Engine overhaul

Engine overhaul

Okay. What to repair, what to replace and what to upgrade?

This section is a recent invention, intended to house thoughts on what to do better than what Honda’s engineers could offer in 1973. Without breaking the bank.

New top-end

The engine is largely original, meaning it sports a choked-down, respiration-abused abomination of a cylinderhead to fit danish moped-regulations anno 1973. The cylinderhead and the accompanying cylinder are a matching 50cc-set, further reducing my desire to press the kit into service as a motorcycle powerplant basis. Also, the cam sports no ball-bearings and is worn.

Easy decision; new 70cc top end sporting a ball-bearing equipped camshaft,  larger valves and an unrestricted respiration. Drop-in-replacement. From China.

Should the need arise down the line, a proper OE topend could be an upgrade.

Yes, I know. THere are lots of big-bore-kits out there. Four-valve upgrades, High lift cams. LOng list, and I choose to not go that way. This is not going to be a race engine, but an upgrade to what the engine was meant to be – which is NOT 50cc choked-down moped-material, but a mini-motorcycle.

New ignition, new alternator

Safety first.

I’ve lived with the crummy 6V system back then because then there was no alternative. To say the headlight is insufficient is a simple understatement. Here, Jeremy Clarksons exclamation “POWER!!” fits right in. Bigger bulb. Newer reflector. More power. 12.

I lived with the mechanical points system for the same reason. No more. The OE system has to go, being replaced by a properly advancing CDI. Again, danish authorities in 1973 mandated that the OE ignitition be ‘frozen’ solid to limit the engine to – wait for it – 1 bhp by abusing the ignition to prevent it revving properly.

Also, there’s the subject of comfort and reliability. I’ll let you come up with your own arguments in favor of mechanical points…

New clutch

The OE clutch was failing. Worn plates. I’ve replaced the unit – and the driven gear –  with a Takegawa heavy duty race clutch. And regretted it. Crappy stuff, making me wish for the old clutch.

For starters; why supply me with a steel bearing sleeve when the OE is bronze? And the plainly apparent crude manufacture finish made me think this was a ‘single use’ object. Oh well, let’s give it a chance to prove its worth…

No. It needs to go. It sticks. And for lack of better words it’s ‘blunt’. No refinement. No smoothness. And an unpleasant ‘klonk’ and whine making my ears hurt.