Lock up

[Tucker44]

Hi I just put together a 49mm steel sleeve engine and I have about 10 miles on it. Some times on the road it would slowly shut off then when I would go to restart it, it wouldn’t turn over and if I could get it started it would make a bad noise. Then I would let it sit of 5 minutes and it would be fine. Does anyone know why this is happening. Thanks

 

[wan37]

Nice to meet you tucker. 4 stroke or 2 stroke . Take pictures of engine and bike . Post them in another message. It’s easy to do . Just hit attach files. Some others or I will help you.

 

[Wrench]

Is this a 4 stroke? Are ya running your engine with no oil?

Kinda sounds like with heat expansion the engine stops working. So when ya let it cool off for 5 mins it starts up again but when it gets hot it stops and ya cant even turn the engine over cause it's locked up. Until it cools off then it seems normal, until it heats up again

Cause - piston ring end gap too tight - under .012" - Heat expansion closes ring end gap -Too tight in Cyl
Cause - piston to cylinder wall clearance under .003" - Heat expands piston - piston contacts cylinder wall
Cause - valve guide to valve stem clearance too tight - normal clearance is .0015" to .002"- Heat expansion stops valve from moving

I bet your piston ring end gap is too tight It should be min 012" max .018"

If ya need to know how check your ring end gap or how to file the rings end gap
I can help ya

 

[Tucker44]

Nice to meet you tucker. 4 stroke or 2 stroke . Take pictures of engine and bike . Post them in another message. It’s easy to do . Just hit attach files. Some others or I will help you.

I’ll take pictures of it tomorrow. It’s a 80cc 2 stoke with a 49mm piston in it.

 

[Tucker44]

Is this a 4 stroke? Are ya running your engine with no oil?

Kinda sounds like with heat expansion the engine stops working. So when ya let it cool off for 5 mins it starts up again but when it gets hot it stops and ya cant even turn the engine over cause it's locked up. Until it cools off then it seems normal, until it heats up again

Cause - piston ring end gap too tight - under .012" - Heat expansion closes ring end gap -Too tight in Cyl
Cause - piston to cylinder wall clearance under .003" - Heat expands piston - piston contacts cylinder wall
Cause - valve guide to valve stem clearance too tight - normal clearance is .0015" to .002"- Heat expansion stops valve from moving

I bet your piston ring end gap is too tight It should be min 012" max .018"

If ya need to know how check your ring end gap or how to file the rings end gap
I can help ya

2 stroke

 

[Wrench]

You describe a "Soft Seize" indicating engine parts rubbing together. In a 2 stroke this can be caused by a lean condition
I recommend taking the cyl off and looking at the piston and cylinder wall. Inspect for damage that may tell ya what's happening

 

[Tucker44]

You describe a "Soft Seize" indicating engine parts rubbing together. In a 2 stroke this can be caused by a lean condition
I recommend taking the cyl off and looking at the piston and cylinder wall. Inspect for damage that may tell ya what's happening

I have before and it looked fine I run 32:1 full synthetic too.

 

[Wrench]

OK did ya check all your bearings and Inspect the clutch, Basically do a engine tear down and inspection?

What ya describe sound like it could be something serious.

That's about as far as I can hep ya I'm a 4 stroke guy.

I'm sure a few 2 stroke experts will chime in tomorrow morning

 

[Tucker44]

OK did ya check all your bearings and Inspect the clutch, Basically do a engine tear down and inspection?

What ya describe sound like it could be something serious.

That's about as far as I can hep ya I'm a 4 stroke guy.

I'm sure a few 2 stroke experts will chime in tomorrow morning

It could be it sounds like it’s whining then shuts off. Since these motors aren’t the best quality I would’ve thought it would have blown up by now if it was something severe. And with the clutch i would have the clutch lock on and it wouldn’t move then all the sudden it would start moving so I’m thinking it’s something on the clutch side of things.

 

[Member 30571]

You DO NOT want to use full synthetic oil when breaking in a china girl motor.