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Boyer Ignition cb750

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gp_st3:
Thanks for the first post welcome Phil, finally ’broken my duck’!

A bit more about the Boyer - in addition to not following the Honda recommendation for the full advance point by some margin, @1100 RPM tick-over the ignition fires about 2 to 3 degrees ahead of the ‘F’ static timing point, which is also a surprise.

Could be that Boyer’s engineers have optimised/improved on Honda’s probably conservative spec (itself constrained by the relatively crude mechanical advance) or perhaps the basic module and timing profile is sold by Boyer for a number of motorcycle models including the CB750 and is therefore a compromise to suit a range of specifications...

It would be good to hear what you think when you have road tested because although happy with the performance, I have only ridden one CB750 so have no basis for comparison!

philward:
Will do but I'm a few months off fire up on the CR Rep. Additionally, I am running a 836 kit, race exhaust and ram air foam pods so I think I will have some set up issues that I wont be able to isolate from any Boyer related issues. There's plenty of members on here though who are running the system on 750's so perhaps they can give you some feedback?

gtmdriver:

--- Quote from: gp_st3 on March 24, 2018, 10:34:42 AM ---

Could be that Boyer’s engineers have optimised/improved on Honda’s probably conservative spec (itself constrained by the relatively crude mechanical advance) or perhaps the basic module and timing profile is sold by Boyer for a number of motorcycle models including the CB750 and is therefore a compromise to suit a range of specifications...


--- End quote ---

Basically yes.

The Boyer advance curve is controlled electronically and has been optimised compared to the OEM mechanical system and, as far as I know, they list the same control unit for all the Honda fours of that period.

Seabeowner:
When we were comparing 300 (750) and 323 (500/550) bob weight advancers some time ago we noticed the difference. The "F" mark is more advanced on the 750.
But according to legend the 750 "F" is 10deg and the advance 25deg and the 500 "F" is 5deg but advance is also 25deg. Both are supposed to top out at 2500rpm.
I think 333 (350) advancers are same as 323, not sure what was on 400s.
So luckily for Boyer the advance is the same for all.
Also rumour has it that the advance of some later 750 was different.

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