[leatherneck77]

I rebuilt this engine on this 250x now it cranks but won't pop off. I took the spark plug off and put my finger over the hole and it seems to have a vacuum instead of compression. Not sure what that's about. Is it possible for the starter to be spinning backwards?

 

[shadetree]

I rebuilt this engine on this 250x now it cranks but won't pop off. I took the spark plug off and put my finger over the hole and it seems to have a vacuum instead of compression. Not sure what that's about. Is it possible for the starter to be spinning backwards?

even if the piston was spinning backwards ?, it still would have compression, just not at the correct stroke to fire spark plug.

 

[leatherneck77]

I set the timing how the manual said not sure what else to do. I'm going to rotate the cam 180° and set it again. Really not a fan of this engine design. My 350x is much more easy to work on.

 

[oldmxrider]

Both the engines work the same !

Just step back and take a break, calm down then look for Your error !