Author Topic: Cam chain tensioner bolt  (Read 741 times)

Offline AndyD

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Cam chain tensioner bolt
« on: January 12, 2020, 12:00:23 PM »
Hi again,
Another question on the cam chain tensioner bits.
The hole in the crankcase for the bolt to lock the tensioner has been repaired at some time with a M6 thread insert - it seems quite secure and thread is good but I wasn't sure how this should really be.
As I understand it the original bolt has M6 thread at the end and then a bit of M8 with a nut further towards the head.
Should the thread in the cylinder case be all M6 or a bit of both to fix properly.
Hope my rubbish description makes sense..

Cheers,
Andy

Offline Bryanj

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Re: Cam chain tensioner bolt
« Reply #1 on: January 12, 2020, 03:04:46 PM »
All m6 the m8 is only on the bolt

Offline AndyD

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Re: Cam chain tensioner bolt
« Reply #2 on: January 12, 2020, 04:41:48 PM »
Thanks Brian

Offline AndyD

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Re: Cam chain tensioner bolt
« Reply #3 on: January 24, 2020, 06:23:53 PM »
Bryan,
Having cleaned everything up and gone through all the parts in the boxes I think I know what's gone on!
The thread in the crankcase for the tensioner setting bolt has been fitted with a dodgy M6 helicoil which was even a bit loose so I've pulled this out and the original thread is only partly intact.
The tensioner bolt also has a partly damaged thread so I guess between these two issues the tensioner would be likely to slip.
I think the PO has then made up an M8 'special' bolt and used this to push down the camchain adjuster from the end to tighten the chain manually'.
To fix this mess I've seen a repair 'kit' on ebay for a reasonable sounding £24 and which seems to include all the parts needed - any idea if these work?
I'll then get a new oil check bolt and washer as standard.
Hopefully this makes sense!
Cheers,
Andy

Offline Bryanj

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Re: Cam chain tensioner bolt
« Reply #4 on: January 24, 2020, 07:07:34 PM »
Have you got the ebay number?

Offline AndyD

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Re: Cam chain tensioner bolt
« Reply #5 on: January 25, 2020, 08:51:10 AM »
Bryan,
The ebay number is
283730100697

Hopefully you can see it from there?

Cheers,
Andy

Offline Bryanj

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Re: Cam chain tensioner bolt
« Reply #6 on: January 25, 2020, 12:51:50 PM »
Looks a good kit from pictures but two comments
1 You will need to be very accurate with set up and drilling for oversize tap, hand drill NOT recommended.

2 That tap may be a special order and not cheap, there are 3 different pitches for 10mm threads and i think(but willing to be proved wrong) that that one is the "non preffered" one

Offline Oggie400F

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Re: Cam chain tensioner bolt
« Reply #7 on: January 25, 2020, 01:52:38 PM »
The external thread of the ‘repair’ insert is M10x1.25 is Metric Fine I.
M10 fine pitch can be 1.25 (I) or 1.00 (II) or 0.75 (III)

See the attached Metric Thread Chart

There are also an ultra fine pitches of 0.5 not shown on this chart
« Last Edit: January 25, 2020, 02:33:19 PM by Oggie400F »
I'm a Radiographer............I can see right through you!!

1999 VFR800 fix in Pearl Prism Black
1978 CB750F1 in Candy Presto Red
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1976 CB400F in Varnish Blue - project bike in many bits.

Offline Bryanj

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Re: Cam chain tensioner bolt
« Reply #8 on: January 25, 2020, 04:09:46 PM »
Thats what i said, there are 3 different pitches on 10mm and only 2 of them are "common" the other is called "non preffered" which means a lot of countries dont use it except Japan, they also used non preffered hex sizes for bolts like 12mm hex on 8mm thread

Offline AndyD

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Re: Cam chain tensioner bolt
« Reply #9 on: January 25, 2020, 07:00:52 PM »
Thanks,
Maybe I'll try contacting the seller to see what the thread pitch is.
I've got a pillar drill so can hopefully set the case up firmly in the right position for this.

Are there other recommended repair routes for this if the ebay one doesn't work out?

Cheers,
Andy

Offline Bryanj

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Re: Cam chain tensioner bolt
« Reply #10 on: January 25, 2020, 11:08:17 PM »
If that ebay one fails i would look for replacement cases.
The kit looks a well manufactured one and having checked 10x1.25 taps are available on ebay but get the taper and plug.

Offline AndyD

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Re: Cam chain tensioner bolt
« Reply #11 on: January 26, 2020, 09:30:33 AM »
Thanks again,
I'll order one up and give it a go
Cheers,
Andy

Offline waffey

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Re: Cam chain tensioner bolt
« Reply #12 on: January 29, 2020, 03:14:42 PM »
I've ordered one as well but have an engineering firm do it for me as they need to remove the broken bolt first. Hopefully get some pictures when done.
Bikes:
Suzuki Address 110 Scooter
Suzuki TL1000s
BMW R1200GS LC
Honda CB400 F2 1977 (restoration started)

Offline AndyD

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Re: Cam chain tensioner bolt
« Reply #13 on: February 08, 2020, 06:06:14 PM »
Well, finally got all the bits ready to sort the cam chain bolt and happy to say all worked out well today.
Spent a fair while trying to find a way to align the case in my pillar drill but finally gave up as it all got far too complicated!
Took a gamble with hand drill and luckily went smoothly and drilled clean hole with no drama.
Tapped new thread and adjuster kit seems to fit really well (only loosely fitted so far until cases are painted).
Relieved as I can now crack on with the engine work.
Bought a cheap oven for the shed so I can cure paint without causing a messy divorce - might get painting tomorrow so fingers crossed.
Thanks again for all advice on the cam chain bolt.
Andy

Offline Laverda Dave

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Re: Cam chain tensioner bolt
« Reply #14 on: February 09, 2020, 11:26:11 AM »
Good to hear Andy. I fitted one of those kits to my 400 as PO had fitted a large bolt! I found it very easy to fit and had no problem with it at all.
Can you provide any details of the cheap oven you bought, I need to get one after being caught red handed recently holding a brake caliper with the o/h oven gloves in a kitchen that smelt like a paint shop!
1976 Honda 400/4
1977 Honda 400/4
1981 Honda CB250RSA
1977 Rickman Honda CR750
1999 Honda VFR 800FX
1955 750 Dresda Triton
1978 Moto Morini 350 Sport
1982 Laverda 120 Jota
1924 Triumph 550SD
2012 Stanley Battery Drill

 

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