Author Topic: David Silver Pattern Cam chain Rollers/tensioner assemblies  (Read 1488 times)

Online AshimotoK0

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Has anyone used or have experience of David Silvers David pattern cam chain rollers/tensioner assemblies ?
 I always shy away from any pattern rubber parts and I have gathered enough NOS Genuine parts over the years for my own bikes.

However, Ben (new member on here and work colleague) is rebuilding his CB350K3 engine and I have advised him to change the cam chain and tensioner and  idler assemblies. We compared his cam-chain for 'droop' with one of my NOS ones and there was a significant difference. The recorded miles is only 8k and the  state of the internals of the engine would indicate this to be correct but I think the cam-chain hasn't been re-tensioned  enough times and has been lashing around.
 
Ben has found a NOS genuine idler mid-roller but the tensioner assembly  itself is ridiculously expensive new. DS does a pattern one but of unknown quality. Hence , the question above.

One thought I had was to get a CB750 SOHC new or NOS one and use the roller/needle bearing assembly from it  in the CB350 one (the roller is the same, as is the cam-chain and mid-idler on both CB/CL 250/350K and CB750 SOHC models .. although that would mean de-riveting and coming up with a way of refitting. We do have full engineering facilities where we both work though. The CB750 assembly is significantly cheaper than the 250/350K variant

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« Last Edit: June 24, 2021, 09:15:36 PM by AshimotoK0 »
“Alright friends, you have seen the heavy groups, now you will see morning maniac music. Believe me, yeah. It’s a new dawn.” Grace Slick, Woodstock '69 .. In the year of the Sandcast.

Offline BenPowell

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Re: David Silver Pattern Cam chain Rollers/tensioner assemblies
« Reply #1 on: June 27, 2021, 09:49:33 PM »
Ash, have a look at this, just seen it while scrolling through eBay.

https://www.ebay.co.uk/itm/233882340721?hash=item3674794d71:g:w5MAAOSwal5YLw6r

it's a tool used to re-fit the 'rivet pin' I'm sure i would be able to make one of these easy enough at work.

All we would need then is a new pin, but again i think that would be fairly straight forward.

If all goes to plan it will save a fair bit of money.

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Re: David Silver Pattern Cam chain Rollers/tensioner assemblies
« Reply #2 on: June 27, 2021, 10:08:42 PM »
Ash, have a look at this, just seen it while scrolling through eBay.

https://www.ebay.co.uk/itm/233882340721?hash=item3674794d71:g:w5MAAOSwal5YLw6r

it's a tool used to re-fit the 'rivet pin' I'm sure i would be able to make one of these easy enough at work.

All we would need then is a new pin, but again i think that would be fairly straight forward.

If all goes to plan it will save a fair bit of money.

I have the proper Capellini tool for peening over the rivet Ben.

Mr. Capellini himself sent it to me. (see pic below)

Also this is what they sell but I might have asuitable sprocket from a 450

http://www.cappellinimoto.it/catalog/motorbike/CL350/product/72

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Online AshimotoK0

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Re: David Silver Pattern Cam chain Rollers/tensioner assemblies
« Reply #3 on: June 27, 2021, 10:10:40 PM »
This is the Capellini mod.

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Offline royhall

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Re: David Silver Pattern Cam chain Rollers/tensioner assemblies
« Reply #4 on: June 28, 2021, 06:54:37 AM »
That appears to be a lot of time trouble and risk to save a one time difference of £24 Ash. It's bad enough when Genuine parts are not available, but when you can get them it must be worth the cost. If a cam chain lets go at high revs it's goodbye engine.
« Last Edit: June 28, 2021, 06:59:26 AM by royhall »
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Online AshimotoK0

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Re: David Silver Pattern Cam chain Rollers/tensioner assemblies
« Reply #5 on: June 28, 2021, 06:58:45 PM »
That appears to be a lot of time trouble and risk to save a one time difference of £24 Ash. It's bad enough when Genuine parts are not available, but when you can get them it must be worth the cost. If a cam chain lets go at high revs it's goodbye engine.

24 quid is 24 quid to a tight Yorkshireman  ;D... Anyway Ben is considering fitting a Capellini style metal sprocket which the racing fraternity use (Graham Curtis does this on CB72/77's and it works really well).
“Alright friends, you have seen the heavy groups, now you will see morning maniac music. Believe me, yeah. It’s a new dawn.” Grace Slick, Woodstock '69 .. In the year of the Sandcast.

Online AshimotoK0

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Re: David Silver Pattern Cam chain Rollers/tensioner assemblies
« Reply #6 on: June 29, 2021, 08:22:42 PM »
Ben, myself and another very young chap, where we all work, have formed WHAM ! ('Water Hydraulics Association of Motorcyclists') We meet every Tuesday evening and sometimes Saturday morning to work on or projects and it gives us all access to the bead blaster, parts washer, lathes, welder, mill etc.

Anyway, we couldn't meet tonight as Ben has been sent away on business and so I spent my time digging out the bits pictured  below from my 'stash' of CB250/350 bits.

The cam-chain tensioner is NOS, circa 1968/9 and came from Honda's UK Service Facility in Nottingham (one of about 5 that I have and was developed for the CYB350 race bike by Alf Briggs and his team ). Pictured also is a Honda Genuine cam chain sprocket from the DOHC 450'S ... it's used but I do have a couple of  brand new ones somewhere. I reckon the sprocket part can be pressed onto the CYB part to create a 'Capellini' style tensioner .  I am no sure about the CYB large steel idler. Ben has already bought a NOS Genuine Honda rubber one and I think I would use that still, to give a bit of compliance within the tensioning system. If you are reading this Ben the parts are yours for nowt if you want to have a bash.

Interested to see what other folks on here think, plus opinions on the pattern camchain tensioners out there for the CB750 and CB250/350K's, all of which use a similar tensioning system. Not sure about the David Silver ones but very bad  reports on the 4 into 1 and Cruzin rubber parts breaking  up after hardly any miles and I would personally stay clear of them.

Ben is a young guy on very tight budget, by the way, on his CB350K restoration. So I am trying to donate what I can to him.

Great to see chaps in their 20's joining our fraternity IMHO.... we need more!!

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CYB Parts List here:-

https://www.dropbox.com/s/jggut4r7j47fq60/Honda%20CB350%20info.pdf?dl=0
« Last Edit: June 29, 2021, 08:31:47 PM by AshimotoK0 »
“Alright friends, you have seen the heavy groups, now you will see morning maniac music. Believe me, yeah. It’s a new dawn.” Grace Slick, Woodstock '69 .. In the year of the Sandcast.

Offline BenPowell

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Re: David Silver Pattern Cam chain Rollers/tensioner assemblies
« Reply #7 on: June 29, 2021, 10:20:10 PM »
Cheers Ash, really appreciate the help with the parts should be back at the club next week all being well so can take a look at the parts then and see what we can do.

It is a build on a tight budget, so being able to make the most of parts available and re-use what I can will leave money spare for other parts later, it actually makes the restoration more of a challenge but also quite enjoyable making and re-using old parts. So far the spend on the bike has been minimal hope to keep it that way to see what is achievable without throwing tons of money at it.

Offline Bryanj

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Re: David Silver Pattern Cam chain Rollers/tensioner assemblies
« Reply #8 on: June 29, 2021, 11:04:32 PM »
From my limited racing experience the steel idlers whilst last longer and probably keepin a more uniform chain tension are noisier and sound harsher.
Rebuilt a fair few "learner" 250 versions with shattered rings and a couple with siezed cams the lessons from these are
1 do not thrash the engine from cold
2 clea the cetrifugal filter regulary, i would say every other oil change and do inspect closely as the "sludge" looks just like its part  of the alloy casting
3 make sure the circular cover over the filter is refitted  correctly
4 be prepared to line the points cover with tape as the points can sort out on the cover.

Apart from that give yourself plenty of time to stop as whilst that front tls was good in the day its not realy, also make sure linings are not detaching

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Re: David Silver Pattern Cam chain Rollers/tensioner assemblies
« Reply #9 on: June 30, 2021, 07:59:47 AM »
From my limited racing experience the steel idlers whilst last longer and probably keepin a more uniform chain tension are noisier and sound harsher.
Rebuilt a fair few "learner" 250 versions with shattered rings and a couple with siezed cams the lessons from these are
1 do not thrash the engine from cold
2 clea the cetrifugal filter regulary, i would say every other oil change and do inspect closely as the "sludge" looks just like its part  of the alloy casting
3 make sure the circular cover over the filter is refitted  correctly
4 be prepared to line the points cover with tape as the points can sort out on the cover.

Apart from that give yourself plenty of time to stop as whilst that front tls was good in the day its not realy, also make sure linings are not detaching

I take your point about the noise Bryan but I wasn't planning on recommending using the centre large idler in steel just the smaller tensioner wheel fitted with a sprocket. The sprocket is actually a CB450 Bomber part and there are about three of them whizzing around in the Bomber engine. Plus the CB250/350K is a notoriously noisy engine anyway, as was the G5. I sold a 250G5 with a pristine engine ..less than 2k miles and had perfect cam and rockers etc but it sounded surprisingly noisy. The 180° crank doesn't help.
My mate Graham Curtis has upgraded quite a few CB72/77 engines with cam chain tensioners he has fitted with the sprocket idler from a Kawasaki Z650 (very similar sprocket to the Bomber one) . I must ask him if he has noticed any significant increase in noise.
“Alright friends, you have seen the heavy groups, now you will see morning maniac music. Believe me, yeah. It’s a new dawn.” Grace Slick, Woodstock '69 .. In the year of the Sandcast.

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Re: David Silver Pattern Cam chain Rollers/tensioner assemblies
« Reply #10 on: June 30, 2021, 04:03:07 PM »
A very well respected HondaTwins.net member has done almost exactly what I described. I found this in a post from 2015

I machined a xt500 lower cam chain sprocket and a insert to fit the honda needle roller bearings, it will replace the small rubber stock cam chain roller. I'm going to run the stock large rubber roller, I don't want any weird noise

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Offline K2-K6

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Re: David Silver Pattern Cam chain Rollers/tensioner assemblies
« Reply #11 on: July 01, 2021, 07:18:49 PM »
The plain (round no teeth) look very different to conventional sprocket form but really do the same thing from a geometry point of view.

The teeth are only important to transmit torque and keep a precise timing relationship for each component,  which doesn't exist for the adjustment device.

Essentially the chain roller comes into contact at a tangent whichever it's approach route, then gets passed round the fulcrum (centre bearing) the same whether it has teeth or not, that distance from centre can't be variable for any of these arrangements else it would input it's own vibration/resonance.
The side plates obviously need to run clear of the centre support such that it only runs on the chain's bearing.

It may involve a very small increase in noise transmission,  but I can't see it making it's own noise.

The whole idea of splitting up chain run length is to brings spans that ordinarily can't be excited by latent system vibrations from crankshaft pulses and camshaft cadence.

If they are roller bearing cranks then they always tend to sound more like a lathe in comparison to plain bearing systems as there's just no mitigation for combustion percussion in preventing it from being amplified by the cases.

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Re: David Silver Pattern Cam chain Rollers/tensioner assemblies
« Reply #12 on: July 08, 2021, 01:25:19 PM »
Thanks for the informative reply Nigel.

I just found that the centre part of the Honda race tensioner and also a  Kawasaki Z650 one I have, have a section of rubber which should help with isolation and give bit of compliance.

I also found a spare Capellini  brand new rivet for the centre, which Ben can have. I also have the Capellini  tool for peening the rivet end over,  as pictured previously.
“Alright friends, you have seen the heavy groups, now you will see morning maniac music. Believe me, yeah. It’s a new dawn.” Grace Slick, Woodstock '69 .. In the year of the Sandcast.

 

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