phil_far
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| posted on 19/1/10 at 05:47 PM |
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General question about Blade carbs/fuelling
Hi,
I have two basic questions regarding the blade (893) carb engine:
1: My fuel pump (original blade pump) is wired on the ignition and should cut off upon pressure build up. However if I leave the ignition on, one
coudl still hear the pump 'tick' every let say 10 seconds when the engine is not running. Is this normal? I have replaced my needle float
valves as one of tehn was leaking. What coudl eb teh issue?
2. i have remove dteh crab vent pipes and left them open. You could see that there is fuel in them and if I insert a skewer its soaked with petrol. Is
this normal?
I have a dyno jet kit fitted as per instructions
Thanks
Philip
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BenB
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| posted on 19/1/10 at 05:53 PM |
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There shouldn't be fuel near the vent pipes. On bike carbs the breathers normally supply
the non-piston side of the diaphragm (assuming you're not talking about the float chamber drains here).
Trouble is there's no way the other side of the diaphragm should have fuel in it.
Something don't sound right.
When the pump has pressurised the fuel you'll get the pump ticking because when it stops pumping you'll get fuel refluxing back up towards
the tank. Certainly if I sit there with the ignition on but without the engine running I can hear the pump tick occasionally. Though to be fair
it's a while since I've done that because I tend to start the engine and drive off 
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phil_far
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| posted on 19/1/10 at 06:20 PM |
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I think I messed up the wording. I was actually referring to the breather (the two poking black pipes coming in between the carbs)
Philip
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Andy B
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| posted on 19/1/10 at 06:44 PM |
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The symptoms you describe are 100 percent caused by the needle valves not seating properly allowing more fuel in to the float chamber until it
overflows out of the breather pipes, usually caused by dirt under the float needle seat, as you have already tackled this it may well be crud in the
tank making its way through each time. Do you have a filter fitted if so is it before or after the pump. The reason I ask is when the pump starts to
break down small pieces of black plastic make their way down the line negating any pre pump filter. Each time you clean the carbs the problem comes
back.
Watch leaving the ignition on too long as I have seen the excess fuel build up in the cylinders and hydraulic an engine.
Remeber that it could be just one needle not seating but you could see fuel in any of the throats as the float bowls are linked
hope that helps, if you still experience problems give me a bell on 01449 736633
regards
Andy
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matt_gsxr
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| posted on 19/1/10 at 11:59 PM |
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"Andy B" knows his stuff. So his comment counts 5 times! Its forum mathematics.
In my limited experiences of bike carbs, if the fuel pump keeps ticking (when its one of the mistubishi ones) then it means you have a fuel leak.
Matt
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phil_far
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| posted on 20/1/10 at 05:55 PM |
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Andy,
Thanks for your detailed reply. My tank is brand new and its packed with foam. I do not have a filter before the pump but I do have one
after. I iwll insert a filter before the pump as I had in my previous set-up.
To further strengthen your statement, when I drain the bowls and spray in some carb cleaner the symtomps dissappear and appear a week later. I am not
using the car as I am in the registration process so I normally start it up on a weekend so that might give it enough time for dirt to settle.
Regards
Philip
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