SOHC.co.uk Forums > CB500/550
Reprofiled camshaft
DomP:
--- Quote from: Oddjob on October 27, 2023, 03:57:16 PM ---5 degrees of overlap and 10 degrees of duration is the recommended settings to give to Newmans. They have confirmed they can do this.
I'll detail the timing issue later
--- End quote ---
There's a timing issue?
Oddjob:
Here's the details of the timing.
Advance the timing 2 degrees static, but cut off one turn from the springs on the advancer and reshape the end of the next coil so the springs will fit back onto the advancer mounts. This slows the advance curve about 5%-8%, depending on the year of your bike.
Not my idea, got that off the web on a well known expert on these engines.
It's done to address the mid range flat spot.
He also added this.
Raise the jet needle in the carb slides one notch. Install a 10-size smaller main jet at the same time (5 size smaller on last-year CB550). Switch from the standard D7E (NGK) or X22E (ND) sparkplugs to the D8E (X24E) at this same time. Check the color of your plugs to make sure it does not get too lean, which can happen if you’ve installed individual air filters and/or headers that actually work (most did not), or longer, megaphone-type mufflers.
DomP:
Does the timing have to be altered with the suggested cam profile Ken or is that just to eek a bit more out of it? I'd rather leave my carbs as stock as possible if I can having spent quite some time sorting them.
What I have noticed is that my advanced springs have been cut and reshaped already, I can see the sharp snipped ends and reshaped loops on the ends.
Oddjob:
No you can leave the timing at stock, although if the springs have already been cut that will have altered the timing somewhat but nothing to worry you. Carbs can be left standard as well. Only do what you feel comfortable doing, if you want stock advance springs I’ll swap you for yours, try counting the coils though to confirm they are shorter than stock
Bryanj:
I vaugly remember fitting a fast street yoshimura cam to a 500 and it neede more advance (38deg ithink) and a bigger rear sprocket to run right as it had more power at high revs but less low down
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