KNOCKING YOUR BLOCK OFF
Keith Livingstone has decided to rebuild his Honda 400 Four after 92,000 miles. He says: “Japanese bikes took reliability to a new level – the only problem is that it’s been together so long now, it doesn’t want to come apart!”
Keith tried the recommended technique of drifting the reinforced ‘408cc’ bit of casting to remove the cylinder with no success and asks if I have any ideas. I had this trouble with the 400 Four I rebuilt a few years back; the cylinder is located on tight-fitting dowels and striking the ‘safe’ 408cc panel just rocks the cylinder when it really needs a vertical lift. Thumping it from opposite sides would be better, but the fins are too fragile. My solution was to lay a block of timber flat against the fin edges and strike it alternately with the ‘408cc’ platform. By supporting the block on as many fins as possible and hitting them end-on, there’s much less chance of breaking anything.
It worked for me, but Keith was not so lucky. Corrosion of the exposed front studs were his problem – and two weeks’ soaking with penetrating oil failed miserably. He then heated the barrel for 45 minutes with a blowlamp, which finally saw the gasket break. A couple more evenings got the cylinder up by 10mm, but the game wasn’t over; the studs are waisted, so having got the cylinder to the top of the studs after further evenings of scraping and drifting, it jammed on the fatter threaded portion! But Plusgas and more effort finally freed it. Well done, Keith!
I must admit, this reminds me how proud I was to get my Triumph top end perfectly oil tight for the first time – until all the cylinder head bolts started going rusty. I guess you can’t have it all ways!