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919,CB900 Hornet Aftermarket Front Sprocket Clunk

6K views 43 replies 10 participants last post by  Pvster 
#1 ·
Hello

I recently obtained a 2002 Hornet 919. I replaced the chain and sprockets with brand new RK GXW chain and sprockets as the OEM ones were well worn. When I put the new front sprocket I noticed a significant amount of rotational play. I figured that must be normal.
Now my issue is that when accelerating (usually when releasing the clutch) I often get this clunk that seems like sprocket play. The chain is tensioned and adjusted correctly and still freshly lubed from the box. I've only ridden about 150kms total.

Before I go buying new front sprockets, has anyone had any issues with different aftermarket sprockets? Does the OEM sprocket do this too?
Is the gearbox just clunky and I should just live with it?

Cheers
Vinny.
 
#2 ·
Did the spines on the counter shaft look square? If you think it has more play than the old one you took off, take it apart and double check the fit of each one. I used an OE sprocket and noticed a loose fit but nothing that made me think it would skip.

Are you sure the clunk isn't from the cush drive?
 
#5 ·
The bike only has 20k kms and I don't recall seeing any significant wear on the splines. I'll be sure to check it again. I'll put the old sprocket back on and go for a quick test ride to see if it clunks. if it doesn't I guess that solves my issue- will just buy a new OEM sprocket.
TBH no I'm not sure it isn't the cush drive at all. How could I check this?

I had "sprocket clunk" when I had an issue with front / rear sprocket alignment with a 520 chain set-up - something you could check?
I'm running 530 at the moment. I just aligned the wheel using the marks on the adjusters but have read somewhere that they can be inaccurate. I'll take the chain cover off and visually check the chain alignment.
 
#4 ·
Just wondering, what was the issue that you had with the 520 setup? I've got a 520 setup, I've heard some get the sprockets on backwards. It was discussed here and I wrote down on the packages how to install them. I remember someone getting it wrong and having some pretty serious problems.
 
#7 ·
OK, so the bike is new to you, so you don't have history to go by.
Perhaps the clunk is not directly related to the new sprockets and chain, but maybe it is, or in concert with something else.

Therefore suggested is:
Check the end float of the front sprocket, noting there is supposed to be some.
Check the amount of play between the front sprocket and the shaft, noting that being a slip fit, means there has to be at least a hair of play.
Check the orientation of the front sprocket re on correctly or reversed.
Check the orientation of the rear sprocket re on correctly or reversed.
After aligning the rear wheel and adjusting the chain, visually eye the chain run for any obvious runout.
One could also use the Rob Tharlson Method of Rear Wheel Alignment re the sound check of the chain.
Check the cush drive.

Go from there.
 
#8 ·
I've not heard the term "end float" before. Does this mean the play along the length of the splines as opposed to across the splines?
I fitted both sprockets with the text imprints facing outwards.

I'll put the bike up on the stand this weekend and see what I can find. Thanks for all the advice guys. This gives me a good starting point. I'll check back soon.

Cheers
Vinny.
 
#10 · (Edited)
update
Finally had time today to get my hands on the hornet.
I replaced the cush drive rubbers with new ones and I thought my problem was fixed given how much play there was in the old ones.
I checked the old OEM front sprocket rotational play and it was indistinguishable from the new one so I left the new one on there.

After reassembling everything my problem remains. *hairpull*

I found this forum post and it seems to be the same issue as mine.

Https://crfsonly.com/forum/viewtopic.php?t=41425

Ive uploaded a video to google drive here:

https://drive.google.com/file/d/1-L1EVEUoVBhMMr7jgZ3jV7JRZje6L8Yd/view?usp=drivesdk
I know the chain looks loose in the video but I tightened it to spec aftwrwards and the issue is still present.

It happens when releasing the clutch while still having forward acceleration. It's really annoying when I'm trying to navigate traffic slowly, using lots of clutch.

I'm totally stumped. Is it time I take it to a grease merchant or does anyone have any other ideas?

Cheers once again

Vinny.
 
#11 ·
Clearly the top of the chain is losing tension when it pops.

Can you remove the front chain cover and place the camera right at the front sprocket and then move your leg out of the way?

Make sure the sprocket is in clear view and maybe add some light. I'd like to see where the sprocket and shaft connect when it pops. If you can go very high res with good lighting we can slow it down.

You said something about rotational play, can you also show that on the video. Is the rotational play between the sprocket and the shaft or just the shaft by itself?
 
#12 ·
I'll see what I can do about getting a closer view of the front sprocket.

The top of the chain is losing tension when the clunk happens because I'm pulling the clutch back in.

What I'm doing with the clutch is as follows:
Clutch in, clutch out, move forward some, clutch in, clutch out-clunk.

With the sprocket off, turning the shaft in neutral was butter smooth. Turning it in first was smooth too until hitting the gear obviously.
The play is between the sprocket and the shaft but after having put the OEM sprocket back on and testing the play, I don't think thats the issue.

Cheers.
 
#15 ·
Yep. Happens in every gear.

The last example of the noise in the video, it looks to me like the noise happens as the chain is pulling tight.
You are correct- The clunk is happening right at the beginning of clutch engagement. If I'm super gentle on the clutch release, the clunk is very quiet- that isn't practical.

Is the chain slide on the swing arm broken? It's easier to see with the front sprocket cover off, the slide should wrap around the front of the arm from top to bottom. Mine is cracked right at the wrap around, but mine stays put. If you remove both the sprocket cover and the rear plastic fender the origin should be more clear when you make another video for annalysis.
I'll have a look at the chain slide.

I wonder if this other clunk I have when going over bumps is related. It's not really a clunk I can hear while riding, but I feel though the seat and pegs.
Maybe rear shock bushing? Anybody had experience with suspension clunks on this bike?

Maybe the main clunk is the shock bushing being flogged out and allowing the shock to move back and forward? It's hard to say because if I roll the bike back and forward it's fine- maybe it only does it under actual powered acceleration.

Clutch maybe?

I need a beer.
 
#14 ·
The last example of the noise in the video, it looks to me like the noise happens as the chain is pulling tight. Is the chain slide on the swing arm broken? It's easier to see with the front sprocket cover off, the slide should wrap around the front of the arm from top to bottom. Mine is cracked right at the wrap around, but mine stays put. If you remove both the sprocket cover and the rear plastic fender the origin should be more clear when you make another video for annalysis.
 
#18 · (Edited)
As requested, here is another video with the chain guard/fender and front sprocket cover removed. In the video you'll see and hear the clunk multiple times in quick succession- that's just me repeatedly reproducing it. Towards the end of the video, I show the clunk then roll forward a bit for easier viewing of the issue.

https://drive.google.com/file/d/132PQIZk2oD6tuOpcievZxF9zqCaxHhHJ/view?usp=sharing

It seems I could only get the clunk really happening once the bike was warm. Was almost unnoticeable when cold. This makes me think it's something clutch related? I changed the oil yesterday too.

Cheers once again.

Vinny.

PS. Please excuse my twiggy stick legs.
 
#19 ·
That's strange, it seems like the chain and gear are fine, but something at the shaft is slipping and catching.

How about one more video? Remove the bolt that holds on the gear and get real close to the gear.

I was going to post yesterday, but I thought this was too much of a long shot.

When I took apart my transmission I noticed a few things. I made a few videos of it. The drum holds tension on the fork and the fork pushes the gears together.

I'm thinking you either have a sprocket/shaft problem or a transmission problem where the gears aren't going into place.

[ame]https://www.youtube.com/watch?v=pX2m3xea8nc[/ame]



Here's a video of the play in the clutch. That's the clutch basket and you can see the amount of play in it.

[ame]https://www.youtube.com/watch?v=OmqSFhfIgl8[/ame]

When you shift, the gears have ears have to line up with the other gear. They wear over time and are harder to get them to mesh.

Q. once you are in a given gear, is everything 100% fine? Meaning, if you go into 2nd gear and you accelerate / decelerate several times, does it make any noise or anything?

If yes, then I'm guessing the transmission isn't meshing. It would be telling to see the shaft where the sprocket goes.

One other thing you can do. Get some black and white paint. Paint the shaft tip and sprocket black and mark a line on both in white so that we can see if they are moving in relation to each other.

You can also use some sand paper and some red or yellow paint and make a thin line or make an "X" so that when it does it's thing, we can see the movement in relation to each other.

Don't forget to have the camera as high res as you can.

I don't know the history of your bike, how long has this been going on, what's the history of the sprocket and chain? Is there any chance the sprocket and chain don't match or there's some odd damage to the chain such that it is loose at the spinners (the inner drum that contacts the teeth). Can you move the spinners, do they have excess play?
 
#20 · (Edited)
Thank you for the generous response. Your time is appreciated!



I'm thinking you either have a sprocket/shaft problem or a transmission problem where the gears aren't going into place.
uh oh.


Here's a video of the play in the clutch. That's the clutch basket and you can see the amount of play in it.
When I'm on the bike, and the clunk happens it feels like slop/slack being taken up (hence why I originally thought it was chain/sprocket/cush). Could it be the play you're referring to in the video if my clutch plates are stuck or something? Would that explain why it only happens when warm?

When you shift, the gears have ears have to line up with the other gear. They wear over time and are harder to get them to mesh.

Q. once you are in a given gear, is everything 100% fine? Meaning, if you go into 2nd gear and you accelerate / decelerate several times, does it make any noise or anything?

If yes, then I'm guessing the transmission isn't meshing. It would be telling to see the shaft where the sprocket goes.
Yes. Once I'm in gear I can ride around and shift and all is good apart from the apparently normal clunkiness of these gearboxes. But shifting happens just fine. All gears work as normal and there aren't any noises apart from this clunk. Although the same clunk happens when I try and add too much power at once while coasting. You expect that when you just slam the throttle on with the clutch out but I can't even do clutch up wheelies because it clunks so hard.

One other thing you can do. Get some black and white paint. Paint the shaft tip and sprocket black and mark a line on both in white so that we can see if they are moving in relation to each other.

You can also use some sand paper and some red or yellow paint and make a thin line or make an "X" so that when it does it's thing, we can see the movement in relation to each other.

Don't forget to have the camera as high res as you can.
I'll see what I can do tonight.

I don't know the history of your bike, how long has this been going on, what's the history of the sprocket and chain? Is there any chance the sprocket and chain don't match or there's some odd damage to the chain such that it is loose at the spinners (the inner drum that contacts the teeth). Can you move the spinners, do they have excess play?
I don't even know the history of this bike haha. It's been happening since I bought it a couple of months ago I think. I replaced the chain and sprockets straight away with all RK stuff so they are basically brand new- only a few hundred kms on them and I just re-lubed it on the weekend. I'll check the chain again tonight.

Is it worth opening the clutch cover and having a poke around? I just don't understand how the bike being warm can really impact much other than the clutch to the point of such a big clunk.

Cheers
Vinny.
 
#21 ·
This could also be the problem. The rear has rubber cushions in it to soften the engagement. They're basically rubber blocks that fit inside the rear hub.

If you remove the rear axle and pull the tire out you can check their condition. You could also place the rear on the lift, place the bike in N and try to rock the rear sprocket while holding the tire still. IDK how much torque it takes to move the rear sprocket against the rubber blocks, but you can try. They're not a tight fit, so they should rock a bit, meaning the rear sprocket should move a bit without the tire/rim moving.

Removing the rear tire is not a huge deal, just pay attention to the way things fit together and the rear brakes make it a bit of a balance act, but still doable.

Some say that those rubber blocks are so cheap, might as well just replace them. If they failed, I think they would do what your bike is doing. The chance of all of them failing is small, but worth checking.
 
#22 ·
See one of my posts above. I thought exactly the same thing so I replaced them. The new ones fit much tighter with far less play (basically none) and so before I put bike back together I was really excited because I thought I found the issue. It wasn't the cush drive. :'(
 
#24 ·
Actually, now that you talk about this, I think my bike [78,000km and climbing] has got a bit of this - shows up clutching in and out in low-speed traffic. Haven't angsted over it, nor tried to track it down - hasn't got worse and hasn't gone away. Mine's an 03.
 
#25 ·
I've pretty much given up on trying to diagnose this myself. It is obviously well beyond my mechanical ability. I've booked into a mechanic this weekend so when I know more I will post here.

Admin- are you able to change the title of this thread to "CB900, 919 Hornet clunk when releasing clutch" to make it easier for people with a similar issue to find this thread.

Cheers
Vinny.
 
#26 ·
I have to wonder if you may have an issue with the detent arm or spring that's causing the issue?

If you're comfortable, open up the clutch basket side (make sure you have a gasket) and take a look. My shifting got so bad on my 02 that I was pretty frustrated with it. Ordered a new, stiffer detent spring and arm, only to discover that my detent arm had a groove where a roller bearing made contact with the clutch star and caused my shifting woes and clunking by the bearing being pushed up the groove. I think it was maybe 1/8th of an inch long, but was enough to move up and not fully engage the star until the star caught at the right angle/tension and clunked into place. It was aggravating.

I think I have some pictures around here of my detent arm. Either on a laptop or already posted, I cannot remember.
 
#27 ·
I'm trying to picture what you're talking about, it's a part of the clutch?

While looking for it, I found this:

http://www.factorypro.com/Prod_Pages/prodh93.html

It's a $139 solution, is this the same thing you're talking about?

Did you have to fight to get it into 1st? That's something I've had to deal with. I come to a light and have to work it to get it down into 1st. Usually I work the clutch to get it to down shift and even then can't be sure I'm actually in 1st, I have to go up to check the N light then back down again to be sure I'm actually in 1st.

I wonder if the pro shifter fixes this.
 
#29 ·
me too!

I'll chip in here and tell of my 'clunk' on an 02 919 w/20k miles.
I recently did the 520 conversion and noticed the dreaded clunk shortly thereafter.
Checked to make sure I had the front sprocket shoulder oriented correctly and the larger one was towards the engine, seems OK.

I don't remember if it clunked before the conversion, and even if it was, I mostly ignored minor sounds coming from the drive chain area because it was very worn and I ran it longer than I should have.
I've got a new set of the rubber jobbies that go in the rear wheel, gonna put those in when I install a new rotor and brake pads in the near future.
That Pro Shift Kit looks interesting and the shift star, too, has anyone tried these? I always felt the shifting was a bit dodgy on the 9er.
 
#32 ·
Yes! I'm very interested in getting the trans to shift smoothly. What was interesting is that it was a REAL fight a few months ago and I changed the oil and she started shifting much nicer. I was blaming oil, then I changed the oil about 2 weeks ago and it didn't seem to change the shifting much.

I don't mind spending $140 for a fix, as long as it works. I guess there's two parts to the fix, so $280 might be the full price, but I don't know if one or the other or both are needed.
 
#34 ·
Whelp. This is rather embarrassing...
Skip to bottom for tl;dr.

Took the bike to the mechanic today. He's a well known guru and tamer of Hayabusas. I'f there was one guy in the world I'd trust for bike advice it's this guy.

He took the bike for a ride, couldn't reproduce my clunk. Came back, I showed him how I did it, and he went again. Still couldn't find it.

We put the bike up on the jack and he had a poke around. Adjusted the chain ever so slightly and said everything was perfect with the gearbox. He said that other clunk coming though the seat was the shock and to replace that- cool beans.
One last try at getting him to reproduce the clunk. I asked him to try and make it do it from a stand still like I did in my videos above. He couldn't. His technique was just different. After he changed his technique to be shitty like mine he got the clunk. So there you have it. He took the bike for one last ride. When he came back he confirmed that the gearbox was perfect, no bent shift fork, and clutch was good.

Apparently I was just letting the clutch out too fast or something and causing gear lash to be taken up too quickly.
My technique is learned from riding only smaller single cyl bikes which are a lot more forgiving. On my ride home I really concentrated on being gentle and smooth with the clutch. And that made a huge difference to the feel. It will take time for me to properly change my habits but it is so bloody lovely to know I didn't buy a lemon.

Thanks everyone for your input. I feel like the biggest numpty right now but I'm glad my bike is just fine.




Tl;dr
My bike is fine - my clutch technique is not. I'm a bit special.

Cheers
Vinny.
 
#36 ·
So you were being too quick on the clutch and the solution was to be slower on the release?

I'm going to try that and see if it changes anything with mine. I'm very quick on the clutch when running thru the gears, but I wonder if slower will help it get into 1st from 2nd as the down shifts at a stop light are a pain sometimes. Maybe not related, but you never know.
 
#39 ·
I down shift through the gears into 2nd coming to a stop then pull in the clutch and toe neutral then first just before stopping, it's a lot smoother than trying to cram straight cut gears into first, After commuting on the 9er for almost 10 years I've come to the conclusion that the 9er's transmission was NEVER designed for commuting
 
#37 · (Edited)
KarlJay, what is your idle set at? Mine came set at 1100. I brought it up to 1300 in very small increments. For me, 1100 was the smoothest and made it easier to shift 2-1 in the garage, idling, not moving. So I went back to 1100. Feels like a gear alignment issue. Not an "issue", but a consequence of different ratios trying to mesh at speed.. First and second don’t line up in too often without a little rotational alignment help. Try this on a centerstand to get a feel for the spacing.
Engine off. First gear, shift up lightly, if it stops in neutral and won’t go into second, rotate the rear tire with a touch of preload on the shifter. It will drop in after a 1\16 tire rotation. Now try to go to first you may or may not be able to without rotating the tire again. There are times when you get a beautiful click, click 2-1, but this window is small in comparison to the one that will get you into neutral, from either direction. I did this for a while to get the feel for the gearbox. I liked the light downshift preload. I do mean light. A blip to 1500-1750 was also in a successful recipe for me.
My take on this is: most of the time 2 and 1 are not in alignment. To try to stab down from second to first, is likely to put you, in between and "clunking". A light but firm, even, pressure held, will drop it out of second into neutral. Then, a little, microseconds, of hesitation here will let the first gear come around until it drops in. "Two step it.", my father would say. Basically treat it as 2, even though it is one downward motion. It should still feel like one shift, just "hold pressure", instead of "kicking down". When idling in neutral, the amount of preload I use is about the amount I takes to turn off the neutral light but not yet make the shift down into first. Right on that edge for smooth engagement. Practice turning off the neutral light without shifting if you don’t have a good a feel with your feet. I drum barefoot. I like the feedback from my feet. So it may just be me. It may sound silly, but it does develop muscle memory.
A baby blip and a two step has been the smoothest for me so far, going down. I apply the same pressure going up to second. Preload and feel the two shifts by applying and keeping, even pressure. As others have stated, and I am learning- the 919 doesn’t reward lazy shifting. Adjust the toe down a bit, too if you happen to be a frequent "hang" in neutral, 1-2, offender.
Not pointing any fingers. Just my mindset; No stabs, kicks, yanks, pulls, taps. Quick but calculated. Rewards for words like ease, roll, pressure, patience, mindful, and smooth. Speed rewards smooth. I don’t need the speed- I am just trying to preserve my transmission, and not look like an idiot around people...

If your oil is older perhaps your clutch is holding on to the rpms a little longer , e.g. sticking a touch?
 
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