Newbie to the zephyr life

For all your mechanical queries, or for sharing your mechanical know-how. Also used for arguing about which oil to use...
Freddy
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Location: Sydney Australia

Re: Newbie to the zephyr life

Post by Freddy »

I got a question.......

The service limit for the primary chain is 25mm of deflection. Mine was 10mm when I measured it at 100,000 kilometers.

My question ..... How much would the engine need to expand between being cold and hot to change the distance between the crankshaft and secondary shaft (I'm assuming this is the logic behind the reason of why the primary chain quietens down when the engine has been running for a while). The distance apart between the two shafts must expand (if the noise is the primary chain) by quite an amount, certainly enough to materially reduce the amount of primary chain slack (and noise generated).

The distance between the crank and secondary shaft would have to increase by at least a couple of millimeters (even possibly more) as the engine warms up to tighten up the primary chain by the necessary amount, sound about right ???
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Richard
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Re: Newbie to the zephyr life

Post by Richard »

millimeters seems a bit much to me...
Could be the amount of oil pumped around is doing a better job damping the noise after a while, or maybe a combination of both?

Guess we need to test a chain externally from the engine, measuring it while slowly heating it up ;)
hugojose
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Joined: 05 Sep 2017, 00:43

Re: Newbie to the zephyr life

Post by hugojose »

Well..we are probably getting off the thread, but.....very valid thougths although I think the chain is got to expand also, and what expands more, the steel chain, or the aluminum cases?? .... .I think there are other factors also as Richard pointed, as the oil getting hot, and this one is always bathed.

Anyway...the irony is that a Hy-Vo chain is considered quieter than a a straight cut gear, and also more efficient at transmitting power...and for those(I heard it before) thinking that is a flawed design, consider the all-conquering (revolutionary) Honda 1969 CB750 had not only one, but two parallel primary chains, and of conventional roller type at that. ....to be as quiet as a Hy-Vo chain, the primary gear has to be helical (as in expensive).

Nonetheless, Kawasaki, pressing the ZR-7 in North America (another, and last KZ750) as a stop gap measure against the high selling liquid cooled V-twin Suzuki SV650, decided to include an internal tensioner for the primary chain, as in; make it sound more refined.
Freddy
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Joined: 06 Sep 2017, 11:06
Location: Sydney Australia

Re: Newbie to the zephyr life

Post by Freddy »

hugojose wrote:Well..we are probably getting off the thread, but.....very valid thougths although I think the chain is got to expand also, and what expands more, the steel chain, or the aluminum cases?? .... .I think there are other factors also as Richard pointed, as the oil getting hot, and this one is always bathed.

Anyway...the irony is that a Hy-Vo chain is considered quieter than a a straight cut gear, and also more efficient at transmitting power...and for those(I heard it before) thinking that is a flawed design, consider the all-conquering (revolutionary) Honda 1969 CB750 had not only one, but two parallel primary chains, and of conventional roller type at that. ....to be as quiet as a Hy-Vo chain, the primary gear has to be helical (as in expensive).

Nonetheless, Kawasaki, pressing the ZR-7 in North America (another, and last KZ750) as a stop gap measure against the high selling liquid cooled V-twin Suzuki SV650, decided to include an internal tensioner for the primary chain, as in; make it sound more refined.
Not sure how its getting off topic? Wasn't the OP asking what is the noise, and can anything be done about it. Answer to that is its primarily coming from a loose cam chain, and correctly setting his manual tension will largely rectify it.

I'm just making the point that it can't possibly be the primary chain that makes all that extra noise in the first couple minutes before it quietens down some. Nothing significant changes in relation to the primary chain within a few minutes of starting the engine. The primary chain length wouldn't change by any material amount whatsoever in that short time. If anything it will expand so should get louder as the engine warms up, not quiter.

The reason for the extra noise when the engine is first started all relates to a loose cam chain. Sitting overnight under tension the automatic tensioner slips back. It can't easily move forward again on a 750 because of how the locking wedge mechanism works (as I understand it a 550 uses a ratchet mechanism). When the cold engine is then started the cams and chain rattle like crazy for a few minutes till the automatic tensioner slowly moves forward to take up some of the slack.

This isn't just a theory, its easily proven by manually resetting the automatic tensioner prior to starting the cold engine. I did that many times, to satisfy myself, beyond any doubt the cam chain tension is the problem. EVERY time the clay cold engine was relatively wisper quite when first started. This was after replacing all the internal parts in the automatic tensioner, constantly removing surface imperfections in the wedge mechanism, etc all trying to get the automatic tensioner to hold its tension. Simple fact, it doesn't.

Not only did Kawasaki add a tensioner to the primary chain on the ZR7, they also completely redesigned the automatic cam chain tensioner. Now why would they have done that to a near 25 year old engine if the existing Zephyr design was working correctly? We can't retrofit a tensioner to the primary chain on a Zephyr, but we can easily and inexpensively replicate the other corrective action taken by Kawasaki on the ZR7, replace the flawed Zephyr cam chain tensioner.
Last edited by Freddy on 08 Mar 2018, 23:43, edited 3 times in total.
Freddy
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Re: Newbie to the zephyr life

Post by Freddy »

And just in case anyone is wondering why I labor the point, that it's an urban myth the primary source of noise in a Zephyr engine is the primary chain. The reason is because I'd like to see this fine motorcycle on the road by happy owners for many years to come.

But that's never going to happen if new or potential owners think the engine is a rattly bag of nuts and bolts that can't be easily rectified. Yes, the primary chain contributes some noise, but not a great deal, and certainly not enough that anyone would find it concerning. If people aren't interesting in fixing the major source of noises on their own bike, fine. But telling other people its just how it is, they are all like it, and there's nothing that can be done (based solely upon what they read on the internet) that's another thing altogether.

Takes about a whole 5 minutes, by resetting the auto cam chain tensioner (and that's having a coffee break in the middle of the process), to conclusive determine beyond any doubt where the problem lies. If people can't be bothered to make that tiny amount of effort to factually inform themselves ....... ERHHHHHHHHHHHHHHHHH!!!!!!!!!

The engine on my Zephyr 750 now has 160,000 kilometers on it. With a correctly tensioned timing chain, replaced rubber dampers in the secondary drive housing, and replaced clutch basket, and original primary chain, it is remarkably quite for an air cooled engine, and not the slightest difference between hot or stone cold.
Last edited by Freddy on 07 Mar 2018, 23:56, edited 6 times in total.
blake12345
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Joined: 01 Mar 2018, 23:48

Re: Newbie to the zephyr life

Post by blake12345 »

Wow, I get distracted for a day or so and come back to an in depth conversation!!

Well this weekend I shall check my tensioner. I have a manual tensioner so should be easy!

The only reason I asked about noises was being new to the motorcycle world I wasn't sure if they were just noisy due to the fact they are right there and not hidden in an engine bay like a car.

But thanks for all the advice. I've got myself a service manual so I'll go through adjust the tensioner, clean the carbs and do some maintenance and servicing and see how I go.
Freddy
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Joined: 06 Sep 2017, 11:06
Location: Sydney Australia

Re: Newbie to the zephyr life

Post by Freddy »

blake12345 wrote:Wow, I get distracted for a day or so and come back to an in depth conversation!!

Well this weekend I shall check my tensioner. I have a manual tensioner so should be easy!

The only reason I asked about noises was being new to the motorcycle world I wasn't sure if they were just noisy due to the fact they are right there and not hidden in an engine bay like a car.

But thanks for all the advice. I've got myself a service manual so I'll go through adjust the tensioner, clean the carbs and do some maintenance and servicing and see how I go.
Don't worry about the 'in depth discussion', same ground is covered every time the topic of engine noises comes up. Bit like Ground Hog Day.

You won't find anything on how to adjust your manual tensioner in the workshop manual being an aftermarket addition. Pretty sure somewhere in the various posts I outlined how I do it. Sing out if unclear, but pretty simple really. Don't let anyone convince you to use the screw it up till the rattle stops with the engine running method. Would you set the valves clearances on a running pushrod car engine by loosening them off and then do up till the 'clack' stops? I reckon doing the same to set the cam chain tensioner is about on a par workmanship wise.
blake12345
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Joined: 01 Mar 2018, 23:48

Re: Newbie to the zephyr life

Post by blake12345 »

Ha right! I find it interesting though so doesnt worry me...

Yeh i knew I wouldn't find anything in the service manual. I was more meaning the maintenance side of things and getting things running right
blake12345
Posts: 15
Joined: 01 Mar 2018, 23:48

Re: Newbie to the zephyr life

Post by blake12345 »

I’ve gone to check the adjustment on the manual tensioner and it wasnt moving in or out. I used a spammer to loosen it abit and it wasn’t tight. So I’ve loosen it up to start from loose and tighten by hand by it won’t move. It feels like the threads are ‘binding’.
Can I loosen it all the way out and put some sort of thread eze or something on to help? Or is there a way to adjust it Gently with a spanner? I don’t really want to pull the full tank and carbs off to get better access to it so hopefully I can make it abit easier to turn by hand
Freddy
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Joined: 06 Sep 2017, 11:06
Location: Sydney Australia

Re: Newbie to the zephyr life

Post by Freddy »

blake12345 wrote:I’ve gone to check the adjustment on the manual tensioner and it wasnt moving in or out. I used a spammer to loosen it abit and it wasn’t tight. So I’ve loosen it up to start from loose and tighten by hand by it won’t move. It feels like the threads are ‘binding’.
Can I loosen it all the way out and put some sort of thread eze or something on to help? Or is there a way to adjust it Gently with a spanner? I don’t really want to pull the full tank and carbs off to get better access to it so hopefully I can make it abit easier to turn by hand

Just to check we're all on the same page .......

Here's what your typical manual cam chain tensioner looks like. Your one may not be identical but they all seem variations on this same theme:

Image

Because of the course thread the adjusting bolt should run freely in/out after loosening the lock nut. If you've backed it out, and it now doesn't want to turn freely by hand you would have to assume the threads are stuffed or something like that. Given the bike was already noisy and a manual cam chain tensioner had been fitted that doesn't seem to be doing what it should, if it were my bike I'd be taking the tesnsioner off and inspecting it.

As I said in a previous post, I don't own a 550, but on a 750 removal of the cam chain tensioner (original or aftermarket) is relatively simple. On a 750 you remove .....

1. Gear change of the splines
2. Front sprocket chain cover
3. starter motor cover
4. starter motor


Now you have relatively easy access to the cam chain tensioner from the left hand side of the bike. If this isn't the same on a 550 I trust someone will jump in to correct it.
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