She's Lost Her Power, Captain!

[klassard]

I've logged over 1,200 miles on my 80cc engine. This last summer on a ride back home on a hot day, the engine started to bog down while at full speed. I figured it was getting too hot so I stopped for a while. Upon starting back up, it ran normally for a bit, then started bogging down again.

After that, it ceased to give power after it warmed up. It would start out strong but lose power after only a couple minutes of riding. Strangely though, when I give it gas with the clutch disengaged, it revs fine but no power - this is the part I didn't see in the searches I did on this forum so I figured I'd put it out there.

I cleaned out the carburetor and changed the spark plug with no success. Any suggestions before I pull the cylinder head off? (I'm not confident I can successfully get the piston rings back in so I'm hoping to leave this as a last resort)

Thanks!

 

[hill climber]

sounds like you got the good outa it. check the compression. might have to put rings in or even a cylinder and piston kit. might be a air leakonce it warms up.

 

[MotorMac]

compression

Take the spark plug out and feel with your thumb over the hole if theres any compression. If not then your rings are gone or theres a hole in the piston. If you have good compression then its probably fuel related or theres an air leak,head gasket leak?

 

[fetor56]

Sounds like a head leak mister.....either that or your matter/anti-matter transformer is cactus.

 

[bluegoatwoods]

If it's not the matter/anti-matter transformer, then check your exhaust.

If it's clogged it can give symptoms similar to what you describe.

I hope that's it because this is a very easy fix.

Good luck.

 

[Mountainman]

tells you a lot in a short time

check the compression.

the good old compression test
can
tell you a lot in a short time

if you don't have a compression tester
you probably know someone who does

that's not many riding miles logged in
with only 1,200 miles
can't see where you got the good out of it ?

fast question for you klassard -- what % mixture were you using ?

get that THING back up and ride that THING

 

[klassard]

Wow, thanks for the responses!

I took the muffler off and rode it a bit. It was loud as **** but still bogged down. Unfortunately, I don't know anyone with a compression tool but I figure I might as well pick one up if I'm going to be making a habit of building these things

As for the mix, I'm running 30:1 with Motul 800. I don't know much about the engine. I got it on eBay and it says "Young An" with some chinese characters on the side.

Anyone know where to get a compression tool?

 

[Mountainman]

Anyone know where to get a compression tool?

Harbor Freight has some inexpensive ones

Sears -- as we know -- one of the best

take your MB into any auto repair shop
they may get a kick from checking out your engine
do a test for next to free

MM

 

[MotorMac]

compression tool?

You dont need a compression guage for a small 1 cylinder 2 stroke engine! just put your thumb over the spark plug hole and if theres a strong pulse of air then compression is fine. your thumb is a compression tool.

 

[Pablo]

Are your head and intake gaskets in good shape?