changing belts on a 4 valve

[mons4r]

what is more important for belt changing....amount of k`s or age of belts

i`ve been told even if you do no k`s, you still have to change belts

in two years or so due to belts cracking...is this fact or fiction.

[ducatiz]

"the sky is green" is a fact

it's wrong, but it's a fact


Thus.. fact AND fiction

the 2 year rule is a "better safe than sorry" rule.  The new belts are kevlar lined, apparently, not polyester and do not break down as easily.

However...

..I have bikes with belts that are 5-7 years old with 10k miles.  i'll change em when i feel like it.

[mons4r]

  green?...really??lol

thanx for your input ..apparently 4valves make a bit of a mess if the belts let go..have you heard the same ...(?)

[ducatiz]

  green?...really??lol

thanx for your input ..apparently 4valves make a bit of a mess if the belts let go..have you heard the same ...(?)

there is a high probability you will rue the day you were born if you have a belt go.  esp with the quattro head, you have piston interference so that piston is gonna slam those valves silly before they can close. 

[zarn02]

Yes. If a belt fails your motor will make expensive noises.

[He Man]

if the bike is ridden often i dont think 2 years of 10k eally matter when it comes to the kevlar belts.

if the belt sits for a long time then yea maybe.

[Slide Panda]

thanx for your input ..apparently 4valves make a bit of a mess if the belts let go..have you heard the same ...(?)

I've seen a couple heads/pistons at a shop from bikes that have lost a belt. Basically looks like one took the head off, flipped it over and let me beat on it with my 30oz cross peen hammer I used for black smithing for a couple minutes. U-G-L-Y

[Desmo Demon]

I've seen a couple heads/pistons at a shop from bikes that have lost a belt. Basically looks like one took the head off, flipped it over and let me beat on it with my 30oz cross peen hammer I used for black smithing for a couple minutes. U-G-L-Y

It all depends on how it hits, what breaks, and how long the owner tried to keep running with it that way. I have a set of heads from a '97 748 at home where the belt broke. The piston came up, smacked two intake valves, bent them, and that was about it. There are no significant differences between this head and the other that did not have a belt break. The valves were bent bad enough that I had to tap them out, and I'm sure the valve guides are toast, too.

[Slide Panda]

These were lest fortunate than your bike.

These had come up an snapped the top of the valve off so it was loose in the bore.

[Desmo Demon]

These had come up an snapped the top of the valve off so it was loose in the bore.

I've seen them like that before. Either the valve snaps off of the stem and get buried into the top of the piston, or the coolest one I saw was that the engine dropped a valve (valve retainer failed), and somehow the valve did a complete 180 in the cylinder and speared through the top of the piston as it came back up for TDC. It was wild seeing the valve stem shoved straight through the top of the piston.

With the Ducati engine, I've heard of it catching just right that a rod would get bent and the crankcase bearings become trash - but this may just be heresay/Internet "facts".