80cc slant head installed...problems...

[DJEEPER]

OK...So i installed my slant head on my happytime motor today. It started on the 2nd or 3rd pull. GREAT! It sounded nice and throaty, idled nice, etc etc.

I let it warm up and took it for a spin. HOLY JEEZ! This thing took off like i wasnt even on it.

I got about 1 mile down the road and noticed if im in a higher gear (numerically) and i gassed it full throttle, it seems like i have a whole lot more carb noise.

Normal?


next thing:

I brought it back home and parked it to recheck my head nuts. They were fine and tight.

I let it cool had some lunch, then went to go again.

Now, it wont start. And im lifting the bike up while pulling on the start cord when im sitting on it. It turns over, but the pull is so intense that it really really hurts my hands. Im no weak person either (22 years old, bike mechanic, etc etc...im used to using my hands).

A couple times it would backfire...which clued me to check for spark.

Yeah, i have spark....i laid the spark plug on the head with the plug wire attached and pulled. It is sparking.

I have fuel because i primed it so much that fuel started coming out of the primer button (only when i pumped it, not constantly)

I checked the spark plug and it was wet.


So what do i do now?

I have spark, fuel and air....but no go....

 

[Rob_E_Rob]

Sounds like you cooked it. Engines definetly run great when they run real lean, but only for a short time. I think you have a piston siezure, but only partially if you can still spin it enough to check spark. Pull the head and have a look. Looking is free.

 

[DJEEPER]

what would i look for?

I idled fine and everything when i pulled up from my ride.

 

[Hawaii_Ed]

pull the plug out, and see if it turns easy with no compression. If not, then you have internal damage. Can then pull the jug and look at the cylinder wall/piston/rings.

Good luck!

 

[DJEEPER]

with the plug out, it spins freely and easily. took the head off and the cylinder wall is smooth as glass. (typical minor superficial scratches up and down, but nothing gouged or "feelable")

 

[HoughMade]

Is it possible the clutch is partially engaged and you need to adjust it?

 

[DJEEPER]

with the plug out, i can turn the magnet by hand. I think the head is just giving me lots of resistance....

 

[DJEEPER]

ok.... just put the old head back on and it is running fine... WTF...

 

[DJEEPER]

im going to get a thicker head gasket...

 

[Hawaii_Ed]

Sorry, took me a bit to get back with ya. Obviously, the internals are fine if it spins easy with no compression. Stock, the slant head motors have two gaskets. I went with one on mine, and I have to kick start it with the shift kit. It took a MUCH stiffer kick running one. I have no idea if a rope start can handle it. Can you still pedal start it with that setup? Or are you CVT clutch too?

Either way, I think you have it sorted!