While my cylinder heads gently weep!

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Sicxtyone
Posts: 121
Joined: 29 Sep 2018 07:34
Location: Worthing
Location: Worthing West Sussex

While my cylinder heads gently weep!

Post by Sicxtyone »

Evening all,
Have done just over 600 miles since getting my 500 sei on the road and have come to the conclusion the head gaskets need changing. I'm no detective but the oil on the front and back of the engine, and drips on the fins above would seem to confirm this.
Please advise, can the job be done on the 500 with the motor in the frame?
I seem to remember on the 350 this is do able but not sure about the 500.
Thanks in advance
Graham
Ps any tips for a successful re assembly greatly appreciated or is all straight forward !
'It must be a .....'
Posts: 365
Joined: 12 Sep 2010 12:25

Re: While my cylinder heads gently weep!

Post by 'It must be a .....' »

Hi, yes the heads and cylinders can be removed with the engine in the frame; just tilt them to clear the studs.
Don't forget the Allen bolt in the pushrod tunnels.
It should all come apart easily once the exhausts, airbox etc are removed.

Have fun
Sicxtyone
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Joined: 29 Sep 2018 07:34
Location: Worthing
Location: Worthing West Sussex

Re: While my cylinder heads gently weep!

Post by Sicxtyone »

I thank you.
harrymuffin
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Re: While my cylinder heads gently weep!

Post by harrymuffin »

You can reuse the head gaskets if you anneal them and don't put any sealant on them when refitting. Torque to the correct figure, run the engine for a while and when cool re-torque, don't forget the allen screw and so you do not drop it down the pushrod tube, magnetise the allen key first so it does not drop off, or a bit of fag paper to wedge it on.
Greybeard
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Location: East Yorkshire

Re: While my cylinder heads gently weep!

Post by Greybeard »

harrymuffin wrote: and so you do not drop it down the pushrod tube, magnetise the allen key first so it does not drop off, or a bit of fag paper to wedge it on.
That sounds like the voice of bitter experience - is there a tale to tell? :lol: I did it myself once with a cam sprocket bolt when rebuilding a Honda CB125 twin engine many years ago :? I had the engine on the bench and it was small enough to turn upside down and shake - didnt help though. It still needed a strip down :roll: Mrs GB learned some new words that day!

Steve
MickeyMoto
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Re: While my cylinder heads gently weep!

Post by MickeyMoto »

Dropped a cam bearing washer down the chain tunnel of a Laverda triple once. Luckily used my magnetic wand to pick it up...

Also dropped the cam chain... Now that is a job n arf... The small hole at the bottom needs the hands of a Gynecologist to be able to get the chain out!
Sicxtyone
Posts: 121
Joined: 29 Sep 2018 07:34
Location: Worthing
Location: Worthing West Sussex

Re: While my cylinder heads gently weep!

Post by Sicxtyone »

Further to this, I have taken both heads off. The front all looked normal so cleaned up and put new head gasket on and head ready for torquing?
The rear however looked decidedly poorly, a puddle of oil in the combustion chamber. So I lifted the cylinder to have an look, there was a lot of oil around the pushrod tunnel, camshaft area that looked pretty dirty. How does the oil drain from this area could there be a partial blockage? Some how causing a build up, up to the head gasket?
The top two piston rings were within tolerance but the bottom oil control ring? Has a ring gap of at least 2 millimetres is this normal. Ps the piston and bore all looked good the piston especially with no signs of blow by etc.
I seem to recall does the rear pot get more oil splash due to the rotation of the crank?
The bike has done 31k and usually goes rather well but I have no history when purchased other than it was owned by a Mr M Challis from Chelmsford about twenty years ago.
Sicxtyone
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Joined: 29 Sep 2018 07:34
Location: Worthing
Location: Worthing West Sussex

Re: While my cylinder heads gently weep!

Post by Sicxtyone »

The picture hopefully shows the oil build up after only ton miles running
Just blew the head gasket straight away
Any ideas! Off to hunt out a valve Spring compressor
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Steve Brown
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Re: While my cylinder heads gently weep!

Post by Steve Brown »

For the oil draining question, with the barrel off you should see a couple of hole of about 3/4mm dia between the cam followers/tappets. Haven't seen them blocked before but suppose it could be done with gasket goo etc? If oil did build up there I suppose it could easily pressurize as the breather in the rocker cover is quite small and that upper chamber will get smaller as the oil builds up. Obviously you have checked the joint faces and the four cylinder studs were pulled down evenly as well as the 6mm screw on the pushrod tunnel? Not much else to go wrong!
All donations to the rest home for old Camels, Leicestershire.
Sicxtyone
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Location: Worthing West Sussex

Re: While my cylinder heads gently weep!

Post by Sicxtyone »

Ok Steve thanks for that, I’ll have a look in the morning. when I had the cylinder off before there was certainly plenty of oil around that area.
Sicxtyone
Posts: 121
Joined: 29 Sep 2018 07:34
Location: Worthing
Location: Worthing West Sussex

Re: While my cylinder heads gently weep!

Post by Sicxtyone »

Lifted the rear pot and the holes near to the tappet/ pushrod are clear.
So going to investigate the breather box.
Tried annealing an old base gasket yesterday, put permanent marker on it then heated on the burner until the marker burnt off allow to cool. Created a lovely pliable gasket, compared to the new ones from nlm that are hard etc. I guess every one uses these though.
Please what is the best torque sequence and values as there seems to be a few out there. 2.7 mkg then back off and re do to 2.2 mkg or Harglo manual 2.5 mkg.
It was reported earlier on this subject don't use sealant. Does anyone still use it?
julianharty
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Location: High Wycombe Area (Bucks)

Re: While my cylinder heads gently weep!

Post by julianharty »

I happen to be learning how to maintain a more involved engine - the Honda VFR400 NC24 where there aren't any known new headgaskets worldwide. They're made in aluminium and have to not only cope with the compression but also the watercooling to the heads. They also have a stepped indentation ring so are more involved generally than the Moto Morini ones in the air-cooled engines. I've learned from the forum (http://www.400greybike.com) and from other owners that they use a spray-on copper gasket (Permatex Copper Spray-A-Gasket) with great success. I managed to restore the compression on one of my bikes by following their advice. It's about £15 to £20 depending on who you buy it from.

I first fully cleaned the old gasket sealant a previous owner had used. That took me hours, and ended with gently polishing them with solvol autosol polish. I then followed the instructions and sprayed 2 thin coats of the gasket sealant - it's a mix between using rattle-can paints and copper coloured gasket goo.

I don't know how this would compare with the process of annealing the old gaskets. I mention it as a possible alternative and one I'd be happy to try in future on my bikes. The nature of the spray-on gasket means you get an even thin coating that's unlikely to leak or block oilways, etc.
Sicxtyone
Posts: 121
Joined: 29 Sep 2018 07:34
Location: Worthing
Location: Worthing West Sussex

Re: While my cylinder heads gently weep!

Post by Sicxtyone »

Thank you for this information I've not heard of this spray on copper method sounds a useful alternative where a thicker gasket isn't required.
Further to this my bike is back together now and touch wood no leaks, I used the annealed gaskets and torqued to 2.5 m/kg
Also cleaned out the breather box that was quite full of (stuff). After a carb tune the motor now starts and runs far better.
julianharty
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Location: High Wycombe Area (Bucks)

Re: While my cylinder heads gently weep!

Post by julianharty »

To be clear, the spray on copper gasket material is sprayed onto your current, cleaned up metal gasket. It's not AFAIK intended as a replacement for the original gasket. It's less about the thickness (and the layer is more like the thickness of spray paint) than helping restore the sealing behaviour of the gasket (at least as I understand the purpose of it).
Steve Brown
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Location: Leicestershire

Re: While my cylinder heads gently weep!

Post by Steve Brown »

All the later engines I've seen had been assembled using a gasket and sealant by the factory. The stuff they used seems a lot like 3 bond aka Yamabond, so that's what I use and it serves me well. This is on all joints including the cylinder head.
It looks like I misunderstood where you are getting the oil build up, I thought in the pushrod tunnel but it looks like you meant the cylinder itself? The head joint would have to be very obviously bad or damaged for it to get from the pushrod tunnel into the cylinder, and the only other ways are up from the crankcase past or round the rings, and through the inlet valve guide. Or cracks from the rocker area into the combustion chamber?
All donations to the rest home for old Camels, Leicestershire.
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