I think, at last, I am on to something

[Don]

Aris,

I can't say for sure that's your problem, but if it *is* an exhaust leak, I think it would have to be a tiny one or you would have known about it immediately and it would be evident all the time as opposed to just under acceleration

I use these:

http://cgi.ebay.com/ebaymotors/79-82-HO ... ccessories

I bought 3 or 4 sets at once, as I'm always playing around with my pipes. I reuse them several times, sometimes reversing the gasket. I've only had one leak and it was after several uses, but then all 6 of my header pipes are individuals and I can wiggle them all for best fit

I'm not impressed at all with the concentricity (is that a word?) of the fit of your pipes to the head or the gaskets - You have a nice fat contact area part way around #1's and 3 and then a very narrow ring of contact in other places. If they're not leaking now, they will be shortly

Don

[Jeff Bennetts]

Don may be onto something, do you have another set of pipes you can compare the flange lip, and the inner/outer diameters to?

[Kool_Biker]

Good eBay seller, thanks Don! Just ordered a few sets, sure I will need them going forward!
Re the exhaust concentricity, what can I say, it is a brand new Delkevic system.
I see the six pipes in your avatar and drool over them .. may be one day ..
But for now, I have more immediate issues to resolve ;)

And frankly, if I did not have the racket with my previous exhaust AS WELL, I would agree, it could be the gasket(s). But we have been through this

Aris

[spencer]

I use these:

http://cgi.ebay.com/ebaymotors/79-82-HO ... ccessories

I used these same gaskets when I installed my new Sankei system, and I agree they are the best. I believe they are similar, if not exactly the same as the originals from Honda.

[Kool_Biker]

Aris:
Every CBX head came from the factory with both 'A' and 'B' buckets and bores. There is an 'A' or 'B' stamped into the head at each bore telling you this. The buckets are identified as 'A' or 'B' by what we call 'grind' marks in the lip of each bucket. Two grind marks top and bottom is an 'A' bucket and one grind mark top and bottom is a 'B'. I think 'A' buckets are the larger of the two, but I'm not sure. Anyway, if you get them mixed during installation, some of the larger ones will end up in the smaller holes and some of them stick, they are that tight. The early shop manual does not make this clear, but page 6-19 of the Pro-Link manual shows this clearly. Again every CBX engine out there has both 'A' and 'B' buckets. I suppose since 'B' is all that is available, then they would be the smaller of the two and work in either 'A' or 'B'.
Dave

Dave, as you can see, plenty of 'A's and plenty of 'B's!
Still, first time I notice these, looking at my zillion old pics from when I was dismantling the engine.
Personally, I went with the old adage, marking and putting each one removed back in its original position, but had no means of knowing that they were correct to begin with as there is no such mention in the 79 shop manual!
Would be interesting to verify that the shop which did the head at least matched them ... which I will do any day now ...

DSC06742.jpg

DSC06743.jpg

[Kool_Biker]

Decided to take the plunge and after 3 short but intense hours, burning the night candle, here we are ...

P1060996.jpg

Now I can begin a proper assessment of each and every part of the engine, starting form the top and the obvious.
Although I am by an expert by any stretch of the imagination, my know how, compared to the time I originally did the rebuild, back in 07, is much - much better.
And of course I know I can rely on the best CBX know how & resource there is!
Cheers, and wish me luck, Aris

[EMS]

Just so that we don't leave any possibility untouched, Aris: Did you make sure the cams were installed correctly. As you know, the early 79 manuals have a mistake and the two cam halves are installed wrong relative to each other.

[Kool_Biker]

Absolutely, fully aware of this well known shop manual errata. Thanks!

[Kool_Biker]

Aris:
Every CBX head came from the factory with both 'A' and 'B' buckets and bores. There is an 'A' or 'B' stamped into the head at each bore telling you this. The buckets are identified as 'A' or 'B' by what we call 'grind' marks in the lip of each bucket. Two grind marks top and bottom is an 'A' bucket and one grind mark top and bottom is a 'B'. I think 'A' buckets are the larger of the two, but I'm not sure. Anyway, if you get them mixed during installation, some of the larger ones will end up in the smaller holes and some of them stick, they are that tight. The early shop manual does not make this clear, but page 6-19 of the Pro-Link manual shows this clearly. Again every CBX engine out there has both 'A' and 'B' buckets. I suppose since 'B' is all that is available, then they would be the smaller of the two and work in either 'A' or 'B'.

Dave

Dave, this is what I had in the 'B' stamped exhaust valves of cyl 1 (and have not looked at any of the others yet).

P1070019.jpg

I can make the two grind at the top, none at the bottom, and if I understand you above, they are both 'A'
Also as you can see, they are both clearly discolored along their bore ... but they move freely up and down (with the engine cold).
Any thoughts?
Cheers, Aris

[Kool_Biker]

Correction, the above are 'B' type.
This became obvious once I saw an 'A' type, where there are 2 grind marks across the head, stead of one as above.
There are several 'A' & 'B' types in the head, and are all populated correctly.
They all seem to have the 'discoloration' described above, guess its normal?
Cheers, Aris

[daves79x]

Aris:
You have correctly identified the 'A' and 'B' buckets. I'm sure I've seen some discolored as you have there. Something else you can do before pulling the head is to measure the height of each piston pair. Focus on #s 1 & 6 of course. Measure from the spark plug hole to the piston top and compare to it's mate. A bent rod will be pretty obvious.

Can you tell if perhaps you have a broken valve spring in #1? Never heard of that, but your noise still seems like a top end thing.

Dave

[Kool_Biker]

Aris:
Can you tell if perhaps you have a broken valve spring in #1? Never heard of that, but your noise still seems like a top end thing.

Dave

I don't suppose I can check for a broken ring BEFORE pulling the head?
Aris

[daves79x]

Aris:
No way that I know of. Really, really wish I could hear it in person, perhaps something would ring a bell. Alas, you are past that point now anyway.

Dave

[Kool_Biker]

PROBLEM FOUND.

The video below is self explanatory ...



Now need to plan course of action .

Trying to turn a problem into an opportunity, wonder what else needs to be looked at at this time ...
Cheers, Aris

Admin edit: Stuck that youtube url in the [youtube] tag to embed it.

[Goss]

Wow, that is a problem! Good luck.

Regards

Goss