Chain tentioner measured at 20mm, about the same as the other engine so I'll button it up and make sure it runs before I put any more money into it. Ran into some problems with the side covers that I posted in a different post. Got to clean up for the night as the rain has set in and my daughter has to get ready for school tomorrow and says I can't work on it without her. She is 15 and the joy of my life so I will not argue. She has been helping me with it all day and I've been grinning like a cheshire cat!! I'll post pics of the finished engine tomorrow if it is not still raining.