Topic: Honda CB400F camchain tension issues and cam rocker nuts missing inside engine!!

[Johnson]

Hi everyone,

I have a UK CB400f and without going into all the major history/story that it has I currently have an immediate problem I need to solve.

First off, suspected camchain noise, went to try to tension but found that the tensioner bolt was fully bolted in at it's end. Would this mean I need to get a new cam chain and or the tensioner is stuck/shot? I had the piston rings done recently and the tensioner blades all looked good, the chain looked ok too but the bolt was always bolted in to the last, which obviously I should have looked at before.

Also, and more immediate, it seems that some of the rocker adjuster nuts have gone missing inside the engine due to working themselves loose.

I really did not want to have to take the engine and split but am not sure where the hell the nuts are, so guess I will have to split it to find them.

If I take the head off or before is there any sure fire way to test the tensioner to see if it's stuck, or due to the nuts inside the engine somewhere would I be better off to just split the lot and then look at the tensioner itself after?

Thanks for any advice in advance,

John

[flybox1]

If the tensioner bolt was turned in all the way when you re-ringed the pistons, it should have been your clue to install a new chain and tensioner unit.
Didnt you hear all that extra noise from the rocker nuts bouncing around inside? 

[przjohn]

I am thinking you are mistaken with the tensioner bolt/nut. The upper bolt is merely a cap. The bolt on the side with the lock nut is the adjustment. Which are you talking about?

[Johnson]

If the tensioner bolt was turned in all the way when you re-ringed the pistons, it should have been your clue to install a new chain and tensioner unit.
Didnt you hear all that extra noise from the rocker nuts bouncing around inside? 

As I did not have the time to do it myself or the tools as I was in the process of moving house, I gave the piston ring job to a shop, the guy in the shop had said the guides and everything looked good, and that he thought there wasn't much wear on the engine that he could see, he bolted it all up and I got it back minus the rocker cover, as that was at mine.

I had such a #$%* fest with the guy in the shop as he messed around for so long making excuses about rings and other reasons why it took so long amongst other things, I am new to the area (moved to another country) and have since found out that many bikers avoid the shop as it has a bad rep, although many others still use it.

Point being if I had time and space at home to do it all myself I would have taken my time and done it properly, naively thinking it would be easier to pay for the job to be done has not worked out well.

[Johnson]

Also, I did not have a gapping tool to do the rocker arms, I used a long nose pliers and was sure they were tightened up properly, I then brought it to a mechanic I found to check the timing properly (as I don't have a timing light) and then got a phone call saying that he found that the rocker nuts were missing, so no I didn't hear any noise before hence why I guess I'll have to just strip it all down and find out where they are... I will no doubt buy a gapping tool now or make a good one.

[Johnson]

I am thinking you are mistaken with the tensioner bolt/nut. The upper bolt is merely a cap. The bolt on the side with the lock nut is the adjustment. Which are you talking about?

As far as I am aware the upper bolt is the tensioner that screws down to put pressure onto the horseshoe that in turn bends the rear blade to tension the camchain. The lower bolt near the oil filter is to lock the adjustment in place.

[Bodi]

The upper bolt just plugs the hole drilled for the tensioner actuating rod. You can take it off and push something thin down through the spring to put extra tension on the rod when adjusting - those springs have lost their original strength over the decades.
The lock bolt is a strange one, it is above the oil filter straight back into the upper case. There's a 10mm head and a 12mm (14mm?) lock nut. You must be gentle with this oddball bolt, the large diameter threads you see are only for the locknut - the working threads deeper inside are 6mm. They get broken off fairly frequently and are not always easy to get out.

[Johnson]

The upper bolt just plugs the hole drilled for the tensioner actuating rod. You can take it off and push something thin down through the spring to put extra tension on the rod when adjusting - those springs have lost their original strength over the decades.
The lock bolt is a strange one, it is above the oil filter straight back into the upper case. There's a 10mm head and a 12mm (14mm?) lock nut. You must be gentle with this oddball bolt, the large diameter threads you see are only for the locknut - the working threads deeper inside are 6mm. They get broken off fairly frequently and are not always easy to get out.

Thanks for the reply Bodi,

I thought the upper bolt would tension the chain as it's tightened, putting pressure on the springs and then obviously that transfers to the rest of the set up. So I gusee my springs may be shot too, is there anywhere I can source these? I have the lower locking bolt, I think at some point someone fitted an insert to it, I will post pics up shortly...

I'm going to go look for these lost bits today, I guess then I will be able to change the cam chain and check or renew the tensioner.

So a recap, I need springs for the tensioner rod, possibly a new horseshoe tension arm, and of course a new cam chain...

If I look at the tension arm is there any sure way of knowing if it's shot?

[Bodi]

The springs are retained in the hole, the bolt doesn't touch them.

[przjohn]

You are now talking about splitting the cases to do that work, those nuts should show up then. I have to say your story sounds like quite a cluster duck with whoever you had work on the bike and then the whole  "Gapping" thing which I assume you mean adjusting the valves. Why not slow down, take a breath, and look at the problem.

Pull the oil pan and see if you can find the nuts, easy enough.

You can adjust the chain with some pressure on the adjuster, there are threads here about that, but try the manufacturer's way first.

Adjust the valves, it's not that hard.

But, before you do anything, GET A SHOP MANUAL AND READ IT!

[Johnson]

Cheers przjohn,

Yes, it was a whole cluster duck with everything...

So to partly explain and share a bit of this back story;

I at that time started to semi restore the bike, stripped it all and then found out my landlord has decided to sell his house, as quick as he could. This meant I had to either pack all the bike (in bits) into boxes and move to somewhere which hopefully had some sort of shed or similar, or try to get it all back together as quick as I could. I chose to try to get it back together. This is why I gave out the engine to a shop to be done quicker and by an expert, or so I thought.

I originally gave only the head to get the valves cleaned and lapped/faces ground and fix a couple of ruined threads.

Looking at the pistons when at home I could see some 'blow by' down the sides and when the bike was running had some smoke so thought it better as the engine was apart to put new rings in.

The shop owner then persuaded me to bring in the rest of the engine to save me time and stress, he said he'd get new rings and hone the barrels, do the work on the head and bolt it all back up for me. To cut a long story slightly shorter, I had to phone up each week for weeks to find out when it would be ready, to which I was told all different types of excuses (including places he had to go in his spare time, lot's of anecdotes about his past to keep me entertained, and how he has been at a boat show and hoped he'd see a guy he knows that may get my rings for me there) but in the end he told me he had so much problems getting rings and finally found some in Holland, but it would take a week or two to come.

Anyway, when he phoned (after quite a while had gone past) to tell me it was ready to collect. I went in and while collecting it just asked in a friendly manner where in Holland the rings he got came from, and (as they were my parts) can I have a copy of the receipt (I like to keep receipts when restoring anything). I then got near enough shouted at by his wife=shady business partner), to tell me no one is allowed to see any of their receipts as they are for their business alone, and then for the guy to tell me that he would write me out a receipt from himself but I can't see the actual receipt for the rings, his wife got very highly strung after such a small space of time, like they had been caught or called out on bad work.

I've been told since by many other bikers quite a few bad stories and that the shop is nicknamed the joke shop.

Sadly I had to find out firsthand. I paid them over 380 euros for all the work that was supposed to be done.

To finish this long story (apologies), yesterday I took the head off, the engine is now out, I still have not found the 2 nuts that are missing, they are not in the oil pan either...

My pistons look as dirty as they did before the rings were supposed to be done, the valve faces don't look clean or any different and this I suspect is why he persuaded me that he would fit everything, so that I would not see inside to check if the work was done.

I'm going to take out the valves and has a look at how they seat and if they weren't done then lap them while i'm waiting for the new cam chain to come.


I will post up some pics shortly.

Thanks to anyone who read all of this and for the replies!