrew(going out) and got all the way to 3 1/2 turns out and it didn't really sound lean still. Only thing it's doing that seems weird is it's surging/popping when I rev it up and it's coming back down(decel). I guess I can go back down from a 55 to a 52 and adjust the air screw from there. Is it common for yz250s to surge on decel, Similiar to little blips of throttle
scraprecon
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scraprecon 12/2/2018 1:27pm
12/2/2018 1:27pm

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FGR01
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FGR01 12/2/2018 2:00pm
12/2/2018 2:00pm
Given the age of the bike, I'm still suspicious of the right crank seal. My buddy just went through this on a 2003. Bike had a little bit of hanging idle or surging but ran like a raped ape...almost too snappy. When he took the top end apart the ports had a coating of burnt tranny oil. In any case, I'd be changing that right seal just to be sure.
scraprecon
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scraprecon 12/2/2018 2:30pm
12/2/2018 2:30pm Edited Date/Time 12/2/2018 2:34pm
Got a video of it running. This was with 55 pilot and more than 3 turns out on airscrew. Actually sounds pretty good but you can hear the surging/popping after I rev it up. You can really hear it near the end. What do you guys think?
https://m.youtube.com/watch?feature=youtu.be&v=1EtcGhU-RkM
FGR01
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FGR01 12/2/2018 2:36pm
12/2/2018 2:36pm
Watched the video. Will it still smoke white like that after it's well warmed up and you've blown it through the gears? I might have missed it, what fuel, oil, and ratio are you running?
scraprecon
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scraprecon 12/2/2018 2:49pm
12/2/2018 2:49pm
FGR01 wrote:
Watched the video. Will it still smoke white like that after it's well warmed up and you've blown it through the gears? I might have missed...
Watched the video. Will it still smoke white like that after it's well warmed up and you've blown it through the gears? I might have missed it, what fuel, oil, and ratio are you running?
Barely smokes once I run it and clear it out. 93 octane pump gas. 32:1 ratio and I run pennzoil semi synthetic but it ran the same with klotz super techniplate.
scraprecon
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scraprecon 12/2/2018 3:09pm
12/2/2018 3:09pm
Also, the richer I go on the pilot/airscrew, the less it surges on decel. If I turn choke on, it has no surging, but it gets loaded up. If I go up on pilot size, I can probably eliminate any surging but it will be to rich on the pilot. Loading up, fouling plugs, no good.
Radfonz
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Radfonz 12/2/2018 7:31pm
12/2/2018 7:31pm
turn the idle down. They're only just barely meant to idle. And 32:1 is too much oil.
1
mattyhamz2 12/2/2018 10:47pm
12/2/2018 10:47pm
Radfonz wrote:
turn the idle down. They're only just barely meant to idle. And 32:1 is too much oil.
I agree with the idling. Never once have we let any of our two strokes be able to idle on their own. Never ran them any other way.

Something is for sure off though. My 05 sat for the last 5 months and I’ve only fire it up twice over that time and it didn’t smoke anywhere close to that much. I know Yamaha recommends 32:1 with stock jetting so you definitely have some other issue. Motosport sells a prox crankseal kit for $7. It’s worth eliminating the possibility of a bad seal.
scraprecon
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scraprecon 12/3/2018 2:59am
12/3/2018 2:59am
Radfonz wrote:
turn the idle down. They're only just barely meant to idle. And 32:1 is too much oil.
I may turn the idle down but I'm sticking 32:1. Never had/have problems running 32:1 on my yz125 and brothers cr125.
scraprecon
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scraprecon 12/3/2018 3:04am
12/3/2018 3:04am
Radfonz wrote:
turn the idle down. They're only just barely meant to idle. And 32:1 is too much oil.
mattyhamz2 wrote:
I agree with the idling. Never once have we let any of our two strokes be able to idle on their own. Never ran them any...
I agree with the idling. Never once have we let any of our two strokes be able to idle on their own. Never ran them any other way.

Something is for sure off though. My 05 sat for the last 5 months and I’ve only fire it up twice over that time and it didn’t smoke anywhere close to that much. I know Yamaha recommends 32:1 with stock jetting so you definitely have some other issue. Motosport sells a prox crankseal kit for $7. It’s worth eliminating the possibility of a bad seal.
I may look into replacing the crank seal for good measure but an air leak test showed a loss of 1 psi within 6 minutes. That's within spec, and my tool was leaking. I will fix leaky tool and retest and see what I get.
mattyhamz2 12/3/2018 6:29am
12/3/2018 6:29am
Radfonz wrote:
turn the idle down. They're only just barely meant to idle. And 32:1 is too much oil.
mattyhamz2 wrote:
I agree with the idling. Never once have we let any of our two strokes be able to idle on their own. Never ran them any...
I agree with the idling. Never once have we let any of our two strokes be able to idle on their own. Never ran them any other way.

Something is for sure off though. My 05 sat for the last 5 months and I’ve only fire it up twice over that time and it didn’t smoke anywhere close to that much. I know Yamaha recommends 32:1 with stock jetting so you definitely have some other issue. Motosport sells a prox crankseal kit for $7. It’s worth eliminating the possibility of a bad seal.
scraprecon wrote:
I may look into replacing the crank seal for good measure but an air leak test showed a loss of 1 psi within 6 minutes. That's...
I may look into replacing the crank seal for good measure but an air leak test showed a loss of 1 psi within 6 minutes. That's within spec, and my tool was leaking. I will fix leaky tool and retest and see what I get.
For $7 I’d do it just to eliminate that as a possible issue. I don’t mean to sound like a jerk or anything but you seem so see on this just being a carb issue and seem unwilling to really check anything else that’s been posted because it doesn’t align with what you think is the issue is.
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kb228
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kb228 12/3/2018 6:35am
12/3/2018 6:35am
mattyhamz2 wrote:
I agree with the idling. Never once have we let any of our two strokes be able to idle on their own. Never ran them any...
I agree with the idling. Never once have we let any of our two strokes be able to idle on their own. Never ran them any other way.

Something is for sure off though. My 05 sat for the last 5 months and I’ve only fire it up twice over that time and it didn’t smoke anywhere close to that much. I know Yamaha recommends 32:1 with stock jetting so you definitely have some other issue. Motosport sells a prox crankseal kit for $7. It’s worth eliminating the possibility of a bad seal.
scraprecon wrote:
I may look into replacing the crank seal for good measure but an air leak test showed a loss of 1 psi within 6 minutes. That's...
I may look into replacing the crank seal for good measure but an air leak test showed a loss of 1 psi within 6 minutes. That's within spec, and my tool was leaking. I will fix leaky tool and retest and see what I get.
mattyhamz2 wrote:
For $7 I’d do it just to eliminate that as a possible issue. I don’t mean to sound like a jerk or anything but you seem...
For $7 I’d do it just to eliminate that as a possible issue. I don’t mean to sound like a jerk or anything but you seem so see on this just being a carb issue and seem unwilling to really check anything else that’s been posted because it doesn’t align with what you think is the issue is.
Preach
scraprecon
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scraprecon 12/3/2018 8:03am
12/3/2018 8:03am Edited Date/Time 12/3/2018 8:06am
What part of air leak test do you guys not understand? Btw, motosport doesn't sell crank seals for 7$ for my bike, closer to 14$. It's not a cost thing, simply not going to waste my time replacing crank seals on an engine that air leak tested fine.
mattyhamz2 12/3/2018 8:48am
12/3/2018 8:48am
scraprecon wrote:
What part of air leak test do you guys not understand? Btw, motosport doesn't sell crank seals for 7$ for my bike, closer to 14$. It's...
What part of air leak test do you guys not understand? Btw, motosport doesn't sell crank seals for 7$ for my bike, closer to 14$. It's not a cost thing, simply not going to waste my time replacing crank seals on an engine that air leak tested fine.
Well, that's your choice. Good luck masking your issue.
kb228
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kb228 12/3/2018 8:51am
12/3/2018 8:51am
Did you do the leakdown test with the piston at bdc? If its at tdc id imagine its hard for air pressure to get to the bottom end to check that...

Look man, your problem doesnt sound carb related. Sounds like an engine issue. Your intake boot could have the slightest crack or isnt sealing. Crank seals arent that time consuming. Youll end up wasting time trying to jet a carb for a motor that has an issue somewhere.
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scraprecon
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scraprecon 12/3/2018 9:04am
12/3/2018 9:04am
kb228 wrote:
Did you do the leakdown test with the piston at bdc? If its at tdc id imagine its hard for air pressure to get to the...
Did you do the leakdown test with the piston at bdc? If its at tdc id imagine its hard for air pressure to get to the bottom end to check that...

Look man, your problem doesnt sound carb related. Sounds like an engine issue. Your intake boot could have the slightest crack or isnt sealing. Crank seals arent that time consuming. Youll end up wasting time trying to jet a carb for a motor that has an issue somewhere.
Yep, at bdc. A leaking intake boot would show in an air leak test.
scraprecon
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scraprecon 12/3/2018 9:09am
12/3/2018 9:09am Edited Date/Time 12/3/2018 9:10am
scraprecon wrote:
What part of air leak test do you guys not understand? Btw, motosport doesn't sell crank seals for 7$ for my bike, closer to 14$. It's...
What part of air leak test do you guys not understand? Btw, motosport doesn't sell crank seals for 7$ for my bike, closer to 14$. It's not a cost thing, simply not going to waste my time replacing crank seals on an engine that air leak tested fine.
mattyhamz2 wrote:
Well, that's your choice. Good luck masking your issue.
Not going to listen to some idiot that says replace crank seals when it passes an air leak test. Literally makes no sense. Bye now
kb228
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kb228 12/3/2018 9:10am
12/3/2018 9:10am
kb228 wrote:
Did you do the leakdown test with the piston at bdc? If its at tdc id imagine its hard for air pressure to get to the...
Did you do the leakdown test with the piston at bdc? If its at tdc id imagine its hard for air pressure to get to the bottom end to check that...

Look man, your problem doesnt sound carb related. Sounds like an engine issue. Your intake boot could have the slightest crack or isnt sealing. Crank seals arent that time consuming. Youll end up wasting time trying to jet a carb for a motor that has an issue somewhere.
scraprecon wrote:
Yep, at bdc. A leaking intake boot would show in an air leak test.
No it wouldnt.
1
mattyhamz2 12/3/2018 9:13am
12/3/2018 9:13am
scraprecon wrote:
What part of air leak test do you guys not understand? Btw, motosport doesn't sell crank seals for 7$ for my bike, closer to 14$. It's...
What part of air leak test do you guys not understand? Btw, motosport doesn't sell crank seals for 7$ for my bike, closer to 14$. It's not a cost thing, simply not going to waste my time replacing crank seals on an engine that air leak tested fine.
mattyhamz2 wrote:
Well, that's your choice. Good luck masking your issue.
scraprecon wrote:
Not going to listen to some idiot that says replace crank seals when it passes an air leak test. Literally makes no sense. Bye now
There's more than 1 person telling you to check the crank seal. But I'm done trying to help you out. Have a good one and good luck bud
scraprecon
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scraprecon 12/3/2018 9:14am
12/3/2018 9:14am
kb228 wrote:
Did you do the leakdown test with the piston at bdc? If its at tdc id imagine its hard for air pressure to get to the...
Did you do the leakdown test with the piston at bdc? If its at tdc id imagine its hard for air pressure to get to the bottom end to check that...

Look man, your problem doesnt sound carb related. Sounds like an engine issue. Your intake boot could have the slightest crack or isnt sealing. Crank seals arent that time consuming. Youll end up wasting time trying to jet a carb for a motor that has an issue somewhere.
scraprecon wrote:
Yep, at bdc. A leaking intake boot would show in an air leak test.
kb228 wrote:
No it wouldnt.
Please explain to me why it wouldn't. It would most definitely show up in an air leak test.
scraprecon
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scraprecon 12/3/2018 9:16am
12/3/2018 9:16am
mattyhamz2 wrote:
Well, that's your choice. Good luck masking your issue.
scraprecon wrote:
Not going to listen to some idiot that says replace crank seals when it passes an air leak test. Literally makes no sense. Bye now
mattyhamz2 wrote:
There's more than 1 person telling you to check the crank seal. But I'm done trying to help you out. Have a good one and good...
There's more than 1 person telling you to check the crank seal. But I'm done trying to help you out. Have a good one and good luck bud
You're not helping me out, you're just trying to make me waste money and time. See ya later kiddo
mattyhamz2 12/3/2018 9:18am
12/3/2018 9:18am Edited Date/Time 12/3/2018 9:37am
scraprecon wrote:
Yep, at bdc. A leaking intake boot would show in an air leak test.
kb228 wrote:
No it wouldnt.
scraprecon wrote:
Please explain to me why it wouldn't. It would most definitely show up in an air leak test.
Because the reeds would stop the air from going toward the carb/airboot.....

Edit: was thinking airboot before carb. my bad
scraprecon
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scraprecon 12/3/2018 9:26am
12/3/2018 9:26am
kb228 wrote:
No it wouldnt.
scraprecon wrote:
Please explain to me why it wouldn't. It would most definitely show up in an air leak test.
mattyhamz2 wrote:
Because the reeds would stop the air from going toward the carb/airboot.....

Edit: was thinking airboot before carb. my bad
I'm putting air through the intake genius. Spark plug is still installed. Do some research before you try to give ideas. Maybe someone who has no idea about 2 strokes might actually believe you. You can leave now, you're useless.
mattyhamz2 12/3/2018 9:34am
12/3/2018 9:34am Edited Date/Time 12/3/2018 9:40am
scraprecon wrote:
Please explain to me why it wouldn't. It would most definitely show up in an air leak test.
mattyhamz2 wrote:
Because the reeds would stop the air from going toward the carb/airboot.....

Edit: was thinking airboot before carb. my bad
scraprecon wrote:
I'm putting air through the intake genius. Spark plug is still installed. Do some research before you try to give ideas. Maybe someone who has no...
I'm putting air through the intake genius. Spark plug is still installed. Do some research before you try to give ideas. Maybe someone who has no idea about 2 strokes might actually believe you. You can leave now, you're useless.
Sorry, was thinking the airbox/boot.

Maybe retry following all of these steps. Here

But look dude, you have a bunch of dudes trying to help you out and give you ideas of what to check, but since it doesn't go with what you think you blow everyone's opinion off. No need to be a dick when people with experience with these issues tries to help. Later
kb228
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kb228 12/3/2018 10:05am
12/3/2018 10:05am
Last time im going to post, because youre being a dick.

A pressure test on a 2 stroke is like 6-8 psi. I promise you the vacuum created in the engine while its running is enough to show a leak in the crank seals.
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scraprecon
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scraprecon 12/3/2018 10:22am
12/3/2018 10:22am
I'm willing to listen to yalls ideas, but everyone keeps saying crank seal but I air leak tested and they were fine. Going past the air leak test, I put propane all around the stator area while it was running, and it had zero effect. I then put propane inside of the trans vent hose. If it had an airleak, I believe it would have sucked the propane and made some kind of difference.
kb228
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kb228 12/3/2018 10:46am
12/3/2018 10:46am
Bro the ignition cover isnt a perfect seal. Its going to keep sucking air from outside before it picks up the propane. Air is lighter and thinner

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