fuel in bottom of engine leaking into magnito

Discussion in '2-Stroke Engines' started by CdubLu33, Feb 7, 2014.

  1. CdubLu33

    CdubLu33 New Member

    My bike has been running funny lately. I thought it was water in the gas by the way it was running so I put new gas in it, no change. The next day it got worse and wouldn't run at all, no spark. So I took off the magnito cover and out poured a gas water mixture. Confused as to why I had gas in there I took the engine off the bike to see what's going on, and found that there was a lot of gas in the bottom of the engine leaking into the magnito case. How can I fix this? Has this happens to anyone else?

  2. BigBlue

    BigBlue Active Member

    Your carburetor needle valve may not seated properly or your carburetor float has a hole in it allowing fuel to enter the engine. Check for these problems first.

    Then, air out the engine, try removing the spark plug and letting the engine air out. Or you can disconnect the black and blue wires from the CDI unit, remove the spark plug and peddle the bike to air out the engine case. ***You don't want your CDI connected to the magneto or you might ruin the CDI***

    It is important to turn the fuel off when you park the bike, especially if you park it in a garage with a water heater or other source of combustion.

    Good Luck,

    AKA: BigBlue
  3. HeadSmess

    HeadSmess Well-Known Member

    the needle valve in the carb is leaking,

    and for the fuel to get into the magneto...

    the magneto side crank seal has bust...as usual...easy repair. pop the magnet, shove in new seal (or old seal thats fine but been popped out if lucky)...
  4. Fabian

    Fabian Well-Known Member

    Sounds like you have a failed crankshaft seal on the magneto side of the crankcase.

    For a newbie, it's not an easy repair (if the seal hasn't popped out) because you have to try and pick out the crankshaft seal without damaging/scoring the area where the seal contacts the crankshaft and/or the area where the seal presses into the crankcase.

    If you score/damage the crankshaft surface, you are totally screwed because the engine needs to come out of the bike; with the engine requiring a total strip down to replace the crankshaft.

    From what it sounds like, the engine needs a new crankshaft seal. Hopefully you have an engine design which uses a thick seal rather than the less common "thin" design.
  5. Huotalicus

    Huotalicus Member

    if yoou got moisture in the magneto id have one on standby anyway..or tak eit out now and clean it and even resolder the joints, they fai from vibtration rather easiy i have a few go bad on me.....my first bike i didnt even break in ..i took it to about 40 by the second tank and by the 3 and 4th tank i was doing near 60...with just few minor upgrades...so i know where im headed !!! You reay can get so much out of these engines!!!
  6. Fabian

    Fabian Well-Known Member

    60 miles per hour or 60 kilometers per hour?
  7. Huotalicus

    Huotalicus Member

    km/h australia so we go by kms..soooo fast
  8. Huotalicus

    Huotalicus Member


    km/h australia so we go by kms..soooo fast

    also with my first bike which is now running stronger then ever, after sitting for about 2 months straight for i was gobsmacked about what was wrong wouldnt fire...changeed the magneto coil and walah!!!! i honestly thought my engine blew....but to my surprise it was just the magneto coil....thisis a major issue on most 2 stroke engines..secure this part!!!! anyhoo...so i first started doing about 25-35 first go...and by second go i ws already doing 35-45..and then by the end of the 2nd tank i was doing 60 down hills.....i also just liek to add....at the start...it was standard...then by 2nd tank i put a 3prong plug....a hd CDI and spark plug lead.... nothing else so far and it was doing 60nicely and consitently down hills.....but on ave it would cruise at 50-55.. now thast with no break in.... so i ask do u break in a lawn mower?...same principle///.. ? im not trying to be smart..its kinda like a opinion only mine! but wouldnt mind some advice or ffeedback
  9. Fabian

    Fabian Well-Known Member

    A gravity assisted speed (as you have described and in km/h) sounds much more believable. There are some on here who claim 80 km/h (on flat ground) and do so with their hand on their heart; trying to convey looks of pure sincerity, whilst doing nothing more than placing a piece of plastic pipe over the air filter, bent to face into the wind and then gutting the muffler internals for that little bit extra; (but giving precious little power improvement) other than making one hell of a racket; not to mention upsetting everyone in the neighbourhood and also those who question the calibration of the speedo and the levelness of the road.
  10. Huotalicus

    Huotalicus Member

    ye your right, creating a racket for notmuch power gain is a waste, thast why all ive done is the plug lead, 3 promg plug, and cdi and it flys, after the exhauhst and sprocket to 33 or 36 should go almost 70kms/hr on flat ground i was doing 50 easy consistenly...and down hill would go 60 62 max....so im hoping with the sprocket down to 36 should go about 70....maybe..... also forgot to mention i only have a speed carby on here now and havent trested it full throttle yet...just installed it yesty..will give it a go soon...... just wanted to add that i prettt much opened fullthrottle on at the start of the dsecond tank ...and still goes strong.....
  11. Fabian

    Fabian Well-Known Member

    To quote Siegfried from "Get Smart"

    Huotalicus, i find that hard to believe.
  12. HeadSmess

    HeadSmess Well-Known Member

    mmmm, wishful thinking can perform miracles.

    i still say i got a genuine 85km/h... with no mods. this was down hill. and it didnt make it back up the hill :)

    while id like to think having to brake behind a car is a sign of my superior speed, unfortunately its usually due to the traffic lights, some idiot in lycra, or a kellogs corn flakes type license...

    note...while KM rules, unfortunately you cant escape this being a predominantly american site, with all the awkward american units of measurement.

    look, i hate fractions but sometimes its really good...like, whats 5/8 doubled? 10/8, 5/4, 1 1/4...easy :) ditto on the halving. seriously, i call 3/4 a 12/16. then its OBVIOUSLY bigger than 11/16. etc ;)

    its the converting that gets painful... whats 0.275 in MM? (i can say its about 7mm off the bat but need the calculator to get any closer...)

    i even was arguing with some old bat (mum) that a mile couldnt POSSIBLY be 167* or so odd feet... yards yes, feet, no. i think its around 5200 feet or so? i didnt grow up in england! i was born metric, always taught metric.. but can use furlongs, feet and thou... now...whats a gill? or a peck? sheeeeeeshush!

    i digress...back to the thread at hand and points raised there within!

    erm... i agree...do you break in a lawnmower? but!

    my personal theory of gentle start up, warm up, followed by fully loaded full throttle blasts has been confirmed from an alternate source. two in fact.

    my friend works on generator plants. big generator plants, multi megawatts.

    i was discussing this break in procedure, taking it easy for the first few hours versus gentle warm up followed by full throttle with load, with my friend (yers, i still have a friend or two :joker:)

    well, i was thinking, that most generators, being steady running engines, should be fairly immune to things like thrown rods etc. this is true.

    i was also thinking that...they would be fairly prone to glazed bores, leaking rings, all the symptoms of bad break in procedures... as the standard "household" generator is pulled from the box, started, is instantly running at 3600rpm or whatever its governed to revolve at, and wont ever vary that speed unless the governor fails! or run out fuel. what comes first is inversely proportional to the initial outlay on said generator...

    well, guess what? after rebuilding a 5000 HP diesel, they have a break in procedure. start them, generator disconnected, let them warm up. meanwhile, send the apprentice around to plug in about 50 or so 2400W heaters. then turn on the generator, WHILST LOADED. bypass governor. rev em up. let em idle. send apprentice around again to make sure all the heaters are still working. they burn out when pumped up to 400 volts...

    and then...they DONT glaze bores.... and run literally forever.

    once again, despite it being hijacking (merely the point was raised) i solemnly and blatantly declare...all this "gentle during break-in" is a load of :icon_bs: of the sloppiest kind :)

    same token...a lot of lawnmowers have bad rings simply due to the fact that noone follows a "break in" procedure. started up, ran full speed (most of them do these days, or near enough. i always tweak mine to do an extra 1000 rpm or so. more power, more grasshackability!) with no load, and possibly forget that they have oil in the crankcase forever after...
  13. Fabian

    Fabian Well-Known Member


    From what i understand, the motorcycle factories put completed bikes on a rolling road, hit the starter button and take the engine to redline in every gear to seat the piston rings. It's ironic that the owners manual tells you to take it easy and be "oh so gentle" running in the engine, when the factory revs the snot out of the engine from first tick-over.

    In a modern engine, there is nothing that requires mating surfaces to "wear-in", because they are machined to such fine tolerances.
    Every engine that has gone through my hands has "never" been treated gently during the so called "run-in" period, although i don't rev the engine past the point where it makes maximum power, and typically run in the maximum torque zone.
  14. butterbean

    butterbean Well-Known Member

    I've gutted a stock pipe before, back when I used to mess with 2 strokes. If you weld the cap back on, it's not much louder than it is with the baffles in it, and it does make decent power.
  15. Fabian

    Fabian Well-Known Member

    :ee2k: maybe your hearing is really, really shot, because i have reasonably bad industrial hearing loss and have also experimented with gutting the internals of a stock pipe.
    I was barely able to ride the bike for more than a 1/4 of a mile before my ears couldn't take the noise any more, and that's not taking the rest of the neighbourhood into consideration, who most likely have significantly better hearing than i do, and want to keep it that way.
  16. butterbean

    butterbean Well-Known Member

    Maybe it has to do with how I did it. I cut the muffler in half, had to drill through the honeycomb because it was actually welded in pretty strong, couldn't cut or break it loose. I didn't weld the half I cut off back on. Instead I took a section of galvanized steel pipe and ground the coating off and my buddy welded that to what was left of the stock pipe. He then welded the original cap to that (again grinding the galvanized coating off before welding). Perhaps the thickness of the galvanized pipe muffled more of the sound? Also, the cap does provide some back pressure, also somewhat silencing the sound. I also had a pocketbike x-chamber, which had no baffling, the silencer was merely a smaller diameter pipe which had the same effect, muffling the sound. I wonder if you read the part of my previous post where I mentioned welding the cap back on after gutting the pipe. No cap would make it an open pipe, causing it to be very loud as you described. But a cap would silence it enough to operate at a reasonable level. I said it wasn't much louder than a pipe with baffles, but it was a bit louder, not so loud in my recollection as to cause any sort of nuisance. You're good at making people sound stupid or like they don't know what they're talking about, i'll give you that. But I'm simply relaying my own experience. Making me look stupid won't accomplish anything except to make you feel smarter, and it won't change my perception of my own experience. I'm a stubborn American, i'll give you that as well. And while my hearing isn't the greatest, it's not completely shot either. A pipe without a cap is considerably louder than a pipe with a cap, baffles or no baffles. In fact, I've had a pipe with baffles and no cap, and it was louder than a pipe with a cap and no baffles. Both were louder than stock, but the pipe with no cap was considerably louder than either of the other two. Now if you wanna sit there and try to tell me a cap has no effect on loudness, i'll not waste the time or energy to argue. You have your experience, I have mine. I'll agree to disagree, nothing more, nothing less.