Kawasaki Ninja 300 Forum

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-   -   Drive train lash anyone? (https://www.kawasakininja300.com/forum/8-ninja-300-general-discussion/135253-drive-train-lash-anyone.html)

SparkyMJ 10-02-2019 03:30 PM

Drive train lash anyone?
 
Hey all,

I've got a '14 300 with 30k miles on it. I really keep up with my maintenance, and just did the valve adjustment myself. The motor runs great, smooth, good power, and only makes some slight ticking noises I would associate with age. However, my transmission has very slowly gotten more and more knock-y and lashy. So when I roll on and off the throttle, it feels like my chain is just totally loose, but it is not. The chain is relatively new as well, DID X-ring chain. Very nice chain btw. And when I changed the sprockets, the rubber dampers in the rear wheel looked okay too.

A few things I have picked up on about this issue:
-it happens in all gears. Therefor, it is not related to a certain gear specifically
-when changing the sprockets, I noticed there was a lot of rotational play in the countershaft, it would rotate perhaps 30-40 degrees back and forth if I remember, it felt like a lot, but my numbers may be inaccurate.
-yes, its still there when my chain is tight, with brand new JT sprockets.

Although drivetrain lash is quite well overcome by good throttle technique, it is still quite annoying.
Is there perhaps a certain single or pair of gears in the transmission shafts that is needing replacement? That is the only thing making my ride not feel premium anymore.
Any help is appreciated.
-Mike

Kennylxix 10-02-2019 04:08 PM

Is it possible you're feeling jerkiness in the engine and not the trans? These bikes are known for having kind of jerky throttles at low speed transition and something may be exacerbating that.
The internal drivetrain is all gears so unless something is seriously going wrong the internal slack can't really change much.

jkv45 10-02-2019 05:28 PM

Even if the rubber dampers are good in the cush drive, there will most likely still be a lot of slop.

With the rear wheel off the ground and the engine in gear, see if you can spin the wheel back and forth without moving the chain/sprocket.

We've shimmed numerous cycles, but our Kawis have been the worst -

https://faq.ninja250.org/wiki/How_to...the_cush_drive

I like to use ABS plastic for shims, cut in rectangles to fit snugly between the rubber damper and the wheel.

SparkyMJ 10-04-2019 07:10 AM

Dont think its my engine, the motor runs really happily. No noises with the lash either. Perhaps I will investigate the rear cush drive, shimming could help if thats the issue, but I am not sure if it is.

That's also the thing, it is not limited to low speed, I know what jerky throttle response is like at low rpms and such, and this bike didn't do this when I bought it, although that was almost 20,000 miles ago.... I've beat the bike hard since I got it, no crashes, but just a ton of wringing it out and hard shifting. But it was my understanding that most bikes, even sport bikes, if actually maintained, could reach well into the 50-100k miles range. And that transmission "gears" were basically a lifetime item.

I havent tried rolling the rear wheel to see if it moves *without the sprocket moving*, but I know it rolls *with the sprocket*. Like I said, the countershaft where the front sprocket is mounted has a lot of rotational play when the bike is in gear, just sitting. Then again, I am not experienced servicing any other bikes, but I am almost sure the lash I am experiencing is coming from the transmission, because my clutch also has rotational play, when I serviced it a few months ago.

I replaced the clutch, and its great. However, the basket had similar rotational play in it. And get this, for example, when I am engine braking to a stoplight, and finally pull the clutch in, then sometimes I will put the bike in neutral for long lights, and when I let go of the clutch in neutral (engine running of course) I'll hear a "clank", that is the transmission becoming slightly loaded from clutch drag. If that makes sense, it's hard to explain, but I guess what I am trying to say is that the lash is experience-able without the rear wheel even moving, or it being in gear.

I bought the bike for 2k, at 12,000 miles, and now its at right under 30,000 miles, only minor cosmetic damage and a slightly bent right bar. Is it worth the money to potentially replace the transmission or sub components of it? I'd value the bike at around 1500-2000, it's in better shape than when I bought it, but it does have much more wear. Im worried if the trans actually does blow, the bike is totaled. (which may be typical of any sportbike, but even doing the work myself, I am wondering if its worth it)

What options do you guys think I have? Would all 6 gear pairs on the shafts be worn evenly, and just had worn teeth? In which case I would just need all new gears? Or is there a "master" gear that comes off the crankshaft that could be worn down alone? Which is more likely? I would think 1st gear would be way more worn than any others except maybe 6th, but I guess it is a constant mesh straight tooth tranny, and they could all be evenly worn... If its a 500-1000 dollar fix in parts alone, I don't think I would do it, just sell the machine to a learner and save for a new machine.

Any more thoughts guys? Thanks for the input.
-Mike

MAL 10-04-2019 07:54 AM

Out of my own curiosity: how much is a new transmission (or a transmission rebuild)?

Kennylxix 10-04-2019 08:48 AM

3 Attachment(s)
So the transmission gears are in constant mesh but only the gear you're in at the time has any load on it so the gears won't exactly wear evenly.

As far as rebuilding; the trans and engine cases are one unit do to get to the trans you're pulling the engine completely apart as well. It could be done fairly economically if you're doing it yourself but paying someone else would probably put it beyond economical repair. Youd be better off buying a used engine off eBay.

I have a difficult time thinking that simple geartrain wear could get bad enough for you to really feel it without something outright failing from the wear.

You said you rebuilt your clutch. Was this issue there before the rebuild? The clutch has some parts that can fail causing looseness (there are damping springs that can break etc). Its not a common issue I've heard of on the 300 but its fairly easy to get to and inspect so it might be worth a shot.

jkv45 10-04-2019 10:20 AM

I don't think you want to get into the trans at this point, and I'm not sure you'd even find an obvious problem in there.

Clutch baskets do wear, but I'm not sure if that type of wear would do what you described - but it could.

Check the cush drive first. Snug it up and see if there's any change. If not I'd look into the clutch basket next.

Kennylxix 10-04-2019 10:32 AM

3 Attachment(s)
If the damping springs are broken or collapsed it would do as described. But the cush drive is a good place to look.

SparkyMJ 10-06-2019 11:07 PM

Well you guys were right! I was able to observe a very slight play in the cush drive when parked, and opened it up and shoved some milk carton plastic in it and the lash was significantly reduced, perhaps 90% better. Didn't think the amount of play I was seeing would make that big of a difference compared to some of the horror stories I have seen online about 250s and practically flopping sprockets.

However, my cush shimming has seemed to wear down very quickly and it is now only slightly better than before the shimming. I put multiple layers of the plastic pieces between the blocks, enough to make it tight enough that I had to put most of my body weight onto the wheel when wiggling the sprocket piece back on to get it to seat.

The rubber as I found before, looks to be in good shape, no tearing or visible deformation or anything, just play that I want out. Should I just get much thicker pieces of plastic and shim the heck out of it and mallet the sprocket back on? It was complete bliss for about half a day, then it was back to lots of clunking.

Thanks for pointing me the right way guys, pretty sure the cush drive was the issue. Just need it keep it fixed.
Thanks in advance.
-Mike

jkv45 10-07-2019 11:13 AM

I use pieces of .060" ABS plastic sheet the size of the contact area, and it hasn't ever changed.

It's a snug fit, but force isn't needed to get it to go back together.


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