Fuel tap question GT550

[Scott]

Hello

I have a 1975 GT550 that has a leaking fuel tap. I left the bike sitting after trying to start it for the first time and after a day the garage smelt of fuel and there was a stain on the floor. I removed and drained the tank, but now I need to fix the cause.

Questions are what position should I leave the fuel tap in and do you folk lean towards putting new seals into this original tap or do you go for a conversion that I say on ebay where it looked like you bolt on an aluminium plate to the tank which a new manual fuel tap screws into.

Thanks for your time and thoughts
Scott

[GTandcbr]

There are three positions for the fuel tap. Up is 'on' middle is 'reserve' and down is 'prime' The fuel tap uses a small vacuum from the middle carb to pull back a diaphragm when the engine is running and fuel flows. Stop the engine the diaphragm goes back stopping the fuel flow. If you leave the tap on 'prime' this bypasses the diaphragm and fuel flows regardless. This usually causes the crankcase to fill with petrol so only use 'prime' after servicing the carbs or the bike has been left for some time. You can successfully service the tap have a look here for help
https://youtu.be/qWNyvjaWfz8" onclick="window.open(this.href);return false;
Cant comment on tap modification someone else may be able to help.
Good luck!

[Scott]

Thanks for that. I just clicked on that link and later on I will watch the video completely.

I also just looked at my fuel tap and I had left it in the Prime position. Mmm should have maybe checked how to use the fuel tap before I used the fuel tap.

Scott

[tz375]

Over time the seals harden and the diaphragm fails to keep it closed. There are re4pair kits which work with spotty results, or buy a new NOS tap or find one from a more modern bike that fits. I got one cheap a few years ago for my 750 off ebay. I want to say it was for a GS750 or 1000 or maybe it was an early GSXR750. Many share the same spacing and filter arrangement.

[Craig380]

As GT&cbr mentioned, before you go any further, I'd remove the spark plugs and turn the engine over gently by hand using the kickstarter, just to make sure the cases haven't filled up with fuel ... you don't want to hydraulic-lock the motor. That way lies bent conrods.

If the carb floatbowls are full, the fuel will usually overflow out of the floatbowl breather tubes. But it can flow into the engine too.