Sometimes it's a bit disturbing to have an engineering background. Part of engineering is anticipating problems, and their solutions, even before they happen. I went for a 50+ mile ride yesterday and another one today as part of the pre-ride testing program. Those thankfully trouble free hours of tiddling around the back roads near my home left plenty of time for my mind to wander. Unfortunately it wandered into a place that I would rather it had not gone. It strayed off into the mental gallery of pictures of motorcyclists (OK, me!) standing alongside the road, immobile. The victim of the treachery of old two stroke motorcycles. Of course it is necessary to consider this. In just 5 weeks now we're going to take off on a trip of almost 3000 miles. Now if I averaged a paltry 40mph for this trip it would take some 75 hours of riding time. Right. 60 minutes to the hour means that's it's a 4500 minute cruise from here to Athena. Now the disconcerting part. At 40mph the 125 Wombat engine is turning about 5200 rpms in 5th gear. Multiply that out and it means that my buzzy little ring-a-ding is going to turn over a minimum of some 23 MILLION REVOLUTIONS during the course of the trip. 23 Million! That poor little piston, which would fit nicely in the coffee cup I'm holding in my hand, is gonna go up and down 23 million times. The tiny crankshaft, now almost 35 years old, is going to spin around in those bearings 23 million times. The ignition points will have to reliably open and close, hopefully firing that poor overheated spark plug, over 23 million times! You get the picture. 23 million is a whole lotta times for anything to happen. The potential for mechanical heartbreak lurks everywhere. I guess that's why a lot of time and thought has been expended in upgrading an already stout (by 1977 standards at least!) piece with durability, reliability, and serviceability improvements. Here, for your consideration are a number of the things we've done to improve our chances of success.
Hopefully this yields a power producing section a little more tolerant of heat, friction, and more resistant to seizing.
The crank got attention too. "Hodaka Dave" Rozier disassembled it, cleaned up the small amount of corrosion on the journals (the bane of old bike stuff that's been sitting around for decades!), carefully checked out the bearings and pressed it all back together while meticulously indexing everything to factory specs. Thanks Dave.
While that stuff was going on with the power producing bits, the transmission and the rest of the drivetrain was getting attention too. First, every rotating piece was crack checked with magnaflux and then shipped off to WPC Metal Treatment Technoligies in California
(http://www.wpctreatment.com/). Better surface finish, less friction, and improved fatigue life are all proven outcomes of WPC's process and a really good thing for 35 year old gearbox parts.
Needless to say, the engine also got the usual new bearings and seals everywhere, not to mention the cleanup and careful inspection of the cases and everything else.
The question of whether to use the oil injection pump or go with premix of oil and gas has been a decision that has brought quite a bit of angst. In order to allow for all eventualities, I went ahead and made the case necessary modification required on 03 Wombats to provide an auxiliary port to let the left crank bearing receive oil from the fuel premix. This is done by drilling a vertical feed hole from the left side transfer port vertically into the bearing gallery.
Now I can run premix should I choose. Of course I also did a great deal of bench testing of the oil pumps that I have in stock and picked the unit with the highest flow. Final decision not made yet but at least I have options.
Of course there are other potential sources of mechanical disappointment beyond the engine. This led to a contemporary o-ring chain,
new wheel bearings, and of course, new tires equipped with Michelin Ultra Heavy Duty tubes. These things are 4mm thick and I swear they are so heavy that one could probably ride to Oregon on just the tubes! And, spares will ride with us.