Convert factory cam chain tensioner to manual - For $4 - Honda CBR250R Forum : Honda CBR 250 Forums
User Tag List

 4Likes
  • 4 Post By cbrlocal
 
LinkBack Thread Tools
post #1 of 3 Old 04-13-2017, 11:04 AM Thread Starter
Senior Member
 
Join Date: Jan 2012
Location: Piedmont, NC
Posts: 1,763
Thanks: 138
Thanked 475 Times in 369 Posts
Convert factory cam chain tensioner to manual - For $4

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!



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.



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.

Here, you can also see the end of my spring is also quite knarled. This thing was ready to let go.



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.



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.



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.



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.



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:



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.

Tis better to be thought a fool and remain silent, than to open one's mouth and remove all doubt.

Last edited by cbrlocal; 04-13-2017 at 11:17 AM.
cbrlocal is offline  
The Following 6 Users Say Thank You to cbrlocal For This Useful Post:
don'tpanic (04-14-2017), jkv357 (04-13-2017), OleKennyRoy (04-13-2017), Schroeder (04-14-2017), shisoshin (04-14-2017), Stichill (04-21-2017)
Sponsored Links
Advertisement
 
post #2 of 3 Old 04-14-2017, 05:49 PM
Senior Member
 
Schroeder's Avatar
 
Join Date: Mar 2014
Location: Soon to be Islamic Republic of Germany :(
Posts: 1,545
Thanks: 198
Thanked 326 Times in 265 Posts
That might come in handy one day.

My computer is fighting Aids and Cancer in it's idle time, and yours?
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
Schroeder is online now  
post #3 of 3 Old 04-18-2017, 03:01 PM Thread Starter
Senior Member
 
Join Date: Jan 2012
Location: Piedmont, NC
Posts: 1,763
Thanks: 138
Thanked 475 Times in 369 Posts
Bonus information: No more 5.5k RPM rattle! Must have been the slop in the tensioner construction or timing chain all along.

Tis better to be thought a fool and remain silent, than to open one's mouth and remove all doubt.
cbrlocal is offline  
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Honda CBR250R Forum : Honda CBR 250 Forums forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in









Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page



Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome