UK Monster Owners Club Forum » .: Technical :. » Mods & How To's » Keihin 41mm carbs

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Old 18-04-2019, 07:56 AM   #16
Kato
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If you are keeping the standard fuel delivery vac pump and associated gubbins you'll not need a fuel tap.

If using an electric pump and ditching all the Vac stuff then you'll need some kind of tap, the FCR's are temperamental beasts and have a habit of draining your fuel tank into your crankcase if left standing fuel tap will sort the problem
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Old 18-04-2019, 08:05 AM   #17
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In light of tales of woe regarding emptying the contents of the tank through the carbs, I fitted an electric fuel shut off valve that opens when ignition is on, in conjunction with the (electric) fuel pump.

I have an injection model tank using an electric pump that pumps a loop from/back to the tank with a take off for the carbs, the valve is after the take-off point.
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Old 18-04-2019, 09:09 AM   #18
350TSS
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I guess it could be down to something like ... the carbs are so high on a monster that there is very little pressure head acting on the floatbowls and hence the float valves may be more prone to leaking ....?
Though why FCRs should be more susceptible than the std carbs I can't imagine.


I suspect that the height of the float bowls vs the position of the fuel outflow on the tank is not the reason.
The pressure to close the needle valve is from the flotation of the float bowls and that should be a constant as the volume of the float bowls and the "floatieness" of the the floats does not change
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Old 18-04-2019, 02:12 PM   #19
utopia
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Yes, I agree with that reasoning.
But on the other hand, the fuel must be getting past the float valves somehow.
Of course float valves do fail sometimes but that wouldn't explain why FCRs are problematic and the std carbs aren't.
So I was pondering the situation when the fuel level in the tank is low enough to only just fill the bowls under gravity.
And also wondering whether the bike being tipped over on the sidestand would make any difference (stiction in the float pivot perhaps) when combined with a fuel level which was "on the cusp".
Clutching at straws I agree, but there has to be an explanation somewhere and if it isn't the obvious stuff then you have to look elsewhere.
Tbh I knew that I was on dodgy ground with my earlier statement but I was hoping to provoke a discussion which may ultimately tease out the elusive answer.
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Old 18-04-2019, 10:08 PM   #20
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After reading this it peaked my interest in FCRs on the Monster as I know nothing about them. After a quick Google I found this on DucatiTech website which has some interesting info on the FCR kits, buying them second hand, peoples reaction to fitting them, fitting them and setting them up:

http://www.ducatitech.com/2v/fcr_faq.html

You may have already seen it but for anyone else in the same place as me it was useful.
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Old 15-06-2019, 05:26 PM   #21
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Talking Flatties

I"ve got 36mm on mine,Arrow cans,performance? cone filters and no fuel tap-3 pumps first thing in the morning(down to minus 4-5 degrees) hit the button let her warm up while I suck down a Benny and then away.No glitches or hiccups and in traffic she gets a tad warm and if stuck she"ll get so hot you can"t get near her but still ticks over without missing a beat and then will pull to the redline without a glitch.Nearly forgot I only use Shell V-Power.;
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