Another cam chain tensioner question

841 Views 69 Replies 11 Participants Last post by K-code, 3 d ago

K-code

Discussion Starter · 23 d ago

My Vulcan 750 is all stock and has the ticking sound that indicates that the cam chains have too much slack in them. I'm thinking of changing to MCCT but have a couple of questions.
Just what is the problem with the stock automatic cam chain tensioners? Is the spring inside them too weak or is the adjuster too short to take up the amount of slack in the chain or is it a combination of them?
Also I see manual cam chain tensioners priced from $20 to over $50 each. I don't see any difference between the high priced vs the lower priced ones. Can someone let me know if I'm missing something about them?

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dirtrack650

· #21 · 20 d ago

O' Darkness said:
On a bike with only 10k miles???

Could also be an issue with the cam chain guides.

dirtrack650

· #22 · 20 d ago

This was my solution many years ago, still working fine. Adjust to eliminate noise, lock the set screw. Boom! Issues solved for about .30¢
Might have 15k+ miles on this.

Purple Pink Automotive lighting Violet Automotive tire

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Spockster

· #23 · 20 d ago

dirtrack650 said:
This was my solution many years ago, still working fine. Adjust to eliminate noise, lock the set screw. Boom! Issues solved for about .30¢
Might have 15k+ miles on this.
View attachment 56483

That looks like the most simple solution.

taco_to_go

· #24 · 20 d ago

There is info here and on YT. Make your own MCCT. I did mine a few years ago for like $1.50 from the hardware store. I remember 2 "bonded washers" was only thing unusual to me. Otherwise, a couple of about 2" boltes and matching 4 nuts.

taco_to_go

· #25 · 20 d ago

dirtrack650 said:
This was my solution many years ago, still working fine. Adjust to eliminate noise, lock the set screw. Boom! Issues solved for about .30¢
Might have 15k+ miles on this.
View attachment 56483

Good idea. Any oil seep out?

Spockster

· #26 · 20 d ago

A little Teflon tape should seal the set screw.

mmart

· #27 · 20 d ago

I feel like I’ve read tensioner threads enough to observe a pattern. That pattern is “tinker with failing ACCT and then ultimately swap to MCCT”. I’m sure if you search you’ll find someone who’s had success with every option possible. This is the first time I’ve heard of an extender, but it just makes me think (as mentioned), if you need and extender something else is worn out.

Spockster

· #28 · 20 d ago

The extender will compress the weak stock spring more.

But I'd go with the set screw before gluing an extension on there.

Honestly, I've only read the threads. Where on the ACCT can you set the tension before locking it down? The bolt at the end of the body?

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O' Darkness

· #29 · 20 d ago

Spockster said:
The extender will compress the weak stock spring more.

But I'd go with the set screw before gluing an extension on there.

Honestly, I've only read the threads. Where on the ACCT can you set the tension before locking it down? The bolt at the end of the body?

According to TOC's site, you use their tool to wind the spring about three turns and then release that tool once the "arm" of the spring is in the relative groove.

But after yesterday's experience, improving on the Grambo trick by sort of combining it with @dirtrack650's trick from years ago, my clacking issue is resolved. With my bike only just now reaching 10k miles, I was forced to think: "Is this really supposed to be such a problematic issue? If so, wouldn't Kawasaki have addressed this?"

I don't have the proper tools to check this, but my suspicion is that many of these ACCT's left the factory with a central shaft that is not entirely true. With radio-control helicopters, the main shaft has to be perfectly true, or else the helicopter will vibrate to death. I found it extremely interesting that manually compressing the spring of both ACCT's resulted in a barely perceptible but identical "binding" at the exact same spot. Just the tiniest bit of resistance, which to me indicates that central screw shaft is out of true.

It would be useful if someone took apart an unused ACCT and rolled that central shaft on a piece of glass. If it makes an intermittent, repeating "clink-clink-clink" sound, then it's not perfectly true.

On a side note, something else that my brother pointed out is that those springs that TOC sells for $30 a pair are only $1 on McMaster-Carr.

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O' Darkness

· #30 · 20 d ago

mmart said:
I feel like I’ve read tensioner threads enough to observe a pattern. That pattern is “tinker with failing ACCT and then ultimately swap to MCCT”. I’m sure if you search you’ll find someone who’s had success with every option possible. This is the first time I’ve heard of an extender, but it just makes me think (as mentioned), if you need and extender something else is worn out.

I only mentioned an extender in passing because I'd not seen that option proposed anywhere. I wasn't so much thinking of extending the tip further, as I was thinking of maybe an additional washer to compress the spring more. However, read my recent comment about the following statement: That central shaft not being perfectly true would account for the problem, and even confirms why some of the solutions (set-screw for example) seem to work fine.

Ultimately, I do like the MCCT option best and I'm ordering a set.

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dirtrack650

· #31 · 20 d ago

taco_to_go said:
Good idea. Any oil seep out?

A bit of blue thread locker prevents oil seepage.

dirtrack650

· #32 · 20 d ago

My theory is the ACCT does extend to compensate for chain wear, but, when the spring weakens, it also backs out. That's why I figured a set screw is all that's needed to cure the problem. It works.

Buddy

· #33 · 20 d ago

One thing I do not understand with the AC CT is when you release it against the guide it holds pressure on it but how can it back out . The spring allows the acct head to rest against the guide once the acct is in place it can’t move backwards it can only turn in to bring more pressure against the guide. When I was winding preload onto the spring and allowing it to unwind in my hand once it is extended it can’t go backwards. What am I missing here in understanding how it works. If it is called automatic then it automatically moves only one way.

Thorn

· #34 · 20 d ago

The spring isn't pushing laterally against the head, it is applying torque to the screw, which in turn pushes the plunger outward. A properly tensioned spring will screw/extend the plunger to the proper depth to hold the guides in place. Pretty much no matter how hard the chain guides push outward against the screw, it won't cause it to retract back into the ACCT housing. That would be like hammering a bolt into a threaded hole while someone is turning the bolt out of the hole with a wrench. The wrench is going to win. If the spring takes a set over time, it will reach the end of it's rotational travel too soon, and won't be able to spin the screw to it's fullest extended position. Any wear in the chain beyond that reach will result in rattle, as the ACCT just sits at some arbitrary half-way point in it's potential travel length.

A set screw like dirttrack65 works well because you can add as much tension manually as you need by turning the screw further than the spring wants to uncoil, then lock the piston in place with the set screw. This eliminates the spring entirely, and turns the ACCT into an MCCT, just with the locking mechanism activating from the side instead of with lock nuts from the end.

O' Darkness said:
I don't have the proper tools to check this, but my suspicion is that many of these ACCT's left the factory with a central shaft that is not entirely true. With radio-control helicopters, the main shaft has to be perfectly true, or else the helicopter will vibrate to death. I found it extremely interesting that manually compressing the spring of both ACCT's resulted in a barely perceptible but identical "binding" at the exact same spot. Just the tiniest bit of resistance, which to me indicates that central screw shaft is out of true.

The straightness of the shaft here isn't nearly as critical is it would be with a high-speed shaft. These would have pretty loose tolerances, and there shouldn't be any interference rotationallly. Was it binding every rotation as you added tension, or just once, at say, 2.5 turns of the spring? If you removed the ACCT and retracted it fully, it should spin it's way all the way to fully extended without binding and without any assistance.

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O' Darkness

· #35 · 19 d ago

Thorn said:
The spring isn't pushing laterally against the head, it is applying torque to the screw, which in turn pushes the plunger outward. A properly tensioned spring will screw/extend the plunger to the proper depth to hold the guides in place. Pretty much no matter how hard the chain guides push outward against the screw, it won't cause it to retract back into the ACCT housing. That would be like hammering a bolt into a threaded hole while someone is turning the bolt out of the hole with a wrench. The wrench is going to win. If the spring takes a set over time, it will reach the end of it's rotational travel too soon, and won't be able to spin the screw to it's fullest extended position. Any wear in the chain beyond that reach will result in rattle, as the ACCT just sits at some arbitrary half-way point in it's potential travel length.

A set screw like dirttrack65 works well because you can add as much tension manually as you need by turning the screw further than the spring wants to uncoil, then lock the piston in place with the set screw. This eliminates the spring entirely, and turns the ACCT into an MCCT, just with the locking mechanism activating from the side instead of with lock nuts from the end.

The straightness of the shaft here isn't nearly as critical is it would be with a high-speed shaft. These would have pretty loose tolerances, and there shouldn't be any interference rotationallly. Was it binding every rotation as you added tension, or just once, at say, 2.5 turns of the spring? If you removed the ACCT and retracted it fully, it should spin it's way all the way to fully extended without binding and without any assistance.

The spring encountered resistance at about a half-turn in, removed from the bike. On both ACCT's.

If the shaft is bent out of true, it would explain that binding. I understand what you mean about the tolerances and such, but because this problem seems to be rather persistent, it's quite possible that a small manufacturing defect has occurred.

mmart

· #36 · 19 d ago

Another thing to mention is the soft aluminum body on the ACCT, the can become worn internally if left being hammered too long.

O' Darkness

· #37 · 19 d ago

mmart said:
Another thing to mention is the soft aluminum body on the ACCT, the can become worn internally if left being hammered too long.

That's a good point. Especially on the higher mileage Vulcans.

mmart

· #38 · 19 d ago

O' Darkness said:
That's a good point. Especially on the higher mileage Vulcans.

I didn’t wait long to swap them out at all. I was at 23K, and the noise just started one day out of no where. As an engineer I gravitate towards “simpler is better”. So MCCT for the win, no internal parts to mess with. Basically set and forget.
After dealing with the stator It’s obvious that Kawasaki engineers miss “the little things” from time to time, so I had no interest in diving into the ACCT’s. I think they’re a “look good on paper” option that helped boost the 750’s virtually maintenance free appeal.

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Checkered Floor Garage

· #39 · 18 d ago

mmart said:
I didn’t wait long to swap them out at all. I was at 23K, and the noise just started one day out of no where. As an engineer I gravitate towards “simpler is better”. So MCCT for the win, no internal parts to mess with. Basically set and forget.
After dealing with the stator It’s obvious that Kawasaki engineers miss “the little things” from time to time, so I had no interest in diving into the ACCT’s. I think they’re a “look good on paper” option that helped boost the 750’s virtually maintenance free appeal.

I was nearly at the same miles with my Vulcan when I replaced my ACCT's with MCCT's! And yes, also as an engineer I agree with "simpler is better". Well put, mm.

It's funny that you said "...Kawasaki engineers miss 'the little things' from time to time" because just yesterday (while riding the Vulcan) I was thinking about how this bike must have been designed and engineered largely in part without the use of computers. So the fact that they made the VN750 as it is (high revving, high power, etc.) with pencil and paper amazed me. But yeah...the stator replacement PITA and the ACCT's are just little things that got missed...and never addressed over the 20 year manufacturing run.

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O' Darkness

· #40 · 18 d ago

Checkered Floor Garage said:
I was nearly at the same miles with my Vulcan when I replaced my ACCT's with MCCT's! And yes, also as an engineer I agree with "simpler is better". Well put, mm.

It's funny that you said "...Kawasaki engineers miss 'the little things' from time to time" because just yesterday (while riding the Vulcan) I was thinking about how this bike must have been designed and engineered largely in part without the use of computers. So the fact that they made the VN750 as it is (high revving, high power, etc.) with pencil and paper amazed me. But yeah...the stator replacement PITA and the ACCT's are just little things that got missed...and never addressed over the 20 year manufacturing run.

Fun fact: The Kawasaki Vulcan 750 was most likely not engineered with just pencil and paper alone. Large scale automotive CAD dates back further than 1985.

In fact, AutoCAD was introduced in '82, so it's more than reasonable to speculate that the Vulcan was engineered with the assistance of computers, especially when you consider that it's a Japanese product.

Just for fun:

Product Font Material property Rectangle Parallel

Even more interesting is that 3D printing dates back to at least 1980, although there's evidence regarding the potential and the process going back even further than that.

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