I have a 78 xs400. I recently replaced the float, needle and seat, gaskets. I adjusted the floats to the specs(1.25in) and the inlet carb overflows with fuel. Ive tried to adjust the tang on the float but the difference in measurement means no fuel in the bowl or it just overflows. I have no idea why but its pissing me off. It floods the cylinder bad enough that the plug wont fire. I would appreciate any help on this issue.

Doug

I have a 78 xs400. I recently replaced the float, needle and seat, gaskets. I adjusted the floats to the specs(1.25in) and the inlet carb overflows with fuel. Ive tried to adjust the tang on the float but the difference in measurement means no fuel in the bowl or it just overflows. I have no idea why but its pissing me off. It floods the cylinder bad enough that the plug wont fire. I would appreciate any help on this issue.

Doug

Hi Doug

Just wondering where the 1.25 inches is measured ? without looking it up I would guess the float height to be in the reigon of 25mm to 35mm, which is somewhat smaller than 1.25 inches, perhpas this has a bareing on your problem ?

Regards Jim

Hi Doug

Just wondering where the 1.25 inches is measured ? without looking it up I would guess the float height to be in the reigon of 25mm to 35mm, which is somewhat smaller than 1.25 inches, perhpas this has a bareing on your problem ?

Regards Jim

Jim, 1.25 inches is around 31.5mm

Jim, 1.25 inches is around 31.5mm

correct conversions in my head are not a strong point but I done some research & the float height (for UK) was 26mm an most modals but again banging around the net found 1 variant at 35mm. The XS400's I worked on that had this problem tended to be a duff float or ( again the memory is failing me now ,I'm old, may have this mixed up with the 250) the brass tube in the float bowl slightly bent, impeading float movement. If I'm on your xmas list can I have an imperial to metric convertor please

Regards Jim

If I'm on your xmas list can I have an imperial to metric convertor please

Regards Jim

I'll put money on it, you have one already...a tape measure.

I'll put money on it, you have one already...a tape measure.

funny enuff I've just ordered a digital vernier guage which at the press of a button will do the conversion, but I dont have it yet .... just thought you may want to pay for it !!!

the measurment is taken on fuel shut off, not floats resting.

also check theat they are not twisted making measurment inaccurate.

BTW i have to use a torque converter programme as I have a newtonmetre torque wrench and the settings are in LBS inch.

are the gaskets for the needle seats good? are the seats tightened down enough?

i had this problem when i picked my bike up. probably why i got it so cheap.

make sure the float needles and seats are not worn.

any luck?