cooling fan hot wired on

[06450F]

Noticed the fan is hot wired to turn on with the ignition on the SP-1 i picked up. Is this a common mod with any benefit worth me leaving it?

I know it will help keep her cool, but the sound is sort of annoying.

Or does this pig run hot enough that the fan will likely be running pretty much always anyhow?

[g-man]

Hot-wiring the fan to run constantly is not a standard mod by any means and depending if the previous owner changed the direction of the fan rotation or not, a fairly bone-headed move.

On the street, my RC51 runs at about 185 as long as the bike is moving but likr all RC51's will climb to 200+ once you get into traffic. The challenge is that once it gets above 210 the fans alone will not get back below. Depending on the track, it's not uncommon for me to consistently run in the 190's (except at TWS were the long straight and higher speeds allow the bike to cool more effectively).

Stock fans are designed to pull cool outside air in through the fairing across the radiator. Obviously designed for optimum air flow while the bike is at rest (or at very low speed) the effectiveness drops dramatically as the the bike's speed increases.

A common mod is to flip the polarity on the fans so that the fans blow air out. While this will tend to reduce the efficiency of the fans while the bike is at rest (the fans are blowing hot engine air across the radiator) the efficiency at speed is increased because the fans are not fighting natural airflow as the bike moves.

Since you have a SP1, the fans are activated by the thermal switch providing ground to the fan circuit. A better option is to wire in a manual switch that will allow you to activate the fans before they come on at 215 or 220 (l forget which) like when you know you will be getting into stop/go traffic.

Another contributor to RC51's overheating is air in the cooling system. If you swap out coolant make sure you burp all the air out of the system and that you have adequate coolant in the reservoir to keep air from being introduced back in accidentally.

Moriwaki air fins (or aftermarket clones) help with airflow at speed. Thorsten Durban also makes CF shrouds that can be installed (in conjunction with changng the fan rotation or removing the fan) that improves airflow through bot radaitors. If you are going to do any track time you may want to consider one of the front-mount radaiotr conversions as they provide impoved cooling and better protection if the bike ever ends up on its side.