The Saga Continues - part 2

[Mike1150]

The story so far (in brief)... 1150gs, 2001, 52000 miles

1) Bought bike, the oil seals faulty, lost compression on right hand cylinder. Had the oil valves ect replaced, bike fixed (Not cheap).

2) Got the bike home, advised that the compression was now back where it should be, 2 days later, the starter chews through the ring gear, ending its own life and obviously the ring gears. Call BMW, advised that a bike of 50K millage would do this due to the increase of compression.

3) Quoted in excess of £500 to replace gear and starter, decide to do job myself, buy and new starter and ring gear and replace myself.

4) Finish the job today, cant get the bike going (struggling to turn over), charge the battery for 5 hours - still nothing, get the battery "health checked" 100% fine (new battery). Dubious about the health check, pull the car battery out of the car, still struggles to turn the engine, thinking that the car battery may be a bit old, get the bike to the car and jump the bike while the car running (thus eliminating battery issues) still struggling to turn the crank, starts slipping and before you know it, sounds like the new starter and ring gear are wrecked again .

What now????

 

[motobiker]

Book it in with that nice Mr Steptoe.

 

[Pukmeister]

Take the plugs out to remove any compression, then try putting the bike in gear on the centrestand and barring the engine by hand via turning the back wheel in a high gear. If it feels really tight without any compression, you have some other 'articulation' problem within the engine, and compression isn't your worry.

 

[Mike1150]

Take the plugs out to remove any compression, then try putting the bike in gear on the centrestand and barring the engine by hand via turning the back wheel in a high gear. If it feels really tight without any compression, you have some other 'articulation' problem within the engine, and compression isn't your worry.

Good idea, will do in the morning!

 

[Mike1150]

Right.... in the light of day, I can see that the ring gear is once again truly wrecked and needs replacing (AGAIN AAARRRRSSSEEE). However it would seem the starter won the battle and is still ok.

Took the plugs out and I can turn the engine, so it would seem the problem lies with the engine having too much compression.

Ill ask you lot the same Question I asked BMW, could the new oil seals I had put in the right hand cylinder create too much compression for the engine?

 

[Shep]

Right.... in the light of day, I can see that the ring gear is once again truly wrecked and needs replacing (AGAIN AAARRRRSSSEEE). However it would seem the starter won the battle and is still ok.

Took the plugs out and I can turn the engine, so it would seem the problem lies with the engine having too much compression.

Ill ask you lot the same Question I asked BMW, could the new oil seals I had put in the right hand cylinder create too much compression for the engine?

By oils seals do you mean piston rings?

 

[Steptoe]

.

Ill ask you lot the same Question I asked BMW, could the new oil seals I had put in the right hand cylinder create too much compression for the engine?

What oil seals have you replaced which are involved in the compression cycle. How can replacing any seals increase the compression in a cylinder. It's valves pistons, cranks and camshafts.

 

[cookie]

Ill ask you lot the same Question I asked BMW, could the new oil seals I had put in the right hand cylinder create too much compression for the engine?

no. the best it could do is to restore compression to what it was when new. i'm assuming you mean rings not oil seals. oil control rings perhaps?

but...if there's some fitting problem, there could be a friction issue. seems a bit unlikely though.

as suggested, take the plugs out and make sure the engine turns over ok.

 

[Deleted account 111026]

You'll need to fit the decompression lever kit. Ask at the dealer.
The R1200GS has it fitted to the right-hand cylinder, it's called 'stuckenvalven'.

 

[MattW]

You'll need to fit the decompression lever kit. Ask at the dealer.
The R1200GS has it fitted to the right-hand cylinder, it's called 'stuckenvalven'.

Now then, naughty...

 

[ebbo]

I don't know how you can have too much compression, but I'd check it with a compression tester, compare side to side

 

[MattW]

I don't know how you can have too much compression, but I'd check it with a compression tester, compare side to side

You can't have 'too much compression' - i.e. even if the piston rings sealed perfectly (which they don't), it'd be fine.

However as other have said, you can have other issues which will increase the effort required to turn the engine over ( failed bearings, mechanical missalignment, other sources of friction, etc).

As others have said, whip the plugs out, put it in 5th gear and try to turn the engine over by spinning the back wheel with your hands. There will be some effort due to internal friction and the valve train etc, but it should turn over smoothly and easily using two hands to grasp and turn the wheel. Quick and easy to do.

And don't compression testers require you to spin the engine over on the starter? - Surely not an option at the moment....

 

[John Armstrong]

I don't know how you can have too much compression,

Fill it with water

 

[Stewart H]

I cannot see a properly fitted ring gear failing after one attempt, even if presented with a totally non turning engine, they do not appear to self destruct in the cases of hydraulically locked "fording" motors, they will bend conrods first, something is amiss here.

Stewart

 

[Womble]

Fill it with water

Surely that's "Not enough compression"?

 

[ebbo]

I cannot see a properly fitted ring gear failing after one attempt, even if presented with a totally non turning engine, they do not appear to self destruct in the cases of hydraulically locked "fording" motors, they will bend conrods first, something is amiss here.

Stewart

That's a very good point...

 

[MattW]

That's a very good point...

Indeed it is.

 

[Deleted account 111026]

The R1100S has higher compression ratio, yet uses the same starter motor.
The dealer is talking rubbish. If the answer is not on the diagnostic computer they normally don't have a clue.
I've attempted to turn the engine, after working on the bike, with the TDC locking bolt in place, (don't ask!), the starter just locates then stops, no damage to any of the mechanical parts.
I suspect the problem lies with the starter motor itself.
If the starter is meshing correctly, but the load is too high, you'll burn out the motor.
If the starter is unable to mesh correctly, even when subjected to normal loading, the engagement gears will be damaged.

 

[Mike1150]

What oil seals have you replaced which are involved in the compression cycle. How can replacing any seals increase the compression in a cylinder. It's valves pistons, cranks and camshafts.

Guys please bear with me, I'm by no means a mechanic, so my terms etc may be incorrect, I find myself "parroting" what I am told

When the bike went to the garage (DWR in Aylesbury) they plugged in the compressed air into right cylinder and air was escaping out the oil filler, they called them oil seals, must be piston rings then? However, these were replaced. I agree that in theory this should return the engine to its original pressure.

This is the second ring gear to be stripped by the starter, the second was replaced by myself with meticulous attention to detail (Lap top with the manual next to me at all times, all torques, greases/oils as per the manual).

I would side with the theory that I may have made a mistake if this was the only gear to get stripped however as the original one went as well, I assume the problem to be someway linked to the work done on the engine, thus when I replaced the gear and starter I ended up fixing the symptoms not the cause

as suggested, take the plugs out and make sure the engine turns over ok.

I have removed the plugs and the engine turns fine.

I suspect the problem lies with the starter motor itself.
If the starter is meshing correctly, but the load is too high, you'll burn out the motor.
If the starter is unable to mesh correctly, even when subjected to normal loading, the engagement gears will be damaged.

I have thought this, I replaced the old starter via a local starter guru who sourced me an identical (theoretically) new one, looks the same?

The starter is a Valeo with the numbers C187259A on the side of the motor and DEM.D6RA75 on the solenoid.

It gripped at first then seemed to fight loose, I would guess I tried it 10 times, assuming that due to having to change fuel lines and connectors I would have to get the fuel to run through all the pipes again. But not during any of the attempts did it turn the engine cleanly, it always sounded like a battle.

HELP

 

[DrFarkoff]

is the starter turning the correct direction these can be either clockwise or anticlockwise rotation

From the rear of the starter on an oilhead you want it to turn anticlockwise to mesh with the flywheel which turneth clockwise

There shouldn't be anything except a misaligned starter or flywheel that should damage the ring gear

Do a compression test just to satisfy yourself that nothing untoward is happening

Also with plugs removed undo the rocker covers and the cam end covers put a kebab stick or wooden skewer thru the plughole and with the bike in top gear on centre stand rotate the back wheel in the same direction as as it would turn when running and watch the rocker arms (the rearmost are inlets and are closed when the rocker is flat/vertical) as the piston approaches the top of it's stroke on the firing stroke (TDC) the inlet valve should close

AS the piston tops out at TDC top dead centre on either cylinder the two arrows on the cam wheels thru the back of the head where the wee black plastic cam covers are should point east-west not above or below or any other shape

If they are misaligned you could be having valve ~ piston contact there are 2 valve chains so make sure both sides arrows are the same

Also When the right cylinder valve is closed the left inlet valve should be opened and just starting closing!
If it is identical to the other cylinder then you have a big bang engine and thats why compression is high cos they are supposed to fire 180degrees apart!