1150GS piston orientation/cam timing question

[seags]

Hi all,

I currently have my engine top end stripped on my 2003 1150 twin spark adventure.

can any help with the following 2 questions:

1. My Clymer manual indicates that the pistons should have marks on them indicating which way round the piston should be mounted on the con rod but i cannot find any marks. I can understand the logic as the inlet valves are larger than the exhaust and it does look like the valve indentation on the piston is very slightly larger on one side of the crown but ant advice would be appreciated.

2. The Clymer manual states that the front engine timing chain cover needs to be removed to set the cam timing and that the engine needs to be removed to take off the cover. Do I need to take the cover off and if so do I need to remove the engine?

Any help would be great,

cheers

 

[(RIP) DitchWater]

There should be an X marked on the inside of the piston indicating the exhaust side of the piston. Don't mix the parts up between left and right.

You don't need to remove the engine to remove the front cover. You may need to remove the front shocks' lower bolt to allow it to swing out a bit and create enough space. I think this is all dependant upon which generator pulley wheel you have on your bike. There are two types and one of them makes life difficult.

 

[seags]

Hi,

Thanks for the reply. There is no X on the piston. It says it is made by MAHLE and has an A2 marked inside and a couple of other bits of writing - any clues?

I have not mixed up what side of the engine they came from.

thanks

 

[(RIP) DitchWater]

The other "bits of writing" maybe the piston sizes.

Is there a raised square on the one of the ribs which connects the piston skirts and and holds the piston pin? This also indicates exhaust.

Also, if you haven't dismantled it yet, start taking pictures and make your own marks with a scriber or marker pen.

 

[seags]

Already stripped last summer!!!

There is a raised mark on one side on the web below where the gudgeon pin is. I guess this must be it??

 

[Steptoe]

2. The Clymer manual states that the front engine timing chain cover needs to be removed to set the cam timing and that the engine needs to be removed to take off the cover. Do I need to take the cover off and if so do I need to remove the engine?

Any help would be great,

cheers

You can remove the front cover but the telelever arm has to be unbolted from it's fixing on the engine and pulled forward to allow the cover to clear the end of the crank.

 

[seags]

Thanks - but do I definitely need to remove the cover to do the timing or is there another way??

 

[(RIP) DitchWater]

You can remove the front cover but the telelever arm has to be unbolted from it's fixing on the engine and pulled forward to allow the cover to clear the end of the crank.

I managed to do it recently for a belt change without doing the above but my front cover is plastic so, that may have helped by it being a tad flexible.

Thanks - but do I definitely need to remove the cover to do the timing or is there another way??

You can use the rear wheel to turn the engine, if it's still on.

 

[Steptoe]

I managed to do it recently for a belt change without doing the above but my front cover is plastic so, that may have helped by it being a tad flexible.



.

Your talking about the plastic alternator belt cover, not the front engine cover.

 

[Steptoe]

Thanks - but do I definitely need to remove the cover to do the timing or is there another way??

Depends how far you've taken the engine apart.

 

[seags]

Hi,

I don't mean the plastic cover over the alternator drive belt, i mean the one behind the pulleys that when removed reveals the timing chain.

Also, the timing i refer to is the cam timing not the ignition timing.

Thanks

 

[(RIP) DitchWater]

Your talking about the plastic alternator belt cover, not the front engine cover.

Correct. He's a busy bee isn't he.

 

[seags]

Depends how far you've taken the engine apart.

Heads and barrels off, engine still in frame...

 

[Steptoe]

Heads and barrels off, engine still in frame...

No need to remove front engine cover - i presume you've cable tied the chain and cam sprocket together which makes it a simple put it back together in reverse order procedure.

 

[seags]

No need to remove front engine cover - i presume you've cable tied the chain and cam sprocket together which makes it a simple put it back together in reverse order procedure.

You'd like to think so wouldn't you?

I actually did do that however as i did the second one the chain jumped a tooth. So now one side is ok and one side is one tooth out - its not something i want to guess so it looks like the front cover is coming off - hey ho.

Thanks for all the help.

Cheers

 

[Myke Rocks]

Piston way round

The gudgeon pin in all pistons is offset - usually around 2mm from centreline.
This is easy to check with a vernier.
Do so, and the wide side goes towards the direction of rotation.
Look here for details:
http://www.jepistons.com/TechCorner/Pin-Offset.aspx

If you put the piston on the wrong way round, you get awful piston slap.

Myke

 

[(RIP) Kaister]

if it has valve cutouts - the bigger ones are the inlets - thats the ones at the back

 

[seags]

if it has valve cutouts - the bigger ones are the inlets - thats the ones at the back

Yes I agree with the logic, however if I do that it contradicts with the mark on the piston webbing indicating the Exhaust side.

 

[seags]

The gudgeon pin in all pistons is offset - usually around 2mm from centreline.
This is easy to check with a vernier.
Do so, and the wide side goes towards the direction of rotation.
Look here for details:
http://www.jepistons.com/TechCorner/Pin-Offset.aspx

If you put the piston on the wrong way round, you get awful piston slap.

Myke

Wow, I did not know that, really helpful, thanks - its amazing what there is still left to learn!

 

[seags]

Wow, I did not know that, really helpful, thanks - its amazing what there is still left to learn!

i have just done this and it backs up the marking on the piston web!

many thanks