Author Topic: lots of fuel in the crank case  (Read 453 times)

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Offline kiwiandy

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lots of fuel in the crank case
« on: January 07, 2018, 03:52:07 PM »
Whats the cause of lots of fuel in the crank case?.... needle valve?

Bought a YZ125N that was proving tricky to start. First time I turned gas on and started it was good.

Next time I tried it was getting way too much fuel and flooding... but a lot of pushing got it started.
Replaced the fuel tap as it didnt seem to be working too gold and was very wobbly.
Put a new plug in and noticed when I kicked it that there was fuel oozing/bubbling/seeping out around the base of the plug when I kicked.
Assumed the needle valve in the carb was playing up, so took the carb off and gave it a good clean. Needle valve/seat seemed to be working ok, float heights seemed ok
Put it back on, and kicked it over without the plug in, noticed lots of fuel still blowing out the plug hole.
Tipped the bike upside down, and hand cranked the starter, and lots of fuel came out!

Not sure why I have so much fuel in the crank?
My present repetoire: YZ250A, YZ250B, TY250B, YZ125X, IT175J, DT175G, TT500E, TT500G, HL500, YZ465G, IT465H, YZ250K, YZ250N, YZ125N, 2 x IT200N, PW50, YZ250FX H,  and lots of other non YamaBikes..

Offline kiwiandy

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Re: lots of fuel in the crank case
« Reply #1 on: January 13, 2018, 11:22:40 AM »
No thoughts from anyone?
My present repetoire: YZ250A, YZ250B, TY250B, YZ125X, IT175J, DT175G, TT500E, TT500G, HL500, YZ465G, IT465H, YZ250K, YZ250N, YZ125N, 2 x IT200N, PW50, YZ250FX H,  and lots of other non YamaBikes..

Offline sweede490

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Re: lots of fuel in the crank case
« Reply #2 on: January 13, 2018, 11:35:35 AM »

 Hey Andy , it’s usually from the float valve stuck open , it’s not uncommon if a bike is parked up

      With the fuel tap left on or a leaking one , that’s why most drain the fuel after riding

     If you’ve cleaned the carb and make sure the fuel tap is ok technically it should be fine




  Muzz
Jack Burn Yamaha   IT490L     IT490L     Desert sled

Offline storie585

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Re: lots of fuel in the crank case
« Reply #3 on: January 15, 2018, 08:16:24 AM »
Mine did the same thing. Filled the pipe even. I changed the needle & seat. They wear funny and stick open... fixed..
Dave

Offline kiwiandy

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Re: lots of fuel in the crank case
« Reply #4 on: January 15, 2018, 06:17:56 PM »
Thanks Muzz, yeah I already changed the fuel tap, I am in the habit of turning off the fuel and running the engine until it starves to empty the float bowl. so hope that helps now that the fuel tap is fixed.

think Ill take Daves advice and replace the needle and seat anyway... thats all I can think of.
My present repetoire: YZ250A, YZ250B, TY250B, YZ125X, IT175J, DT175G, TT500E, TT500G, HL500, YZ465G, IT465H, YZ250K, YZ250N, YZ125N, 2 x IT200N, PW50, YZ250FX H,  and lots of other non YamaBikes..