OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Edgers Two Stroke Edgers Tilt-A-Cut tinkering

full crank motors are supported by both ends ofthe crankshaft rather than on a powertorque motor that i supported on one end.

The full crank motors need TLC but will outlast any powertorque ever made.

It may well be worth starting off cleaning float chamber earea, (the primer cap area inside the carby, just dont lose the needle as you pull the primer cap away from the carby!

ok, i think i understand what the difference between a full and half crank is. (correct me if im wrong).

When i pulled the legend2000 mower apart (to replace the starting spindle, directly below it was the crankshaft (which was only supported by the bottom), ie: A powertorque/halfcrank.

With this edger, the starting mechanism is offset (i can see how yanking the cord engages a gear) so i can imagine with no impeding starting mechanism that the crankshaft is supported both underneath and above it. Is that correct?

Obviously my technical jargon is way off but if a diagram would express my understanding more clearly i am willing to draw one up representing my understanding of full vs half crankshaft.

Thanks for the offer of $100 Bruce, but i know you know your stuff, i was just pointing out that two different users had a difference of opinion and i didnt know who had it right (because i know squat compared to you fellas).

Hi Johno, I made the mistake mate, I forgot about the gear start full crank motor.....Opps!
I have corrected the previous post. Sorry for the confusion.

no probs deejay, i was just a little confused that's all.

So, can anyone correct my understanding of half vs full crank motors?

thanks in advance!

A normal single-cylinder crankshaft has two bearings that support it - one on each end. In between it has an offset bearing ('crankpin') that supports the connecting rod. The loads transferred to the crankshaft by the connecting rod are resisted by a crankshaft bearing on each side of the crankpin - the 'main bearings' at the two opposite ends of the crankshaft. An el cheapo engine, not intended to last very long, may leave out the second half of the crankshaft: in effect, by sawing it off at one side of the crankpin. This does not support the crankpin very well, and results in the crankshaft vibrating and whipping about.

With good design, the result of leaving out half of the crankshaft can be a quite satisfactory operating life and a considerably cheaper engine. If a reputable manufacturer like B&S can run an aluminium piston directly in an aluminium cylinder bore - which metallurgy tells you is a no-no because aluminium loves to seize onto other pieces of aluminium - then why not commit other engineering atrocities as well? How long do people expect a lawnmower to last anyway, and how many owners do something awful to it themselves, such as leaving the oil out of the fuel of a 2-stroke, or failing to keep oil in the sump of a 4-stroke?

The answer to your actual question is that a full-crank is simply a normal crankshaft, such as you will find in just about any engine intended to last more than a few hours. A half-crank, or cantilevered crank, is a single-main-bearing crankshaft - the mere contemplation of which makes some of us retch.

Thank you for that explanation grumpy! makes perfect sense!
Unfortunately in these throwaway days, people just want to see a sparkly looking mower with a nice price tag, they dont necessarily think about the quality involved (they in effect think they have bought a bargain).

I always thought that a mower should last you 15+ years, but looks like my standards will need to drop (either that or i need to start buying older mowers)

hi guys, its been a while (i was getting hitched) :P

I have finally had a bit of time to pull out the mower and give it a bit of tinkering again to try and get the bugger running.

I have fully cleaned out the carby and fuel flow is good, but now it wont even start.

I can flood the motor and achieve smoke on the start but it just does not want kick over and run!

getting mighty frustrated. Anyone with any other suggestions?

do you have decent spark?

a very decent spark

in fact, i replaced it with a brand new spark plug as well.

Johno123,

Do you have fresh fuel from the servo or using the old fuel in the can?

great question bruce!

ill go get some new fuel and give it a shot.

will let you know how it goes in a bout 2 hrs.

Johno123,

I would suggest that you drain the tank and carby before trying to start it. One other thing try putting some fresh fuel down the plug hole because if it has old fuel in the sump it will still be hard to start.

just bought some new fuel, emptied the fuel tank, injected fuel straight in through the spark plug hole but still no luck, smoke but no starting.

im laying in my own pool of sweat atm from all the pulling!

any other clues?

If that smoke is black, the mixture is too rich to fire or there isn't enough compression or the spark timing is wrong. You've probably carboned-up your new plug a bit too, but hopefully it will recover when you get it running.

To get it to run you need 4 things: a suitable mixture of air and fuel in the intake manifold beyond the carburetor; compression in the crankcase when the piston descends; compression in the cylinder when the piston ascends; and a strong spark at the right time. If you haven't done so you should check that all four things are happening, each in its due season. Starting with the induction process, is there a pulsating suction at the open end of the carburetor when you spin the engine with the spark plug installed (but disconnected, for safety)? If yes, can you feel crankcase compression on the down-stroke and cylinder compression on the upstroke, so you feel two resistance pulses per revolution? If no crankcase compression, you may have severe piston scoring, or leaky main bearing seals. If no cylinder compression, you may have a problem with rings, or with a decompressor if you have one. If you pass those tests the base engine is probably OK and you just have to worry about air/fuel ratio, spark, and spark timing.
Bruce has told you the usual way to test for air/fuel mixture problems. It bypasses things like intake manifold and bearing seal air leaks - if you have cylinder compression and correctly-timed spark, it should start and run for several seconds. If it doesn't, and you have good blue spark, there has to be some suspicion that there isn't enough compression - it is hard for a Victa's ignition timing to change.

Have you got the belt on?

its alive ALIVE!!!!!!!!


finally the b@#$h started!

Heres the problem.... (my fault)

After i cleaned the decompressor i was wondering how come it was so easy to pull start (even though i still felt the compression somewhat). I took off the decompressor and replaced it with a spark plug to check compression, compression was good!

I then took apart the decompressor and noticed that i reassembled it in the wrong order! Once the decompressor was reassembled it started on first pull!

Basically i wasnt getting enough compression is seems because of my silly mistake!

ill go run her in now and see if she runs for a while, will post results in the evening!

YEY!

Johno123,

Good to see you sorted it out.

thanks bruce , deejay, Grumpy and Joe!

i gave it a bit of a go (15 minutes doing the edges in the rain!) and its running like a dream!

wohoo!

Good work Johno123, glad to see it's up and running.