So what's the benefit of running an open primary belt drive? I know they're cool to look at, but is there a performance benefit to it?

 

Mostly to get your britches leg caught in it.

 

Beefcake,

The primary beltdrive is used for higher horsepower motors, basically they drive a larger beefier clutch with more plates for more friction/lockup area hence the wider belt for a wider clutch (more plates) transmitting the crank driven H.P. to the clutch/transmission then to the usually larger rear tires. The clutch is a dry unit -vs- stock wet oil bathed unit. Stock clutches and the primary chain just won't hold up to the higher H.P. to get the power to the ground.

John TN

 

gee john you sound like a guru!! thats good!!

 

That's probably cause he is!

 

I ran closed primary belts on both my '72 XLCH and my '78 FLH. Open primaries don't interest me on a street bike. If you ride the snot-stuffin's outta your bike an open primary will allow the dust, dirt, weeds, gravel, rain, log truck droppin's, animal parts, etc. to eat your belt, sprockets, and clutch plates.

 

They offer a sound way to transmit high TQ/HP to the rear tire without having chain issue's or clutch. There are two types, a diaphram type( Primo) and a spring tension type( BDL) You will see many bikes that are kit types with the BDL set up. They are cheaper in cost mainly. THey have a much heavier clutch pull rate over the Primo. The BDL are not of the same caliber as the primo, they have several problems. The newest desing they offer is stock with a outer bearing support, as they are known for the clutch hub bearing going south. THe primo has no problems at all. I run a primo that is a Brute IV with a 3 inch belt. It handles 160+/160+ on my daily ride here in phoenix without any problems. I have never had any issue with clutch draggin or disengagement and I beat the snot out of scoot.

Plus I really like the sound they whine and the rattle of the plates is music to my ears.

A draw back of them is they can cause problems with ground clearance and left turns on lowered bikes. I have a billet flamed cover and it is ground up on the bottom. But what can you do I never bought my Deuce for high speed cornering.

As far as thing getting into the belt it can happen, but I have run mine now for 2 years on the factory belt and have no problems or any belt wear.

 

If you ever go to a run or rally and see someone with a digit or three missing from their left hand.... check out the primary
on their ride....

 

OOPS I did forget to mention that the kick stand is no longer a foot deal you have to reach inder and grab with hand. I ALWAYS SHUT MINE OFF FIRST I like all my fingers LOL My ole pan is a open with a meat grinder, I do have a few pair of pants that are tattered on the left leg. But common sense would( should) tell you that it is not a good idea to stick you fingers any where near the system wheil it is running. I have a shoe that is a bit ground up on the heel as well ahh well I would not go back to the closed system for anything. The other benifit is the motor plate helps keep all parts lined up over the cast inner which will flex under big tq. I have broke chains and threw them out on the on ramp hammering it. My buddy comes up with the chain tells me I dropped something. It is a bit of a mess ha ha . PLUS the cool factor is there if that matters to you. I see the big top fuel ones that are 5 inch!!! it hanges out there a mile, I got to se what happens when they hit something. I was on a run in the spring and the ground was heaving still. A manhole ring was up 3-4 inches and the guy made a left turn through the intersection and it hit the front pulley. Destroyed the pulley outer guard, belt and broke the clutch hub, not to mention it threw the rider over the bars. He was going 25 mph or so. OUCH!!!

 

Not a pretty picture at all!