Yamaha R6 shock into CBR250(how I did it) - Honda CBR250R Forum : Honda CBR 250 Forums
User Tag List

 7Likes
Reply
 
LinkBack Thread Tools
post #1 of 107 Old 05-24-2013, 11:28 PM Thread Starter
Senior Member
 
powertoweight's Avatar
 
Join Date: Mar 2013
Location: Courtenay(Vancouver Island),British Columbia,Canada
Posts: 132
Thanks: 30
Thanked 47 Times in 25 Posts
Yamaha R6 shock into CBR250(how I did it)

Like a few us here,as an experienced rider,I bought the CBR (in March 2013)as lightweight fun "sportbike",not as a learner or commuter.

After a very short while I realized that I was not really happy with the fork or the shock.The fork was just way too soft for me(I'm only 140#) and under damped.Easily fixed with Racetech springs and ems.
The rear shock gave me a very jarring shot up my back and shook my kidneys when I hit certain bumps above 80kph.I really wanted some adjustment on the shock.

Then on May 1 is succeded in giving my self a compression fracture of my T8 vertabra while mountain biking.Basically I crushed the front of a vertabra between my shoulders to about 50% of its original height.I'm lucky,and VERY happy to be walking Needless to say it has made my back a bit sensitive,so something had to be done for sure now.

After much internet searching and research I discovered a cheap alternative to a Penske,Ohlins or Racetech could be a 2008-2012 Yamaha R6 shock.The R6 shock has adjustment for high and low speed compression damping,rebound damping and of course preload.

The R6 shock is about 6mm. shorter and has about 7mm. more travel but it has the correct top and bottom mount(well sort of).





Last edited by powertoweight; 05-25-2013 at 01:16 AM.
powertoweight is offline  
The Following 4 Users Say Thank You to powertoweight For This Useful Post:
Cat (12-21-2013), Cbr-Lu (09-13-2013), Lulu7404TX (09-07-2013), sjdc1982 (12-15-2013)
Sponsored Links
Advertisement
 
post #2 of 107 Old 05-24-2013, 11:36 PM Thread Starter
Senior Member
 
powertoweight's Avatar
 
Join Date: Mar 2013
Location: Courtenay(Vancouver Island),British Columbia,Canada
Posts: 132
Thanks: 30
Thanked 47 Times in 25 Posts
The upper pin mounts were of different diameters(10 and 12mm.)but I just swapped the CBR one onto the R6 shock.



The lower mounts had different size holes.The CBR 8mm. and the R6 10mm.The bolt that goes though this hole also goes through a hardened sleeve that is also an inner bearing race for part of the suspension linkage.So the sleeve cannot be drilled out to accept a 10mm. bolt.So I sleeved the R6 shock holes down to 8mm.
powertoweight is offline  
post #3 of 107 Old 05-25-2013, 12:24 AM Thread Starter
Senior Member
 
powertoweight's Avatar
 
Join Date: Mar 2013
Location: Courtenay(Vancouver Island),British Columbia,Canada
Posts: 132
Thanks: 30
Thanked 47 Times in 25 Posts
As you can see in the above pics the R6 spring is loose.I had a local bike shop remove the spring so that once I had the shock mounted I could move the suspension and wheel through its full travel to check for clearance and or interference.Do NOT attempt to remove any compressed spring without the correct tools.I paid $30 to have the spring removed one day and reinstalled on another..Seemed a bit dear to me but was happy to pay it.

My bike is equiped with ABS and that made the job a whole lot more challenging.The ABS modulator is hiding in that big plastic cover located between the the shock and the hugger fender.

Now the SCARY part.
I CANNOT recommend this because it involves grinding away some of the frame crossmember that the top of the shock attaches to.
Here is a pic of the untouched (other than the paintpen marks) crossmember.I unbolted the mounts for the ABS module and gently moved it back a bit.I left the brake lines attached for the whole retofit but really it would have made it much easier if I had just completely removed it for the grinding/fitting stage.I used a compact 90* air powered angle grinder with a tapered burr to do the grinding but it was very tight.



Here are some shots after it was ground away enough to clear the top of the shock and the piggyback resevoir.I later finished it off a little smoother and painted it to match the frame.







Once I got it so that the top of the shock just cleared the frame I installed a 3mm. shim(read,washer) between the top of the shock and the crossmember to gain back 3mm of the 6mm. difference in shock lengths ,this also gave me another 3mm. of frame clearance.

Now the ABS module hit the shock's rear side.I Removed the shock again(it was in and out dozens of times) and bolted the ABS module back up to it's original mounts and gently levered the whole assembly rearward probably 20mm. until it's plastic cover just touched the hugger when the rear wheel was almost at full upward(compressed) travel. Now I reinstalled the shock again,the shock just lightly rubs on the ABS plastic cover and the plastic cover just touches the hugger.I figured what's the worst that can happen?A squeek?
I got the spring reinstalled onto the shock and installed the shock for the last time.And reassembled the rest of the bike,which was thoroughly dismantled.


Last edited by powertoweight; 05-25-2013 at 01:21 AM.
powertoweight is offline  
The Following 4 Users Say Thank You to powertoweight For This Useful Post:
Cbr-Lu (09-13-2013), djvirus (02-11-2014), ML1022 (09-23-2014), sjdc1982 (02-09-2014)
 
post #4 of 107 Old 05-25-2013, 12:25 AM
Super Moderator
 
Join Date: Apr 2012
Location: Calgary, Canada
Posts: 2,030
Thanks: 2,190
Thanked 814 Times in 497 Posts
Awesome!! Keep it coming.

Everyone has the right to be offended but just because you're offended doesn't mean you're right!
Jme250RA is offline  
post #5 of 107 Old 05-25-2013, 12:34 AM Thread Starter
Senior Member
 
powertoweight's Avatar
 
Join Date: Mar 2013
Location: Courtenay(Vancouver Island),British Columbia,Canada
Posts: 132
Thanks: 30
Thanked 47 Times in 25 Posts
The great guys at Racetech told me that for my weight the ideal spring rate for the rear would be 9.4kg/mm.
The R6 stock spring is 9.8kg/mm. pretty dang close.That is only one spring rate off or in imperial terms about 22lbs/in difference.
The ride height is virtually the same and the sag without me on it is very close with the preload set to full soft.
I just completed this a few days ago and have not had an assistant to measure rear rider sag yet but will post it.
I set the damping adjustments to where Yamaha recommends as the "standard" setting to start with. and took it for a test ride.
powertoweight is offline  
post #6 of 107 Old 05-25-2013, 12:40 AM
Super Moderator
 
Join Date: Apr 2012
Location: Calgary, Canada
Posts: 2,030
Thanks: 2,190
Thanked 814 Times in 497 Posts
so that spring rate should be good for someone up to about 200 lbs? I'm 180 lbs so that shock shouldn't be too far off for me.

Everyone has the right to be offended but just because you're offended doesn't mean you're right!
Jme250RA is offline  
post #7 of 107 Old 05-25-2013, 12:54 AM Thread Starter
Senior Member
 
powertoweight's Avatar
 
Join Date: Mar 2013
Location: Courtenay(Vancouver Island),British Columbia,Canada
Posts: 132
Thanks: 30
Thanked 47 Times in 25 Posts
AWESOME is right JME!!!
As I stated earlier:I CANNOT RECOMMEND THIS MOD because of the mod required to the frame crossmember and I am SURE that I will get flamed from some of the nannies on this site BUT........

I REALLY LIKE IT!!!!

The ride AND handling improvement from the Racetech parts up front(I have 20w fork oil to replace the 15w(needs a little more rebound damping)) and the "upgraded" rear shock is FANTASTIC!
After a spirited ride on the winding country roads around here I realized that my back never once complained(remember I just broke it) and I found myself riding over bumps and broken pavement just for fun to see what it would soak up.

Front springs and emulators and oil ~$300
Used 2008-2012 Yamaha R6 rear shock $60
Shipping shock to Canada $50
Spring removal and reinstall $30
Labor........at least 10 hours,yes I took my time but I am an experienced auto mechanic.

It is also my hobby,so WELL worth it.
If anyone finds an easier fitting, equally good and equally inexpensive alternative please post it here.
To my knowledge this is the first documented "retrofit" of another OEM shock to a CBR250 yet.

REMEMBER: I cannot recommend altering the frame of any motorcycle

HAPPY RIDING

Last edited by powertoweight; 05-25-2013 at 01:25 AM.
powertoweight is offline  
The Following 4 Users Say Thank You to powertoweight For This Useful Post:
KTM144 (05-25-2013), R Runner (08-13-2013), SDM (05-25-2013), shisoshin (09-10-2013)
post #8 of 107 Old 05-25-2013, 02:14 AM
Super Moderator
 
Join Date: Apr 2012
Location: Calgary, Canada
Posts: 2,030
Thanks: 2,190
Thanked 814 Times in 497 Posts
That is the closest shock that I have seen that matches the stock. Great write up.

Everyone has the right to be offended but just because you're offended doesn't mean you're right!
Jme250RA is offline  
post #9 of 107 Old 05-25-2013, 05:41 PM
SDM
Senior Member
 
SDM's Avatar
 
Join Date: Jun 2012
Location: Fairview Quezon City Philippines
Posts: 601
Thanks: 402
Thanked 185 Times in 117 Posts
Looks like you did your homework before you ever did anything to the bike nice job, its your frame do as you want with it thanks for the write up nicely done. Might look into this myself as I hate how stiff the ass is on this bike

June 2013 BOM winner
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

Custom Painted
Steel braided brake lines
CORBIN front and pillion seat
HID Projector, W/ orange demon & red, white angel
305cc Big bore kit, PCV + Auto tuner, Ohlins rear shock, Emulators, .95 springs, Sintered HH pads. S.S. header, 2 Bros slip on, integrated brake turn signals, -1/+2, flush mount turn signals, tail tidy, T-Rex sliders, and rear spools
SDM is offline  
post #10 of 107 Old 05-25-2013, 09:40 PM Thread Starter
Senior Member
 
powertoweight's Avatar
 
Join Date: Mar 2013
Location: Courtenay(Vancouver Island),British Columbia,Canada
Posts: 132
Thanks: 30
Thanked 47 Times in 25 Posts
Measured rider sag today.
Me(140lbs)on it with preload set to full soft and 3/4 tank of fuel the rear sag is 32mm.Many would say that is optimal.I may go 1-2 notches up on preload(R6 has 9 notchess) just to try it.
powertoweight 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













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