carb. problems....

[reeseyz125]

1st,i need help, i have a 2000 yz 125 that i bought from a guy. i never got to run it like i wanted to until i moved. so after a few runs it starts bogging and shutting down, or it will bog real low and rev its self back up when i grab the clucth, and after 10 mins of sitting it will start back up ad then shut back down in another 10 minutes. so i pulled off the carb and realized that one of the hoses was plugged with a twig (overflow hose). well i took it out and put the carb. back on and ran the gas. well the gas was pouring out like water. so by a shop i was told that the float valve was either stuck or not working right. so i replaced it and did some adjustments to the floats. but im still getting the same thing with the gas coming out. what do i need to do to get that to stop?. 2nd, when i gave up on the carb. and buying new jets for it. i ended up putting the twig back in and it runs fine for twenty minutes and starts to bog again. oh yea, i went to stock on the jets. should i go smaller on the float valve and jets? and finally 3rd, it turned my air screw 2 out and my plugs are still getting fouled up about three threads up, and my mixture is 32:1.


but thanks for your time in reading all this, i just wanted to explain everything thats going on with the bike.

[MXtras]

The gas flowing out the vent tubes has to be resolved. Plugging is not a fix. There is no magic here - the float raises to a point and shuts off the flow of gas to the bowl.

It sounds like your float might be set too high. With the carb upside down, carefully bend the tang on the float pivot until the seam in the float is parallel to the bowl mounting surface. On my 99s I adjusted it a bit low - maybe 2MM lower than they suggest because I had issues with slosh.

Anyway - get your float working correctly first, then we can guide you through the potential jetting problem. With the float not working properly, there's no way to know if your jetting is off.

Also - there are two torx screws in the "roof" of the float chamber. Check these two screws for tightness. They have tendancy to come from the factory barely snug and the plate that these retain is essential to the pilot circuit.

Scott

[Ford]

Hey,

Before you start bending anything turn the fuel pidcock off at the tank. start the bike and run it for a good minute or two without burning all of the fule in the bowl, then stop it and turn the fuel pidcock on again and see if it overflows then, sometimes that helps to stop the floats from sticking. Thewn onceit is finished then take it apart and clean the carb upo and then make sure you have clean fuel for it after.

Just worked forme on my 2006 as it was doing that too!

Cheers,
Ford

[reeseyz125]

ok thanks ill try doing the overflow thing first before ill adjust it once again.

[reeseyz125]

ok so i removed the carb. and the reeds to inspect them while i was in that area of the bike. i happen to look inside to look at the piston for damage and low and behold i found a huge chunk missing from from the piston. so im guessing that this is cause of my problem with it bogging. is it? its on the back side of the piston. so im guessing that it was sucking in alot of gas and air for it to be bogging, am i right?. im open to alot of suggestions here.

thanks so much for the help......

[reeseyz125]

ok i need help once again, i redid my top end and i did the break in procedure last week, so today i took it for a ride and went through the gears. after riding in sixth gear the rear wheel locked up for a moment. i grabed the clucth before i was launched over the handle bars. but when i stopped i tried kicking it over again with nothing weird going on. its getting compression and spark. but what i noticed was some coolant leaking out the bottom. anyone know what kind of sign is this? did it over heat?. should i check the piston for damage? please help..... thanks.

[Ford]

reeseyz125,

When you took the top end off and the cylinder itself did you find the chunk of piston you seen missing when you pulled the reed valve? If not then, that would be my guess causing some damage inside the crank and thus now you have a major leak or crack that is now leaking anitfreeze. This also would be my guess for it locking up insixth gear that the chunk has seized the tranny up or something inside. My suggestion at this point would be to tear it all apartcompletely or have a technician do it for you (as they have the crank case pullers etc) and crack it all open and clean it out as that old piston piece has to be removed. Then i would inspect the cylinder for any scoring or even gouging marks as that would most likely have to be replated due to this too.
To be real honest i am afraid that because you didnt remove or find the chunk of piston that was broken off and then rebuilt the top end without making sure every piece of the broken piston had been removed, that this is going to be a real costly repair for you.

Drop the oil out of it and inspect it thourghly for parts and pieces, even strain the oil to see what is cominfgout of it would be a good start to give yourself an idea of what is going on but with what you have shared so far i am afraid you are in for a total engine rebuild.

Does anyone else have any ideas or think i am wrong (I hope i am for his sake)!

Goodluck buddy!

Ford

[MXtras]

Great points, Ford.

Scott