I have a 79 flh I changed the primary from chain to belt . the belts keep breaking I went thru 4 in one year. Its a 80 inch but stroked it to 96 inch . I thought heat was doing it so put slotted primary cover. But it broke again and it was cold out I'm running a inter primary. I just can't figure out why they keep breaking any ideas anyone .

 

my first thought was misalignment but if you are running an inner primary then that shouldn't be a factor. Over tensioned maybe?

 

what size belt if its the 1.5 you need a carbon belt and you need to check tension regularly my shovel has one and I go thru 1 belt every 2 years

 

Harley tried running belts from the factory in the mid '70s but found unless alignment was spot on, breakage was an issue. Without finding a suitable for mass production fix, they stopped.

 

What manufacturer are you using for you primary drive and what kind of hp n tq are you putting to it?. I am using a BDL Brute III extreme with a 1 5/8" Kevlar belt and so far no problems. 97 HP n 97 TQ. Alignment is critical and spacers are necessary at times to get the proper alignment. A total of a 1/2" of belt flection should be achievable (up and down) with some effort. Aren't your trans and engine separated. Make sure the are aligned properly.

 

Years ago I converted a 1978 FLH to belt and found out many frames on AMF series Harleys have engine and trans mounts which are not in alignment from factory. The instructions from the belt conversion supplier also told me this is a common problem prior to installation. Very common for trans mount to be on different plane than engine mount and then trans mount to not be parallel with where rear axle should be in swingarm. You may have to shim one side or the other on trans mount.