Compu-Fire 55402 R/R dimensions: 3.5" x 2.5".
So the mounting holes' center to center is about 3.00" (76.2mm), and should be easy enough to adapt. Stock is 70mm center to center.
posplayr: "Wheat dog has confirmed a nominal 30 degF drop in (engine) operating temp for an 83 GS1100ED with 1166 kit after making this change over to the Compufire-Fire R/R... Bottom line this is a very nice unit, my bike is running even cooler just going 4-5K RPM and I can put and hold my gloved hand over the stator cover (which was painful before).
Just to summarize the issues; Most all motorcycle charging systems (except some alternator equipped bikes) use Permanent Magnet (PM) multi phase generators and the ubiquitous SHUNT regulator. The SHUNT regulator is easy to implement and is cheap. That is the only thing good about it. The PM generator is capable of producing power in relation to the square of the RPM but only up to limit in proportion to the magnetic strength of the rotor. The SHUNT regulator shorts the stator out when too much voltage is going to the electrical system. At high RPM's the stator is producing the max power as limited by the rotor magnetic Field. It produces a lot of heat. For example for the GS1100ED I have I measured about a 250W drop in power which equates to about 30 degree drop in operating temperature for an 1166 inline 4.
The PM generator with shunt regulation is a brute force implementation with a delicate balance to keep it functioning and avoiding frying the stator too fast. A SERIES r/r solves these problems and is more efficient than even an alternator."
The MOSFET term gets thrown around a lot, in an imprecise way that I think is going to confuse a lot of people.
When sorting through all of this information, it's important to realize that the word MOSFET is not really that helpful in describing the regulator that the merchant is selling.
The term "MOSFET" describes a particular type of semiconductor -- a generic Metal-Oxide-Semiconductor Field-Effect Transistor. This kind of generic transistor can be found in all sorts of devices, including shunt regulators, series regulators, and switching regulators. From a practical standpoint, when a supplier is marketing their Vreg to you using the term MOSFET, their pitch doesn't really give you any useful information. You'd probably be best of ignoring the word MOSFET and looking at other details.
When sorting through all of this information, try to recognize the deceptive marketing practices of some of the merchants for what they are; Some suppliers are leveraging the word "MOSFET" to try to exploit the confusion that it will cause for many people.
"MOSFET" sounds fancy, and the expectation of some merchants is that using this term will make some potential customers think that their regulator is something more special than it really is. This is particularly true of Shindengen, who uses the term to try to put lipstick on that pig that is their shunt regulator. They try to use the word "MOSFET" to blur the distinction in the mind of the customer between their shunt regulator and a true series regulator, or a switching regulator.
Don't be fooled when a manufacturer hypes the word "MOSFET" in describing their shunt regulator -- they're hoping that someone who doesn't know any better will confuse their shunt regulator with a more desirable, more electronically sophisticated series regulator and buy their product.
You probably already realize from all of the posts on this forum that you want to avoid a shunt regulator at all costs, and buy a true series regulator. Be careful so that some merchants' don't pull the wool over your eyes when they tell you that their vreg uses MOSFET. What you really want to know is whether the design you're looking at is a shunt, series, or switching regulator.