Honda SL125 Engine

I was asked to restore this Honda SL125 engine, the current owner thought the bike had been found in a lake. 

This would explain the very rust condition of the internals with a seized and unusable barrel and piston and a seized and rusty gear box. Thankfully a donor CB125 engine was also supplied as source of needy parts.

Looks OK at this stage :-)

With the head, cam and timing chain removed the rust on the barrel can be just seen even though there is evidence of oil, the piston took many hours of persuasion to leave it's home

Not sure it's worth trying to free those valves, I'll be restoring the head from the CB as they are identical

Many hours later and the piston is free from the barrel

Possibly the most rusty barrel I've seen, would rebore ok, but again the CB barrel will be the one used

Oh dear, lots of evidence of water in the oil and most things are rusty and seized

Cogs don't look that worn, but don't want to move much either

Thankfully the CB engine is in much better condition

Both Engines fully stripped

Next job is to degrease all the casings, remove the old bearings and get the casings sent off for vapour blasting

Now that's a bit better - super job by Peterborough Plating

Just as good on the other casing

Side casings nice and clean but quite pitted so will need work before they can be painted

It's a few years since I had to grind valves in

Perfect non pitted valve seats

Valves, followers and cam fitted with new seal ready

Crank rebuild and bearing set from CB Tuning installed with gears

Gears stripped checked and cleaned

Clutch plates checked, cleaned and re-oiled

Cam chain and adjusters installed

Ready for side casings

Alternator and final drive installed

Head bolts and valve caps polished

New piston and barrel installed

Head fitted and timing all set

Finished engine with painted and polished casings