Overheating

[HKVolty]

Hi everyone,

I have a TU250 Volty, same engine as the GZ. Its a 1998 with 30,000km (20,000 miles)

I bought it about 6 months ago, my first bike. I'm not really hands on with mechanical stuff, but I know most of the bits and pieces and what what they do.

My bike was running fine except the clutch was slipping. So I took it to a mechanic who changed the clutch for me. Rode the bike home and parked it and everything was fine. The next time I took it for a ride, it struggled to maintain power and then started stalling after about 5 minutes on the highway. I nursed it off the highway and to the side of the road and by the time I got it there it had stalled all together and wouldn't turn over. There was smoke coming off the engine and it seemed like it had overheated quite a lot. I was in a rush to get to work so I parked it at the side of the road and walked to the train station.

I came back after work, about 10 hours later and started the bike. It started and ran, but sounded terrible. I nursed it slowly back to the mechanic and left it there for him. He adjusted the valves and told me to come back and get it. I went to pick it up and it was running fine, but on my way home it would still heat up and start stalling at temp. I turned around and took it straight back to his shop to show him. He thought it might be the spark plug cover getting the wire too hot so he changed that and readjusted the valves. The stalling seemed to stop. So I took the bike and got on the highway for about 10 minutes.

Coming off the highway at the first red light I got to the bike stalled and was in the same condition of being overheated (this time the top end had a hint of gold colour) and not being able to turn over. Let it cool down again and started it, same condition with the valves way out of spec making it sound horrible. I nursed it back to the mechanic again. I suspected he might have used the wrong grade of oil when he changed the clutch, causing it to over heat and subsequently throwing the valves out of spec. I left the bike with him and asked him to road test it next time before I come.to pick it up.

After changing the oil and adjusting the valves again, he's ridden it with the same result, the engine runs fine but overheats, struggles and the valves get out of tolerance. He suggests the problem is worm valve guides making the engine over heat and thinks I need a new top end and I should potentially replace the cylinder and piston.

The mechanic keeps blaming the guy who sold me the bike, saying the thing had a weak engine, but I had it for 6 months and it was fine until this guy changed the clutch. Has anyone heard of this before? Do you think I need to replace all these parts?

HK