1100 head skim?

[MattW]

Finally had a moment to go for a run to try and identify why my 1100 is still giving me an oily left boot after a head gasket change (and subsequent rocker gasket and oil pressure switch change). Having dusted the pot and its surroundings with talc beore the run, I've identified that the head gasket is definitely still leaking - arse! I changed the gasket for the updated pattern and did it 'by the book' (or at least Steptoe's how-to) and all seemed to go well, but it appears that something is still amiss.

So, when it cools down I'm going to try re-torquing the head. Failing that, I guess I'll have to take the head off again (at least all the exhaust studs are new ). If it comes to this, I'm thinking it might be worth having it checked for 'flatness' and skimmed?

Anyone been down this route? - Is there enough meat in the head / tolerance in the compression ratio to stand a fine skim?

ta
Matt

 

[Nobby]

funny that i have the same on my right cyclinder some where.tighten all the bolts around the barrel but still a leak all.over me right boot .but i haven't got round to doing a gasket change yet as i want to do valve seals on both heads at the same time.this is one for the gs god

 

[Geno]

Mine also started to mist on right boot , nothing serious as yet , just started .

 

[D6]

have you tried changing the cyl head bolts?could have lost elasticity

 

[Deleted account 111026]

I had a similar problem with a cylinder head on my R1100GS. I had an exhaust stud removed at an engineers, insteading of removing the stud by machining on a milling machine as requested, he decided to apply excessive amounts with an oxy-acetylene torch to the head and wind it out.
I replaced the head with the latest gasket but after the first trip out, I found a few oil drips at the base of the head.
There is an oil feed which runs on the gasket face near to the exhaust studs and this is where it was coming from.
I re-torqued the head but no change.
I ran a DTI over the gasket face and it was only 3-4 thou dished in this one area.
The head was skimmed the minimum necessary to remove the 'dish' a new gasket fitted and no problems since.

 

[MattW]

Thanks for the replies guys.
Guess I'll re-torque the head tonight and take it from there. Good to know that skimming is an option if necessary.

cheers
M

 

[MattW]

have you tried changing the cyl head bolts?could have lost elasticity

Anyone know where I could get hold of some new cylinder studs? - I've tried Sherlock's and Motor Works but can't find them listed.

Hope they aren't a 'dealer only' item

 

[Nobby]

try motobins.com think thats right

 

[MattW]

Thanks spa

However I can't find studs on their site either (but I have to say, the site seems to be designed specially to make it impossible to actually find anything useful! - perhaps it's just me.... )

I'll see how it goes after the re-torque and if necessary I'll phone around (bottled it last night as it was about -2 in my unheated garage, and I'm soft, or perhaps I should I say - "I was concerned that the low temperatures would affect bolt tension" )

 

[motobiker]

you'll be better off ringing them Matt... rather than relying on the website. Quite often they will have parts that aren't listed. Or point you in the right direction if the parts needed are commonly used for other reasons/bikes.

 

[MattW]

Think you're right Tony

I'm hoping the retorque will fix it, but being honest with myself I know it probably won't so it'll be head off again and get it skimmed (and I might as well chuck new cylinder studs in at the same time). At least I know the exhaust studs and front section of exhaust won't be a problem this time

 

[Pukmeister]

Just a thought, but wouldn't it be best to skim both heads evenly whilst you are at it? (assuming enough metal for a light skim). It would balance the compressions, and you'd be sure that both heads were flat and won't leak again in the future.

Why not get the valves and seats lightly refaced whilst you are at it? It will also help to restore the clearance between valve and piston.

I paid £4 per valve and seat last time my local cylinder head specialist did any work for me (Peugeot 1.5D engine with oval valve seats due to casting stresses).

 

[MattW]

Just a thought, but wouldn't it be best to skim both heads evenly whilst you are at it? (assuming enough metal for a light skim). It would balance the compressions, and you'd be sure that both heads were flat and won't leak again in the future.

Why not get the valves and seats lightly refaced whilst you are at it? It will also help to restore the clearance between valve and piston.

I paid £4 per valve and seat last time my local cylinder head specialist did any work for me (Peugeot 1.5D engine with oval valve seats due to casting stresses).

You're right Adam - I did wonder about this - one cylinder will end up with a (hopefully very slightly) different compression ratio. However, no one so far has rung warning bells about it and I've read about others just having one cylinder done, so I think I'll suck it and see (I'm hoping that it should be fairly apparent if something's amiss when it goes back together). If it comes to a skim I'll ask the engineering shop to record how much they take off so I can replicate it if need be.

But you never know - a retorque might fix it (not holding my breath though!)

 

[Steptoe]

I'll state the obvious - you did remove all the old bits of gasket and cleaned up the mating faces, didn't you ?

 

[MattW]

I'll state the obvious - you did remove all the old bits of gasket and cleaned up the mating faces, didn't you ?

Yep Steptoe.
The old gasket came away intact and I cleaned the head and barrel faces thoroughly. I never thought to check for flatness - assumed it was just the usual problem with the old pattern gasket.

cheers
M

 

[Pukmeister]

Matt, if you have a small engineering firm nearby (Yellow pages search ??) you could ask them if they have a surface table and some engineers blue. A quick rub of the head across a blued-up surface plate or table will show the high spots. Low spots won't show blue. You can also try a feeler gauge between the low spots and table surface to gauge how far out of flat it is. Best to estimate how warped the head is before committing to a skim. Once the metal is removed you can't put it back.

Agreed that a few thou off one head from stock shouldn't cause too much imbalance/rough running. A pretty low-stress and low compression design of engine.

Obviously be sure to spanner the engine over a few times after rebuild to ensure no piston/valve contact.

 

[davegs]

Head

Take it off and put a steel rule across it edge wise down should show up if it's warped.

 

[MattW]

Matt, if you have a small engineering firm nearby (Yellow pages search ??) you could ask them if they have a surface table and some engineers blue. A quick rub of the head across a blued-up surface plate or table will show the high spots. Low spots won't show blue. You can also try a feeler gauge between the low spots and table surface to gauge how far out of flat it is. Best to estimate how warped the head is before committing to a skim. Once the metal is removed you can't put it back.

Agreed that a few thou off one head from stock shouldn't cause too much imbalance/rough running. A pretty low-stress and low compression design of engine.

Obviously be sure to spanner the engine over a few times after rebuild to ensure no piston/valve contact.

Hi Adam,

Yes - there's a very good local engineering firm near me (I got them to drill out and helicoil a snapped exhaust stud when I originally changed the gasket). If the retorque doesn't sort it, I'll take the head off and take it to them to inspect and skim. However, I've a diy surface plate made from a piece of 1" thick plate glass which I'll have a go at using to check it myself first (no engineers blue, but I'll invent a substitute!)

cheers
Matt

 

[MattW]

Well, I retorqued it and went for a spin this morning - still leaking from the front of the head near the exhaust port

I wasn't that surprised to be honest, so head off again. Much easier this time as nothing was seized and I'd done it before a month ago!

With the head off I cleaned it up and got my makeshift surface plate (a 300mm square piece of 20mm thick glass). An unintended advantage of this surface plate is that you can see through it :

and waddya know - it looks like it's slightly warped in the region of the exhaust port oilway (my thinnest feeler gauge fits betwixt surface plate and head in this area as you can see in the pic). So of to my local engineers tomorrow for a professional inspection and skim.

I'll be glad when I can stop taking it to bits and ride it

 

[Vern]

Just slap some grinding past on the piece of glass and lapp it down yourself.If that's a 1.5thou feeler it won't take long at all