Fuel Hose
- Thread starter Vince
- Start date
Or 7.
Paul
Rob
Hero member
- Location
- Midlands, UK
If you're using the usual 12x7mm fuel hose then you'd want something larger than 7mm to avoid leaks
Dellortoman
Hero member
- Location
- Tasmania, Australia
I use polypropylene fuel hose. It's available in a range of colours and stays flexible a lot longer than PVC (I suspect Cavis hose is PVC because it goes hard in no time).
Only problem is that I haven't found polypropylene hose in 7mm ID, which is about the perfect size for 8mm spigots. It's readily available in 1/4" (6mm) and 5/16" (8mm).
The 8mm size works, but you need to use nice tight hose clips to make sure it seals on the spigot.
Only problem is that I haven't found polypropylene hose in 7mm ID, which is about the perfect size for 8mm spigots. It's readily available in 1/4" (6mm) and 5/16" (8mm).
The 8mm size works, but you need to use nice tight hose clips to make sure it seals on the spigot.
Dellortoman
Hero member
- Location
- Tasmania, Australia
I discovered a limitation of polypropylene fuel hose yesterday. I hadn't ridden the Jota for a while, so I went for a short blast to blow the cobwebs out. As soon as I parked it and got off, there was smoke coming off the right side of the engine. It was fuel dribbling from the right tap and boiling off the hot engine. I quickly turned the taps off and waited for it stop looking like a potential fireball waiting for an ignition source. After a few minutes the fuel had evaporated away, and I went to investigate.
I found that the polypropylene fuel hose was cracked just at the end of the tap spigot. There was plenty of length in the hose, so I figured I'd undo the hose clamp, take the hose off, cut the damaged bit off the end and re-connect it. That plan was abandoned when I pulled the hose off the tap spigot and it fell apart in my hands (the hose, not the spigot).
Polypropylene hose doesn't go hard like the other type of clear hose (polyethylene?). The hose was still nice and supple, but it had gone as weak as wet tissue paper. It just crumbled apart in my hands.
That piece of hose has been on the bike since I fitted the Mikuni carbs in 2013, so 10 years. Oddly enough the hose on the left side seems to be relatively OK. At least it came off the tap spigot without falling apart. I'll have a closer look when I replace it in the next few days. The bike gets parked in the garage with the right side towards a window, so it gets exposed to a marginally higher light level of natural light than the left side. It's not in direct sunlight though. It's only diffuse light bouncing off the walls of the garage. And I'd have thought the window glass would filter out most of the UV anyway.
Maybe the degradation of the plastic is a combination of exposure to fuel and UV light. It might also have something to do with fuel additives I've tried over the years, including a brief flirtation with octane booster, Castrol R as an upper cylinder lube, and acetone as a surfactant (surface tension reduction agent recommended by Phil Irving to aid fuel vaporisation). Those additives were only in very low concentrations though.
Anyway, the message from this experience is for anyone who uses polypropylene fuel hoses: check their condition from time to time.
My mistake was fitting them and forgetting about them for 10 years. I'd suggest giving them a good hard tweak occasionally to make sure they're not about to fall apart. Or perhaps a safer policy would be to replace them every few years as a regular maintenance item.
I still have some of the same 10-year-old hose that I cut the fuel hoses for my bike from. It appears to be in perfectly good condition. It's still quite strong under tension while also flexible and supple. That would tend to confirm that the failure of the hose on the bike is related to the conditions it's exposed to while in use, rather than its age. I don't have any reservations about using that same hose to make new fuel lines for the bike. I just won't leave them on there for so long.
I found that the polypropylene fuel hose was cracked just at the end of the tap spigot. There was plenty of length in the hose, so I figured I'd undo the hose clamp, take the hose off, cut the damaged bit off the end and re-connect it. That plan was abandoned when I pulled the hose off the tap spigot and it fell apart in my hands (the hose, not the spigot).
Polypropylene hose doesn't go hard like the other type of clear hose (polyethylene?). The hose was still nice and supple, but it had gone as weak as wet tissue paper. It just crumbled apart in my hands.
That piece of hose has been on the bike since I fitted the Mikuni carbs in 2013, so 10 years. Oddly enough the hose on the left side seems to be relatively OK. At least it came off the tap spigot without falling apart. I'll have a closer look when I replace it in the next few days. The bike gets parked in the garage with the right side towards a window, so it gets exposed to a marginally higher light level of natural light than the left side. It's not in direct sunlight though. It's only diffuse light bouncing off the walls of the garage. And I'd have thought the window glass would filter out most of the UV anyway.
Maybe the degradation of the plastic is a combination of exposure to fuel and UV light. It might also have something to do with fuel additives I've tried over the years, including a brief flirtation with octane booster, Castrol R as an upper cylinder lube, and acetone as a surfactant (surface tension reduction agent recommended by Phil Irving to aid fuel vaporisation). Those additives were only in very low concentrations though.
Anyway, the message from this experience is for anyone who uses polypropylene fuel hoses: check their condition from time to time.
My mistake was fitting them and forgetting about them for 10 years. I'd suggest giving them a good hard tweak occasionally to make sure they're not about to fall apart. Or perhaps a safer policy would be to replace them every few years as a regular maintenance item.
I still have some of the same 10-year-old hose that I cut the fuel hoses for my bike from. It appears to be in perfectly good condition. It's still quite strong under tension while also flexible and supple. That would tend to confirm that the failure of the hose on the bike is related to the conditions it's exposed to while in use, rather than its age. I don't have any reservations about using that same hose to make new fuel lines for the bike. I just won't leave them on there for so long.
The Sock
Hero member
- Location
- London, England
Sunlight, probably the UV part, definitely degrades polypropylene.
I had an exposed white, poly drainpipe running down the corner of a north-facing, upstairs toilet which has a small, high-set window.
Trying to trace the source of occasional drops of water on the floor, i worked my way up the pipe checking joints, I came to the small section which gets morning sunshine for, maybe, three to four weeks around mid-summer. As I ran my hand up the pipe, it fell apart, like a graham cracker, only in the light-exposed section. The rest was still sound.
It'd taken nearly thirty years, to fail, and I'll be replacing it in ten to fifteen, which should, probably, see me out.
I had an exposed white, poly drainpipe running down the corner of a north-facing, upstairs toilet which has a small, high-set window.
Trying to trace the source of occasional drops of water on the floor, i worked my way up the pipe checking joints, I came to the small section which gets morning sunshine for, maybe, three to four weeks around mid-summer. As I ran my hand up the pipe, it fell apart, like a graham cracker, only in the light-exposed section. The rest was still sound.
It'd taken nearly thirty years, to fail, and I'll be replacing it in ten to fifteen, which should, probably, see me out.
piranha-bro2
Hero member
- Location
- Melbourne
For the SFQ I bought a metre of Motion Pro MP Premium Fuel Line, Clear 5/16" ID X 3'. Wasn't cheap and hoping it will stand the test of time. It was adaptable enough to fit both the Laverda fuel tap and the Keihin FCR fuel inlets that are slightly different. I like the clear finish as it allows me to see any fine crap getting past the tank filter, usually a fine 'silt' that sits in the bottom of the fuel line loop before the carbs - some residues in the tank I haven't been able to remove.
Anyone recommend a low-resistance inline fuel filter?
Anyone recommend a low-resistance inline fuel filter?
chrisk
Hero member
- Location
- Brisbane, Australia
That’s why you should dry your favourite safari suit in the shade. Sunlight kills all plastics, even polyester safari suits.
Nano plastic particles in the oceans are not solely from discarded fishing nets, but mainly from your washing machine.
Next time you want to wash your favourite back seamed stockings, put them on a gentle wash.
Nano plastic particles in the oceans are not solely from discarded fishing nets, but mainly from your washing machine.
Next time you want to wash your favourite back seamed stockings, put them on a gentle wash.
Reunited Chris
Senior member
- Location
- Sydney
Seems to me (not stocking seams, I don't have Chris' experience to call on) that rubber fuel hose would be the go here Vince, certainly remains pliable and less prone to disintergrating as plastic based hose would.
Q I like the ability to strip and clean these, but I guess you need to test if they are restrictive. I bought a couple when I first had Idle Jet blocking issues but never fitted them as the left side fuel tap came std with a spigot that pointed 90 deg to the bike's wheelbase towards the carb causing it to only fit a 40mm length of fuel line so no room to fit this filter. Today I swapped that constantly leaking tap with my spare Pantah tap with its spigot pointing to the rear allowing a longer fuel line to fit and maybe this filter as well. Off to Gowys tomorrow for a mitre of their fuel line as the old left one is now too short.
www.mxstore.com.au
Ballards Silver Alloy Fuel Filter at MXstore
Buy your Ballards Silver Alloy Fuel Filter online at MXstore. Australian owned, amazing service & fast free shipping* on over 100,000 products.
www.mxstore.com.au
I should add as their website says nothing, that filter that screws apart contains what looks like a really fine brass mesh quite dense that is the filter medium. It's a solid piece that fills the complete interior. Much more durable than those plastic see-through ones, I broke one of those once causing a big issue mid-ride to bypass it.
piranha-bro2
Hero member
- Location
- Melbourne
Look good, Vince but a tad long for my double fuel lines.
Many of the chemical stabiliser were removed from RoS banner products, in order to meet the emerging standards. Rubber products used in WC connections ( older pan styles ) went from lasting many years to around 3 years, degradation cracking a notable. There was mention of Ozone attack, in addition to UV attack being a factor. What is certain, modern synthetic rubber parts do not retain long term integrity compared to older rubber items in plumbing. Yes i dabble in plumbing, mainly replacing hotwater systems, old school copper pipe and fittings, plastic plumbing can work, specific tooling a barrier for low volume work. j.
I do.
I also need to see if particles are accumulating in the bottom of the linking tubes between the carbs.
Run of the mill looking after a bike.
Paul
hooksey
Hero member
- Location
- Vic , Australia
Undoing compression joints only requires an 8inch shifter......... tooling for pex piping........?? pair of tube cutters will cover that!
piranha-bro2
Hero member
- Location
- Melbourne
Me too Paul. Very useful my clear fuel line. I bought some Motion Pro stuff and it appears to be excellent quality. Wan't cheap.
