Post
by pc13cb92 » Fri Apr 15, 2011 5:13 pm
Hi, I can't add to this technical discussion, but I have rebuilt my spare C72 over the winter. It's now in the bike on my workbench and it starts and revs well, but the revs don't drop immediately when the throttle is closed. I've done all the checks, fitted new carb O-rings (both), can't find a leak, and have put a new correct throttle cable on. From what I've learned through this forum it points to worn advancer springs. This means its coming out again!
When I rebuilt it I had a choice of 3 used cam sprockets, and I hadn't realised the differences in them apart from the big bulky one ( which I thought was the later type - and went with that one to fit). At this point I must say that all of my used engine parts have ended up in one box, due to several house moves over the last twenty years, and they include a mix of CB72 CB77 C72 and C77. Due to this method of storage I managed to build the c72 engine with a CB72 points shaft!. When I couldn't set the timing it took me a while to work out what I had done. I ordered a brand new one from Dave Silver here in the UK and it fitted with no problem. I didn't realise there were different thickness shafts.
From the pics on this thread I have identified the correct Dream sprocket, and I will source some new springs and then fit this one.
This forum has helped me enormously with all of the info I needed, (usually after the event) and I would be embarassed to list all of the wrong things I did during the rebuild, but realised and went back to redo.
When the bike comes down from the bench I will attempt to post a pic.
pc13cb92
