Carby Gas leaking where fitting attaches to carb

Discussion in '2-Stroke Engines' started by gearhead222, Dec 5, 2010.

  1. gearhead222

    gearhead222 Member

    Dear Fellow Motorheads-I tired Teflon tape and it's a no go. The fibre washer with the nipple is shot. Should I try a small amount of Hondabond and toss the fiber washer? This leak is so bad that the bike was empty when I went to ride her!. Thanx for any feedback:)-Gearhead222

  2. AussieSteve

    AussieSteve Active Member

    You should be able to get fibre washers from an auto accessory store.
    Either way, it's good practice to turn off the fuel tap on 2-strokes when the engine is not running, otherwise it's possible for the crankcase to fill with fuel if the needle/seat is leaking.
  3. gearhead222

    gearhead222 Member

    Thanx Stevo! I researched this and discovered that a rubber O-ring might work. Used Teflon Tape and the rubber O-ring and it's not leaking!:)-Gearhead
  4. AussieSteve

    AussieSteve Active Member

    Good one. Just keep an eye on the 'O' ring. Some types swell and distort when in constant contact with fuel.
  5. HeadSmess

    HeadSmess Well-Known Member

    it shouldnt be leaking anyways...

    if the fuel level in the bowl is correct, it sits about 5-10mm clear of the fuel... fuel goes through the hole in the centre...

    me says look closer...
  6. gearhead222

    gearhead222 Member

    Thanx Head! I adjusted the float level once- a real PITA!-Gearhead
  7. motorpsycho

    motorpsycho Active Member

    you are 100% correct, if it is leaking, i would look for a crack in the carb where the fitting threads into it.(as long as the float level is set right.)
  8. Turtle Tedd

    Turtle Tedd Member

    Switch the gastank petcock off before you get to the house..motor should be starving for gas just as your getting off
  9. HeadSmess

    HeadSmess Well-Known Member

    i did this once and ended up with a 10km ride with most of it uphill...with half a cup of fuel for assistance...
  10. AussieSteve

    AussieSteve Active Member

    Try turning it off when you're almost home, as Tedd meant, instead of 10km from home.
    What did you expect???

    Personally, I agree with Tedd - NEVER leave the fuel petcock 'on' while the bike is parked.
    As I mentioned earlier, if the needle and seat leaks the crankcase can fill with fuel, not desirable.
    This is separate to the actual problem.
    All the talk about float level and so on means nothing in this situation. There's a reason there's a fibre washer originally fitted to the carb's fuel inlet tube. Regardless of float level, if there isn't a fibre washer fitted, fuel will leak. The fuel doesn't sit obediently at the float level all of the time. It is splashed and shaken around as you ride, and will cover the base of the inlet tube during (RH) cornering. I've had that leak in the past, on a few carbs, on a few different types of bike, (not MBs). The float level was set correctly in all cases.
    Last edited: Dec 9, 2010
  11. gearhead222

    gearhead222 Member

    Thanx for all of the posts guys-very informative! I checked the float level and it was around 3mm low-reading 18mm instead of 21 mm. These brass levers just don't seem to keep their adjustment that wall-at least that's been my experience. Still looking for a source for the fibre washers-Gearhead222
  12. gearhead222

    gearhead222 Member

    Dear Fellow Members-After searching the local nut and bolt house and several auto parts stores, I FINALLY found some fibre washers after scrounging through several old carb rebuilt kits at my crazy Iranian mechanics shop. doesn't carry them-you'd have to buy a carb to get the washer.I even checked the local motorcycle shop where I buy my synthetic 2-stroke oil. If ANYBODY knows a source, I'd like to know. Current rubber O-ring is holding up well. I realize that these carbs are cheap, but would like to know if there are any gasket sets out there for these carbs. It's labor intensive and a waste to me to replace a well running carb just because it has a bad float bowl gasket, fibre washer or other bad seal that can be fixed with a replacement gasket or seal-Gearhead
  13. gearhead222

    gearhead222 Member

    Last edited: Dec 10, 2010
  14. HeadSmess

    HeadSmess Well-Known Member

    its a common fibre gasket/washer, available from fastener supplies. or engineering supplies. etc.
    about 10c... but usually a pack of ten... should even be in the local hardware in plumbing...

    but the washer isnt the isssue.

    look at the object...its basically a brass TUBE.

    the fuel in the bowl is BELOW the thread. fuel, like water, dont go uphill!

    the thread is below the washer. so fuel wont normally ever touch the thread, hence the washer is unnessecary. the thread never has to SEAL.

    if there is fuel leaking around here...have you clamped the hose? the hose doesnt have a tiny pinhole? the tank isnt leaking from one of the studs and throwing you off the track?

    youve already checked the fuel height apparently, so...

    the only other thing possible, which i refuse to believe, is the brass fitting is cracked...
  15. gearhead222

    gearhead222 Member

    Dear Sir-Replaced the fuel line, adjusted the fuel float level and replaced the paper gasket. Brass nipple and carb body appear fine. Bike is not leaking now. Keeping fingers crossed:)-Gearhead
  16. DuctTapedGoat

    DuctTapedGoat Member

    I can tell you what I did in my experience about this.

    That screw at the bottom of the carb leaks. It's leaked on most of the builds I do. Common sense tells me that the purpose of that screw is ONLY for draining the fuel before removing it and tinkering - it could serve no other purpose. I too tore down and rebuilt my carb many times in hopes of finding a leak around the gas intake nipple or gasket, but alas, no dice. So, I just leave it alone and let it drip!

    The solution I found for this is... turning off the petcock from the tank! It's a pressure driven fuel line powered by gravity, this is why there's no fuel pump, this is why the tank is above the motor. When you stop the pressure from pushing gas unrestricted (due to the gas tanks venting), it will leak for a minute, but all that will leak is the gas that has collected under the float, and even then - not all the gas from that chamber will leak out! So, if you're turning off your petcock and you see leaking, that's why - don't freak out.

    Personally, I don't mind the leaking. It's leaking unburnt fuel out of the exhaust and out the carb drain screw. Eh. I leave the petcock on all the time (with the exception of storage for weather reasons). The reason I leave it that way is so that when I fire it up the next morning it fires up immediately without setting the choke. I know it's slightly irresponsible maintenance, but there's a reason behind it at least.

    NOTE!!! If you see a leak like this, it is a VERY MINOR leak. If you are noticing a very MAJOR LEAK, then check your gas tank and fuel lines. My first build I didn't think twice about mounting the gas tank above the metal brackets for the brake line (the ones welded to the frame). After a season of riding I lost a full tank in about an hour while it was parked, and there were two holes! One was about 2mm, the other about 1mm. The vibrations of the motor caused the brake line brackets to bore holes. I was able to remedy this by JB Welding the holes shut, and placing 5 or so strips of denim between the tank and the frame. I considered using a cut tire, which would work better, but denim was more easily accessible. So, before you diagnose it as the carb drain screw, be sure you have checked everywhere else!
    Last edited: Dec 15, 2010
  17. gearhead222

    gearhead222 Member

    Dear Sir-I've stopped the leak between the brass fitting and the carb with another paper gasket, and just noticed ANOTHER leak where the fuel line attaches to the gas filter. I think that the main problem is the cheesy spring expansion type 1/4" fuel line clamp that has the 3 ears that you squeeze with pliers to open. Does ANYONE know of a good source for quality 1/4" spring or screw type fuel line clamps? Cannot find anything locally. Should I even use a separate fuel filter? Getting rid of this filter would decrease my leak probability.
    As always, thanx again for any feedback-GREAT forum:)-Gearhead
  18. DuctTapedGoat

    DuctTapedGoat Member

    Well, maybe you should get some different fuel line and just a metal screened filter. I just got gifted a metal screened one yesterday, so I can say good bye to my paper filter.

    I say get some wider walled fuel line (same tube inside, about 3/4 - 1" diameter outside), and just get some small standard threaded hose clamp.
  19. motorpsycho

    motorpsycho Active Member

    The fuel line that i use is 1/4 inch inside diameter and it's clear. It's made and sold for lawnmowers and is sold at auto-zone.
    once you put the line on, and it comes in contact with gas, it slightly shrinks, making a leakproof seal and no clamps are needed. the line is soft and felxible when it's newso it's easy to bend without kinking. Once it's on it does get slightly hard over time and it will hold it's shape. I have not had a leak yet and i've had the same line on one bike for 2 years, and on another bike for almost a year.
    I use clear mini fuel filters that are slightly bullet shaped and they have a fine screen filter inside. They are also for lawnmowers and sold at auto-zone.
    Last edited: Jan 20, 2011
  20. Dave C

    Dave C Member

    Or you can go to any motorcycle shop and get 1/4 fuel line for about $1 a foot and a stainless steel screen filter for about $5. $7 out the door and your set up. The hose I got is a clear blue and the filter is clear so you can easily see any crud build-up. No clamp needed.

    If your useing the stock fuel tubeing throw it away, it's junk.:poop:
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