yz125x flooding

[Bondi Rabbit]

Just finished a rebuild but did not reco the carburettor. However have ridden it twice with no real issue's but very hard to start. After I got the bike home took it off the ute and petrol poured out of the exhaust outlet. Tried to start it and with and without choke and more petrol poured out. Havent taken it off yet. I know it has to be carb issue but what does everyone think it is , needle stuck ? float chamber sinking , . I did give it a good clean before putting the bike back together and I admit it did not idle but the bike has run perfect at the track twice , so this has confused me. Taking it off this weekend , but can I ask what should I look for and are some things obvious or hard to visually see   

[Lozza]

float valve/float level to high

[yamaico]

Float arm in upside down...

[YZ250H]

Leaking Needle and seat and/or fuel tap 

[Nathan S]

Ii agree that it sound like the float level is too high, however:
If it only happened while on the back of the ute, it's probably just the bouncing on the ute causing fuel in the float bowl to splash up into the intake and then flow into the motor.

I've seen it happen a few times - including the time I got a very distressed phone call from my mate who had just bought my GasGas off me, got it home and couldn't start it...

The solution is simple: Make sure the bike's fuel tap is turned off before you drive off.

[VMX Andrew]

Or get a new carby ?

[jimg1au]

thats not as easy as you think if the owner wants to keep it original.
1976 x had a bigger carby than the other yamaha 125s befor and after
jim
125x owner

[Charlie B]

Float arm in upside down...

Having similar issues..... Speaking to a mechanic, he claims he has also seen needle valves and seats miss matched or go in upside down (not sure how this possible, dependant on the type of needle valve I guess - there are some with dome shaped heads out the apparently...  )

Some light reading .....http://www.thumpertalk.com/topic/347305-is-your-two-stroke-running-rich-read-here/

Please share the fix if you find one..... Thanks

[RD]

Check that the bowl vent isnt blocked.

[80-85 husky]

make sure it isn't pointing at anything valuable when you get it going as the fuel in the pipe sprays everywhere and is loaded with all the gunk in the pipe!!! very exciting!


sounds like a high float level(they creep up over time) coupled with a leaking or left on fuel tap and a ride in the back of a ute...dogs stick their tongue's out, bikes just pump fuel into the engine..... as the floats go up and down...

if it pisses out when stationary or floods everything while sitting, its a carb problem...if its only travel related, fix the fuel tap...

[Bondi Rabbit]

thanks for all of this, I will be exploring these suggestions tomorrow, and hope for a result

[Charlie B]

** UPDATE **

I was having similar issues with a KX, fuel pouring out of the exhaust pipe. 

Cleaned carbie for a third time (just to bre sure there was no rubbish under the float needle and seat, adjusted float level - all fixed.

Not sure how float levels change, I always assumed it was a set and forget arrangment.  I understand thermal tempts and the effect of fuel volumes (hot days fuel expands / cold days fuel contracts) but didn't imagine it would make such a difference. Anyway made an adjustment to the float needle tab, which resulted in float levels coming down 4mm and problem gone.

Tip:  Make changes gradually, too big a change in float levels can starve the bike of fuel when running fuel throttle if the float levels are set too low.  Should this happen in means the bike is using fuel faster than it is flowing into the carburetor.

Hope this helps some chasing the same frustrating issue....

[Bondi Rabbit]

Well ,
I flushed and cleaned carb twice. adjusted the air intake screw to factory setting.  all levels seemed fine  Did not see any obvious issues. Still did it. I then took the fuel line off and kept kicking till it pumped though and it got started. Ran the motor till no more fuel in the carb then pumped air into the fuel intake. Placed fuel line back in started first kick and idled perfect. Though it may have been that it was not hot so easy start. Left it overnight started first kick and no sign of issue. Wont be working on it for a another week as the bike lives at the in laws . So will be interesting to see what happens. COuld I have cleared some dirt out when running it dry ?
 

[80-85 husky]

I had this issue with a bike I sorted for a mate. long time no go. fuel went everywhere on first attempt. turned fuel off and cleaned up, tapped carb with a screwdriver in case floats were stuck. fuel on.. more overflowing! turned it off and it stopped. got the bike started and turned the fuel on and its been fine ever since. I think the needle and seat were gummed up and it took a while for the fresh fuel to dissolve the goo.

[Charlie B]

Well ,
I flushed and cleaned carb twice. adjusted the air intake screw to factory setting.  all levels seemed fine  Did not see any obvious issues. Still did it. I then took the fuel line off and kept kicking till it pumped though and it got started. Ran the motor till no more fuel in the carb then pumped air into the fuel intake. Placed fuel line back in started first kick and idled perfect. Though it may have been that it was not hot so easy start. Left it overnight started first kick and no sign of issue. Wont be working on it for a another week as the bike lives at the in laws . So will be interesting to see what happens. COuld I have cleared some dirt out when running it dry ?

Running it dry may have dislodged any foreign bodies or new fuel has dissolved the goo as suggested on the previous post.  Another possibility may be ( as I suspect was my case) having so much fuel in the exhaust that it could take a while to push through the excess.... Either way sounds like its working for you....good news.