Honda-SOHC

I have noticed that some people mention dynamic timing.

I have always static timed mine and it seems to run fine.  Does dynamic timing actually make a difference?

What is dwell? Does this only apply in the USA?

"This was the CG125...not sure if this engine is retrofittable to other 125 single frames or not though."

I believe it does fit into both 125s and J models and is a little more reliable.

Riding in the snow is great fun.  However, I had a near miss in the snow a few years ago.  I was riding my CX500 in terrible snow late one night on a quiet country road.  After about four attempts at getting up a particularly steep hill (Shropshire) I fell off and the bike landed with the wheels uphill.  I couldn't get enough grip with my feet to pick the thing up so I paused for a roll-up and to think about what to do when I noticed headlights in the distance.  I had to run up the hill as fast as I could because I worried that the approaching motorist would not be able to stop and would skid into the bike with obvious disastrous results.  I managed to flag down the bemused driver.  He kindly helped me lift the bike onto it's wheels and together we scraped a track down the hill so I could get it bump-started again.

Some bikes are better than others in the snow.  My CX was terrible because it was just too heavy.  My CB500/4 is no better because you have to rev too much to get moving.  I think the best bike I've had for snow was my CB350K.  Lowish centre of gravity, not too heavy and torquey at the bottom end.

I had one of these many years ago. unfortunately, being very young, I used to thrash the life out of it and eventually the exhaust valve snapped and wrecked the engine.

I also had several CB125S models.  When they were running they were fine and fun to ride but they all suffer from being a little underpowered.  I rebuilt several of these engines.  They are very easy to work on but they were always worn out when I got hold of them and I would try to get them going on a limited budget.  As Dave says, the camshaft runs straight into the head. The contact breaker points run on the end of the cam and if there is wear it is difficult to time the ignition correctly and consequently they become very prone to overheating.

The slightly later CG125 engine has push-rods and is very much more reliable.

The best 125 I had, by far, was a 1977 CB125 Twin (not the restricted later model) which was SOHC and was very reliable despite my excessive throttle hand.  It would just touch 80 MPH and accelerated quite well for a 125 four stroke as long as you wound it up to 11 000 RPM!  They are great bikes and sometimes come up for sale.  The only downside with them was Honda's awful cable operated front disk brake, but actually when adjusted correctly just about worked well enough.

...hard to find when riding.  I find that it only needs choke to start and then only for a few seconds more.  I then switch it off and move away.

Make sure you have the ring gaps in different places, say 12 o'clock, 4 o'clock 8 o'clock.......
Start with the middle cylinders, smear the cylinder wall with lots of oil.  Once the piston is introduced into the lip the rings should guide in by themselves.  Use your fingers to squeeze them in but don't force the piston too hard.  Gently rocking the piston on the gudgeon pin axis helps too.  Take your time and you should find it easier than you might think.

My motad system is just about to fall off and is mostly held together with gun-gum.  Can anyone recommend a way to put a four into two system on.  What I really want to do is to have two, two into one down-tubes, going into dunstall type silencers.  Any ideas about what is available in the down-tube deptartment? cb650?

Thank you, If I can repair the old one that would be really good.  I noticed also that the odometer stopped turning.  If you can let me have the pdf that would be excellent.