KC@ BRG Racing
New member
This is an article that I get a for the SV section on my website and thought the SV riders on the barf list might like to see. Sorry if it comes across like an and their other router setups out there some cheaper some a lot more expensive.
Since the inception of the SV650 in 1990 the bike has come along way. When it was first released, the bike was making approximately 70 hp, not a monster but certainly good enough to get it down the freeway at reasonable speeds. The picture below is the result of racing on the stock crankshaft, stator, and rotor.
.
At first, we all stepped back and said, I wonder how that happened? Being a curious sort, I started looking closely at how much the stator and rotor weigh along with all the starter mechanism and come to find out that it weighs in at what I think is pretty heavy 2300to 2400 grams. That is just over 5 pounds. Now on the stock motor with a stock power pulses this is not a big problem, but as soon as you start screwing the motor down and getting over 85 to 100 hp, it becomes a big problem. Every time the piston fires, the crank shaft will try to accelerate. The rotor, being this rather large heavy mass, especially at eight - ten thousand RPMs is countering, trying to stop it. With enough stress cycles (accels / decels) the crankshaft, having that little stress riser of an oil supply hole becomes a sacrificial part. As we know, when the nose of the crank breaks off, this lets the ignition rotor loose and it goes into the charging coils usually wiping those out. In really bad cases, takes out the ignition. At that point, you're looking at replacing the whole motor. Big dollars
Well, in looking at all of this and talking with some other tuner friends of mine, we came to the conclusion that there is considerable weight to get rid of on that ignition rotor set up. Starting with the huge one-way roller Sprag-clutch assembly, it alone weighs in at approximately 626 g.
Certainly we could get rid of some weight here.
Here is a picture of the roller Sprag assembly after being cut on the lathe (left). Next, we put it in the cnc lathe and take even more weight off of it (right). We go from 620 + grams to 302 grams. A significant drop in rotational mass
Then, the rotor itself is almost a quarter of an inch thick; certainly we could lose some weight there. We take almost .100 off the circumference, leaving the ignition triggers (bottom).
Lastly, the magnets that run the ignition, do we need all six? Well, for the hard-core SV race or where less is always more, we have found over the last couple of years that we really only needed two magnets to keep the charging system functional. The race bikes don't have lights, turn signals handgrip warmers or any of that other stuff to keep working. All we have is ignition system, (and in the second GEN the fuel pump) two magnets work just fine.
So, if you have had problems with crank breakage on your SV, or you've seen the carnage done by a broken crank on your buddies SV and you'd like to try and avoid it, this is the solution. We've got a good reputation for making good horsepower and durability with our motors. This is one reason why.
Thanks for reading and let us know if we can help.
The Home of A Sickness for Quickness
K.C. Owner of BRG Racing Products and Dyno Services
kc@brgracing.com
Shop # 925-680-2560
Toll Free # 1-877-ride-brg
Address
110 2nd Ave South Unit D 12
Pacheco Ca 94553
Since the inception of the SV650 in 1990 the bike has come along way. When it was first released, the bike was making approximately 70 hp, not a monster but certainly good enough to get it down the freeway at reasonable speeds. The picture below is the result of racing on the stock crankshaft, stator, and rotor.
.
At first, we all stepped back and said, I wonder how that happened? Being a curious sort, I started looking closely at how much the stator and rotor weigh along with all the starter mechanism and come to find out that it weighs in at what I think is pretty heavy 2300to 2400 grams. That is just over 5 pounds. Now on the stock motor with a stock power pulses this is not a big problem, but as soon as you start screwing the motor down and getting over 85 to 100 hp, it becomes a big problem. Every time the piston fires, the crank shaft will try to accelerate. The rotor, being this rather large heavy mass, especially at eight - ten thousand RPMs is countering, trying to stop it. With enough stress cycles (accels / decels) the crankshaft, having that little stress riser of an oil supply hole becomes a sacrificial part. As we know, when the nose of the crank breaks off, this lets the ignition rotor loose and it goes into the charging coils usually wiping those out. In really bad cases, takes out the ignition. At that point, you're looking at replacing the whole motor. Big dollars
Well, in looking at all of this and talking with some other tuner friends of mine, we came to the conclusion that there is considerable weight to get rid of on that ignition rotor set up. Starting with the huge one-way roller Sprag-clutch assembly, it alone weighs in at approximately 626 g.
Certainly we could get rid of some weight here.
Here is a picture of the roller Sprag assembly after being cut on the lathe (left). Next, we put it in the cnc lathe and take even more weight off of it (right). We go from 620 + grams to 302 grams. A significant drop in rotational mass
Then, the rotor itself is almost a quarter of an inch thick; certainly we could lose some weight there. We take almost .100 off the circumference, leaving the ignition triggers (bottom).
Lastly, the magnets that run the ignition, do we need all six? Well, for the hard-core SV race or where less is always more, we have found over the last couple of years that we really only needed two magnets to keep the charging system functional. The race bikes don't have lights, turn signals handgrip warmers or any of that other stuff to keep working. All we have is ignition system, (and in the second GEN the fuel pump) two magnets work just fine.
So, if you have had problems with crank breakage on your SV, or you've seen the carnage done by a broken crank on your buddies SV and you'd like to try and avoid it, this is the solution. We've got a good reputation for making good horsepower and durability with our motors. This is one reason why.
Thanks for reading and let us know if we can help.
The Home of A Sickness for Quickness
K.C. Owner of BRG Racing Products and Dyno Services
kc@brgracing.com
Shop # 925-680-2560
Toll Free # 1-877-ride-brg
Address
110 2nd Ave South Unit D 12
Pacheco Ca 94553
