998 Bayliss - Blown Piston - Page 2

**Mr.R** · 27 Apr 08, 04:14 PM

Quote:

Originally Posted by safetyfish

It was autopsy time again today between race 1 and 2 at Assen. (Wont spoil it if you have not watched the SBK race yet)

All theories went on the table, and then we looked at what is there to support a theory.

Unfortunately for me, and this is a hard one to admit, it would appear that I did mess up the belt change.
Looking at the piston face itself you can see two neat little circles where both the exhaust valves made contact with the piston face for an extended period of time. The circles have carbon deposits in them (difficult to see after the fact with all that metal flying around in there at 8000 plus rpm) and all the damage is super imposed on top of the circles. AT 8000 plus rpm that piston and exhaust valve was making contact at in excess of 130 times a second. From the time when that exhaust valve finally snapped and started to do its thing until the engine reduced its rotation to zero was enough to cause a lot of damage.....to the engine, to the bank balance and to my pride.

In the end, I must have slipped a single tooth on the belt change and when the engine was doing top rpm all hell broke loose. Now that is an expensive lesson to learn......there is not much to say other than "you stupid bloody idiot!"

I now have to go and humbly appologise to the bike

SF

It takes a BIG MAN to admit he's ****ed up!
So respect to you Mr Safetyfish...
I bet you don't make that mistake again.

Steve

**Ghost** · 27 Apr 08, 04:43 PM

Just a thought, as I'm not sure of manufac process. But can you be sure that the valves were a one piece component. As valves were made by welding the head of the valve to the stem.

If you had it that wrong, you would have felt that the engine was not right within the distance you had travelled.

But sorry to see the mess you have to contend with.

**stevel** · 27 Apr 08, 07:08 PM

Yep, an honest man.
I think this post should be obligatory reading for all the chancers with an Aldi socket set and ten minutes watching diy belt change vids on Youtube who then change their belts then post about how easy it is, how all mechanics are cut throat con men etc!
No disrespect to SF or anyone who does know their onions - really, but some times I think a little knowledge is truly a dangerous thing, and too many enthusiastic spanner wielders get in too deep without the awareness that this could be the result

**Ghost** · 27 Apr 08, 07:15 PM

I've welded a few spanners up in my time Stevel.

Good to meet you at Oulton and kenoir also.

**CJS ducati** · 27 Apr 08, 08:03 PM

Quote:

Originally Posted by safetyfish

I recently was lucky enough to buy a Bayliss edition off a guy who had money issues. Lucky for me.
The bike was in pretty good nick, but it needed attention. First order of business was a new set of belts. The bike has 3200 km on it and it is still running on its original belts.....

Fitted the belts, cleaned up things like air filters and greased up suspension parts and other small bits and bobs while I had the rims off to fit a new set of Bridgestone 015's.

The morning broke and I was out the door like a rabbit with its tail on fire. I just could not wait to finally start her up and hit the road. I noticed that the oil level is high.... strange? Never touched the oil....
Start the bike up and let it tick over for a minute. Switch it off, and check out the oil level... Back to normal?

She was handling completely differently to my 999, a more involved experience. Took a few turns to get used to the quirks of this bike and new started to step things up a notch.

Bang!!! Sound of metal doing something and then nothing. I wheel to a stop with the clutch in and my first thought was the bike is on fire. Take a few steps back and realise it is all steam....thank goodness for small concellations.
But the steam was coming out of the exhaust pipe also, now that is not good. There is coolent everywhere, it is even running out of the joints on the exhaust pipes.

Got home with some kindly help and took the bike apart.

After having driven it for less than 30 minutes or 25 km's, this is what we find.

If you look closely, you will see the exhaust valve imbedded through the piston.
The titanium conrod is bend to hell and gone and the engine can not turn over with the amount of metal inside of the gearbox. It was somewhere around here when I said FAAAAARK!!!

This is going to hurt financially.

SF

I have seen the heads drop off the exaust valves on three 998 engines around the 2002 year mark. On rebuild i normally fit my own design valves wich are much stronger and resistant to heat. I personally think with your engine the rod let go first or the shell spun out of the rod causing the piston to smack the valves. I have also seen issues with crank oilways not being large enough leading to rapid shell wear that brings the piston right to the valves at tdc.
Any how i prob have everything you need to fix it. I could repair the head to as new condition but it would be cheaper to buy a secondhand replacement. I can be contacted through cjsracing.co.uk

**Mr.R** · 27 Apr 08, 08:11 PM

Quote:

Originally Posted by stevel

Yep, an honest man.
I think this post should be obligatory reading for all the chancers with an Aldi socket set and ten minutes watching diy belt change vids on Youtube who then change their belts then post about how easy it is, how all mechanics are cut throat con men etc!
No disrespect to SF or anyone who does know their onions - really, but some times I think a little knowledge is truly a dangerous thing, and too many enthusiastic spanner wielders get in too deep without the awareness that this could be the result

Yes Stevel,
But with the old adage of "Measure twice and cut once", (yes I know that's from the carpentry lessons the older lads amongst us had at school) but getting in there and doing it is the only way to really learn...
Always check your work at least twice, before hitting the button!
I know I've made the odd fcuk up, but I've never made the same mistake again.
When you DIY and you've done it with care at least you'll know the job was actually done, which's more than I can say for a lot of dealer jobs that people are charged for and I've been in and around the trade for a looong time.

Steve

**stevel** · 27 Apr 08, 08:48 PM

Aye up Steve, agree with you 100%, just worry about the diy'ers who haven't had their fingers burnt on a cheap / easily fixed fcuk up, then tackling belts armed with little experience and no-one on hand to point out their errors........bit like the first few ops a junior surgeon does, with an old hand on standby!
I too am old / daft enough to have done woodwork at school, the teacher used to show us how to put our name on the back of the job ready for the next lesson......on his piece he always used the name "Percy vere"....oh how we laughed every week! Good lesson for life though, esp if you own a Duc

**safetyfish** · 28 Apr 08, 03:16 AM

CJ, you should have an email in your inbox that arrived over the weekend.

I still can not understand where I messed it up. The marks are still visible on the pulleys and they ligned up exactly as they should, but the piston face tells a seperate story. A warning for people who fly in blindly into an engine, definately. My other bike is now standing there half naked after I replaced the main drive gear bearings on it. All I now have to do is torque the clutch basket nut and fill her up with oil and take her for a ride...... That should have been done three days ago, but the old confidence took a kick in the clackers somewhere in there.....

Will keep you posted how the surgery progress

SF

**Ghost** · 28 Apr 08, 10:40 AM

Quote:

Originally Posted by safetyfish

The marks are still visible on the pulleys and they ligned up exactly as they should, but the piston face tells a seperate story.
SF

If the marks are all still aligned then it must have been ok, one cam tooth out is 36 crank degrees a lot you would have felt the difference.

The marks on the piston are there as a result of the clash with the valve heads dropping off or the conrod letting go.

**ziggi** · 28 Apr 08, 11:33 AM

Often like me, you seem to have learnt the hard way ... what are you going to do SF? Rebuild (new engine), sell or insurance claim?

**nelly** · 28 Apr 08, 03:18 PM

Thing with the stretta pulleys is that only the lower, twin, pulleys' marks bear ony relevance now. The marks on the cam pulleys are for the pulley assembly only. To align the pulley and back plate to a "safe" setting.
When the belts are changed "by the book" if you like, the cam timings should be reset. This is done by undoing the vernier pulleys, and fixing the camshafts with a couple of setting tools using the T slots in the shafts themselves. The belts are then fitted and the pulleys can be moved to aid this. The belts are then tensioned to a "hot" setting and the verniers fixed. Once that's done, the belts are tensioned cold and job done.
What could've happened in your case is that the setting procedure has been done prior and the markings have been moved. If you've aligned them on the belt change, then you could concievably be one or maybe 2 teeth out??
At tickover, maybe the valves were kissing the piston a little. Once hot and the revs lifted then bang......

**safetyfish** · 28 Apr 08, 04:17 PM

I will rebuild the engine, with some professional help off course. Spoke with Chris over at CJS, they might have some bits and bobs lying around that will come in usefull.

Anybody perhaps got a schematic of an engine stand including dimensions?????? Anybody?

Insurance in this country cover you for third party only. Even in a crash I am liable for the repair costs on my own bike. That is why you have to drive so carefully out here, or anywhere really for that matter.

SF

**funkyrimpler** · 30 Apr 08, 05:24 PM

Ouch! Ive been reading these threads with much interest..SF, i really feel for you there big man..and such an easy mistake to make. I hold my hands up..im no mechanic..i understand the theories, did a bike mech course years ago-but thats as far as I'll go. A little knowledge and all that, i just dont risk any clever stuff as i just dont trust myself. I really hope you get her back on the road-that is one special bike. Good luck with the rebuild, or tracking down a new motor!

**jet057** · 15 May 08, 03:43 AM

sounds like no oil got to the main parts,oil cooler may have went out,or a defective oil filter,something got real hot then let go,sorry dude..an over-filled engine then warmed up then back to normal does not seem normal,that filter may have been bad or someone poured surgar in the engine or some thing else???