Piston Broke

[TVS44]

Advice needed please..
Was riding along nicely at 50-60mph when the bike (1150GS Twin Spark) began to run on the left cylinder only.
I decided to turn round and head for home obviously taking my time.
A look in my mirror and I saw a huge cloud of smoke coming from the exhaust.
After letting the bike cool down, I began to take off the right hand cylinder head hoping to find maybe a leaking gasket or a bent exhaust valve.
No valves broken or bent.
On further inspection, as you can see from the photo`s proved me drastically wrong.
The photo which, as you view the piston face on, the left side with the half moon shape hole is the inlet side.
The other photo`s show all 3 rings have also broken in the same position (inlet side)
The bike has done 82,000 miles.

Any comments as to how it may have happened, to prevent it happening again, would be appreciated.
Having looked at the, www. maxbmw parts website, it quotes 2 part numbers for a replacement piston.

Part Numb 112/576/526/63 AB+584-594GR

And 112/576/526/64 AB-574-584GR

Which one do I choose?
My understanding is that one piston is heavier than the other?
Does it matter?
My original piston measures 101mm diameter and I believe to be the original part (not re-bored).
Thanks

 

[warmshed]

Have you checked the bore?

 

[AndrewD]

I'd be worried where all the bits went, might have battered the head or valve ports

Might help you to know Sherlocks are breaking a GS and have a whole bore and piston for £100 on ebay here is a link, both are there on separate listings...

http://www.ebay.co.uk/itm/BMW-R1150...12?pt=UK_Motorcycle_Parts&hash=item23188b831c

They also have a head....

 

[Pauly S]

Mixture

too weak maybe?what colour was the carbon on top of the crown?

 

[Ugly Cow]

Any comments as to how it may have happened, to prevent it happening again, would be appreciated.


Possibly caused through Pre-ignition (severe pinking) caused by advanced ignition/weak fuel mixture/low octane fuel/ to high compression ratio

 

[TVS44]

Thanks for the replies. Much appreciated.

warmshed... After speaking to Pidcocks BMW this afternoon they advise me that the letter corresponding to the piston size/type is to be found, as you rightly say, on the bore NOT the piston crown. Apparently a blue colour spot aswell. I`ll have a look later, see if i can find it.

AndrewD.... I shall check the listing. Thanks for the links. BMW quoted £190 for piston, Rings and Pin. so its definately worth a look. As for the bits, i dread to think where they`ve gone. I suppose theres only one way to find out. shame i couldnt drop a sump like other bikes.

Nomad biker.....The crown of the piston was as if it had been sprayed a layer of black paint, smooth`n`dry with no soot or deposits.

Ugly Cow....You mention pre-ignition, advanced ignition, yes it was pinking quite badly but no more so during previous rides, in my ignorance i guess it was just a matter of time before something went wrong.You Know what they say `if it aint broke...` that was till now !! When the bike is re-built i shall have it all set up correctly

Thanks again guy`s

 

[John Armstrong]

Being nosy, do you have a y-piece and end can fitted?

 

[TVS44]

Yes I have a y-piece and Remus end can. Been on the bike (On & off) for the last 3yrs.

 

[TVS44]

Think ive found the letter i`ve been looking for.
I`ve been told it`ll be an A, B, or AB. (Im sure the guy on the phone said a C, never mind)
You can just make out the letter B which has been stamped with a 3L next to it.
These were found stamped on the cylinder bore.

 

[AndrewD]

Thanks for the replies. Much appreciated.

AndrewD.... I shall check the listing. Thanks for the links. BMW quoted £190 for piston, Rings and Pin. so its definately worth a look. As for the bits, i dread to think where they`ve gone. I suppose theres only one way to find out. shame i couldnt drop a sump like other bikes.

Thanks again guy`s

I doubt anything could have made it into the sump.

 

[Rob Farmer]

Hi tvs.
Just been speaking to Timmo about this.

Have a look at your cam lobes. Noel who used to be on this site had a cam lobe come adrift on his 1150

 

[Smug]

I doubt anything could have made it into the sump.

I think that bits of the piston and piston rings will be in the sump. Nowhere else for them to go.

How badly is the bore scored? Does one deglaze the bore when fitting new pistons and rings to this engine?

 

[warmshed]

you have to be careful what you do to plated bores, Nikasil and the like, if they have been damaged a new barrel is the cheapest option. I have only fitted new pistons or rings, never had the bore glazed over like on a iron barrel.
Bit worrying about the bits, some could have gone out through the valves so check them and the seats, not sure the best way to clear out the crankcase without a major dismantling,

 

[Ugly Cow]

Piston Broke

Maybe it would be a good idea to remove the other cylinder head to inspect the other piston crown for damage. As it is rare to find one cylinder has a far higher compression ratio than the other ( ie. 1 cylinder head skimmed without the other). Do you think the TPS is way out so making the bike run too lean. Highly unlikley living in the UK it can be low octane rating.
If I had this problem I would go for TPS giving a lean mixture, any oil passing the rings would normally turn to a heavy carbond deposit. The hard thin finish on the piston crown suggest that the engine is running lean amd hot so burning all within the combustion chamber.

 

[Ugly Cow]

Piston Broke

Sorry, and obviously make sure the ignition timing is correct. HES fitted without checking without a timing light.

 

[TVS44]

Piston broke

Once again thanks for all your advice and recommendations

AndrewD. Have dropped the oil, typically, only a small lump of piston came out.
My only option is to split the engine in case more debris gets sucked up to the crank and bore. i will admit i`m not sure how the oil is transfered around the engine, so i`ll have to do some more reading.

Rob Farmer. Hi Rob, i got your message from Timmo this morning,
thanks for the advice, I`ll check the cams etc as you say.

Smug. Strangley the bore isnt damaged at all, I`m not sure about the`deglaze` thing, however due to extreme lack of funds i`ll probably go for a second hand barrell & piston.

warmshed. I`ll check the valve and seats as you say.
My only option for piece of mind is to split the engine to (hopefully) find the bits, A pain in the ass but the only way to do it.

Ugly Cow. I`ll take your advice to check the TPS and check the other piston, which, when i take the engine apart will be part of the dismantling,

Thanks again to all above, Its going to be a busy wknd...

 

[Ugly Cow]

Piston broke

When you dropped the oil, what debris came out is all that will matter. It is VERY unlikely that anything left internally can do any damage at all.The suction side of the oil pump has a gauze strainer, I have seen all sorts of junk in the bottom of sumps, it just sits there.You should not de-glaze the bore (it has a Nicasil coating thats as hard as hell.Nic-nickle Ca-cadium Sil-silicon) The piston and top piston rings damaged through pre-ignition is caused by (as in normal ignition, is a controlled burn) a totally uncontrolled burn, this causes a concentrated mini explosion, creating intense heat on the edge of the piston crown. This burns down the side of the piston (melts the alloy) with all valves closed. With this in mind any debis will be pushed past the piston skirt into the sump. Just to be sure, just pour a little parafin onto the upturned cyl head and see if there is any loss of fliud past the valves, before you strip the valve gear. Once again it may be prudent to remove the other cyl head to inspect the other piston.

UC

 

[AndrewD]

Piston broke

When you dropped the oil, what debris came out is all that will matter. It is VERY unlikely that anything left internally can do any damage at all.The suction side of the oil pump has a gauze strainer, I have seen all sorts of junk in the bottom of sumps, it just sits there.You should not de-glaze the bore (it has a Nicasil coating thats as hard as hell.Nic-nickle Ca-cadium Sil-silicon) The piston and top piston rings damaged through pre-ignition is caused by (as in normal ignition, is a controlled burn) a totally uncontrolled burn, this causes a concentrated mini explosion, creating intense heat on the edge of the piston crown. This burns down the side of the piston (melts the alloy) with all valves closed. With this in mind any debis will be pushed past the piston skirt into the sump. Just to be sure, just pour a little parafin onto the upturned cyl head and see if there is any loss of fliud past the valves, before you strip the valve gear. Once again it may be prudent to remove the other cyl head to inspect the other piston.

UC

I'd not be splitting the engine either, your better looking for a donor at that point as the cost of gaskets etc is

 

[ktmmark]

Have had similar when there has been an air leak causing a weak mixture (pre detination) was the rubber in place under the throtal body (used for setting the ballance)

 

[Pauly S]

debris

we found debris in the airbox and in the exhaust too,we had to split the cases on the 1200 to get the debris out, in fact were still doin it.
dunno if you can remove the sump on the 1150, aint been there yet.