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I wont give up!!!! with a little help


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2005 yz 125

Sea Level (home), 2000-4000ft where i ride

Main 400

Pilot 37.5

Needle 6CHY5-80

Clip: 4th position

Air Screw: 1.75 turns

Problem: Used to run fine, but now it wont (home or at the riding area). Starts up normal, crisp, idle... Once warmed up it'll start bogging at half throttle. (which means it's running rich some where) It never did this before even after the new top end. Look at the spark plug and it's wet (again it's running rich). It doesnt even run long enough for me to take a test run. Dies while warming up.

False fix:

Took carb apart and cleaned it well. Still same thing.

Changed plugs (i've tried ### different types of plugs. BR9EG, BR9ES, BR8EV, BR8ES, BR8EG etc etc)

Changed

Main: 400 -> 410

Pilot: Same

Needle: same

Clip position: 4th -> 3rd position

Air Screw: 2.5

I drove 2 hours yesterday to go ride only to find out my bike is on strike!

🙂🤣

From what i can see... the jetting is not significantly off enough for the bike to die like this. Reeds are fine... Air filter is clean but has been sitting for a bit. Not enough to restrict that much air flow ( will try fresh one and see)

The only other thing i can see is the Tranny oil leaking into the cylinder, but the bottom end is dry and no signs of oil leakage. how else can i check?

I reach out to you professionals and Carb gurus to please... lend me some advice! This is my 2nd two stroke (first one was nothing but headache and it NEVER run right even from the factory.) I've been stranded out in the desert numerous times from the bikes fouling. :banana:

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Your correct in that even with your jetting it shouldn't die or bog horribly at mid throttle. Top end is in good condition and your pv is operating correctly?

At 3000ft average riding you should be able to do:

410m

clip 3

35p

AS at about 1.5T out

BR8 plug

This should run rather well and if it doesn't I'd look for other problems. Could be issues with a seal on either side...doubt it's your floats if it changes based of temp of bike.

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thanks for the help

the top end is fairly new, and the power valve should be fine... i cleaned it out when i did the top end awhile back.

which seals are you referring to?

Your correct in that even with your jetting it shouldn't die or bog horribly at mid throttle. Top end is in good condition and your pv is operating correctly?

At 3000ft average riding you should be able to do:

410m

clip 3

35p

AS at about 1.5T out

BR8 plug

This should run rather well and if it doesn't I'd look for other problems. Could be issues with a seal on either side...doubt it's your floats if it changes based of temp of bike.

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which seals are you referring to?

Crank seals on left and right side

Bad right side seal will start pulling in transmission oil. It'll act rich, wet plug, smoking more than normal, etc.

Left side will pull in air and start to act lean.

Simple testing on right side would be loss of transmission oil. For right side if you spray something like carb cleaner on it while the bike is at idle, the rpm should increase.

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Thanks Kan!!!

I sure hope i dont need to split the cases to replace the crank seal!

[

Bad right side seal will start pulling in transmission oil. It'll act rich, wet plug, smoking more than normal, etc.

Left side will pull in air and start to act lean.

Simple testing on right side would be loss of transmission oil. For right side if you spray something like carb cleaner on it while the bike is at idle, the rpm should increase.

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I've never had cracked or chipped reeds but I've had reeds that weren't sealing correctly. It caused a low end sputter in the 1/8-1/4 throttle range that felt like the bike was very rich. For reeds, you shouldn't be able to see any light through the sealing surface. If you can get to the point where you can slip a playing card between the surface and the reed it is definitely replacement time.

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  • 1 month later...

I ripped the bike a part and changed the seal... ripped the carb a part and soaked it in carb cleaner, cleaned all jets. STILL the same problem! ***!!!

Took forever to start this time and bogged out the first 2 times. 3rd time it started up nice and bogged out after 5 seconds. Changed spark plug and it fired up with 5-6 kicks, crisp throttle for 4-5 seconds and bogs out and dies. whats going on here?!?!?!

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I honestly dont think it would be a carb issue... I soaked the carb in cleaner over night and made sure all the holes werent clogged.

fuel tank vent working? muffler plugged up or core broken?

The vent is working... I blew into it and air goes through. also tried with the gas cap open. Muffler I will check. Whats a broken core???

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what should i be checking for in the sparkplug cap? I swapped ignition coils so it cant be that.

not the muffler because i started it up without the muffler.

i'm thinking it's the float bowl... this is such a PITA!!! you guys are a huge help! thanks! i appreciate it

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make sure your carb. vent lines are not pluged up with dirt

just checked.. they're clean.

Some are saying i could have sucked the head gasket. there is a bit of fluid in the cylinder.

compression is at 140-145 still a bit low from 180, but better than 120.

Piston seems to be ok, but when i crank the bike slowly i can see bubbles from some liquid on the sides of cylinder(i've attached video) 8 o clock and 4 o clock position. Look closely and there are some "Bubbbbleeessss".

i was thinking maybe coolant leak, but my coolant level is the same.

http://www.facebook.com/video/video.php?v=10150255442050113

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