CB400 - Upper Blanking Bolt

[Integra99]

Right.. engine running well.. just needed cam chain adjusting.. what I thought was am adjuster bolt turned out to be an M6 X 12mm bolt hence my cam chain was rather slack.

However where the adjuster push rod locates I'm clearly missing the blanking bolt.. I can see the end of what is the adjuster rod.. It looks like an M8 thread.. I'm assuming I can just pop a suitable M8 bolt in here?

Any ideas.. ?

[Integra99]

I think this is what I'm missing...

[Laverda Dave]

Yep, that's all it is. If you want to fit the correct bolt make sure you use a close fitting washer under the bolt head to ensure no debris gets in there otherwise you'll be rebuilding the engine. Personally I'd only do this as a temporary fix whilst I wait for the correct blanking bolt.

[Nurse Julie]

As above.

[Integra99]

Great thank you both! so its simply a blanking bolt.. really appreciate the reply and I will ensure its a tight seal.

Right on to the next problem.. !

[Seabeowner]

I’m no expert on the 400/4, so shoot me down. But doesn’t that M8 bolt bear on the two springs that are supposed to provide the tension when the special M6 bolt at the front is released. Problems are that the special M6 bolt is overtightened and then the tensioner jams. Plus the tension provided by tired springs is not enough and some manually push the tensioner with a bolt in place of the special M8 bolt. Dangerous as you can overtension. I see the M8 bolt is a bargain 35Euros +VAT from CMS.

[tom400f]

No it's just a blanking bolt at the top of the drilling the push rod runs in. If you choose to push down on the end of the rod while tensioning, then as always on all these engines, just enough and no more is what you need. They used to say "gently while the noise lessens" or something like that.

[Integra99]

So its no. 11,  I have to be honest I'm not aware of the springs. My Tensioner is working as the adjuster bolt when taken out reveals the flat section on the adjuster rod.. however the blanking bolt is missing ..

What a bargain.. same as DS bolts.. hence I'm best friends with my local fastener shop

Here is the image..

[Seabeowner]

Its been highlighted recently on the US site (but they lost 10 days data last night). A member makes a special, but it's also available from 4into1 or you can make your own. This gives a positive positioning for the tensioner. (you hardly need the M6 bolt at the front) Or you can just press in the plunger and lock with the M6 bolt at the front. The springs were meant to take the skill out of the tensioning but always were too weak and the push and lock method was used. But the m6 bolt was often overtightened and the plunger jammed. About £40 for the M8 bolt says it was no ordinary bolt.
500/550 is much better, but then I'm biased.

[Nurse Julie]

The M8 bolt (No 12 in the pic) is very special. It starts off as M8 and then goes to M6. You should never put pressure on the plunger as this will overtighten the cam blade. TTR 400 (Kevin) is a member on here, met him at our day out at Sammy Miller's a couple of years ago, nice chap.

[Integra99]

Yes I have the no.12 bolt so I can lock the cam adjuster.. this works as my rattle has now calmed down and it locks... I dont want to mess to much with it and think that upgrade bolt looks a really good solution for a worn M6 thread!

But I have an open hole where bolt no.11 should fit. So technically just need an small M8 and washer to plug it and we are good to go.

I'm assuming those springs can only be fitted/removed by splitting the cases??

[Nurse Julie]

Yes, split cases, if you look at this photo you can see the springs compressed sitting up against the inside of the casing

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[Integra99]

Brilliant, do you know I've searched Google over and over to find that picture.. ha ha thats great so I can see how it works.

[K2-K6]

Putting it in perspective,  lucky you've not got one of these to assemble.
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Can't imagine what that lot costs to replace!

 

[Nurse Julie]

Brilliant, do you know I've searched Google over and over to find that picture.. ha ha thats great so I can see how it works.

Picture from the other side if it helps

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And all the internal components. Except the bracket at the top left of the photo

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