Cam Chains

jotajoe

jotajoe

Hero member
Location
Warwickshire UK
I'm after some sage advice..and Andy Chain may be able to advise on this one.

At what point should a cam chain be changed ?

My theory is this..over time the chain wears and as it wears valve timing becomes sloppier in terms of timing, which is detrimental to the performance and longevity of the engine.

I believe that well before the chain itself is complaining and becoming rattly that it should be chainged because of stretch / wear ..In worst case can valve seat recession combined with this insidious chain stretch cause a piston to hit an exhaust valve..a combination of wear factors..?

What is the best rationale on this...Do we change the chain because we believe it may be old/worn  and potentially break or do we change it because it is causing poor performance  in our jewel like engines ?

joe

 
You make a valid point. I usually change them way before the adjuster is quite a way in. You get a good idea by flexing the chain between the cam sprockets with the adjuster backed off.
Cheaper than a broken chain (which I have had).
There is another school of thought that just like fitting a new drive chain you should by rights change the sprockets as well as the chain and sprockets will both wear.
But hard to change the crank sprocket though!  :o
I guess as they are in an oil spray/bath then they should survive a lot longer than drive sprockets.

The cam chains Andy sells are proper kit and look like they will outlast the engine. Much better than camchains I have bought over the years from the usual suppliers.
 
Grant said:
You make a valid point. I usually change them way before the adjuster is quite a way in. You get a good idea by flexing the chain between the cam sprockets with the adjuster backed off.
Cheaper than a broken chain (which I have had).
There is another school of thought that just like fitting a new drive chain you should by rights change the sprockets as well as the chain and sprockets will both wear.
But hard to change the crank sprocket though!  :o
I guess as they are in an oil spray/bath then they should survive a lot longer than drive sprockets.

The cam chains Andy sells are proper kit and look like they will outlast the engine. Much better than camchains I have bought over the years from the usual suppliers.
Click to expand...

Thank you Grant,

Interesting point on the sprockets too.....

joe
 
Laverda owners as a rule tend to change chains far too frequently.

The real answer is to do it when you fell happy doing it.

As they have a connecting link and are relatively cheap it makes
sense to change them frequently. This way sprocket wear is reduced.

Cam chain stretch does have a marked effect on valve timing but with
road engines would be hardly noticed. On race engines regular changes
are a good idea. Those of you with variable valve timing will know when the
chain is buggered as your engine will start missing, Jags and Nissans :D :D :D :D.

I would expect a cam chain to last 100000 miles or more, some Mercs go
on into the millions. More important is regualr oil changes.

Andy
 
andychain said:
Laverda owners as a rule tend to change chains far too frequently.

The real answer is to do it when you fell happy doing it.

As they have a connecting link and are relatively cheap it makes
sense to change them frequently. This way sprocket wear is reduced.

Cam chain stretch does have a marked effect on valve timing but with
road engines would be hardly noticed. On race engines regular changes
are a good idea. Those of you with variable valve timing will know when the
chain is buggered as your engine will start missing, Jags and Nissans :D :D :D :D.

I would expect a cam chain to last 100000 miles or more, some Mercs go
on into the millions. More important is regualr oil changes.

Andy
Click to expand...


Thanks Andy,

Hope you are keeping well Andy...

Yes , take your point, clean oil = less chain wear..Keeping a good chain on reduces sprocket wear....

So, A high revving engine high comp. like an MV F4 would you have a policy of changing before wear is perceivable...?

joe

 
I have to agree we change the chains too often. Although I never had a JAP bike with cam chains, I have had a number of BMW's. My current ride to work R1200RT has 104,000 miles and the cam chain has not been replaced. I put 211,000 miles on a R100RS with the chain also never replaced. Why do we think a Laverda needs a new chain at 20,000 miles? A few months ago I met a guy with a Yamaha FJR13000 and it had 130,000 miles, also on the original cam chain. Are the factory Regina chains crap compared to what a BMW and the JAP bikes use?

Bruce
 
1200ts said:
I have to agree we change the chains too often. Although I never had a JAP bike with cam chains, I have had a number of BMW's. My current ride to work R1200RT has 104,000 miles and the cam chain has not been replaced. I put 211,000 miles on a R100RS with the chain also never replaced. Why do we think a Laverda needs a new chain at 20,000 miles? A few months ago I met a guy with a Yamaha FJR13000 and it had 130,000 miles, also on the original cam chain. Are the factory Regina chains crap compared to what a BMW and the JAP bikes use?
Click to expand...

Not exactly, but not far off... ::)

Replaced one just yesterday, a well-kept RGS with 33700 km on the odo.  Tensioner was wound a fair way in, tensioner blade in excellent(!) condition, chain correctly tensioned.  Chain was obviously the one the factory fitted, as the bike came with a documented history going back to 6000 km from new, no mention of either a timing or primary chain renewal.  The Regina primary chain was also well past its best with the tensioner quite chewed up as well.  Apparently was far too tight for most of its life.

Replacement IWIS chains seem to wear well, have found quite a few that I installed over 15 years ago at Moto Witt that have now surfaced at the OCT workshop.  Very little wear after more than 50000km.  The D.I.D items OCT sell (sorry Andy, I did try!) have also been extremly reliable.

Many jap engines have toothed (Morse?) timing chains, these seem to wear extremely well, probably due to over-sizing, with hardly any wear on the sprockets.  That these chains can wear is evidenced by early Honda 4s, their toothed primary chains produce one hell of a clatter at idle once a little wear sets in.

I've witnessed the mess a broken primary chain can produce, reckon a new timing chain is a lot cheaper than a half dozen bent valves...

piet
 
sfcpiet said:
Not exactly, but not far off... ::)

Replaced one just yesterday, a well-kept RGS with 33700 km on the odo.  Tensioner was wound a fair way in, tensioner blade in excellent(!) condition, chain correctly tensioned.  Chain was obviously the one the factory fitted, as the bike came with a documented history going back to 6000 km from new, no mention of either a timing or primary chain renewal.   The Regina primary chain was also well past its best with the tensioner quite chewed up as well.  Apparently was far too tight for most of its life.

Replacement IWIS chains seem to wear well, have found quite a few that I installed over 15 years ago at Moto Witt that have now surfaced at the OCT workshop.  Very little wear after more than 50000km.  The D.I.D items OCT sell (sorry Andy, I did try!) have also been extremly reliable.

Many jap engines have toothed (Morse?) timing chains, these seem to wear extremely well, probably due to over-sizing, with hardly any wear on the sprockets.  That these chains can wear is evidenced by early Honda 4s, their toothed primary chains produce one hell of a clatter at idle once a little wear sets in.

I've witnessed the mess a broken primary chain can produce, reckon a new timing chain is a lot cheaper than a half dozen bent valves...

piet
Click to expand...

It's the worn tensioner blades that cause the clatter, Piet! pain in the a.. to remove and replace on 500/550 or 750 engines, timing chain will last forever, running happy at 8-10.000 rpm :D
 
Gerald,

Been quite some time since I did fours, mainly little ones, can't remember primary tensioners, only slipper blades/pads.  New chain and all was good, for a while at least!

piet
 
A question for Andy, if the very best quality cam chain you sell was fitted to Laverda triple, how long would you think it would last before needing replacing?

Bruce
 
Bruce, think he answered that already:

"I would expect a cam chain to last 100000 miles or more, some Mercs go
on into the millions. More important is regualr oil changes."
 
The Regina product is an OK product although I have noticed a few grumbles both here and
on other sites regarding wear. I must make the point that there is a difference in quality not
ony between brands but also between industrial and automotive product.

In the main the overall quality has dropped with many producers due to a low DIN standard,
and I know the vast majority of so called cam chains on the market are in fact industrial.

With modern engines running at higher revs there have been problems with roller failure so many
current automotive chains have a split roller. These were considered a bad feature years ago, but
the current crop have very special steel and other features which means they work very well
at high rpm. It may sound crazy but Bantam racers have experienced many roller failures even with
the iwis industrial product which is superb. By using the spilt roller cam chains this problem has
not happened for the past 2-3 years.

If you are buying cam chains from any source just make sure they are automotive and if they
are covered in grease it is a good sign they are not.

Andy

(Sad anorak chain geek)
 
I agree with focussing on the oil changes as number one priority over all else (unless there is a clear symptom of something failing).

In a slightly parallel universe I read all the time that belts need changing on the later Ducatis way more frequently than I'm sure is the case - sometimes a bike on offer with less than 5k miles will come with a number of receipts for belt changes (not too difficult a job to do on the air cooled twins in fairness).

While it is good to be careful the majority of these on the market (even those with poor service history) do not seem to be exploded shrapnel.

 
I have run one of Andys cam chains for 40,000 miles, and it is the split roller type.I replaced it because I was doing other major things, when I compared the new one with the old one it was very hard, actually nigh on impossible to tell the difference, and this I did by joining the chain ends with the split link, and stratching a "loop" around two mandrels about 3 inch diameter,Witht both chains on the mandrels they were still very close to aparrallel, if the old one was worn, then they would not have remained parrallel.I have also done the same mileage on one of his triplex primaries and have one currently installled.They dont make that any more!! That new cam chain cost me "about" twenty quid and the usual suspects were selling chains of the dubious "3M" variety (wrapped in Regina grease proof paper and packaged in Regina boxes) for about eighty quid

I sold (as spares) my trusty old Mercedes  E class diesel estate last year, and the cam chain was original, and not even showing any signs of wear and the mileage waas close to 250,000 miles.This is the chain that Andy recomends for primary drive use on triples and twins, many use them and swear by them.I will be installing one when I need it.

As Laverda riders we are all a bit better off for having Andy sell us chains at good prices and just as importantly provide us with plenty of free information.I have heard his stew is a bit good when dished out at meets etc.but never tried it myself.
CLEM
 
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