Seven Day Montesa Motor Rebuild

My posts usually are about some of the high-end restorations that I do when everything has to be just so. In this case, a good friend has this Montesa trials bike that he wanted to ride and enjoy, but would like it to still be presentable. The bike was a well preserved, running motorcycle when he purchased it. He rode it around a bit, but wanted to go over everything to make sure it would work and last a long time. So that meant the usual tires, chain, lube and adjust. And a spray can refinish. He asked me my opinion on what to do with the motor. My belief on a 40 year old motor that ran but had never been apart should have a little love and attention. Seals dry up as well as gaskets too. Rust can form on parts that will turn into a grinding wheel and may cause something to fail that could be expensive to fix on the other end. After a couple of texts back and forth on a plan, I told him to just send it to me and I would be happy to go over it. Below are photos and descriptions on the process that took seven days here in the shop. Showing that you don't always need to go overboard to have a presentable, running motor. And it does help when you start with a bike that is all there to begin with.

Another personal tip: It seems like everyone is on the 'vapor blasting' train. I have nothingr against it for some things. It does a good job. But in my opinion, a good quality 100-200 grit glass bead (not the junk bag of sharp rocks from the big box stores) does just a nice of a job.