Honda-SOHC

Hello all.

Sorry for disappearing on you all late last year. I have been flat out clearing my Callander ready to attack the rebuild.

I am pleased to report that I have now got my teeth well into the rebuild and thought it was time I gave you all an update on my progress so far.

Since my last posts, I have spent many an evening researching and violating parts and knowledge from friends and the beloved you tube.

I now have the crankcase split and have retrieved the cam chain guide which appears to have been the initial offending part that caused the cam chain to break in the first place. In 600 miles since the previous owner had done a “top end” rebuild. The cam chain had been orb completely through the guide face and then right through the steel backing, getting caught on the backing and subsequently breaking the chain. Lucky for me, as the engine had only been running for a short time under these conditions it has not done a huge amount of damage. The big end and main bearing are caked in steel particles from the guide and are no good, but this has not damaged the journals.

So. After this investigation, I have now a big long list of parts on the way for the rebuild. Luckily I only needed one pair of A bearings (the rare and elusive A bearing) my local engineer shop has measured the crank and has said a B bearing still brings me within clearance. 

I have had the top and bottom end vapour blasted and some of the covers, I’ve also made a couple of repairs to the bore fins and painted the block. Whilst in the bottom end I’ve found the reason for poor fifth gear selection. Worn main shift fork. I’ve sourced all new bearings apart from three which are no longer available and again, luckily. These three are still good in the original, so will be going back in along with a multitude of new parts. David Silver and CMSNL have both done very well out of me over the past few months.

I have spent hours cleaning up parts and polishing out some slight corrosion on some parts in the bottom end. It seems this bike may have been say for a while at some point in its life. A few parts like the shift drum had some minor pitting and the shift fork spindle. So out came the polishing paste’s and away I went.

So enough of my waffle. Here are some pics for your rainy days.

Ah!

Thanks for that info Steve. Sensible!

You may all regret me passing the initiation proc as though!

Richard

Thanks Laverda

That all sounds a bit long winded for this technophobe! Not even sure I have messenger.

Thanks for the suggestion though. I checked the file sizes and they were well within the plaited KB stated on the site?

I'll give it a go and see what happens!

Richard

Hi Bryanj

The main problem it seems I may have is that the cam seats may be worn and it is suspect that some of the rocker arm spindle seats may also be worn. Couple that together with what we may find in the bottom end and it's looking as though it could be an extremely expensive rebuild.

It would be good to know if any of the later model lumps would fit straight into my 1976 frame?
I am maybe looking down the route of a later doner bike that I can rob the engine and rebuild before fitting back into my new/useless toy.
 
Any info on this as an option would be greatly appreciated.

Richard

Hi all.

Thanks for the response to my cry for help!

I am having trouble with posting a reply. So if 3 appear I do apologies.

It seems so far that the chain broke on a link and has done no extra damage other than taking the guide out with it. The top sprocket is damaged on the teeth edges and I have not got to the bottom one yet. Next job is to split the crankcase and have a good look around at what may need doing whilst in there retrieving parts.

Thanks for the offers Oddjob and Brynanj if either of you do dig a top sprocket out of your stored, I would be very happy to part with beer tokens for your efforts. Let me know if you have any joy on that front.

Richard