I took my baby to a shop to have a valve replaced after i pulled the engine, replaced the head with a used one with good valves, and couldn't get the timing right, which resulted in another bent valve. So this time I figured I'd best not play with it and take it to a professional. they told me 2 days max, and asked me to pay up-front. I don't usually do that, but I had heard from some friends of mine that it was a reputable shop so I went ahead and payed. A week and a half later, they call me and tell me I need a new engine. Keep in mind, before i took it there I had it running perfectly fine, except for the out of tune timing. Now, when you try to start it it backfires hard and smoke comes out of multiple places. They showed me a spark plug they said it had smashed, and also said that gas was pouring out of the rear right spark plug hole when they removed the spark plug after failing to start the bike. They refused to give me a refund and said to fix the current problem it was going to cost 475 dollars. Anyone have any ideas on what I should do?