I think I've done something wrong!

[McCabe-Thiele (Ted)]

That's bad luck Sean - I've generally  ensured that the dowels are on the fixed surface first so they can't drop out. It has meant I have had to replace a few as they chewed up a tad on extraction.

As has been said any unaccounted for big lumps should drop down into the sump - goes without saying to change the oil filter. Have you fitted a magnetic sump plug might be worth it as belt & braces.

[Skoti]

I can see how the bolt came out if you didn't put locktite on it but I can't fathom out how the dowel got involved in the failure 🤔🤔🤔

Julie, maybe Loctite is something you recommend, but there's no mention of that in the official Honda CB400F shop manual over in Aladdin's cave.
I built a fair few of those Honda engines during my years in the trade and never had fully tightened cam sprocket bolts come loose.

Bit of bad luck for Sean tho, hope he gets it sorted out.

[Nurse Julie]

I can see how the bolt came out if you didn't put locktite on it but I can't fathom out how the dowel got involved in the failure 🤔🤔🤔

Julie, maybe Loctite is something you recommend, but there's no mention of that in the official Honda CB400F shop manual over in Aladdin's cave.
I built a fair few of those Honda engines during my years in the trade and never had fully tightened cam sprocket bolts come loose.

Bit of bad luck for Sean tho, hope he gets it sorted out.

Indeed you are correct Scoti but if locktite or similar had been applied, it wouldn't have come undone. It's just belt and braces really. It's like the cap / plate that holds the cam chain guide in place at the top, I would advise using locktite on those 2 bolts as well.

[Oddjob]

I've never used Loctite on those bolts, so long as they are torqued up they should be fine.

As for the dowel, I tend to locate any dowels in the head rather than in the rocker cover, they shouldn't fall out if they are in the head, as gravity keeps them in place.

TBH I suspect the cam sprocket bolt was never tightened rather than came loose, you tend to fit one but not tighten it, just in case it locks the sprocket out of alignment for the other bolt,  spin the engine until the other comes up so you can fit that and then forget you haven't torqued up the first one and move onto something else, anything can cause this, someone speaks to you, a phone call, just something that breaks your concentration, easily done.

[ST1100]

TBH I suspect the cam sprocket bolt was never tightened rather than came loose, you tend to fit one but not tighten it, just in case it locks the sprocket out of alignment for the other bolt,  spin the engine until the other comes up so you can fit that and then forget you haven't torqued up the first one and move onto something else, anything can cause this, someone speaks to you, a phone call, just something that breaks your concentration, easily done.

Which is why I prefer to work on my own...
And I adapted the Japanese way: Edding 8750 industrial paint marker...

[McCabe-Thiele (Ted)]

So that's why I have yellow dots on my engine bolts to remind me they have been torqued up!

[Oddjob]

Yellow paint was used by Honda on the production line for that very reason Ted, it also showed if the owner tampered with the bolts in case of warranty claims.

[SeanFD]

Using a magnet, I was able to fish out a couple of additional bits.

Then I turned the motor over slowly - yes Ted, the plugs were out - and all seemed fine.

So now it will have to sit for a while until I get back to Belfast, when amongst the other things, I'll drop the sump, check the strainer and change the filter.

Until then ...

[McCabe-Thiele (Ted)]

That's bad luck Sean - I've generally  ensured that the dowels are on the fixed surface first so they can't drop out. It has meant I have had to replace a few as they chewed up a tad on extraction.

As has been said any unaccounted for big lumps should drop down into the sump - goes without saying to change the oil filter. Have you fitted a magnetic sump plug might be worth it as belt & braces.

[SeanFD]

Or new title: Everything happens to me!

On my enforced sabbatical from my USA trip, belfast2belfastbybike.com for those who don’t know, I decided to get this bike up and going.

I took the rocker cover off and almost the first thing I saw was the dowel I thought was the culprit; intact and lying against the oil pipe. Obviously it had just dropped out of the rocker cover when I removed it.

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Replacing the bolts into the cam sprocket was difficult - they felt tight. I got one in and torqued and was doing the second when it stripped! (Original Honda bolt)

I was thinking to take the camshaft out to inspect the threads more closely when I noticed what looked like a crack in the lobe where the bolt goes. I touched it with a screwdriver and the result was not pleasing!

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While trying to gat a hold of this piece and not being careful enough, (how could such a chunk of metal fall down that small hole?) I dislodged it and down it went. I think – I hope – that I can retrieve this by dropping the oil pan, because my efforts to find it from the top were unsuccessful.

So that put paid to my hopes of getting the bike running quickly. A replacement camshaft is on its way from Steve Cooper at 400FourBits, along with some new bolts and a gasket from DSS.

Anyone seen this happen before? No I didn’t drop it, but someone else may have I suppose. I guess I should be happy that I found it now and not when to cracked at 6000 rpm, but sometimes it’s hard to be philosophical 😢

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[Bryanj]

Yes i have seen but not on 400, could be sprocket was not on shoulder properly

[florence]

I see you described your process as 'I got one in and torqued and was doing the second when it stripped!'.  It is better to get both bolts in finger tight first and make sure everything is aligned before final tightening, equally, to full torque.  I thought I might mention this before you put in your new camshaft.  These castings are very strong in the directions they need to be but surprisingly brittle in other directions where force shouldn't be applied.

[K2-K6]

Agree with likey cause being unintended force in wrong direction whilst tightening bolts unevenly, or missing alignment of sprocket throughout the assembley/ location part.

Good advice to get them all but fully assembled by fingers before just a tightening torque at end to finish the work.

Many years ago, watched someone tightening a jaguar XK camshaft (they are very long) by just going along from one end to the other in assembly, only to snap it in half as it bent against one of the valve springs.

Very strong in direction needed, but simply vulnerable to bending forces that are not part of running when in use.

[SeanFD]

I did think about the possibility of the sprocket not being properly on as suggested by Bryan, and that may have been the case given the relative tightness as I put the bolts in - not overly tight, just not turntable by hand.

The first one was in snugly and I then put in the second and was torquing it when it stripped. Maybe an off-centre sprocket meant the bolt wasn’t lined up correctly so was cross-threaded.

The shaft broke after I had removed the sprocket bolts.

Good news is that I retrieved the missing part, sitting on top of the primary chains.
But not till I had already removed the sump …. And the exhaust to get at the bolts! 

The camshaft I had ordered turned out to be damaged, so now on the lookout for another.

[Bryanj]

Only one on ebay at moment and thats in us and 100 postage!
I could get that reduced via a freind but not sure by how much, dont have any 400 ones about but try a wanted on the forum somebody may well have one, if you are very flush there are a couple of Yoshi ones on ebay at just north of a grand!