I have a 2003 honda 350 rancher TM. How can I tell if it jumped time or if the head gasket is bad. It is blowing back through the carb and backfiring when I go to start it

 

That happened to me once and you'll never believe what the problem was. Spark plug. Yep. I replaced it and all was fine. Worth a try.

 

i changed the plug i still have the same problem

 

I'm going to assume you adjusted the valves...right?

Since the engine uses a push rod, overhead valve arrangement, it most likely is not a valve timing problem. I would double check the valves to make sure they are set correctly and are not being held open when trying to start the engine.

 

yes i adjusted the valves. when it took this fit it was running fine i shut it off and it hasn't started since. I cleaned the carb and installed a new plug still the same thing. Could the head gasket be bad I am lost. It is getting fuel and has good spark

 

Okay... a good spark at the right time and fuel...it should run....

Only other thing to check is cylinder compression.

I would double check those valve adjustments again. I'm not trying to berate you or cause you to think that I doubt what you are doing but we are human and we do make mistakes.
If the valves are set with too little clearance, they won't seat properly, in other words, stay open and the cylinder can't build up the proper compression to run.

So please double check the valve clearance. If it is blowing back through the carb, that tells me the intake valve is not seating which could be improper clearance or carbon build up on the valve seat.

May be time to pull the head and have a look in the combustion chamber..

 

I want to thank you for the replies. It turns out my old rancher jumped time. I took it to a shop and the guy took it apart while I was there and showed me what the problem was He said as wore out as it was i was lucky that it didnt tear up more but it didnt. We also checked out the reat of the motor the only other thing we found was the bored was egged shaped so i am having it bored and a new piston and rings installed too again thanks for the info that you gave me