[KeepTheFeather]

My bike has been showing a very annoying issue, Im gonna explain the issue first before my maintenance part to be more complete.

So Issue presented was:
Without messing with the clutch or gear shifting, at the initial moment when opening the throttle to accelerate the bike ''Thumps''. This happens every time especially at lower speeds, instead of a smooth transmission of power it gives this aggressive ''power push''. This only happens the moment I open the throttle and not during the ''rest'' of the throttle opening action. This is a mechanical physical ''thump'' of the whole bike starting from the rear wheel, and not a noise or engine noise ''thump''.

Reason why I think it is the damper set/cush drivers:
At first I thought the issue was too much chain slack , this would create a build up of force before the chain stretched enough to actually transmit power . I tightened the chain and the issue subsided. However I recently learned the chain was actually over tightened as I didn't account for my weight on the bike. After tweaking it to the right place the issue was again more noticeable. I believe the issue relies on the explained core concept however perhaps I was looking at the wrong transmission point for the rear wheel. Because between the rear wheel and chain/sprocket there are cush drivers aka a rubber damper set that cushions the transmission of the chain to the wheel. If the cushions are worn/smooched I expect the same build up of force previously explained to happen.

Ok now for my questions:
First did anyone have a similar issue to what I described and was it fixed by a damper set replacement?

Does anyone know how long a damper set lasts? My bike showed this issue after about 1.5 years of riding and around 15K km.

Does anyone know of good aftermarket damper sets or if they are reliable? Honda ones are ridiculously expensive at 52 euros. I found these guys at wemoto for way cheaper by Schuring and my friend has had to replace them because of the same problem on his bike and for at least a year they have shown no issues. Honda CBR 250 R 11 Cush Drive Rubber Set By Schuring Parts at Wemoto - The UK's No.1 On-Line Motorcycle Parts Retailer

Now for the maintenance, any tips you guys have for someone who never removed the rear wheel? Do I have to realign the axle when putting the wheel back on? Should I use a torque wrench for the 88nm axle nut?

Thanks guys!

 

[Tamir]

Hi. A lot of good Q
Here is my A

...did anyone have a similar issue

A: Not me

Does anyone know how long a damper set lasts?

A: I get to 67,000Km model 2013 NOT have a similar issue

Does anyone know of good aftermarket damper sets

A: WEMOTO are great I also have good experience with AliExpress(Free shipping).
The prices are quite similar, don't thay?

my friend has had to replace them because of the same problem on his bike and for at least a year they have shown no issues.

A: So I think you've got the answer you're looking for.

any tips you guys have for someone who never removed the rear wheel?

A: My tip. You must have a central stent to leave the rear wheel in the air. In this situation the whole motorcycle is not really stable. Mechanics tie the motorcycle to an elevator. If you do everything on the floor without ties it to anchors, then you really have to be careful with the use of force, so that the motorcycle does not overturn, and then it can cause damage to property and life!

Do I have to realign the axle when putting the wheel back on?

A: Yes, because for lowering the rear wheel you open the adjusting screws. Shoot the number of lines in the tuning bar and it will save you later a part of the adjusting time.

Should I use a torque wrench for the 88nm axle nut?

A: It's depends, if you do not have the feeling that veteran mechanics have you must have a torque wrench.

 

[KeepTheFeather]

Hi. A lot of good Q
Here is my A

A: Not me

A: I get to 67,000Km model 2013 NOT have a similar issue

A: WEMOTO are great I also have good experience with AliExpress(Free shipping).
The prices are quite similar, don't thay?
View attachment 45394

A: So I think you've got the answer you're looking for.

A: My tip. You must have a central stent to leave the rear wheel in the air. In this situation the whole motorcycle is not really stable. Mechanics tie the motorcycle to an elevator. If you do everything on the floor without ties it to anchors, then you really have to be careful with the use of force, so that the motorcycle does not overturn, and then it can cause damage to property and life!

A: Yes, because for lowering the rear wheel you open the adjusting screws. Shoot the number of lines in the tuning bar and it will save you later a part of the adjusting time.

A: It's depends, if you do not have the feeling that veteran mechanics have you must have a torque wrench.

Thanks for the reply!
Fo you usually ride aggressively? I like to accelerate quite aggressevely, so maybe that was the reason. Either way I do want to inspect the damper set b4 hand to see if it us indeed the cause.

Ive heard a lot of good things about wemoto! Problem with ali is things take ages to arrive X_X but good to know they also have them.

Would a rear paddock stand work or should it be with a center one? A universal L shaped one? Also should I have the front wheel on a stand as well or is it unnecessary?

 

[Tamir]

Fo you usually ride aggressively?

A: No

I like to accelerate quite aggressevely, so maybe that was the reason.

A: YES

Ive heard a lot of good things about wemoto!

A: YES They are really as good as you have heard. Unlike AliExpress, they have technical people who know how to guide you in purchasing and know how to advise you technically. The service is excellent.

Would a rear paddock stand work

A: YES

A universal L shaped one?

A: Yes, BUT it hits the OEM exhaust and therefore needs some adjustment. And there are more solutions, see here:

DIY centerstand

I've uploaded the original images using an upscaler.

www.cbr250.net

Also should I have the front wheel on a stand as well or is it unnecessary?

A: NO

 

[DannoXYZ]

Definitely use torque-wrench on axle-nut! Without calibration tools, humans tend to over-tighten small fasteners and under-tighten large ones. Not safe having loose axle-nut!

Another thing you may test is measure free-play in cush-drive. Once you get wheel off, rotate sprocket by hand back and forth and see how much slack there is between rubber cushions. One common trick is to shim this gap so there's no play.

What you are describing is actually very common on EFI bikes. The ECU has separate "idle mode" setting and transition to "partial-throttle" settings may cause an abrupt jerk.

Most ECUs will turn off injectors when you release throttle at high-RPMs, then re-start them as engine drops near idle-speed. But this causes too sudden of change when you're at high-RPMs. I usually just disable idle-mode by re-programming ECU, or disconnecting idle-switch in TPS. This prevents sudden jerking when you open throttle at low-speeds or let off throttle from high engine-speeds

 

[KeepTheFeather]

Yeah Im getting this guy once its in stock so ill just wait till then!

Sealey Torque Wrench Micrometer Style 3/8 | Recambios | Wemoto.es

En Wemoto.es tenemos Sealey Torque Wrench Micrometer Style 3/8 para tu moto. Entra en la tienda online y encuéntralo.

www.wemoto.es

And yeah definitely checking the slack and condition. I have heard of people putting stuff like rubber bits from old tyres in there to deal with the play lol. Im guessing thats what you meant with shimming the cush drivers?


hmm thats actually really interesting, at first I definitely thought perphaps it was the engine, that maybe an issue with the fuel injector or like you said the ecu commands. But assuming its the ECU it would be a permanent feeling, so I dont think its the case, seeing as its a new and worsened issue for the bike. I clearly remember acceleration not having this thump. Being able to one hand accelerate without fearing for a tyre skid.
But I will keep that in mind. Are there cons to disconnecting idle mode? Did you buy a power commander to fiddle with the ECU settings?

 

[jkv357]

A common issue with older Ninja 250s as well.

We shimmed the cush drives in all our Ninjas, and it helped a lot. Even the 1990 model didn't need new parts, just shimming.

This page shows the basics of the process. We used ABS plastic sheet, cut to the size of the rubber pad -

https://faq.ninja250.org/wiki/How_to_shim_the_cush_drive

As you mentioned, you don't want the chain too tight.

This page has some good tips (and a video) on chain adjustment and alignment -

How to Adjust and Align a Motorcycle Chain - CanyonChasers

Your chain needs to be adjusted properly. Of course, your owner’s manual will have exact requirements for your bike, but the rule of thumb is about 1 to 1.5 inches of slack. But what does that mean and why is that important? Slack is how much the chain will move up and down freely at a point...

www.canyonchasers.net

 

[KeepTheFeather]

Interesting, im inclined to shimy them but i think considering how sorta cheap the schuring cush drivers are im just gonna get them and see.

Yeah so ill defo have to realign and retighten the chain after getting the wheel back in uh. Its one of the things I hate to do the most lol

 

[Tamir]

Most ECUs will turn off injectors when you release throttle at high-RPMs, then re-start them as engine drops near idle-speed. But this causes too sudden of change when you're at high-RPMs. I usually just disable idle-mode by re-programming ECU, or disconnecting idle-switch in TPS. This prevents sudden jerking when you open throttle at low-speeds or let off throttle from high engine-speeds

Yes, I've heard of it, I do not get into these situations, but it seems to me that KeepTheFeather does.
"The rigid transition in the injection system between open and closed mode (accompanied by a blow to the chain), even under a very gentle hand" [Kobe Liani - Originally written in Hebrew]

 

[jkv357]

You can check the play before installing the wheel back on the cycle by just rotating the hub when seated in the wheel.

Ideally, you want it just loose enough to be able to get it back together with a little effort. If you can rotate it back and forth, I would add shims until there is almost no movement at all.

That's the way we have done it, and it made a noticeable improvement in on-off throttle smoothness.

 

[KeepTheFeather]

Thanks for the tip! Im gonna do new cush drivers for now, but after these if necessary I will be shimming.

As for the ECU, thump happens on every RPM, being in fact more aggressive at lower rpms and gears. I can be in 3rd gear at 4K rpm and just opening the throttle creates this thump.

 

[jkv357]

Thanks for the tip! Im gonna do new cush drivers for now, but after these if necessary I will be shimming.

As for the ECU, thump happens on every RPM, being in fact more aggressive at lower rpms and gears. I can be in 3rd gear at 4K rpm and just opening the throttle creates this thump.

Do them, but confirm they are an improvement before putting it all back together.

They may not be any different, in which case you would want to shim to solve the issue.

 

[Tamir]

Do them, but confirm they are an improvement before putting it all back together.

They may not be any different, in which case you would want to shim to solve the issue.

For that to happen(free play with new rubbers) the metal has to wear, which is not what happens.
What happens is that the rubber wears and also loses its shape and loses its elasticity.
It is possible that the test you are proposing when the axle nut is not tightened will not go up well, and will result in an incorrect shims adjustment.
And why do you need these rubbers if you eliminate most of their elasticity when you leave old rubbers and dry rubbers and shims it with an inflexible ABS plastic?
After all, the shims does not return the original flexibility to the old rubbers.

So it seems to me that our friend (as recommended by his friends) chose the right solution, and also an inexpensive one.

P.S. I'm just mentioning the obvious:
Maybe the chain is too loose?
Maybe the chain is worn or the gears are worn, or that both?

 

[jkv357]

For that to happen(free play with new rubbers) the metal has to wear, which is not what happens.
What happens is that the rubber wears and also loses its shape and loses its elasticity.
It is possible that the test you are proposing when the axle nut is not tightened will not go up well, and will result in an incorrect shims adjustment.
And why do you need these rubbers if you eliminate most of their elasticity when you leave old rubbers and dry rubbers and shims it with an inflexible ABS plastic?
After all, the shims does not return the original flexibility to the old rubbers.

So it seems to me that our friend (as recommended by his friends) chose the right solution, and also an inexpensive one.

P.S. I'm just mentioning the obvious:
Maybe the chain is too loose?
Maybe the chain is worn or the gears are worn, or that both?

Not necessarily.

The rubber can shrink and dry from age, or just not be made large enough.

Ninjas had that problem from Day 1. The size of the rubber wasn't correct to fill the opening, and it created too much play.

 

[Tamir]

Not necessarily.

The rubber can shrink and dry from age, or just not be made large enough.

Ninjas had that problem from Day 1. The size of the rubber wasn't correct to fill the opening, and it created too much play.

Okay. Thanks
So your clarification is important.
Here is not about the Ninja (I do not know the Ninja).
Therefore my comment still remains relevant. Our friend did the right thing when he ordered himself a new set of rubbers.
And new rubbers do not need to be shims.

 

[DannoXYZ]

so I dont think its the case, seeing as its a new and worsened issue for the bike. I clearly remember acceleration not having this thump. Being able to one hand accelerate without fearing for a tyre skid.
But I will keep that in mind. Are there cons to disconnecting idle mode? Did you buy a power commander to fiddle with the ECU settings?

Yeah, it could be all-mechanical issue caused by cush rubbers. Let's see how it behaves after you replace rubbers.

Only issue with disabling idle-mode is cold-starts. ECU won't engage cold-start mode with fuel-enrichment and high-idle speed using IACV if it doesn't detect that TPS is closed. Not a problem if you live in warm climates.

BTW - I do this on all my EFI track/race bikes. The slight jerk when letting off throttle at high-RPMs can disrupt smooth cornering at limit.

 

[jkv357]

Okay. Thanks
So your clarification is important.
Here is not about the Ninja (I do not know the Ninja).
Therefore my comment still remains relevant. Our friend did the right thing when he ordered himself a new set of rubbers.
And new rubbers do not need to be shims.

Similar system.

If they don't fit snugly, they do.

You like to argue about s***...

 

[Tamir]

Similar system.

If they don't fit snugly, they do.

You like to argue about s***...

This rubber pads patent is an expired patent from decades ago. You will find it on every rear wheel of every motorcycle (Or something on a similar principle).
My Honda Innova125i also has such rubbers.
You claim that in a Ninja (which I do not know), this is how you claim, you claim that a Ninja has a production failure in the factory at that rubbers sys and there are free play even when the whole system is new.
In our Honda CBR250R there is no such problem of malfunction coming from the factory.
You admit that your claim(problem) is only in the Ninja, and you now admit that unnecessary shims use damage the rubber flexibility, and you admit that old rubber is less flexible than new rubber.
So you might be arguing with yourself? with me you have no argument about s***...

 

[jkv357]

Whatever...

Just trying to give a possible solution to a common problem I've solved before.

 

[Tamir]

Whatever...

Just trying to give a possible solution to a common problem I've solved before.

It's always good to learn something new, and that's part of the fun here, you share, I share, I learn, others learn, and I say thank you. I just added that at the moment shims became irrelevant, because the guy ordered new rubbers, when he could have compromised on shims, but he had already ordered, so it turned out that this time he chose the better quality solution. I personally like that there is always a cheap and simple solution in my pocket, even if it is not the perfect solution. So thank you again