News 2004

23rd December

IN September I dropped of the crank at P.B. Engineering and then began to finish off some of the details ready for return of the crank.

A second plug was added to each cylinder (just visible in the photo) and external oil pipes plumbed in for the cylinder head. Initially I envisioned nice shiny braided hoses and anodized fittings, but at over £130 this was out of the question. £3 of reinforced hose and a few hours work later the job was done, with the bonus of very light weight.

A fuel cut off valve has been designed to be incorporated into the carb float bowl cover and lots of other little details finished. Unfortunately Steve was very busy with his regular cylinder refurbishing work and so I didn't get the crank back for 3 months. The next couple of weeks should see some frantic work rebuilding the engine and modifying the cams.

17th August

WHEN it came to fitting the liners and boring to size I decided to find an expert in the field. Steve at Piston Broke Engineering in Bristol (0117 9412300) was highly recommended; so the block, liners and 2nd hand Wiseco pistons were dropped off in Easton. This proved to be a very good move as Steve is a perfectionist and did a beautiful job, matching the bores precisely to individual pistons. Better still Steve has the facilities to rephase a crank to any angle I cared to suggest.

I didn't really fancy taking out the cylinder studs, as I thought it might weaken the cases in this critical area. In fact the standard case was swollen around the threads. So I made an extreme extension for the boring head and completed the job without drama.

FILLED with enthusiasm, after talking to Steve, I selected an old exhaust camshaft for trial modification. 2 keyways were cut at 45° and the cam hacksawed in half. A tubular sleeve was inserted into the cam bore and the 2 halves reunited with the keyways aligned. Welding was a bit of a trial, as I was concerned that either it would chill and become brittle or the cam lobe would be soften. Miraculously it seems fine, and better still alignment is spot on so it seems as though crank modification is ON!

THANKS to all those who contacted me with helpful tips on twin cylinder crank phasing. I've now decided on a compromise of 60° for various reasons: cylinder filling, ease of cam modification etc.

24th July, revised 25th

HOW'S about this for frequent updates?

WHILST stripping the race engine to bore the crankcase mouths I couldn't resist dropping the new billet cylinder block on and fitting the clutch cover to see what it would look like.

I'M still pondering what to do about the crank configuration; even more so now I have thought of a way to cut, twist and weld the cams. Do I go to 360° for even filling, but filling loosening vibration? How about 90° for smoother running or 45° for a compromise? Or do I leave it at 180° to begin with, suggestions welcome!

21st July

WHERE did the last four months go, and what happened to those more frequent updates?

DESPITE the lack of updates, work on the bike is progressing well, though even I have to admit it probably won't be on the track this season.
After careful consideration I decided that I didn't want to run the supercharger backwards and so the casing has been turned 180° whilst the drive end stays as before. Four of the screw holes had to be plugged and then redrilled and helicoiled. The outlet now faces to the rear and has worked out really well, giving a reasonable volume between blower and cylinder head. I had to cut off the rearward facing inlet scoop and weld a plate over it to take a swoopy new inlet manifold for the carb.

A new engine pulley (incorporating degree disc) was made to take the multi rib PK type drive belt, sourced from a local VW/Audi parts centre for less than £10 (the toothed belt used last year cost £60!). The belt guard is nearly finished, footrests repositioned and aluminium controls made; in fact the bike is more or less ready to come apart for the frame welding to be finished and the race engine fitted. However the special big bore engine is still under construction.

AFTER a great deal of thought about low slung fuel tanks and fuel pumps, sanity prevailed and I made a gravity feed tank to go alongside the top frame tube. Next up is an automatic fuel shut off valve, possibly integrated into the carb float bowl.

GIVEN that we probably won't be out on the track in 2004 I am considering changing the crank to 360° format in order to be sure we get even cylinder filling. Being of built up construction, changing the crank is easy enough but the cams are a different story. They are cast iron with integral cam sprockets and have a hole up the centre which may be helpful if it is bored rather than cored. Having some spares I think one will be chopped in half for experiments, more winter fun in the workshop!

24th January

WELL that's the easy bit over (below) all I've got to do now is open out those pilot holes for the cylinder bores from 12mm to 80mm!

Some time later and were ready to machine out the cam chain tunnel. Check back next week for more exciting (?) progress.

1st February

TIME was a bit short this weekend but as you can see the cam chain tunnel has been roughed out and some material removed to expose the base flange. Now you can see why the lump of metal was so big, those pockets front and rear are to clear two of the many camchain guide rollers.

5th February

SOME spare time this week has allowed me to push ahead: as below, the hole for the camchain tensioner is milled, and right some hours later it's beginning to take shape.

22nd January

AT last work on installing the Eaton supercharger has begun. Having pondered at length over exactly how to position the blower, I decided that the mountings could be combined with some additional frame bracing which I feel sure will soon be necessary anyhow.

DUE to the shape of the blower, the CofG is on the centerline of the bike unlike the previous Shorrocks. Manifolds are going to be a little complicated crossing over one another, but the carburetor will be lower than before which should help with last years fuel starvation problem. An electric fuel pump is planned at some later point.

THE new clutch cover and external oil filter is ready to fit, and this weekend has been set aside to carve a new cylinder block from solid to take larger spun cast iron liners. Honda didn't make my life easy by having studs and dowels in an asymmetric layout for each cylinder!

NOW I've joined the digital revolution photo updates will be much more frequent.