Head-aches G1000

[Jackbob]

Hi,

I realised that i didnt check that i had placed the wider portion of the metal sealing ring facedown when recently replacing the Vesrah head gasket on my GS, and dont know if its right or not. I searched various threads relating to head gaskets posted previously which lead me to establish that i was possibly meant to fit the 4 rubber rings that came in the full gasket set on top of the head gasket either. Durrr.

I must say, i looked at these 4 rubber seals during assembly, but assumed they were from the oil pump or something as i bought a complete set. I was pretty sure from memory that there were seals rings moulded into the gasket anyway. My manual refers to OEM gasket so didnt mention them either i guess.

NB I am not refering to the 2 egg shaped oil seals.

I havent run the engine, as i am waiting for shims ex Suzuki Japan, but have torqued it all up.

The head was also taken to a reputable engine overhaul shop that are very experienced with bikes, and i had the valves ground. They also machined the cyclinder head mating face (mainly to clean it up) and it came back looking fantastic. This is all good, however i also read somewhere here that it may be necessary to degree the cams after machining metal off the head?

I have no idea how much they may have removed, although i suspect not much, and the shop didnt mention anything to me regading cam timing.

I have 2 obvious questions;

1. Can i lift the head, check the gasket is the right way around, install the rubber rings and expect to be able to use it again?
2. How do you check that the cam timing is spot on? I have lined up the marks and counted the cam chain links etc as per the manual, and it all looks OK. Can i set up a dial gauge somewhere and check relative timing? do i need to if only a few thou was removed? There was no indication of the head being warped at all.

Thanks

[Billyboy]

Well, this is a good frikken question. 'Cause I just bolted up my head and was pondering those little rubber, gasket/washers seals too. What are they for?

[hampshirehog]

I'm guessing that the seals you are on about are for the top end oil passage ways (lube for the cams). If you look at the head front on you'll see what looks like 2 alloy plugs welded in on either side - that's where Suzuki drilled the holes in the head - and you can follow the oil route down. (Does that make sense?)

If you haven't run the motor yet you stand a chance that your gaskets will be ok.

[Billyboy]

I'm guessing that the seals you are on about are for the top end oil passage ways (lube for the cams). If you look at the head front on you'll see what looks like 2 alloy plugs welded in on either side - that's where Suzuki drilled the holes in the head - and you can follow the oil route down. (Does that make sense?)

If you haven't run the motor yet you stand a chance that your gaskets will be ok.

Hmm... That makes sense...:?

I hope you're right.
Anyone else?

[first timer]

give this a whirl to time your cams, most gs bikes, the cam timeing is off from the factory, quality control think.... any ways take a look at this

http://medlem.spray.se/biker661/Camtiming.htm

should help you degree your cams exactly where you want them, hopeflly pick up a little hp too.

[tkent02]

My guess is that the gasket will work, but if not you will find out soon enough, and can replace it at your leisure.

[Jackbob]

Thanks everyone - i will remove the head again and recheck the gasket/oil seals as suggested, and the timing.

I will reuse the head gasket - but take it easy and re torque it after running a few miles.

Will let you know how i got on in due course.

Cheers.

[SqDancerLynn1]

I see NO problem reusing the gasket if the motor has not been run, Even if it had you could reuse it in a pinch

[psyguy]

gidday, mate
hey, what's the weather like in akl ? :-\"

i dont think that it matters much which way the gasket is, it's a really small difference in the width of those metal rings in the gasket
i think i'd leave it as it is as far as the o-rings in question, i'd be interested to know wheather there'd be any leaks there - i bet not, as the gasket would provide enough seal
btw, those o-rings are a pain to fit (keep in position) while positioning the gasket and the head...
i had the head/cylinders planed as well, no need to fiddle with the cams (other than adjusting the shims)

[trippivot]

worried about the material removed from the head surface??

I use a piece of solder the check valve to valve clearance on overlap
and another fresh piece of the solder the check valve to piston both intake and exhaust.

turn the engine slowly and make the valves and pistons gently pinch the soft wire you'll get a place to measure and verify if the height difference causes any clearance/cam timing problems.

minimum 0.060" valve to valve
minimum 0.080" valve to piston

to go further you'll need a dial indicator and a degree wheel

[Footy.]

When i rebuilt my 78 GS750E, i skimmed 12 thou ( .3mm) off the head. I work in an engine machine shop, and i wanted to raise the comp to around 9-1. I also bored it out using 850 stock Suzuki pistons to increase torque (low down power).

No problems in valve to piston clearences with standard cams/pistons.

The effect of skimming heads on cam timing is to retard this slightly. This "tilts" the power curve very slightly, so the power comes in slightly higher up the rev range. But on my GS i didn't notice any major shift in power curve when riding.

On some engines, the exhaust valves can get too close to the pistons when skimming the heads, as there is a "double wammy" effect.

The skimming itself gets the valves closer to the pistons, and this is magnified with the exhaust valves because of the retarding of the cam timing. The exhaust valves are closing as the piston gets to the top on the exhaust stroke. The retarded (later) closing of the valve, means the piston moving upwards gets closer still.

But as i said, i didn't need to worry on my GS as the measured clearence after was well within accepted specs.

If you just had a "cleanup" head skim, chances are it was less than the amount i quoted above.

Footy.

[Jackbob]

Thanks again regarding the last 3 replies to my query.

Psyguy - the weather here is looking good for the weekend and the last round of the NZ Superbikes - although given how fickle our weather can be...

Thanks Trippivot - i will check the piston/valve clearances as suggested, good info here.

I remebered i took a couple of photos prior to installing the head on the block, and I have tried unsucessfully to attach a pic - but you can see the red elastomeric seal rings at the outer stud positions. I assume that the seal washers fit inside/over these red seals. Doesnt really seem logical and to be honest, i may just end up leaving it all alone and hoping for the best.

The parts list that came with the Vesrah kit does not list these 4 rubber backed "seal washers".

The original head gasket did not have the additional sealing rubber backed washers - are they perhaps an "improvement" to cater for damaged surfaces or something? The Haynes manual and the Suzuki manual make no mention of these either.

I guess i should just ask Z1 for their advice.

Ta.

[Billyboy]

Let me know.Please.

[psyguy]

yes, as i said, those rubber rings are pita to install as they overlap with the gasket cut-out (as you found too), and they overlap just so they're neither in nor completely on top of the gasket cut-outs
in the future i think i would omit fitting them, on purpose

[psyguy]

the piston to valve distance is 1,5mm or greater
your head/cylinder probably lost only 0.5mm at the most so you should be fine there
you can advance the timing a little if you're too worried, haynes manual tells you how to do this without any timing tools (not very scientific method but sufice for your needs unless you're into getting every possible hp or torque that's in that engine)

whereabouts are you, i'm in massey, cud get together someday to compare bikes perhaps :-D