CG - Instant Head Gasket

themadatter · Nova Slayer Joined: 20 Jan 2005 Karma :

Hi All !

My CG125 is not up to scratch in the performance department.

I have just noticed that around the base of the cylinder head there is some goo flowing out.

Also noted that there was alot of instant gasket around the outside of the head in between the fins.

Instant gasket for a HEAD ! ? whats the world comming to.

anyway, would this lack of 100% working head gasket be affecting my compression enough to see a performace drop ?

Also, tappets rattle and I adjusted them to 0.05mm each and they STILL rattle ! any ideas ?

Thanks

Jamie

Git · Brolly Dolly Joined: 17 Dec 2003 Karma :

If the head gasket is leaking yes, you will loose compression and the power output will surely be affected but I guess this depends on the size of the leak. tried a compression test??

You mention goo flows out, Is it definitely the head that's leaking or the cylinder base gasket, this could quiet easily chuck oil out if it's leaking...

If you think the head has an instant gasket head gasket type affair it would be good idea to replace it asap. May also give you a good chance to have a good look at the valves and seats to see if there is a reason for them being noisy, perhaps if the engine oil is a bit old this will not help with the valve noise.

Should be a piece of cake to change a gasket on cg125. Thumbs Up

themadatter · Nova Slayer Joined: 20 Jan 2005 Karma :

Hi there

Thanks for the raply.

I'm pretty sure its the head, The leak is comming from around a third of the way down from the top of the barrel.
its between the rocker cover and the base of the barrel.

the thing is I seem it before when I got the bike to start with but It never really clicked that this was the head becasue I was used to a 2 stroke that had a tiny plate for a head and didnt need something big enough to hold valves etc.

Heres a pic, let me know what you think !
Thanks again for the advice !

Jamie

Git · Brolly Dolly Joined: 17 Dec 2003 Karma :

Looks a bit like someone may have tried to cover up a leak with the instant gasket. Is this the only location the gasket goo is visible?

I think check compression. Oil leak up top, lack of performance possible noisy valves?? this will tell us to some degree the state of the top end, If a compression check isn't an option, maybe check head bolts for tightness, if they ok off with it's head for inspection, if they loose, tighten and fingers crossed it seals again.

That's how I would play it anyway.

stinkwheel · Bovine Proctologist Joined: 12 Jul 2004 Karma :

A full, genuine Honda gasket set for a CG125 is less than 20 quid from https://www.davidsilverspares.co.uk/

You could do the valve-stem oil seals while you are in there too.

Red gasket goo is a complete pain in the arse to get off.
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Git · Brolly Dolly Joined: 17 Dec 2003 Karma :

Bargain, I'd just dive in there and rip it to bits Thumbs Up

themadatter · Nova Slayer Joined: 20 Jan 2005 Karma :

Hi all

Thanks for the replies !

cant to compression test as i dont have the equipment.
Oil is new.

Ok, I have never had a 4 stroke top end apart and unlike my 2 stroke which consists of (from the bottom up)

gasket
barrel
gasket
head
gasket
waterjacket

there are alot more bits to a pushrod 4 stroke.

You mention valve stem seals ! >?

If there is somebody kind enough out there to take maybe ten miinutes to explain everything on the top end I should replace in the persuit of good karma; please let me know !

I imagine the full top end gasket set is the first thing on my list, what would this include ?

Also, should i check valve springs, valves, valve seats ?
Becasue I set my tappets the other night and they where right out at .25mm , i set them back to 0.05mm and they still rattle !

Is there anything else I can do while its in bits that really should be checked ? piston ring gap etc !

If anybody has the time to respond to this list of things thne please do as i'm not just asking for the sake of it, i'm here to get adviec and follow it !

thanks all !

Jamie

mr.z · World Chat Champion Joined: 04 Feb 2004 Karma :

I have the haynes manual for the cg but..

A its for the older pre brazil verison
and
B its a a mates house Rolling Eyes

I can pm you the page with the topend rebuild bits...

To be honest though you really need one if your going to take the cylinder head appart, even just for the torque values (which may be different on mine)
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