Page 1 of 2
Fuel tap mod - does my bike have it or not?
Posted: Mon Dec 07, 2009 1:53 pm
by Snap
With the tank off, if the fuel tap has been switched on, should the fuel come out on its own if the fuel tap mod has been done?
I havent tried it yet but i wanted to know what to expect.
Thanks.
Re: Fuel tap mod - does my bike have it or not?
Posted: Mon Dec 07, 2009 2:16 pm
by CMSMJ1
yes..

Re: Fuel tap mod - does my bike have it or not?
Posted: Mon Dec 07, 2009 2:23 pm
by ibby4585
forgive the ignorance whats fuel tap mod? ive got mine apart at the moment ready for the tank to be blasted!
Re: Fuel tap mod - does my bike have it or not?
Posted: Mon Dec 07, 2009 2:27 pm
by CMSMJ1
The removal oof the diaphragm to make the tap "always on"
Commonly called the HRC tap mod...so lots of people do it and have problems..lol
not the best thing to do unless you have absolute confidence that your carbs won't have a leaky float valve and allow fuel into the cylinders. When you try to start it you can get hydraulic lock...and bend conrods etc...
Not recommended unless you are racing and suffer from fuel starvation
Re: Fuel tap mod - does my bike have it or not?
Posted: Mon Dec 07, 2009 2:35 pm
by ibby4585
ahh i see, ok ta Kris
Re: Fuel tap mod - does my bike have it or not?
Posted: Mon Dec 07, 2009 2:38 pm
by Neosophist
Yep!
As been said, it's known as the 'HRC' mod as it's detailed in the HRC book, many people think.. oooh HRC must be good and do it to their bikes when it isn't necessary.
As you are aware the VFR uses a vaccumn operated fuel tap, even if it's set to on, fuel won't flow until the engine is cranked over, this suck opens a rubber diaphram that lets fuel flow.
On the tuned HRC bikes, at WOT during racing this diaphram, even though open still restricts fuel flow slightly, this restricion is enough to starve the carbs of fuel so they removed it.
Not really recommended for road bikes. Racing bikes that suffer from fuel starvation then yes! These usually have the fuel drained from them after racing anyway so it isn't a problem.
If you do it and your carbs leak you'll fill the cylinders / oil with petrol, can result in broken engine

Re: Fuel tap mod - does my bike have it or not?
Posted: Mon Dec 07, 2009 2:40 pm
by ibby4585
nah wont be doing that. cmsmj1 did you have any pics of the exhaust??

Re: Fuel tap mod - does my bike have it or not?
Posted: Mon Dec 07, 2009 2:55 pm
by CMSMJ1
ibby4585 wrote:nah wont be doing that. cmsmj1 did you have any pics of the exhaust??

lol..am at my sisters house...my moto is at mine and I cannot get my laptop on their cack talktalk connection
I do have a ti stack in a box in the boot though

Re: Fuel tap mod - does my bike have it or not?
Posted: Mon Dec 07, 2009 4:17 pm
by ibby4585
how much!!

no worries i will be patient!!
Re: Fuel tap mod - does my bike have it or not?
Posted: Mon Dec 07, 2009 6:48 pm
by duncan
If fuel is leaking past the carbs into the cylinders then the fact that the tap is off will not make a lot of difference to the outcome because of the volume of fuel available in the wide diameter pipe between tap and carbs