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Discussion Starter · #1 ·
Greetings all....

Just getting back into riding after 15 years and test rode a BRAND NEW (1km) CBR250 2012 yesterday. It has been so long that I was pretty shaky for most of my ride. So you can get an idea of my experience at this point.

I do know my throttle control, though and I was very smooth with it. However, the whole drive train would 'clunk' at the slightest movement if i reduced the power (if I was under power) or if I changed from even light deceleration to adding even the lightest touch of power. Is this pretty normal for this bike?

I did check the chain before I started riding. It had about 1.25" of play give or take a bit. Are my expectations of smooth transitions unrealistic or is there something out of adjustment here?
 

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Yeah, I get the same 'slop' feeling with mine. I got the chain tightened up and it did improve but very slightly.
I can't say if this is normal 'cos I don't know anyone else with the 250 around here. So am anxious to hear of other replies to this post :)
 

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No slop in mine. Sure you were right gear for the rpm,s you were in? Or the right speed for what rpm's you were in?
 

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There is more drive train lash in the CBR250R than my other bikes. I noticed it when it was new and other people who have taken a spin on it have noticed it too. My cush drive in the rear hub has about 1/2 an inch, 1.2cm, rotational play measured at the outer spoke/ rim junction. I asked my service manager about it so he could look up the permissible spec. I will call him back to get the answer tomorrow. He is thinking off hand that 1/2 inch rotational and zero axial wobble will be considered normal and would not qualify for a warranty repair. He just replaced the cush drive in a 1000RR that had an inch of rotational play and had to call Honda to get special permission as this could be considered a rubber wear item. We can take an easy survey by anyone that reads this. When the cush drive is really bad you will start to notice some wobble in the rear sprocket when you grab the rear of it and yank side to side.
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Rock your bike back and forth in gear with the engine off (all your bikes) and have a friend look at the rear wheel. How much does it move before the rear sprocket moves to take up the normal chain slack?
 

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Discussion Starter · #5 ·
No slop in mine. Sure you were right gear for the rpm,s you were in? Or the right speed for what rpm's you were in?
It was not a matter of engine compression slowing you down when you release the throttle...I noticed that, too! That was a surprising thing to me about how much deceleration is offered when you close the throttle, if felt like I hardly needed to use the brakes on the highway: just close the throttle, and the engine is going to slow you down big time!

But this is not what I'm referring to. I am talking about actual drive train slop. I'm already in a gear, driving along at a particular speed and SLIGHTLY reduce the throttle - before the engine compression comes into play things sort of jerk into place as if there is either tremendous slop in the chain, or the gears are not meshing nice and tight. If I then roll on the throttle again ever so slightly, almost imperceptibly, again, it jerks/clunks again. Though using the word "clunk) may be a bit strong.

Curious how many are noticing this, and how many are not getting that issue.
 

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Discussion Starter · #6 ·
There is more drive train lash in the CBR250R than my other bikes...

...My cush drive in the rear hub has about 1/2 an inch, 1.2cm, rotational play measured at the outer spoke/ rim junction. I asked my service manager about it so he could look up the permissible spec. I will call him back to get the answer tomorrow.

.Rock your bike back and forth in gear with the engine off (all your bikes) and have a friend look at the rear wheel. How much does it move before the rear sprocket moves to take up the normal chain slack?
Ah, yes, Sendler, the correct terminology "drive train lash". That exactly what I'd call it. As for "cush drive" I'd never heard the term before, but from what you describe I had the exact same issue as a kid with an XR80. Lots of rotational play between the rear sprocket and the hub. I was wondering if it was the same issue here, but being out of bikes for so long I really wasn't sure.

As you say, hopefully others will chime in. As it is right now, however, I really did not care for that much jerking around.

Thank you for your input.
 

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The cush drive is made up of several pieces of rubber which couple the rear sprocket section to the rear hub. I rode my (new to me) Ninja650 to work today to show a friend and it has zero play in the rear drive sprocket. I will have to harp on my service manager and get him to replace the rubber just to see if it can be improved. It is a cheap job to try.
 

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Discussion Starter · #8 ·
The cush drive is made up of several pieces of rubber which couple the rear sprocket section to the rear hub. I rode my (new to me) Ninja650 to work today to show a friend and it has zero play in the rear drive sprocket. I will have to harp on my service manager and get him to replace the rubber just to see if it can be improved. It is a cheap job to try.
Being a brand new bike, the one I test rode should have been better than that. It literally had 1 km on the odometer! That made me pretty nervous, too, not wanting to scratch a brand new bike.

Is there a mod or a fix to that, if most are like that. I don't suspect having the dealer try and swap it with another cush drive will improve it, if this was a manufacturing issue.
 

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Sounds like it is behaving like a dirt/dual-sport bike, which, because of the greater amount of swingarm movement, has the chain set up a bit looser, so it won't be too tight under full swingarm extension or compression of the rear shock.
 

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Multiple cushes need replacement on a virtually new bike? This sounds like a QC or design problem.

I decided to replace 3 of 6 cushes at 24K miles on the NX250 because I was tired of mating the broken ones every 3K or so when I pulled the rear wheel for a new tire, but the fitment was still acceptable on the original cushes.
 

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Mine clearly got worse today and Ive only got 600k on the odo! There's got to be something wrong! I've done 14000km on a ybr125 and never felt such slack in the drive. (and never really bothered to adjust the chain either!)
The other thing thats really getting to me is the literal 'clunk' when shifting up into 2nd. It sounds embarrasing!
Whats the best way to test the cush drive ?
 

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Thanks sendler
I checked my cush and its clearly in order. So decided to remove the slack in the throttle for nothing better to do and miracle of miracles - the slop was no more !
I guess I may have mis-diagnosed the slop.
Thanks for all the suggestions people. This is what makes this forum so great.
 

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There is quite a bit more than average slop in the transmission on this bike too but the play in the cush drive seems like something that could be easily improved with new parts. I checked two bikes at the dealer and they had almost no play in the cush drive yet. My bike has quite a bit. Eventually there may be an after market upgrade for the rubber drive pieces. The service manager doesn't seem to be too interested in attempting a repair but I may press him to try it with the factory parts to see if it is any better.
 

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Mine has that same slop. Replacing the rubber bits in the cush sounds about right. Aftermarket will step up if Honda doesn't, but I'm doubtful just replacing them with another OEM set will change much.

Could be that the material is too soft, or fitment is sloppy. Anyone have some mid-high durometer (90 or 92 maybe?) polyurethane laying around to try out?
 
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