Cylinder head repair - advice pls

[Dave_Q]

Hi gang, 

 

I have just bought, based on the second least informative ebay description ever, a 1990 Honda CBR600.

 

It has a damaged cylinder head around one of the exhaust studs. Have a terrible photo.

 

 

The exhaust is clearly blowing from here and is going to prevent an MOT.

 

How can I go about repairing this for a maximum expenditure of 99p?

 

Will any of the cold weld epoxy type things be any good here?

 

Or is welding a new stud in an option? I have a gas/no gas MIG but as I'd be trying to weld a steel stud into alloy would this work?

 

All helps and/or laughing and pointing appreciated.

 

P.S. I know a new cylinder head is probably the proper thing to do but I would would like to try and get it through an MOT with the minimum fuss in the first instance.

 

Ta.

[MrDuke]

** points and laughs **

 

 

Clearly, the only true shiter option is to shovel in large quantities of JB Weld. What's the worst that could happen?

[jonny69]

You could try hammering a coach bolt into the hole... oh wait.

 

Well what's the worst that can happen with Chemical Metal. I've used it to fix a lot of things in the past including radiators and cast parts and it's worked a treat. The only thing to remember with epoxies is that they don't like heat, so even if you wire brush it back to bright it'll probably last a bit longer than the MOT but crumble out soon after. Give it a go and see what happens. If it's any help, silicone mastic can take exhaust manifold heat. Just boggo bathroom stuff, nothing exotic.

[Dave_Q]

Will have a go with the chemical metal, it's worth a shot and I might even have some in the cellar.

 

We may LOL at the previous owner's attempt at fixing it, but looking through the paperwork I think it actually passed it's last MOT like that! Advisory for exhaust blowing but not too loud.

[Mr_Bo11ox]

I'm sure you could get that built up with Alu weld and the hole redrilled/tapped.

[twosmoke300]

Coach bolts .....................grrr

 

JB weld (not the quick stuff) is great if the prep is good . In the past ive drilled several 1mm holes around the area to give the jb weld a good key. Then leave for a couple of days before drilling and tapping.

 

The other way is to lightly grease the bolt before using the chemical metal around it . wait for it to set then it should screw out.

[Station]

Sod all this! Quiksteel it, then apply a couple of jubilee clips!

[Dave_Q]

Have used quiksteel before and wasn't massively impressed.

 

I know this could be repaired the proper way but I could get a head for something like £40-50 which would be something like what I imagine a machine shop would charge to weld, drill and tap. 

 

Plus I'm trying to avoid the ballache of removing the engine for now.

 

I will give it a go with JB weld and keep an eye out for a cheap head to swap over during the winter.

[Bren]

I used some epoxy stuff from halfords - I had a 2.9 granada with blowing manifold joint.

 

One of the studs had snapped and took some of the head with it.

 

The stuff worked - it held for as long as I had the car.

 

However, it was cast iron, your CBR will be aluminium, so it may not work as well.

[alf892]

Make an aluminum stud and get it welded in in situ. Fit new gaskets to manifold so it doesn't need loads of tightening to hold?

[dieselnutjob]

how well is the coach bolt in there?

can you cut the head off of it and put a nut on the threads of what is left?

[Dave_Q]

Aluminium stud I hadn't thought of so thanks for that.

 

Haven't even attempted to remove the coach bolt yet, I'm sure it's barely wedged in and will come out easily.

 

I'm most likely going to get the correct stud and JB it in place for now.

[blackboilersuit]

Don't think about changing the head until you've checked the price of the gaskets. Jap bike engine rebuilds can get very expensive.

 

Using a bolt to hold in an exhaust flange is not good as it is rotation in the alloy thread as it tightens makes it more prone to strip IMHO. A nut on a stud is only exerting a pulling force on the alloy thread as it is tightened as the stud does not turn so a bodge is more likely to hold.

 

If there is any remains of a thread in the alloy then you can try winding in a new stud (bit of threaded rod) using two nuts on it with bits of coke can wedged into the hole to take up the slack.

 

If it really does need welding up and fixing properly then I'd pull the engine. The repair cost will likely be much less than the cost of a replacement head and new gaskets.

[fordperv]

I'm sure it wouldn't cost a great deal to get welded properly and then re tap at your local friendly fabricators that way the job only has to be done once

[Dave_Q]

Well it's fixed.

 

After removing the coach bolt, it appears that prior to the attempted epoxying in place of said coach bolt, someone has drilled and tapped a deeper hole which still has good thread in it.

 

Had to make my own stud about 110mm long.

 

I was tempted to slop on some chemical metal as well, but it won't last in those conditions and I'm sure it will hold without.

 

[michael1703]

I was going to interject with " put it in for an MOT and see if it fails" but glad you got it sorted

[Bucketeer]

I've got a bike mechanic mate over in Barnsley who always has old CBR bits knocking about (including most of my old CBR600, long since deceased, in his garage). Give me a shout if you need anything and I'll get him to have a root around.

[Dave_Q]

Thanks for the kind offer Mr Bucketeer, I will give you a shout when I've got a bit of a list going.

 

A picture of the bike if anyones interested.

 

 

Seems mostly alright, rear indicators are broken but I have some somewhere.

 

Doesn't want to idle without choke which is probably pilot jets bunged up. 

 

Paint needs attention, I will attempt to find a match for the blue and spray the white bits to match*

 

Any suggestions on a similar blue would be good.

 

I've got at least a couple of weeks before I'll have a licence to ride it anywhere so might as well do what I can with it while I'm waiting.

[Bucketeer]

Looks good that, unusual colour combo.

Just shout away when you have a list, there's always loads of bits kicking about and he's often over Huddersfield way (well, Emley) for easy delivery/collection.

 

Paint needs attention.

Any suggestions on a similar blue would be good.