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side effect however it looks like it’s a known issue for the cbr300r, cfr250 and cbr250r
The accompanying problems do not come by themselves, they come when we not replacing the CCT in time. Ther are no other side issues.

Heavy load increases abrasion, a single ride at 7000 rpm does not constitute an unusual load. The motorcycle is cooled by liquid and not air, so the temperature is stable even when the speed is low. At high rpm the cooling pump flows more coolant and the engine does not heat up.

I repeat I suggest you try to activate the warranty. If you trust your mechanic go to him and try to check what is wrong.
 

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I repeat I suggest you try to activate the warranty. If you trust your mechanic go to him and try to check what is wrong.
Warranty is already gone since the job was done more than 3 months ago. Yesterday I took a look in the first cct that was removed and the issue was pretty obvious, the more the plunger is out the screw tension is way weaker and theres nothing to help the spring keep its current position.
This weekend I will try to do the manual conversion too see if the noise is removed.
 

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Warranty is already gone since the job was done more than 3 months ago.
In any case I suggest you contact your mechanic, the CCT should hold at least 20,000Km.

the more the plunger is out the screw tension is way weaker
YES

theres nothing to help the spring keep its current position.
NO.
The patent there is not built on the spring force, these on one-way plunger. The plunger only goes out, and does not go back inside (Only by the special screw). The power of the spring is only to push the plunger to the closest position that possible. Therefore it is an automatic mechanism.

I will try to do the manual
(y)(y)(y)
 
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Hmm, I wonder where oil-pick up is in oil-pan? Is it in front or rear of pan? With or without baffles?

I've seen lots of bikes that are used for stunting and wheelies have premature bearing-wear because oil pick-up tube sucks in air instead of oil. Might be case with going uphill for long time?

Have you measured cam-chain stretch amount?
 

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Hmm, I wonder where oil-pick up is in oil-pan? Is it in front or rear of pan? With or without baffles?
You are made me to curiosity. Now we both have no "wonder" anymore. Thanks!
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I've seen lots of bikes that are used for stunting and wheelies have premature bearing-wear because oil pick-up tube sucks in air instead of oil. Might be case with going uphill for long time?
YES: It's need really crazy angles, like situations that stunt riders get into.
No: There is no road in the world that the motorcycle can climb on in terms of slope, and the fuel pump will not get oil.
 

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So after going through 2 brand new factory tensioners in less than 1000 miles (original made it 28k), I decided that I wasn't going to buy another factory one to destroy my engine, and I also wasn't going to pay $50 for a bolt and nut shoved through a tensioner housing. Here is the original post with a video showing the symptoms and details of what I was experiencing: Cam chain tensioner dying

So, since I had an extra (bad) tensioner laying around, I decided to do some surgery, find the underlying culprit, and solve this once and for all. So here goes. $4 in Lowes hardware and half an hour later, and no more ticking.

Supplies needed:
1 package of M6x1.00 40mm stainless steel bolts (need 1 bolt)
1 package of M6x1.00 stainless steel nuts (need 1 nut)
1 package of M6x1.00 stainless steel nylon lock nuts (need 1 lock nut)
1 package of stainless steel washers (need 1 washer)
Total cost: $3.96, and enough leftover to do 3 more tensioners!

Remove the hex cap bolt on the back of the tensioner and remove the small black o-ring. Do not lose this!

View attachment 44553

Remove the tensioner from the back of the motor with the two 8mm bolts on each side. Hold it in towards the motor when removing to prevent stripping the other bolt.

Remove the snapring from around the base of the plunger using a small, thin, flat head screwdriver and working around the housing a little at a time. Be careful to not warp/bend the snapring out of shape, as you'll be re-using this later. (Sorry, no pics of this. Needed two hands and didn't want anything flying out in my face.)

Once you have the snapring off, you can remove the plunger and all the guts of the tensioner. BE CAREFUL! There is a spring inside under tension, and it can slice you if it pops out.

Here are the parts in their glory. We'll only be using a couple going forward: 1. The housing 2. The snapring 3. The plunger. The spring, plastic sleeve, wormgear, and washer will not be used. Here, you can also see the end of my spring is also quite knarled. This thing was ready to let go.

View attachment 44555

And this brings us to the crux of the tensioner debacle. The spring tension does both duties: Providing outward tension, and preventing the wormgear from backing off; there is no lock on the wormgear. Unfortunately, once the spring weakens to a point where it is no longer providing adequate pressure outwards, it is also unable to prevent the wormgear from backing off under vibration, allowing the cam chain to rattle around and make that cringe-worthy noise at idle.

Ok, now is when the magic happens. Take your stainless bolt, then place 1 regular stainless nut on the bolt, followed by 1 stainless washer, followed by the black sealing o-ring from earlier. Begin threading the bolt into the tensioner housing from the back side. Here you can see the order and the orientation.

View attachment 44557

You will want to move the nut to the head of the bolt so that you can bottom the bolt out on the housing as far as it will go. Make sure your o-ring is in the recession on the housing so it doesn't get pinched or torn.

View attachment 44558

Now grab your stainless nylon lock washer and place it on the end of the bolt that is now pushed through the housing. Use a 10mm wrench on the bolt head, and a 10mm socket on the nylon lock nut to tighten the nut until it is flush with the end of the bolt. If you feel paranoid, you may place some locktite on the threads before doing this.

View attachment 44559

Now back the newly completed bolt apparatus out of the housing until it hits the lock nut. Place the plunger back over the housing and lock nut, then reinstall the snapring.

View attachment 44560

View attachment 44561

Place the gasket back on the tensioner housing and reinstall in the bike.

Now make sure the o-ring is in its recession, and the washer is laying against it (this will keep oil from weeping out around the bolt). Turn the main bolt in finger tight until you hit resistance. I turned it one-half turn further, then held the bolt head with a wrench to keep it from moving while I snugged down the nut with another wrench to lock it in place.

Here is the completed install:

View attachment 44562

This may take a little adjustment. If you hear rattling after this, loosen the nut and turn the bolt head another half turn in. If you hear a whining sound on deceleration, then it may be a tad too tight and you should back off a smidge.

No rattles, no more failures, and no overpriced custom manual tensioners. Bling, blang, blao. :smile2:
Thank you so much for posting this. I tried it and it's working absolutely perfect. No more rattles. I wish i knew this 5 years ago...i would've saved 20k. I wish to thank you personally...please contact me on 9915746406
 

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Thank you so much for posting this. I tried it and it's working absolutely perfect. No more rattles. I wish i knew this 5 years ago...i would've saved 20k. I wish to thank you personally...please contact me on 9915746406
No one who destroyed an engine are here to tell us they destroyed an engine because of this nonsense: That the manual is better than the automatic.

I disassembled the automatic mechanism, and studied it in depth, there is nothing that can broken in it, it is very reliable, and bulletproof.
LINK TO MY STUIEDS (My YT Channel)
Even though, it is customary to change the automatic tensioner every 20 to 25 thousand kilometers, it is not clear why, but the legend says to change it, and I change it too, because it is an easy to replace and relatively cheap (LINK to Partzilla).
Product Font Screenshot Line Parallel

The characteristic vibrations of our engine, The Rattling Issues, come from the exhaust gas valve(One-way relief) that located at the top of the valve cover. It's frequencies are amplified by the valve cover, and that's the noise we all hear. It's a noise you get used to it, and it doesn't cause any harm.
Map Font Parallel Auto part Slope

On the other hand, a timing chain that is too tight is immediate causes an Heavy Damage!
If you have a reduction in the normal CBE250R engine vibrations, such that the independent frequencies are now more restrained, I would advise you to be concerned about an overstretched timing chain.
 
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No one who destroyed an engine are here to tell us they destroyed an engine because of this nonsense: That the manual is better than the automatic.

I disassembled the automatic mechanism, and studied it in depth, there is nothing that can broken in it, it is very reliable, and bulletproof.
LINK TO MY STUIEDS (My YT Channel)
Even though, it is customary to change the automatic tensioner every 20 to 25 thousand kilometers, it is not clear why, but the legend says to change it, and I change it too, because it is an easy to replace and relatively cheap (LINK to Partzilla).
View attachment 45542
The characteristic vibrations of our engine, The Rattling Issues, come from the exhaust gas valve(One-way relief) that located at the top of the valve cover. It's frequencies are amplified by the valve cover, and that's the noise we all hear. It's a noise you get used to it, and it doesn't cause any harm.
View attachment 45541
On the other hand, a timing chain that is too tight is immediate causes an Heavy Damage!
If you have a reduction in the normal CBE250R engine vibrations, such that the independent frequencies are now more restrained, I would advise you to be concerned about an overstretched timing chain.
The tensioner doesn't retract back. If it extends more than necessary, the cam chain runs tight and thus wears out very quick. My CBR's cam chain got loose just after 8k kms. Since the change interval was no where close, nobody suspected this to be a problem and ASC asked me to observe for some time. The damage was done. Had to overhaul the engine. After 7k kms , i started to hear the same noise again. Replaced tensioner but no good because cam chain had elongated way too much. Had to open the head and replace timing chain, tensioner and rocker. Again after 9k kms, i heard the same rattle and ticking noise. This time i made this manual cam chain tensioner and it has solved everything. I use hit and trial method to check how tight the cam chain is. I know my machine and i know how it should sound.
 

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The tensioner doesn't retract back. If it extends more than necessary, the cam chain runs tight and thus wears out very quick. My CBR's cam chain got loose just after 8k kms. Since the change interval was no where close, nobody suspected this to be a problem and ASC asked me to observe for some time. The damage was done. Had to overhaul the engine. After 7k kms , i started to hear the same noise again. Replaced tensioner but no good because cam chain had elongated way too much. Had to open the head and replace timing chain, tensioner and rocker. Again after 9k kms, i heard the same rattle and ticking noise. This time i made this manual cam chain tensioner and it has solved everything. I use hit and trial method to check how tight the cam chain is. I know my machine and i know how it should sound.
You're absolutely right. Running a tight cam chain is a hazard for engine. This is exactly what automatic tensioner does, it just keeps extending, thereby making the cam chain tighter and tighter. After 3 engine head level repairs, i cannot trust automatic tensioner made by Honda.
 

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Running a tight cam chain is a hazard for engine. This is exactly what automatic tensioner does,
??? The automatic tensioner do the job without causing any damage to the engine
In my opinion, you should look for the problem elsewhere.
AND maybe there is no problem at all, because for example:
You ride the motorcycle all the time at a high rpm of 8k-10k rpm, and therefore the lifespan of your engine is relatively short (7k-9k kms).
 

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Discussion Starter · #33 ·
I disassembled the automatic mechanism, and studied it in depth, there is nothing that can broken in it, it is very reliable, and bulletproof.
Bullet-proof-Ish. :) It's only problem is the opposite; a super weak spring that doesn't apply enough tension to keep the rattling at bay. Best case it's an annoyance. I do not think in 99%+ of cases that it would be enough to case any damage from the chain slapping around, based on its design it kind of prevents this.

The characteristic vibrations of our engine, The Rattling Issues, come from the exhaust gas valve(One-way relief) that located at the top of the valve cover. It's frequencies are amplified by the valve cover, and that's the noise we all hear. It's a noise you get used to it, and it doesn't cause any harm.
There are many sources of vibrations in these little singles; indeed, many are ignorable and just come with the territory. However I can say in my case, it was not the exhaust valve, as I have the PAIR bypassed and the valve blocked after I installed my exhaust long ago. The rattle was unchanged, however converting the tensioner solved that. Caveat being: You have to be familiar mechanically with your bike and experienced enough to be able to "feel" and "hear" when the tensioner is too loose or too tight.

So depending on the unique bike and case, "rattles" can come from 100+ different sources, from lose engine mount bolts, a sticky/loose chain, gear noise, chain tensioner, exhaust valves, plastic fairings, even the washers behind the footpeg cotter pins, and each bike will have to be troubleshooted and evaluated by the owner. :)
 
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The tensioner doesn't retract back. If it extends more than necessary, the cam chain runs tight and thus wears out very quick.
If chain is already tight, how can tensioner extend even more than necessary to apply extra. tension on chain?

Problem is actually opposite, what cbrlocal pointed out. As spring extends, it looses too much tension. So automatic tensioner works fine initially, maybe 1st 1/2 of its stroke. But on 2nd half of travel, there's not enough preload to push on chain enough to apply sufficient tension.
 

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So depending on the unique bike and case, "rattles" can come from 100+ different sources:
(1) from lose engine mount bolts,
(2) a sticky/loose chain,
(3) gear noise,
(3) chain tensioner,
(4) exhaust valves,
(5) plastic fairings,
...
(100) even the washers behind the footpeg cotter pins,
But that vibration noise that you only hear on our motorcycle, thousands of "RATTLES" threads were born on its name, and it comes from a very specific place, and according to my opinion :
THE VELVE REED;):cool::ROFLMAO::LOL:
 
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what cbrlocal pointed out. As spring extends, it looses too much tension. So automatic tensioner works fine initially, maybe 1st 1/2 of its stroke. But on 2nd half of travel, there's not enough preload to push on chain enough to apply sufficient tension.
The ability of the mechanism to close gaps is NOT related to losing a small and negligible percentage of the spring force.
The upward angle of the screw does not allow the plunger to go back in, it has nothing to do with the force of the spring, the screw is locked the plunger that cannot go back in.
Locked due to the force of friction and not the force of the spring.

In the opposite direction, plunger out, a minimal spring force is enough to cause the screw to push the plunger out (provided the plunger has clearance that allows it to come out).

The mechanism ensures that there will always be surplus closure for the new free play that are created. That mechanism is bulletproof.

But it is customary to change it every 20k-25k km,
  • (1) because this is the custom,
  • (2) this is a fairy tale,
  • (3) it is a psychological matter,
  • (4) a religious matter,
  • ...
  • (100) and as such...
So I also respect the rules of the ceremony
AND change it too every 20k-25k km(y):cool::LOL:

:coffee::coffee::coffee:
 

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Sure, wedge prevents mechanism from retracting, but there's not enough spring force after 1/2-way to push it further out to add more tension on chain. Measure actual spring tension at various lengths. A spring that's fully extended exerts zero force. Fully compressed tensioner exerts maximum force that decreases as it extends.

I suspect there's also some fatigue involved as well. We should measure spring-rate of old worn-out tensioner and compare to new one.

That's why on more high-end bikes and autos, hydraulic tensioner is used. This design exerts identical tension force along entire length of travel.
 

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Without blaming the Brilliant Automatic Tensioner
Anyone who wants to arrange a new tensioner for himself for free, takes an M6 screw and arranges one of these for himself exactly as the thread opener explains Very nicely(y)(y)(y)

And of course with the manual tensioner you have to be careful:
  1. not to tighten it too much,
  2. and adjust it every 5k km,
Because otherwise
the savings can come at the cost of destroying the entire engine
💀☠☠💀
 

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Measure actual spring tension at various lengths. A spring that's fully extended exerts zero force.
NO
Danno. Inside the engine the plunger never reaches the end of its stroke, and always at the end of its stroke (when it is outside the engine) the spring have to enough force to take it out (to his end- till stop).
That is way:
  • there is no problem of the kind of spring that gets weak,
  • and there is no problem of the kind that the spring reaches to zero force.

You are describing something that never happens in this mechanism.
The Brilliant Automatic Tensioner Is A Bulletproof Mechanism.
 

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NO
Danno. Inside the engine the plunger never reaches the end of its stroke, and always at the end of its stroke (when it is outside the engine) the spring have to enough force to take it out (to his end- till stop).
That is way:
  • there is no problem of the kind of spring that gets weak,
  • and there is no problem of the kind that the spring reaches to zero force.

You are describing something that never happens in this mechanism.
The Brilliant Automatic Tensioner Is A Bulletproof Mechanism.
Then why does it need to be replaced every 20k? What is difference between old unit @ 20k vs. new?

We must assume there is difference because bikes that do not have them replaced on schedule ends up with worn-out cam-chains and noises.

As with everything else in life, the important distinction is in numbers. We need to devise tests of various sorts of measure different physical properties of new vs. old tensioners. Just because you have not measured the numbers, does not mean there isn't something about old tensioners that's different from new ones.

You yourself have accepted this by replacing your tensioner before it "wore out", whatever the property that changes.
 
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