I have a DT75 fuel leaks out the overflow when running and even when priming bulb is pushed, rpms wont go above 2000 when in drive and 3rd cylinder not sucking air like the other 2, I have cleaned carbys and replaced fuel lines, any suggestions!
tonyrockyhorror,
Dec 22, 12:45am
The float valve is leaking.
tonyrockyhorror,
Dec 22, 12:46am
Oh, and it's not an overflow. It's a breather,
You need to test compressions too. That will tell you #3 is down unless you have a massive vacuum leak.
sandyelmo,
Dec 22, 1:04am
Just done compression test and they are all the same, apart from rubbish under the needle what else could cause float valve to leak, no holes in it and it sits level to gasket when i hold it upside down,
tonyrockyhorror,
Dec 22, 1:12am
A leaking float.
You don't check float levels by hanging the carb upside down. You check it with the needle just seated and the float hanging below the pivot pin.
tonyrockyhorror,
Dec 22, 1:14am
But my money is with the leaking float valve. It doesn't just need rubbish to cause a leak. Wear will also allow them to leak.
sandyelmo,
Dec 22, 1:23am
Ok thanks I will remove carby again tomorrow and check float level again, i have replaced needle and seat, sorry about the weird terminology I'm not a mechanic just a female that enjoys working with motors
tonyrockyhorror,
Dec 22, 1:31am
Does your Dad own a brewery! You could be the perfect woman!
But seriously, which carb is leaking out the vent!
sandyelmo,
Dec 22, 1:34am
The bottom carb, I persume its #3 not #1
tonyrockyhorror,
Dec 22, 1:42am
Yeah, #1 is the one closest to the timing marks on the flywheel which is the top.
tonyrockyhorror,
Dec 22, 1:43am
So the same one that's not drawing vacuum.
I'd say the over fuelling has also fouled the spark plug.
sandyelmo,
Dec 22, 1:49am
Yeah same one, i am still getting spark just not as strong as #1 & #2, when i took the air cover off the front and pumped the primer bulb it had fuel pissing out the front of the carby, so it getting fuel but not burning for some reason! Its got me stuffed.
tonyrockyhorror,
Dec 22, 4:09am
Because the fuel is gushing out the float valve must be letting fuel past when it shouldn't because that valve is meant to prevent the entry of more fuel into the bowl when the float rises and closes the valve at the correct fuel bowl level. The fuel you're seeing is making its way up the main jet and into the carb venturi when you squeeze the primer bulb because the float valve is not shutting off.
It's either maladjusted (bend the float tang to correct and make the valve close earlier as it rises on the fuel) or the seat and/or float needle is worn.
klrider,
Dec 22, 12:38pm
Buy a Yamaha, quickly
mm12345,
Jul 2, 1:45pm
A 25 year old one will be better!
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