Question I acquired a '76 CB750A Hondamatic as a winter project. It has about 17k miles on it. I rebuilt the carbs and synchronized them, adjusted timing, checked points, etc. It runs pretty well now. However, when starting cold, the bike makes a terrible clanking noise from (or behind) the torque converter housing. It decreases as the engine warms up or if the idle is raised. Some people have suggested that this is a common problem with the "A" model. One person thought that it sounded like the primary chain. Is that likely with 17k miles. It seems to have been well cared for otherwise. I'm just curious if you remember any service related issues with these from your dealership days. I received a spare torque converter today from e-bay and may swap it with the one in there. Thanks for any advice.
AnswerI found these on the web:
www.sohc4.net site:
http://www.greenspun.com/bboard/q-and-a-fetch-msg.tcl?msg_id=00AOue
From those answers, it isn't necessarily a sign of impending disaster. I have had little to do with these bikes, really, although my stepdad had one for a year or so.
They have a fast idle system that helps keep the bike running, but not too fast when it is dropped into gear.
It could be some kind of defect on the converter or perhaps it is draining out overnight and has to refill.
We used synthetic oil in Dad's bike and the temperature dropped markedly and it seemed to run quieter with it.
Be sure that the carbs are set to specs, the spark timing is right on the money, including smooth spark advancer action.
Best to get a factory book to use for setting up the carb and idling circuitry.
http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1&item=4513054171&ca...
http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1&item=7942819220&ca...
http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1&item=4513873019&ca...
Bill Silver
