Gravity fed fuel

[Benjamin]

So I’ve seen some talk about changing the gt125 to a gravity fed fuel tap i.e. from a bandit. Does anyone have experience with this. What’s the pros and cons.

[♠️ M77]

Hey,

Cons

• If the tap gets faulty , it will try to force the dodgy float valves open if so much fuel  (ie. full tank)  is trying to rush through
  Then fuel flows down inlets  (wearing them down a bit) it is still a weird rubber thing but complicated to buy enmasses (hence rarity)
  Then fuel makes its way down the engine
  Then we have hydrolocking
  Then at some point, fuel constantly mixing with oil = hotter engine, soon gone crank bearings , etc…  Nothing good.
• If the tap is OK, but the float valves are fishy  = Problem above still happens

Pros

• Less pipe work. Less vacuum lines.  (Assuming a tap is a simple ON/OFF type.

For my experience with the 125cc  (mostly fixing customer ones) , there was never no need to bypass what Korea does.
– Better vacuum tap  (precaution thing / preventative maintenance)
– New fuel pump  (if customer one is bad)

The bikes do 80 indicated  (likely 72 GPS)  with everything stock ,  there is NO power gains bypassing the vacuum pump ,   the carb will drink the same amount of fuel until the floats shut up the door for fuel entry in to carbs.

I do personally think those that try to outdo Korea’s fuel system have other issues with the bike or just feeling frankeinstein or being cheap skates and the next owner is going to be annoyed at someone taking shortcuts.  It’s just my 2 pence really haha.

Carbs are Mikuni Japan = They have enough power to run a 400cc.    They are almost overkill for a 125cc but they don’t like poor jobs & like to be clean.
Pump is the SAME one used on a 650cc Hyosung (hard facts here) = So if they say bypass it  on a 125cc , their pumps are shot that’s why 😉 or they half-arsing it.

The 125cc will not exceed the capacity of the Mikuni DF52 pumps  (hell even SV650 uses the same DF pump as hyosung does) ,   both Suzuki and Hyosung use Mikuni Carbs  = You will be alright here with the 125cc Hyosung specific BDS26 carbs.

The Fuel TAP = Made in Korea ,  it works.  But can fail sometimes.  So we just upgrade them.   Fuel pumps ? = They last well.  (What kills em is E10 fuel, long standing for years or owners using chinese clones of the pumps)

I am digressing 😀

[♠️ M77]

If you have a comet that has ON/OFF tap  (Silver Frame type) = Just clean it out well as it does its job quite well.  When its OFF,  there is zero chance of hydrolocking the engine anyways

As dodgy pumps can STILL allow fuel to the carbs if the tap is left on the ON position.

If the frame is black and tap is  “Vacuum” type = Disconnect fuel hose  (safely!!!) , if it pours out while the bike is switched off  = Just replace it.

[Author]

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