Cam chain tensioner dying - Page 2 - Honda CBR250R Forum : Honda CBR 250 Forums
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post #11 of 20 Old 01-26-2017, 02:14 PM
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Good luck with your bike. Hope you able to sort it out without major problems.

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Last edited by Mufasa; 01-26-2017 at 02:15 PM. Reason: I should learn to read.
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post #12 of 20 Old 01-27-2017, 10:28 AM Thread Starter
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Used a small precision screwdriver to turn the worm gear counter clockwise (out) a tad last night; no improvement in the noise on the commute this morning, but I was also timid to not turn it too far. There is still plenty of travel left in the CCT mechanism (chain not excessively stretched), so I'm thinking that the spring tension just isn't strong enough to not back the worm gear off slightly.

Again, this CCT checks out with all my tests. But pushing on the plunger as hard as you can is very different than a chain guide slapping into it at 8000 RPM. I will likely turn it out a tad further, and replace the pan head bolt with a hex bolt, nut and washer, then snug it against the back of the worm gear adjuster to make sure it's not backing off.
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post #13 of 20 Old 01-28-2017, 03:29 PM Thread Starter
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So, if you're having CCT noise and you suspect your spring just isn't creating enough pressure to push the worm gear out enough, here's a quick fix for you as long as your worm gear is working properly. This will also allow you to adjust the CCT without removing the clutch cable or bracket.

Remove the pan head hex bolt from the CCT with your toolkit hex key.



After removing the bolt, make sure you don't lose the black o-ring around the bottom.



Get a 90 degree ratcheting screwdriver, and a 3/16" flathead bit. Got this for $3 at Harbor Freight.



Insert the bit into the CCT bolt hole and rotate it until it slides into the worm gear slot.



Set the screwdriver to lefty-losey/turn counter clockwise, and slide it over the bit. You may have to rotate the screwdriver a bit before it will slide on.



Give it a couple of clicks until you're feeling tension. Do NOT overtighten this. Play it safe if you're unsure.

Replace in reverse order and test. If it needs a little more tension, remove the bolt and give it another click or two. Do this incrementally.

If your worm gear isn't locking into position, instead of the hex cap bolt, replace that with an M6x1.00 bolt, nut, and washer. You snug the bolt down until it bottoms out after setting the CCT tension, then snug up the nut to lock it in place. You can't tighten the bolt or you'll rotate the worm gear clockwise with the tension, thereby backing it out again. The object here is to keep the worm gear immovable, not to actually put tension on it.
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post #14 of 20 Old 02-01-2017, 11:51 AM Thread Starter
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No ticks for 3 days after applying this fix. I would get the tick/chatter at idle when the bike was cold, and it seemingly vanished or lessened greatly after the bike was fully warm; I'm guessing the heat expanding the parts took up the slight bit of slack that was causing the noise. I would encourage anyone who has this problem to try this fix first before replacing your tensioner.

Seems this is a chronic Honda problem that hasn't changed over the years; interesting, since most manufacturers utilize the same basic CCT design, Honda seems to be the one to have the chronic failures.

My theory, since my CCT technically hadn't failed (and I suppose my original didn't either), is that the spring tension is much weaker as the plunger extends from its initial bottomed out position, and the weight of the cam chain guide itself is enough to keep the CCT from extending that extra slight bit more that it needs to keep the cam chain quiet. Particularly since the amount I adjusted probably totaled 1/4 turn or less of the worm gear.

After the adjustment, my engine is much smoother and quieter. You can tell a vibration difference throughout the rev range.

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post #15 of 20 Old 03-02-2017, 10:00 AM Thread Starter
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Update: The chatter returns yet again. I have had to tighten the CCT at least once a week since it started its shenanigans to shut it up. I took note of the screwdriver bit's angle when placed in the CCT worm gear at each adjustment, and EVERY TIME, it had returned to its original resting angle. Meaning in a nutshell: The wormgear is backing off over time. It does not progress beyond that point, so there is no danger of skipping timing, but it is obviously not enough to eliminate the chatter in the chain. Maybe this is why Honda has elected to not revise or address this problem.

I will be applying the Thai fix with a bolt, nut, and washer soon and hope for it to be a permanent fix. It is amazing to me that a manufacturer like Honda simply can't make something as simple as their CCT work properly.
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post #16 of 20 Old 04-12-2017, 03:20 PM Thread Starter
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Both tensioners are totally shot and have completely stopped holding their positions. Such an expensive part for what it is (~$24) and for how flimsy and flawed its design is, you'd think a company such as Honda would have fixed such a straw on a camel's back by now. I've tried the "Thai" fix with a bolt, nut and washer to put pressure on the back of the worm gear to no avail. So, using my spare old failed CCT, I've ripped it apart and found the culprit of everyone's woes.

I also did not feel I should have to spend upwards of $50 for a manual tensioner to fix this problem, being that all it is is a normal CCT housing with a bolt stuck through it.

So, stay tuned; there will be a tutorial up soon for making your own manual CCT from a factory stock CCT, all for less than $4 of hardware at Lowes and 20 minutes of your time.
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post #17 of 20 Old 04-12-2017, 11:15 PM
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bit like the search for the golden boomerang...
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post #18 of 20 Old 04-13-2017, 11:18 AM Thread Starter
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Link to tutorial for permanent and cheap fix: https://www.cbr250.net/forum/cbr250-s...nual-%244.html

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post #19 of 20 Old 03-27-2018, 11:01 AM
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Quote:
Originally Posted by cbrlocal View Post
Link to tutorial for permanent and cheap fix: https://www.cbr250.net/forum/cbr250-s...nual-%244.html
How's your CCT and timing chain so far ?

I also have the same problem. https://www.cbr250.net/forum/cbr250-p...ing-chain.html
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post #20 of 20 Old 03-31-2018, 04:37 PM Thread Starter
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Quote:
Originally Posted by zelta32 View Post
How's your CCT and timing chain so far ?

I also have the same problem. https://www.cbr250.net/forum/cbr250-p...ing-chain.html
Absolutely, perfectly, 100% awesomely fine. Haven't had to adjust it once since converting and setting it, and there's been absolutely no noise or clicking. Highly recommended mod.

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