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Discussion Starter · #1 ·
So there’s a lot of info on this forum about the switch from ACCT’s to MCCT’s. But I just can’t find anything definitive if I need to get the engine to TDC or not. I just put in the order with TOC and want to make sure I do this right. Please help.

FYI, if this post seems foreign to you allow me to try and explain. From the factory, the Vulcan 750’s came with two Automatic Cam Chain Tensioners (ACCT’s), one for each of the two cylinders. Their role is to provide the appropriate tension for the cam chain of each cylinder. Over time, the ACCT’s tend to weaken/malfunction and this results in some chain slap noise. If left unattended, this could be a catastrophic issue.

So the common fix when this issue comes up is to install manual cam chain tensioners (MCCT’s). The intent here is that these can be easily tightened/adjusted and can basically last for the rest of the life of the bike.
 

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Discussion Starter · #4 ·
Not sure why you need to check for TDC unless you removed the cam chain or believe it skipped a tooth. From what I understand replacing the stock tensioners with a manual one is a simple remove/install and then adjust.
I found this YouTube video that says to not remove the tensioner unless it’s at TDC otherwise an open valve can close under the tension.


IMO it seems unlikely for the tension of a single valve to move the entire engine/valve train and thus get out of timing. But still I want to make sure I do this right.

What do you make of this? Seems like it’s unnecessary given the other comment here on this post.
 

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I found this YouTube video that says to not remove the tensioner unless it’s at TDC otherwise an open valve can close under the tension.


IMO it seems unlikely for the tension of a single valve to move the entire engine/valve train and thus get out of timing. But still I want to make sure I do this right.

What do you make of this? Seems like it’s unnecessary given the other comment here on this post.
I would follow the manual, it's quite possible for valve spring tension to cause the engine to turn, I've seen it happen. However, I haven't known anyone to have that problem on the Vulcan and nobody has posted about TDC that I know of.
 

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I do not see any way it is possible for the removal of one ACCT and its replacement with a MCCT to result in the rotation of the crankshaft. You are removing the tension on one cylinder's timing chain and everything else stays static. Even if the chain in question was completely worn the pressure from the valve spring would not result in the engine rotating, only the camshaft moving a bit. The chain loops over the top of the engine and 2 camshafts. If one is closed the other is open and it would offset the pressure from that valve. Also the other camshaft is still in play and you would have to "move" those camshafts as well. If there is enough stretch in the timing chain it might drop down when you remove the ACCT but I do not think it would be likely you would even loose 1 tooth of timing. The engine's design just would not allow it. The guide holds the chain such (even with no chain tensioner at all) so that the opposite side of the chain drops over the crankshaft's teeth, Keeping the chain pretty much in place

Were this a single overhead cam engine maybe in theory but overall there are 4 camshafts to be considered here and releasing the tension from 1 of them will not result in the engine crankshaft moving. If you assume that while one valve may be trying to close and move the chain (then perhaps the crankshaft, 2 pistons and the other camshaft and its valves) you have to realize the other components are trying not to move. I do not believe it would move even if you were to remove all 4 spark plugs and not have compression to overcome. The other valve springs and the friction of the pistons would have to be overcome.

I know it is advisable to put a engine at TDC when replacing a timing belt, or chain, depending on the number of cylinders for the engine being worked on, However, it really is more for the ease and convenience of maintaining proper valve timing. It is not a requirement to stop the engine from rotating. My experience with overhead camshaft engines up until this Kawasaki is limited to Ford 2.0 liter, 4 cylinders and Jaguar 4.2 liter, 6 cylinder engines. At no time have I ever encountered a incident of engine rotation when relieving the tension from the timing belt (Ford) or chains (Jaguar).
 

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It's possible for valve spring pressure to move the cams and crank. If one or more rocker arms is on the ramp of the cam lobe, the cam can move.

It's critical on some engines to block the cam gears.

As I said above it hasn't been reported to be a problem. Just remove the ACCT, without turning the engine, then install MCCT and adjust it.
 

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Hers a dumb question. Simply because I don’t know any better, but if the concern is that removing a tensioner can misalign the timing isn’t the other tensioner on the other cylinder holding everything in place? Meaning if you did them one at a time it would be a non issue??
I simply just swapped them out., don’t move the bike at all even in neutral and be careful with the oil line on the front cylinder and you should be good to go.
Hand tighten the MCCTs then tighten the main nut with a wrench about a half turn. Start the motor and listen. If it’s too loose, it’ll clank and if it’s too tight it’ll whir and slow down the cylinder. Rinse and repeat on other cylinder.
 

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Hers a dumb question. Simply because I don’t know any better, but if the concern is that removing a tensioner can misalign the timing isn’t the other tensioner on the other cylinder holding everything in place? Meaning if you did them one at a time it would be a non issue??
I simply just swapped them out., don’t move the bike at all even in neutral and be careful with the oil line on the front cylinder and you should be good to go.
Hand tighten the MCCTs then tighten the main nut with a wrench about a half turn. Start the motor and listen. If it’s too loose, it’ll clank and if it’s too tight it’ll whir and slow down the cylinder. Rinse and repeat on other cylinder.
The other tensioner will keep tension on the other chain, but the other chain being slack, that cam could move.

But ... The chain would have to jump at least one tooth for movement to be an issue. Without jumping a tooth, the cam will still be aligned after re-installing the tensioner.

Most MCCT installs have gone just as you posted.

This looks like one of those cases where the manual gives you an extra step that's not needed.
 

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Finally got a look in the .pdf manual. It doesn't mention anything about TDC and alignment marks on the rotor for replacing ACCTs. TDC is mentioned in the next section which is checking the timing chains.



The manual does have some interesting notes about the ACCTs. One of the notes ... The plunger can't retract after it's extended, so you can't partially loosen the ACCT or remove/replace it without resetting the plunger. Failing to reset causes the ACCT to be too tight.
 

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When I removed one for the first time to see if the spring was broken or not, I made the little tool that is shown in the Chilton manual. Then when I watched Roach's videos I saw him install one while holding it (with the plunger retracted) with a small screwdriver.

The design of the spring and threaded rod inside the plunger will not allow it to "float" against the chain. The spring though is so weak that it does not place much actual pressure against the timing chain though. I have replaced 4 ACCTs when they became noisy and the Gambo trick didn't work anymore. None of them had a broken spring. They just got so weak they didn't do their job any more. Even then you couldn't compress them by hand without retracting the plunger rod.
 

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Discussion Starter · #13 ·
Finally got a look in the .pdf manual. It doesn't mention anything about TDC and alignment marks on the rotor for replacing ACCTs. TDC is mentioned in the next section which is checking the timing chains.



The manual does have some interesting notes about the ACCTs. One of the notes ... The plunger can't retract after it's extended, so you can't partially loosen the ACCT or remove/replace it without resetting the plunger. Failing to reset causes the ACCT to be too tight.
Thank you for taking the time to look thru the manual to help me out. I appreciate it! As soon as I get the MCCT's from TOC, they're going in!
 

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Thank you for taking the time to look thru the manual to help me out. I appreciate it! As soon as I get the MCCT's from TOC, they're going in!
I like the TOCs, they have that nice large bolt.
 

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I like the TOCs, they have that nice large bolt.
And the TOCs fit on the rear cylinder without messing with the coolant overflow tank. Heres a little trick for that. I took a combo crescent/box wrench and cut it in half. Once you put the coolant tank back on it’s hard to make the adjustment. You can slide the box head down onto the lock nut to loosen it and the open end to grip the adjustment bolt. Comes in handy for the rare occasional tweak.
 

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Discussion Starter · #16 ·
And the TOCs fit on the rear cylinder without messing with the coolant overflow tank. Heres a little trick for that. I took a combo crescent/box wrench and cut it in half. Once you put the coolant tank back on it’s hard to make the adjustment. You can slide the box head down onto the lock nut to loosen it and the open end to grip the adjustment bolt. Comes in handy for the rare occasional tweak.
How often have you needed to adjust your MCCT's?
 

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Just once over the last 2+yrs, the TOCs are a low maintenance item. But I’ve used the wrenches just to check that things are tight as normal maintenance. When you install the rear cylinder you’ll see just how little room you have to work with. The cut wrench is just a time saver if you ever need to get at them but again once you get them set right they’re pretty solid.
 
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