Fuel Taps/Solenoids

DaveB

DaveB

Full member
Location
Modbury North down the hill(s) from Legs
Given some of the scary photos and stories of big Laverdas getting a stuck fuel float and hydraulic locking the engine, with resultant bent rods, anyone here running fuel cutoff solenoids to reduce the chance of this happening. I know a chunk of grit can stick a solenoid as well, but it’s a double redundancy when you have float valves as well.

My Guzzi 1100 Sport has solenoid taps, so asking what Laverda owners do?

Yeah/Nah/Maybe????? Thoughts?
 
Not tried solenoid valves, but it sounds like a good idea if you're not in the habit of switching taps on and off. I guess no system is 100% reliable, but a solenoid valve is way more reliable than a forgetful human.

Ideally you'd want a bypass system so that if the solenoid fails you can still get home without having to fart about rearranging fuel lines.

I reckon the simplest arrangement is a solenoid valve on one side and a manual tap on the other, with both feeding into a manifold for all the carbs. You'd leave the manual tap off for most of the time, leaving the solenoid tap to do all the work of switching on and off as required. You'd only need to use the manual tap if you need to prime the carbs without switching the ignition on, or use the reserve capacity. That assumes you get enough flow through the solenoid valve to run the engine at maximum fuel demand.

I've had vacuum operated fuel taps arranged as above (vac tap on one side, manual tap on the other). They work OK for a while until the diaphragm eventually fails. The last one I had (on a bevel Ducati) buggered up only about a year ago after 35 years of reliable service, so it had done OK. I replaced with a manual fuel tap.

These days I just rely on the habit of turning taps off. Oddly enough I don't tend to get confused when riding one of my fuel injected bikes that don't have taps. I guess it's like changing from left to right gear shift. There's a switch in your brain that deals with the different setups.
 
We have a man in our club who takes photos of those bikes he finds with the taps on and puts them in ride reports. He is very good at this job and has created solid habits in those that know him. We are happy to comply as the alternative is BLOODY EXPENSIVE. Thank you that man.
 
After reading the horror stories on here, I’ve become a very good boy with turning off the taps.
Not so good at remembering to turn the bloody things back on. But I suppose that’s the lesser of two evils...
 
Either something has changed with the intro of unleaded that makes float valves a lot more dodgy than they ever were or I've just been lucky over the 30 years I used my SF constantly. Never ever turned off the fuel taps unless i was taking the tank off and only ever had the dreaded leakdown once - a cylinder would (partly) fill, caused by me fitting the float valve seat without the fibre washer under it. It just used to block on the starter and I'd remove the plug and spray the raw fuel out.

Definitely not saying that dire things can't happen, but only that I musta have been very lucky - cos other than that series of episodes i've never once had an issue.
 
piranha-bro2 said:
Either something has changed with the intro of unleaded that makes float valves a lot more dodgy than they ever were or I've just been lucky over the 30 years I used my SF constantly. Never ever turned off the fuel taps unless i was taking the tank off and only ever had the dreaded leakdown once - a cylinder would (partly) fill, caused by me fitting the float valve seat without the fibre washer under it. It just used to block on the starter and I'd remove the plug and spray the raw fuel out.

Definitely not saying that dire things can't happen, but only that I musta have been very lucky - cos other than that series of episodes i've never once had an issue.
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Same experience for me.
I recall solenoid fuel taps from the '70s were unreliable and often swapped out. Maybe better today.
 
they might cause an issue with the fuel flow rate, which is - at high revs and with tuned engines - anyway a bit on the low side...

aside of that, I feel it is a solution looking for a problem. I learned early (basically when I bought my first Laverda) from my brother never ever ever to leave the bike even for a minute with the fuel tabs on. I even developed the habit of turning them off roughly 500 meters before I reach home. This gives fresh fuel into the float bowls every time you start the bike. Turning them on before turning the key is deep in my DNA now, never left them open, not even if I refuel the bike at a gas station.
 
Laverdalothar said:
they might cause an issue with the fuel flow rate, which is - at high revs and with tuned engines - anyway a bit on the low side...

aside of that, I feel it is a solution looking for a problem. I learned early (basically when I bought my first Laverda) from my brother never ever ever to leave the bike even for a minute with the fuel tabs on. I even developed the habit of turning them off roughly 500 meters before I reach home. This gives fresh fuel into the float bowls every time you start the bike. Turning them on before turning the key is deep in my DNA now, never left them open, not even if I refuel the bike at a gas station.
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+1, once bitten twice shy as they say.
Regards Andy 😁
 
Laverdalothar said:
they might cause an issue with the fuel flow rate, which is - at high revs and with tuned engines - anyway a bit on the low side...

aside of that, I feel it is a solution looking for a problem. I learned early (basically when I bought my first Laverda) from my brother never ever ever to leave the bike even for a minute with the fuel tabs on. I even developed the habit of turning them off roughly 500 meters before I reach home. This gives fresh fuel into the float bowls every time you start the bike. Turning them on before turning the key is deep in my DNA now, never left them open, not even if I refuel the bike at a gas station.
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Yeah me too Lothar, never ever leave the taps turned on. A couple of corners from my house I shut the taps off, took a bit of practice to get it just right but now the bike runs out of fuel when I hit the driveway.
:)
 
DaveB said:
I like that idea - it’s a habit independent of which bike you’re on...
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If I do develop the habit of turning off taps, I like the 'before you arrive home' method, as stale fuel after a bike sits for a while is a pain in the arse, requiring excessive use of choke at first startup until the fresh fuel flows through - also leaves the carbs dry to avoid varnish developing.

Out of interest, for those of you who rode your Laverdas when they were reasonably new (eg in the 70s) were you aware of this issue and did you also back then religiously turn off your fuel taps?
 
I was taught, when I first had anything to do with engines, aged six, that any gravity-fed fuel system must be turned off after use. I've seen the effects of fuel hydraulic locking: broken con-rods and massive engine damage and don't understand why anyone would risk it.
Like Lothar and Dave B, I turn mine off before I get home, aiming to have it shut down from fuel starvation on the drive. The empty fuel lines also serve as a check before restarting that the taps are shutting off correctly.
 

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Out of interest, for those of you who rode your Laverdas when they were reasonably new (eg in the 70s) were you aware of this issue and did you also back then religiously turn off your fuel taps?


Nope!!!
 
using only one tap through a solenoid valve or a manual type would result in fuel starvation at thrashing it levels, it happens with two taps open if you are nearing the reserve point, so one tap? I don't think so, when I was racing I used a tank modified with three taps, never had a fuel starvation issue even when using the old (= very long straight) circuit at Snetterton in Norfolk and I was geared for max revs about three quarters of the way down, even sometimes needing to (attempt) at backing off to preserve the reving its balls out motor, not that brill on that straight, but compensated for by being bang on everywhere else, top speed is not the be all and end all, getting out of thew cormners, fast or slow ones definately is! but why solenoids? they will introduce reliability issues, manual pet cocks? I never turn mine off until stopped, I forget on occasions, usualy quickly reminded that I am an idiot by onlookers (I know about the idiot bit thanks) and anyway the floats should hold the fuel, if they dont, the motor may well even run badly or thirstily, but yes, still turn them off.
CLEM
 
Ernesto said:
I heard that, if you park your bike on OCT's patio with taps open,
you immediately get told off by Roger.
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true. And you get a loooooot of stories of what can happen... :eek: :geek: You feel so bad afterwards (just like a nasty little boy having dropped mum's best porcelain vase, you will never forget - believe me...
 
motoddrob said:
Out of interest, for those of you who rode your Laverdas when they were reasonably new (eg in the 70s) were you aware of this issue and did you also back then religiously turn off your fuel taps?


Nope!!!
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Rob, I am surprised you didn't I always have I thought all Laverda owners and other bike owners did this I remember looking at a bent conrod (at John Paul Benelli shop)the result of the dreaded fuel tap flow. That was back when I had a 2 stroke Suzuki, took to the habit right there and then .:eek:o_O
 
Just to jump on this post for help. I always used to turn taps off. Except – recently – when I may have left it on reserve rather than off, oh, for about 3 months. My 'excuse' is I've hardly seen the bike in 5 years and 'may' have forgot which damned way they go. Stored while travelling then Keith did some significant work on the bike in September (thanks Keith), before I rode it to France. A few rides before the snow here, then it was driven underground in perfect nick.

Odyssey was low and drained very quickly when I first tried to start it a few days ago (very cold winter). Charged it and it turns better, but no joy. Need to find someone to test it properly as first step... still suspect it's the culprit.

If not, just wondering what the effect of leaving taps on really is, and the cure? Can't find a description on the forum. Once I know the battery is ok, fresh fuel, fresh plugs (although only done 1500 miles) were my next thought. Excuse the lack of mechanical nous – I've had it as long as the bike, but I scrape by.
 
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