Points Float Solution? Double Spring The Points?

[IanOberholtzer]

So when reading the how to build a CB350 racer page and here about Tips From CB350 Racers there is mention of when using the stock ignition setup to double spring the points to keep float at high rpm at bay.

Sounds like a good idea right? Cheap, simple, more revs out of the stock ignition but..

But if points float is pretty much the limiting factor in the ignition that keep it from over revving, this pretty much de idiot proofs the motor and could lead to trouble?

Id like to hear if anyone has tried this or has experience, and what the results where, and any pros and cons of this mod.

 

[IanOberholtzer]

found a few references

from http://www.motorcycleproject.com/motorcycle/text/sohcign.html

The Kettering system is prone to what is often called "point bounce." Actually a misnomer, point bounce really refers to point float, because it is when engine rpm overcomes the points spring. Since a floating point cuts into the coil's saturation time, the result is reduced system voltage. Point bounce is even worse with aftermarket points. The solution to point bounce is simple and like these machines, vintage. It's called double-springing, and it's easy to do. Just grind the rivets off both a used set and a new one, and bolt up the springs, piggy-backed, using the screws from the old set in place of the rivets. The difference, particularly on bikes that have engine work in them (even if just exhaust, jetting and air filters) will surprise you.

 

[tweakedlogic]

good to know. I've been looking into electronic systems to solve this problem. But I can't see spending over $500 to replace something that essentially works.

 

[Rocan]

id leave single springs. as the points float it acts as a mechanical rev limiter. in street riding you shouldn't be cranking the motor out past 11,000 rpm... and if you are, I hope you do a hell of a lot more work then just double springing the points.

 

[crazypj]

id leave single springs. as the points float it acts as a mechanical rev limiter. in street riding you shouldn't be cranking the motor out past 11,000 rpm... and if you are, I hope you do a hell of a lot more work then just double springing the points.

Cool, he beat me to it
The cam is designed to 'float' the points around 11~11,500 rpm.
Unless your doing some major top end mods, it really isn't necessary
If points 'float' at lower rpm, you need new ones.
(Ignition has probably been left on and spring overheated, 'drawing' the temper)

 

[Rocan]

see, I'm listening pj

 

[IanOberholtzer]

My thoughts exactly, keep them at regular strength to prevent me from blowing up the engine at high rpm


but would it give a better spark at rpm ranges from say 7.5k - 11.5k?

does anyone have pictures or other references of this mod just for future reference?