Cannot get HT to fire up

[fm2200]

I believe its the kill switch is probably defective it's an easy check isolate that wire first, then try to start it after checking and cleaning the spark plug before starting it.

 

[Stink Bike]

I had a similar problem.It was the kill switch.
Try bypassing it.

 

[Irish John]

It's a two stoke engine - one of the simplest pieces of machinery.

Got air

Got fuel

Got spark

Still thinking something is up with that magnet.

John,

If you have an inductive timimg light handy, make some timing marks on the magnet at TDC, remove the plug (to relieve compression) and roll the bike forward and see if the ignition timing is close. Might need two people to do this. One to roll the bike, the other to aim the timing light.

I'm refuelling it now cos I can't trust fuel I didn't put into it. I'll replace carb with a proven oldie from 2004 Grubee stock. Then I'll replace the lead.
I know the plug is good I know the magneto is OK cos it gets a spark and it's a brand new replacement magneto.
I think the compression is good cos it feels good but this motor is only 4 weeks old and isn't run in yet.
Stinkbike's comment is no longer relevant cos I've removed the kill switch until I get the motor to fire so it wasn't that.
I'll press on. I'm thinking it's bad fuel maybe but I really don't know anymore what it could be.
I'll report back after I've tried new fuel, lead and carby. I've replaced the pet cock with one that lets the fuel through faster although the old one wasn't that slow on letting fuel through.

 

[Irish John]

I had a similar problem.It was the kill switch.
Try bypassing it.

Read a couple of post above and you'll see I've tried that.

 

[BoltsMissing]

treat the fuel as tainted and refuel the bike cos I didn't put the fuel in there.

Hang on Irish, that's equivalent to a "Protest" or a "False Start".

One minute ya say it ain't got spark, then ya say ya mixed the wrong fuel.
Wrong fuel mix don't cause a weak spark !

Is it the spark or is it the fuel ? or equal favs, both ?

 

[Irish John]

Hang on Irish, that's equivalent to a "Protest" or a "False Start".

One minute ya say it ain't got spark, then ya say ya mixed the wrong fuel.
Wrong fuel mix don't cause a weak spark !

Is it the spark or is it the fuel ? or equal favs, both ?

No Bolts I've never said I haven't got a spark. I've always had a spark. The reason for suspecting impure fuel was that I didn't fuel the bike cos it's not my bike. That's why I refueled it so I now know it can't be bad fuel.
Bike has been refueled, Spark plug is good but wet after each try to get it to fire up downhill. chaged the leads (tried 3 good leads).
Put new gasket on air intake and sealed everything for air leaks really tight
Thought it might be fuel starvation cos the filter takes a long time to fill up but that is normal.
I can now only deduce one thing and that is loss of compression because a piston ring has broken. I can't tell by the sound of the motor turning over but owner now says there was a bit of a bang before it stated misfiring and then not firing.
I notice I can turn the engine over by pedalling with my hands when the bike is up on the stand and although it is a long time since I worked with 48cc HTs I reckon it shouldn't turn over that easily unless the plug is out.You can't turn my 66cc over unless you sit on it and get speed up pedalling before letting the clutch in.
I have to assume it's the piston riings. Any ideas about this?

 

[Irish John]

It's a two stoke engine - one of the simplest pieces of machinery.

Got air

Got fuel

Got spark

Still thinking something is up with that magnet.

John,

If you have an inductive timing light handy, make some timing marks on the magnet at TDC, remove the plug (to relieve compression) and roll the bike forward and see if the ignition timing is close. Might need two people to do this. One to roll the bike, the other to aim the timing light.

I haven't got a timing light. The magnet is the same as any other. It has a key in there to prevent it turning on its spindle. I'll try to pull in off and look closely at it but they don't come off easily and my little gear pullers can't get a grip from behind it cos it's hard up against the casing. I've never had a magnet break a key and this engine worked good last time I had it in the workshop 3 weeks ago.

 

[biken stins]

Readjust clutch. Engine turns easy when not engauged.
Narrow plug gap (.22).
Wires black to black. Blue to blue.
Black wire from kill switch to ENGINE.
What ever color left from swith to Blue wire.
Toggle on/off switch are great. Just make you make sure its on when trying to start. Try a O-ring for carb.

 

[BoltsMissing]

loss of compression because a piston ring has broken. I can't tell by the sound of the motor turning over but owner now says there was a bit of a bang before it stated misfiring and then not firing.

That now changes things. ( Late Form)

 

[BSA]

No Bolts I've never said I haven't got a spark. I've always had a spark. The reason for suspecting impure fuel was that I didn't fuel the bike cos it's not my bike. That's why I refueled it so I now know it can't be bad fuel.
Bike has been refueled, Spark plug is good but wet after each try to get it to fire up downhill. chaged the leads (tried 3 good leads).
Put new gasket on air intake and sealed everything for air leaks really tight
Thought it might be fuel starvation cos the filter takes a long time to fill up but that is normal.
I can now only deduce one thing and that is loss of compression because a piston ring has broken. I can't tell by the sound of the motor turning over but owner now says there was a bit of a bang before it stated misfiring and then not firing.
I notice I can turn the engine over by pedalling with my hands when the bike is up on the stand and although it is a long time since I worked with 48cc HTs I reckon it shouldn't turn over that easily unless the plug is out.You can't turn my 66cc over unless you sit on it and get speed up pedalling before letting the clutch in.
I have to assume it's the piston riings. Any ideas about this?

sounds like bad compression. The only other thing I can think of, you say your plugs wet so maybe your float level isnt set right and its flooding the engine.

BSA