Topic: CB750A Advancer Question

[HondaMan]

I have a question for those of you who have looked inside the points cover at the spark advancer: I have just finished building a 750A into an 836cc bike and F2 cam. But, this engine had been previously (badly) modified, and one of the seemingly odd things is: the spark advancer is from a CB350F, but with VERY strong springs. Have any of you seen this in your bikes, or is it just another one of the oddball things the PO did to this one? There was considerable back-burn up the intake tract when I took it apart, indicating the spark timing was way off, which started the investigation that landed me there...

Honda was known for swapping parts like these into the bikes when they were short of production parts (especially in 1975-1976), but this one seems a little far-fetched?

[TdLpps]

I have a question for those of you who have looked inside the points cover at the spark advancer: I have just finished building a 750A into an 836cc bike and F2 cam. But, this engine had been previously (badly) modified, and one of the seemingly odd things is: the spark advancer is from a CB350F, but with VERY strong springs. Have any of you seen this in your bikes, or is it just another one of the oddball things the PO did to this one? There was considerable back-burn up the intake tract when I took it apart, indicating the spark timing was way off, which started the investigation that landed me there...

Honda was known for swapping parts like these into the bikes when they were short of production parts (especially in 1975-1976), but this one seems a little far-fetched?

Mark,

In doing a little research I found that the advancer assembly (at least in the '77 & '78 models, but I believe the '76 as well) part # is 30220‐333‐004.  This also shows up as the correct advancer part # for 1972 CB350F, 1974 CB350F1, and 1975-77 CB400F.  It doesn't explain the heavier than normal springs, but it looks as if Honda did include this advancer in the "A" model bikes intentionally.