Went to start my 350 TR 77 after a carburettor rebuild And because of a recent injury I can't kickstart it so I used a roller starter I noticed that the bike was backfiring on start up and wouldn't run .It was then I noticed that some of the back fire was between the head and the barrel so it definitely looks likely the head gasket is fubar.. sorry for the long post but how easy is it to fit a New gasket And is there anything that I should be aware of?? 

Many thanks 

Phil B 

Phil, it’s very easy to replace a head gasket/o-rings. I did it for the first time and it only took about 15 minutes and I’m no mechanic. Simply unbolt the head, lift it off, clean the surfaces, place new gasket/o-rings on then bolt it back together, tightening the bolts in a criss cross pattern, little by little, until the torque requirement so you don’t bend/warp the head. I believe your bike is air cooled so you don’t need to worry about draining the coolant. I had a friend in high school years ago, who had no experience mechanically, and he replaced his head gaskets on a TY 250 with no internet or YouTube to help. It’s very straightforward.
 

You can do it yourself for sure. Good luck!

On 9/21/2025 at 1:04 AM, RonH said:

Phil, it’s very easy to replace a head gasket/o-rings. I did it for the first time and it only took about 15 minutes and I’m no mechanic. Simply unbolt the head, lift it off, clean the surfaces, place new gasket/o-rings on then bolt it back together, tightening the bolts in a criss cross pattern, little by little, until the torque requirement so you don’t bend/warp the head. I believe your bike is air cooled so you don’t need to worry about draining the coolant. I had a friend in high school years ago, who had no experience mechanically, and he replaced his head gaskets on a TY 250 with no internet or YouTube to help. It’s very straightforward.
 

You can do it yourself for sure. Good luck!

Many thanks 👍