Honda C90g 12v Cylinder Head

[Gompho]

Hi everyone,

Does anyone have a cylinder head for a 12v c90 they would sell?

[Alan CF]

What's up with yours.

[Gompho]

Hey Alan,

You came up in conversation today when I was chatting with Dave Wilkins about this engine. Basically someone tried to drill out my broken exhaust stud and made a bit of a cock up. It's drilled out crooked and I'm sure that there's a bit of a bolt still left in there.

So after talking to Dave I took it to a machine shop but when they said it would cost a fair bit to do the setup and get the old bolt out and fill it since it's too crooked to put a time-sert in.

Basically looking to see if anyone has a spare since it might be the cheaper option right now

Also the exhaust blow out has melted some of the head as you can see so I'm not sure what the seal would be like

Here's some pictures

https://photos.app.goo.gl/4zhnxZyXRYnw5fKn8
https://photos.app.goo.gl/cVNhdkxVqbTgR7No9
https://photos.app.goo.gl/Rvsp6fpuxAS9iHgz5
https://photos.app.goo.gl/Qomam2m3VhjXxQhX7
https://photos.app.goo.gl/cnSDyR3nzTBp644L9

[Newtsalad]

Doesn't look like blowout on the exhaust seal seat to me, just some crud and old gasket in there. The gaskets are also notorious for compressing and looking like part of the cylinder head, an agressive attack with a flat bladed screwdriver sometimes reveals gaskets stacked on top of each other, encased in carbon and polished by the header it looks all the world like the alloy seat, but to be fair that doesn't look to be the case with your cylinder head.

I'll tell you what I would do for what it's worth....

I've dealt with many stuck studs, and despite care and great pains and oodles of patience, some will always snap. I had a head like yours. I MIG welded the stud up, very easy to do quick squirts and it will build up with no affinity or effect on the surrounding alloy. Don't ask me why but that's what it does. I was then welding a nut on, and trying to turn the stud out. Each time, despite the heat put into the head, the nut was shearing off. On about the third go, I realised i was using almost as much force to shear off what I had built up, as a 6mm stud would take anyway.

At thet point, I built up the stud again, welded on a 6mm bolt, cut the head off the bolt, and the job was a good 'un!
A bodge maybe, but one that worked so more a dodge than a bodge.

[Gompho]

I really wish I could save this head but without a mig welder or any other special equipment I can't try any of that stuff so I think it's probably going to get replaced by a Chinese copy from OO Racing for now

Been lookin for some used ones on eBay and Facebook but all are either 6v ones with points or little inlets or also have broken studs. I can keep looking in the meantime

Yeah it's definitely not gaskets. I had a few stuck in there before. It's melted because after the stud came off I had to hold it on with wire I rode it for 20 hours and 600 miles wide open

[loadedtoad]

Never been a fan of time-serts i've seen too many put in without enough metal left around them to support them or they just unscrew themselves when trying to undo the original fastner.
Others disagree i know i prefer Helicoils as they remove less of the original metal.
Always difficult from pictures but fixed in a machine vice and drilled out on a press drill i'm pretty sure a 6mm Helicoil insert with a new stud would fix this.

[Alan CF]

I wouldn't say it was the timecerts fault but the knob who fitted them,

[loadedtoad]

Knobs being plural considering the amount of badly fitted one's i've seen.