justin , i think you should have spent a bit of time cleaning up the excess resin and rubbing the parts down a bit more mate.
you will be amazed at how much of a difference this makes .
you can also use the spark plug leads and accs off of the engines you have removed from the models and transplant these to the yb engines.
here is one i finished and sold to steve on here a while back.
all the same parts i supplied you .