problem starting 500 rotax

[sbb52y]

Hi there, I have a Harris Matchless with 500 rotax and its got an issue when trying to kick it over, engine turning over ok but when going through the starting procedure it locks up at tdc on compression.
William Patterson

[jam23a30]

Have you done any work on the bike or know its history? Sounds like the valve timing may be way out and you are getting a piston to valve contact. I would double check the valve timing first to make sure it is not 180 degrees out?

Maybe then try it with the spark plug out to see if it rolls over but be gentle if the piston is hitting a valve and you have been trying to kick start it, then it is likely the valve is now bent. Before you do that check the valve clearances and see if you can detect a valve opening as the piston rises?

Hope this helps, Andy