A guy brought a 99 670 HO to me the other day. He claims it was running fine when the belt blew at about 70mph. It wrapped around the primary, killed the engine, ruined the seal, all that good stuff. When he got it all cleaned out and fired it back up it acted as if a plug was fouled, which it is still doing. Once the rpm's are up to 5K or so, it seems to be okay. Carbs look okay, spark is good, rotary valve looks fine. It is as if the timing got thrown off. Any ideas as to what it could be? Thanks alot.

my ho did the same thing, blew the belt, broke the bellypan, ripped the seal out. i found that the belt had wrapped around the backside of the clutch, acting like a fouled plug. i changed the plugs several times, before i noticed the fine belt shavings wrapped up around the clutch.

I am assuming you have replaced the seal on the PTO side. If that has been done, here's what will cure the missing problem. Are you listening? as it is quite complicated!!!! CHANGE THE SPARK PLUG CAPS!!!! Trust me, this has happened to a many 99 H.O.'s at my shop.


Dr. Doo 800

Really! For what they cost, I will certainally try it, but how do you explain that!?! Thank you.

Interesting, blowing a belt Fu(ks up the spark plug caps :0:

My buddies did the same thing and took out the pto crank seal.

A buddy of mine has a 670HO and it has scars from when it blew a belt earlier in it's life... why is this thing so hard on belts? Oh, and the spark plug boots have been replaced on it just two weekends ago :)

What is the secondary wound at? 25# pre-load worked on my 96 formula SS 670, after I wound it up the backshift was great and I didn't blow anymore belts. :D

i blew a belt on my ho last winter. It cracked my belly pan a destroyed the metal belt cover. i didn't use it much after that last year, but this season i had to rplace my plug caps and she is fouling plugs on a regular basis.

Not a good idea to put a cheap belt on a ho. one good ride and all thats left is a ball of thread.