Engine Trouble Engine wont start? TROUBLESHOOTING GUIDE

CrazyDan

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Hi what would it mean when I undo my mag cover an fuel come out of were the magneto sits and also will a small imperfection in a piston stop a motor running I've got like a little graze tYpe thing on the edge of my post on an its,a tiny bit deep can rub my nail on it and deal it
Fuel leaking out from around the mag sounds like a blown out crank seal.
 


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Hi what would it mean when I undo my mag cover an fuel come out of were the magneto sits and also will a small imperfection in a piston stop a motor running I've got like a little graze tYpe thing on the edge of my post on an its,a tiny bit deep can rub my nail on it and deal it
Your side seal needs to be replaced sits beneath the magneto
 
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fuel in the magneto is likely a bad seal behind the magnet rotor. I had a seal come out with the rotor when changing the rotor. Thing is the seal was not leaking. I got a seal retainer off EBay $7.00.
Was a little worried about the rotor touching it, but so far so good.
Ok thanks mate an also my other motorised motor bogs down at top rev an starts to die them come back

That would mean it running to ritch right was gonna move my needle clip either up to very top an see how it went but don't wants to stuff or so I'd thought I'd asked if it would be wise to do so
 

FurryOnTheInside

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Ok thanks mate an also my other motorised motor bogs down at top rev an starts to die them come back

That would mean it running to ritch right was gonna move my needle clip either up to very top an see how it went but don't wants to stuff or so I'd thought I'd asked if it would be wise to do so
If you really think it's rich at high RPM then I would upgrade the air filter.
In fact, I would upgrade the air filter anyway, always, because the stock air filters are just awful.

The needle setting affects fuel flow at 0-3/4 throttle. The jet size affects fuel flow at 3/4-full throttle.

At high RPM the engine is trying to get all the fuel and air it can. If the air filter is at all restrictive then there is an undersupply of air (choke!) and perhaps the resulting vacuum is also drawing fuel directly rather than by purely Venturi action.
 

crassius

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if it is surging (slowing down, then going back up, and repeating) that usually is caused by vibration in carb foaming the fuel

several threads about that here
 

gary55

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Like crassius is saying. If it repeatedly speeds up and slows down at wot with no change in throttle position There is a good chance the motor mounts are not tight enough to keep the engine from vibrating and foaming out the fuel bowl.
 
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When the engine speeds up at WOT due to frothing/ foaming caused by vibration, it's a lean condition. The same thing happens when your fuel level in the float bowl is low. (Forgot to turn pet cock on) or running out of gas.
Also if the float is not correct or lack of fuel flow from tank to carb (dirty fuel filter), Will cause the carb bowl to be low enough to suck air with the fuel and create a lean condition.
 

gary55

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A to lean condition such as a intake or seal leak often causes the engine to speed up. The foaming of the fuel in the bowl caused on a engine when it reaches it's harmonic point and has loose mounts does just the opposite. The engine slows down then when it drops below the harmonic point the vibrations cease, the fuel settles down and feeds properly, it then speeds back up. It is not speeding up cause it's lean. It's speeding up cause it's running correctly. This will be a repeating cycle with no change in throttle position.
 

crassius

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if you mean the head studs, then you have a bad (or maybe just loose) gasket

spark plug or muffler loose could sometimes blow air up there
 
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I found the leak theres some huge casting flaws in the spark plug area theres some slag that goes from the tread all the way threw to the side about a half inch of travel im going to jb and see what happens after i burn of impurities on stove
 

Eric Hall

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hope its alright i'm posting in an older thread, but just have a few questions...


okay, so i shocked myself testing the spark plug (idiot), so i know thats working.

the clutch works great, i can feel and hear it turning the piston when i try to start the engine, so thats not the problem either.

what i have come to think is that it is a carb or throttle problem


i get the engine to turn over, hear it start firing, but as soon as i pull in the clutch it cuts out.


things i have already tried:
the fuel line is 'on' at both the tank and the carb, i used the tickler button and could see gas flow down the line (an air bubble anyhow).

PS, glad to be joining the MB community :D
I am having the exact same problem. Have you found a solution yet ????
 

crassius

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there is a thread here with all the steps to get a motor to start - if you have spark, then next check is to see if spark plug is wet
 
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My engine seems extremely flooded with the muffler off and the plug out and the clutch locked engaged you can hear it sounds like the engine is full of gas how do you fix that I'm wondering if my petcock is broken it seems the fuel filter stays full no matter on or off I tried haluing ass and it shoots out of the exhaust port but never seems to really make a difference should I drain my tank
 

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