Ok well lots to report since my last posting. The carb went back together nicely and I spent some time curing the distortion I mentioned from the overtightening of the mounting nuts. This basically consisted of a piece of 600 grade wet and dry on a flat surface upon which I gently sanded the carb mounting plate true again. I had to do the same to the carb to cylinder head mount as well which was displaying quite a pronounced warp.
Following the carb re-build and re-attach to the cylinder head the tank was tackled. The tank is easily removed from the frame following removal of the seat. It slides back and away from the bike to reveal the bikes backbone that flares down towards the back wheel/swingarm mount. The latter part of the backbone is formed using a distinctive pressed steel construction. The newly liberated tank was cleaned carefully the mud was removed from the underside and the fuel tap was cleaned up.
A quick swill with fresh petrol and that was it at this stage. New fuel line was fitted and the tank offered back to the frame and plummed in. So now the little bike was ready for the first attempts at starting. I opened the fuel tap, put on the choke, and made sure there were no airlocks in the fuel system by backing off the float bowl screw until fuel seeped from it… ignition switch in the on position I gave the bike a hefty kick… there was a slight attempt to fire, another kick and a bit of throttle and away she went… a bit tentative at first I carefully listened for any tell tale rumblings, cam chain rattles or cam journal knocks… there was a slight miss fire and after setting the idle and pilot jet screws, conservatively to start with it appeared that the cam chain was a bit rattly.
So it runs and not at all badly by all accounts. This alleviated a few of my fears as to the history of the bike and the extent of the restoration work ahead. As I was playing in the garden with the carb settings my neighbour leaned over the garden fence to find out what the noise was all about. I told him of my attempts at ressurecting the TL todate and that I was not sure it would start to which he replied:
“What do you mean you didnt think it would run… its a Honda!”
So now the engine is running with no smoke or strange noises its a tune up and check through… The points cover was removed (something I had not done to date as I had initially observed that there was a good spark from the ignition) I was greeted by a clean and tidy set of points but all of the surrounding screws including the nut that secures the mechanical advance weights to the cam were chewed up beyond all recognition! I had to use some very specific screw driver bits and a bit of force to remove them and even had to resort to an impact wrench to drift the cam nut out. (These were all replaced with equivalent allen head bolts on re-assembly except for the points gap adjusting screws.) After removing the timing plate and points the mechanical ignition advance unit was clearly visible. Essentially working on the same principles as a traction engine regulator unit and relying on centrifugal force generated by the cam spinning as the engine runs to advance the ignition timing the weights are retained by a pair of light springs and two magnets. There appeared to be a few mm’s of play in the wieghts so the springs were carefully nipped up and the play was removed completely. Removal of the cam nut using the impact wrench meant that I could take the newly reconditioned advance unit off the cam, remove the ignition houseing and reveal the cam sprocket behind.
The heads of these early tl machines were a single casting with no cam bearings as such, they just run in the head, which means that there was no option when they become worn other than to replace the head or insert some sort of bearing or bush using a local machine shop. the cam seemed solid and as the initial engine run had shown it seemed that there were no real signs of serious wear other than a rather tired looking cam sprocket that had obviously suffered from a loose cam chain thrashing around for quite some time… so I will put the cam sprocket on the xmas list and after spending an hour soaking the cam chain adjuster and lock nut in penetrating oil adjusted the cam chain to a more acceptable tension. Once all was done and put back together it was just a matter of adjusting the dynamic timing using a strobe light to align the F mark on the flyweel with the middle of the observation window in the caseing…… more to follow, it will soon be time for engine to come out and focus to switch to the frame and suspension components.