I know a month is a lifetime in the world of blogging but the last month has been particularly tight in terms of time available to do anything other than work and so something had to give.
I have been working on the Scott Super Squirrel racer though, and after a trip to Leicestershire to visit my Father, Roger (and his workshop!), I’ve now at least got the bottom end of the engine together and working on the top end build.
I’ve been checking the piston to head clearances with a neat extendable rod he made years ago.
You pull it out to full length with the side clamping bolts nipped up against the spring washers, not to lock to assembly but to provide some resistance, and then you attach the piston with a dummy pin. Next barrel and head and then simply turn the engine over. Then lock the slide retaining screw up and remove. Then the centre to centre length of the rod can be compared against the length of your rod to give a reasonable indication of clearance available.
Before I re-assemble the rest of the engine, I’m taking the opportunity to start to mock up the twin carb manifold setup as it’s marginally easier to access everything without the barrel and head fitted.
I’ve had the manifold fitted before, back in about 2006, but unfortunately the engine I’d built back then suffered a rather catastrophic failure (unrelated) and by the time a new engine was built, it was put back in with the old single carb that the bike had always run with.
Excellent idea, that extendable rod- But then your dad is a very clever engineer.
Glad to see that you are following in his footsteps. Absorb all that you can, while you can. His knowledge needs to be preserved.
Herb Kephart
Hi Herb,
The rod serves as a very useful piece of equipment and though it isn’t the final word in establishing actual working clearance, it’s a good indicator.
As for Roger’s engineering ability, of course you are right. He’s also someone who get things done and that is not to be forgotten. His physical work to keep developing the engine, the fixturing, the tooling is of course critical in letting us benefit from his abilities.