Carby NT carby/inlet leaks - a reliable solution

Discussion in '2-Stroke Engines' started by AussieSteve, Dec 22, 2009.

  1. AussieSteve

    AussieSteve Active Member

    I finally got sick of using Permatex, (and cleaning it off), every time I removed and refitted the carby.

    I've considered the traditional 'o' ring approach, but it's not mechanically reliable, in my opinion. (Three hands are needed - one to push the carb firmly against the 'o' ring and two to tighten the clamp bolt. Even then, a perfect seal can't be assured.)

    Here's an 'o' ring method that should be reliable.
    I used a 100mm 'warding b a s t a r d' file, about 1-1.2mm thick and cut a 1.5mm groove about 2mm from the end of the (after-market alloy, $10) inlet tube, to fit an 'o' ring. I finished off with a green (nylon?) pot scouring pad, to remove any rough edges before fitting the 'o' ring.
    A smear of 2-stroke oil helps when fitting the carby.
    No more problems, (I anticipate).

    I measured the 'o' ring as best I could:-
    ID=16mm OD=19mm (Cross-section diameter=1.5mm)
    Fits like a glove. Any similar 'o' ring would do it, just cut the groove to suit. Not too thick, though, or the groove will need to be too deep.

    After the groove is cut, the 'o' ring fitted and the carb tested for fit, it's not a bad idea to remove as much metal as possible from the end of the tube, to move the 'o' ring closer to the end. This will ensure a really good seal. (That's next, down to about 1.5mm)

    Found a local supplier with 'o' rings that are close, if stretched slightly. Actually, it sounds like a common size and probably isn't hard to get. I suspect that the one I'm using is exactly that size and that my measuring was out. We'll see.

    When they arrive, I'll report.

    For Aussies:-
    30c each. $7.70 deliv, though. I bought a good few.
    Fitch Rubber, Adelaide, Australia

    ... Steve


    Attached Files:

    Last edited: Dec 22, 2009

  2. gothicguy64

    gothicguy64 Member

    my billett inlet has a o ring fitted .
  3. AussieSteve

    AussieSteve Active Member

    Hello Brad, I have one of those too, (yours is from RSE, isn't it?), but had 2 problems. You probably didn't strike these, having an after-market carby:-

    1. Because the billet inlet is only 1 1/2" long and straight, the carb float bowl of an NT carb interferes with the clutch cable.

    2. Without a bend in the inlet, my carby would sit on about a 25-30 degree angle with the billet inlet.

    Also, a minor problem is that the billet inlet is machined for allen-head screws, so the stock studs must be removed and allen-head screws procured.

    On top of this, RSE billet inlet - $35AU.
    (I'll probably post a review of Rock Solid Engines re billet heads, laser-cut inlet gaskets and inlet tubes once the latest order is resolved.)

    The alloy aftermarket inlets have the right bend for most engine installations, bolt straight on and are relatively inexpensive. Also, readily available in the US for about $10US.

    N.B. The 'o' ring I used came from my billet inlet, at least I got something for my $35.

    ... Steve
    Last edited: Dec 22, 2009
  4. arceeguy

    arceeguy Active Member

    Looks very nice and professional!

    For the cheapskate, a reliable way of ensuring that there are no leaks at that joint is to wrap some teflon pipe sealing tape on the end of the inlet tube. No messy silicone sealants, and it comes off easy if you need to pull the carb off.
  5. AussieSteve

    AussieSteve Active Member

    After the above pic was taken, I further shaved the end of the tube to place the 'O' ring about 1mm from the end of the tube. Works really well.
    Also, smooth the edges of the four slots in the carb or the 'O' ring could be damaged during installation and removal.

    ... Steve
  6. gothicguy64

    gothicguy64 Member

    yerr the lot other than pipe an tank from RSE .
    i was lucky i got billett inlet thrown in for free .
    ohh i forgot that when i ordered bike an hp1 motor i added the coated piston ..

    i out dragged a std grubee 48 with my long street pipe on ..
    can keep up with a std 66 ...
    next after i get a new bike an transfer motor i intend to try a boost bottle an nitrous setup coz after all i have a nitrous capable motor .
    cost for bottles 90 bux us plus mail ..
    its the 3 in 1 setup ..
    unknown if i,ll get a sikk bike expansion or order from RSE a power pipe .
    i could ride with rim split but unwilling too .so im saving for a cell mx1 ..
    350 bux 21 inch frame in black then desticker it .. mbb sells it too
    ohh mbb has a better chain that doesnt strech 20 or 25 bux an im goin to try a 36 tooth rear too since i can only go 55 kmh .
    or if i use RSE exhast i,ll get 65 kmh but tooo loud .
    2500 kms an no leaks no probs other split rim
    my fault for hittin a huge pothole

  7. gothicguy64

    gothicguy64 Member

    ohh i for got about the bilett clutch arm an cover much better than std
  8. AussieSteve

    AussieSteve Active Member

    Yours sounds like a nice bike. Sorry to hear about the rim. Shouldn't slow you down for long.

    What's 'much better' about the billet clutch arm and cover?

    ... Steve
  9. gothicguy64

    gothicguy64 Member

    well for starters its billet
    but the arm is very cool lookin
    an the cover isnt that bad either
    ohhh whole motor has allen bolts same for rear

    when u first rode did ur chain stretch like crazy mine did for first 100 km
    but george at mbb has a much better 415 chain looks o ring

  10. AussieSteve

    AussieSteve Active Member

    I think I'll skip the billet clutch cover. Mine's fine.

    My chain seemed to stretch, but it turned out to be my chain tensioner bracket slipping. I originally used insulation tape under the bracket to protect the paint. Trouble was, the adhesive on the tape acted like a grease, allowing the bracket to slide along the chainstay.
    Once I figured it out, I removed the tape and roughened up the contact areas of the bracket with a grinder in a cross-hatch pattern. No more chain stretch.
    Since then, I haven't had to adjust the chain for about 300km and it's still fine.
    These 415H chains are actually intended for 70cc to 125cc dirt bikes. Our little engines shouldn't stretch/wear them too quickly.

    ... Steve
  11. gothicguy64

    gothicguy64 Member

    i know what u mean ive a tube under my tensioner an havnt had to tension it for last 500km .
    im not too sold on the chainless forks tho just cheep 1.1/4 disk forks with a rubber seal on stem but i intend to keep front wheel an caliper an use it on nxt bike ..
    ohh i forgot the stop for clutch has popped off so i have to hold clutch in at lights ,,,,no biggy or i kill engine an pedal start ..
    with the poo poo pipe bike goes quikk as to 30-35 kmh then steady till 55 .
    i usually go 45-50 kmh
    no point goin flat out unless it slighty downhill ..
    an ive added 3mm rubber vac tube around tank so i dont cut myself on join

    Attached Files:

  12. AussieSteve

    AussieSteve Active Member

    Wow, Brad, that seat looks painful. (VELO?)
    Should try a VELO Plush Recreational (or similar). What a difference.
    Like the idea of the tubing. I just fitted a 3L tank and it's wider than stock.


    No pics of the bike with either fitted yet, but:-


    Attached Files:

    Last edited: Dec 28, 2009
  13. gothicguy64

    gothicguy64 Member

    looks cool my old seat an by far the best i liked is from kmart
    a matress seat had springs under seat an takes a lot of the jolts ...
    ummmm 18 bux but when i hit pothole i both fell off an ripped seat so i had to use the RSE seat an ur right it is painfull an aftertaking pic i see what u mean its too far up ,silly me .ohh pedals repco metal ...
  14. AussieSteve

    AussieSteve Active Member

    My 'O' rings arrived from 'Fitch Rubber' today. (Imperial 'O' ring 5/8" ID x 1/16")
    Perfect for the inlet tube and identical to the one I originally used, from my RSE billet inlet.
    (A good source of spare 'O' rings for RSE billet inlets)

    ... Steve