manual camchain tensioner fitment guide

[VNA]

Got my valve clearances checked today.

Asked the mechanic about manual Yamaha spring tensioners and maybe switching to a manual one.  He said he'd replaced a few tensioners but never had a bike come in with bent valves due to a tensioner fail.  He used to be the mechanic at the main dealer and has set up by himself.

He too said he only puts manual tensioners on race bikes.

I'm not personally convinced for the need for a manual tensioner, and wonder if you maybe cure one problem that has only happened to a handful of folks if that (how many folks do we have that have bent the valves?), only to set up another. 

[nick crisp]

I can't really see how you'd get more wear with a manual tens. Trying to think it thro, ok, it's not moving. But neither is an auto once it has taken up current slack? Do you have any thoughts about what kind of other problems a manual one might cause? Both types are just a foot sitting against the guide, applying the tension. The manual one can't move unless you slacken it yourself. The auto one will increment out to take up slack as the chain stretches. But the spring can fail on an auto. What can fail on a manual?

[VNA]

You can put too much tension on.  Or not enougth?  Which equals wear.
On a race bike I wouldn't think it matters.  Or you might set it up spot on with the cam cover off or something.  But on a road bike you could maybe racking up big miles with too much tension.

The auto tensioner should apply just the right amount of tension automatically.  If the spring gives or fails, then simple fit another tensioner. 

And why do they insist on fitting auto tensioners?  I'm not convinced about the initial stretch explanation, modern chain is so much better than stuff from a few decades back - well I tend to think so.

It's a puzzle to me.  I remember my first car with a belt drive cam.  It had a manual tensioner.  Now they all have auto tensioners. 

Anyway my decision, based on don't fix what ain't broke, and that if it does fail the odds are now't bad will happen, is not to do anything.

My choice.

[nick crisp]

Aw heck, every bike I've owned has had auto tensioners and I've caned and abused many of them and never had a tensioner fail on me. My manual is there ready and waiting to be fitted but I think I'll hang on for a while longer before I decide, just see if anyone comes up with a bit more info! :rolleyes
(Might also be cos I'm too damn lazy to have gotten round to it yet too! :lol )

[fireblake]

Aw heck, every bike I've owned has had auto tensioners and I've caned and abused many of them and never had a tensioner fail on me. My manual is there ready and waiting to be fitted but I think I'll hang on for a while longer before I decide, just see if anyone comes up with a bit more info! :rolleyes
(Might also be cos I'm too damn lazy to have gotten round to it yet too! :lol )

But how gutted will you be if it fails and you had a manual tensioner in your shed?

Mickey

[nick crisp]

Tech info, I need more tech info! I can't decide based on supposition! My last thou I put x-thousand miles on, thrashed it soundly every chance I got, same with the 2 before that. Same with an FZR1000, GSXR750, 3xZ650s, Z1, FZ750, GSXR1100 and - ok, I won't mention the 400 Superdream...damn, let that one slip - but that was a friggin Honda ferrchrisakes!!
Oh, leave my head alone, I'm going to bed! :lol

[VNA]

But how gutted will you be if it fails and you had a manual tensioner in your shed?

You fit a new tensioner and continue as before.

My take is one, tensioner failures today are fairly rare but do happen.  Two, it usually rattles before the chain jumps.  There only seems to be a handful of folks, very few, who have had a chain jump.  Nasty, considering the silly price of parts, and the labour cost if you can't fix it yourself if it happens to you.  It's probably look for another engine time.  But still so rare.

Pilgrim seems to have been hit by lightening twice, and I can understand that he wants now't to do with an auto tensioner.

Would be great to hear from somebody with knowledge of engine design and why all, or the bulk of marks, cars and bikes, have now settled on auto tensioners.  And why race engines are converted to manual, and indeed how they set them up.

Afraid I don't have the answers.  Just not changing until I'm 100% sure it's the right move. 

[PieEater]

Was passing my local bike shop so I thought I'd get the chief mechanic to have a quick look to see whether I'd got the tension right, he said the engine sounded as sweet as a nut, so no problems there. He said that he personally prefers manual tensioners because the automatic ones can be prone to failure.

[nick crisp]

Sigh. I bet there's as many opinions as there are mechanics... :\
Taking mine in to a guy who's (hopefully) going to sort this little glitch I've got tomorrow. He does tuning for road and track, as well as more day to day servicing etc and is highly recommended around here (I've met him and he is really enthusiastic about what he does) so I'll try to remember to ask him about it - but of course, is it then just yet another opinion? Perhaps he'll have some first hand experience of the subject.

[VNA]

Yup worth asking about it.

I think what is really needed is somebody knowledgeable in engine design, ie an engineer who works in engine design.

One thing about race engines is that they tend to get attention.  I don't think they do 6000 miles between services .  Plus at the end of the day their total mileage is low, but wear and tear is high. 

But not being knowledgeable about race engines, well I don't know how much attention they need say during say one race season. 

Personally I'm just not going to worry about it, there's thousands upon thousands of this type of engine out there, 99.9% of them running auto tensioners.  Only heard of a handful, if that, of bent valves.

Here's another thought.  To prove that manual tensioners are better (as we lack the informed opinion of a respected engine designer), we'd have to get a thousand or so folks to convert their bikes to a manual tensioner and perhaps collate the data over say 5 years.

Or look at it another way.  The history cam chain and belt tensioners suggest that chain and belt drives involve some sort of small compromise in keep the tension in check.

Or how about persuading Mr Yamaha to re-introduce the Gen1 Fazer but with gear driven cams?  A la VFR750 - and didn't they sound just great!

Anyway I'm more worried, or paranoid about a puncture come blow out wiping me out, than I am about cam tensioners wrecking ma valves - and by a country mile.  (fingers crossed touch wood)

[pitternator]

Cant help but think we could all focus on any  part in our bikes and convince ourselves to change it " just in case"....even to the point of panic.
Have to say in all my10  years of fazer ownership, I aint heard of a tensioner failure till now... :\
meanwhile several bikes have gone well over 100K miles with no mention of such. My own 2 fazers have racked up 37k and latest one now 40k with no engine issues at all. In fact the only " failure" on any part was a front wheel bearing on my first bike at just 9k miles, caused by an faulty batch of bearings.


My conclusion is where do you start and stop in " preventative replacement "....? :rolleyes

tbh I would focus more on keeping the bike well serviced and looked after than feverish bandwagonning to replace the latest part anyone suggests ....

[nick crisp]

So, asked my mechanic for his take on the subject. We spoke about road bikes, I didn't ask him about race bikes, as it doesn't apply to what we want to know. He thinks that generally speaking there is no need to swap to a manual tensioner. He said there is no reason why you shouldn't fit a manual if you want to, as long as you adjust it when necessary. He knows of no problems or failures with manual tensioners generally. He said it is very rare for most bikes to have auto tensioner failures, but it can happen - you're likely just unlucky if it does. He said it is highly likely to end up being catastrophic if one does fail. He said certain Hondas are the most likely candidates for failure, usually certain models of CBR600. He said if you are riding along and your cam chain starts to get noisy, stop the bike and DO NOT restart it until the problem is fixed, as it is then usually on the restarting that the chain will jump a sprocket. He has seen examples of this with customers he has had.

[pitternator]

well any body with any sense would not restart an engine with suspected cam chain tensioner failure.....surely ????

like I said, only on this thread have I ever heard of a failure since buying my first bike in 2001, ridden 77k miles since then , on 2 seperate fazers , no issues at all...so just how big is the " risk " ??    :rolleyes

[PieEater]

like I said, only on this thread have I ever heard of a failure since buying my first bike in 2001, ridden 77k miles since then , on 2 seperate fazers , no issues at all...so just how big is the " risk " ?? :rolleyes

You've already made your point (twice) there's no need to denigrate those of us who have made an informed choice to replace the automatic tensioner, and FYI there are at least 6 other threads on this forum that discuss this issue.

[nick crisp]

well any body with any sense would not restart an engine with suspected cam chain tensioner failure.....surely ????

Well, you'd think so, but apparently some people do. He did say that the couple of cases he had in mind, the riders heard a rattling noise, stopped the bike and looked for obvious problems, and when they couldn't see anything wrong, they restarted the bike only to have the cam chain jump. So it seems they didn't actually know it was cam chain noise following tensioner failure that they'd heard. Not everyone is knowledgeable enough to identify the noise a rattling chain makes - some people just ride their bikes and let their mechanic do all the worrying for them. Nothing wrong with that, except of course you won't know when your cam chain is about to cause mayhem! Perhaps such people are ideal candidates for a manual tensioner?!

[PieEater]

Not everyone is knowledgeable enough to identify the noise a rattling chain makes - some people just ride their bikes and let their mechanic do all the worrying for them. Nothing wrong with that, except of course you won't know when your cam chain is about to cause mayhem! Perhaps such people are ideal candidates for a manual tensioner?!

I don't follow this logic - if you are mechanically inept and can't recognize the noise made by a loose camchain you should have a manual tensioner that requires mechanical competence to adjust as and when when you recognize your camchain is noisy?

If you're the kind of guy that lets a mechanic do all the worrying then it's not going to make any difference what tensioner you have fitted, unless you think there is a fair chance the automatic one will fail in which case it's safer to have a manual one fitted

[VNA]

The mechanic at the dealership I spoke to said - we get people riding in with rattling cam chains now and again.

He also said - it's not that uncommon, usually newer lower mileage bikes, but he's never come across bent valves due to a failed tensioner.

So presumably, whilst starting the engine with a dodgy tensioner perhaps isn't a great idea, it doesn't often result in damage.

I'd have thought (guessing) the biggest risk is from those who hear the rattle, and think, I'll have a look at that at the weekend, but continue to ride the bike and give it a bit of a thrashing. 

Got a young lad at work with an old BMW car, the cam chain is rattling.  I told him best fix it or get it fixed before the chain jumps and you end up with bent valves and a much much bigger bill to fix.  He's been driving it for months like that now!  Wouldn't be me.

[nick crisp]

[quote author=nick crisp link=topic=8884.msg94565#msg94565 date=1376587894]
Not everyone is knowledgeable enough to identify the noise a rattling chain makes - some people just ride their bikes and let their mechanic do all the worrying for them. Nothing wrong with that, except of course you won't know when your cam chain is about to cause mayhem! Perhaps such people are ideal candidates for a manual tensioner?!

I don't follow this logic - if you are mechanically inept and can't recognize the noise made by a loose camchain you should have a manual tensioner that requires mechanical competence to adjust as and when when you recognize your camchain is noisy?

If you're the kind of guy that lets a mechanic do all the worrying then it's not going to make any difference what tensioner you have fitted, unless you think there is a fair chance the automatic one will fail in which case it's safer to have a manual one fitted
[/quote]

Sorry, yes I think you're right, guess I'm too tired to think straight tonight! :\

[fazer-rat]

This attitude that you must do this or don't do unless such and such has done it bull crap
Everyone can make there own minds up
I've done it and I'm happy I did - I thought I'd share the experience
But one again I forgot about the keyboard hero's
It's a free world for now go enjoy it

always makes me smile luke,, its the peeps with no mechanical knowledge that i feel sorry for cos given the choice between this mod or a fancy set of grips they'd buy the grips lol.  they just don't understand that if one somewhere has failed it's a problem and if theirs fails it will cost them more than the bikes worth to pay for the repair.  you won't get any warning at all and up until the moment of sudden and dramatic catastrophe your bike will be perfectly normal in every way. it can fail on startup,, at low revs,, at high revs anytime the result will be the same.  anyone with mechanical knowledge will have one fitted immediately, anyone else i'd urge you to do the same.  lukes guide on fitting it is excellent and even my mum could follow it i reckon.  read the american and english z1300 forums about this type of problem.  we used to advise people once they bought a z1300 not to even start the engine until this type of mod was done cos of the rarity of spare parts.

[nick crisp]

I think I've made my decision. As there doesn't appear to be a way the manual tensioner can fail, even if the chances are a 1000 to 1 that the auto fails, it's still a chance. So there is a reason to go manual, and doesn't seem to be any reason not to. Good logic?