Rear End Hopping

I purchased an 08 WRX about two months ago. The other day I accelerated and the rear end began to hop. I'm thinking the chain might be loose, but I didn't have time to check it. Anyone else expierence this?

Sounds like a slipping chain. Your're likely way too loose.

Check you swing arm protector on the bottom side of the swing arm while you're down there. It's pretty well known that running either too loose or too tight will tear it up fast.

Its an known factor that because of yamahas NOT so supergood silent sprocket/ chain system that the chain is slipping if you dont tension the chain enough.

I think they removed that system on the later models......
(plastic piece surrounding the rear sprocket and also some plastic is mounted to the front sprocket too.)

Tension it once in a while and it will be better after some use when the outer plastic is worn down a bit or buy new aftermarket sprockets.

mr-cave wrote:

Its an known factor that because of yamahas NOT so supergood silent sprocket/ chain system that the chain is slipping if you dont tension the chain enough.

It worked just fine - I went through two sets of those stock sprockets, and the second set might still be with us today if not for The Golden BB rock from hell I encountered. No slipping at all - but then I'm one of them crazy people that actually checks chain tension every few days and adjusts if out of spec. Not to mention squirting a little chain lube on that chain every few hundred miles, even though it is an O-ring chain.

Yamaha made a serious error in assuming people would actually regularly check and lube their chains when they came out with those sprockies. Most people don't of course. I wonder how many even take a second for a squint at their oil level in the sight glass before touching the magic button.

Quote :

I think they removed that system on the later models......

My guess is they finally admitted defeat and realized a fair number of people will go months without either checking chain tension or lubing their chain.

I wouldn't go looking for that same sprockie setup again as I don't think it delivered enough benefit to prefer it, but I check chain tension and lube regularly, and I never had a single problem with the '08 sprockies in 2.5 years.

Be interesting to hear if the OP has a munched swingarm.

When i got mine from the store everytime i flicked the clutch or tried to wheelie it jumped a few knockles....

So after adjusting it, it worked well. But i guess the first 500-1000 km is worst before the plastic is worned in?

I also lube my chain almost after every ride or atleast check it so it is not dry.

mr-cave wrote:

I also lube my chain almost after every ride or atleast check it so it is not dry.

+1!!!
I am using chain tech wax on my new Tsubaki x ring chain/Rentahl sprockets. Bike DEFINATELY runs faster! I figure I paid a lot of £££ for this, & have total respect for moving parts. How long does it take? 30 seconds to inspect & 15 minutes to clean with cloth & re-wax chain?? Time on weekend well spent, & you can have a beer on the side

Well, we've kind of experienced thread diversion while waiting to see if the OP's swingarm got munched...

I don't usually clean the chain unless is really is dirty. If it isn't, I don't think wiping and rubbing is going to get at the dirt that matters down around the O-rings anyway, and scrubbing with bristles must incur some wear on the rings itself. When it is really dirty, the bike goes on the stand, and I sit on a milk crate with a grunge brush and give it a quick scrub as I run water over the rear sprocket. Then a little five minute ride to get rid of the water and warm the chain up.

Either way, I end up lubing with some spray on DuPont teflon lube. Sit at the back with the straw on the lube can, a little shot on each side of the links at the O-rings as you rotate the tire. Nice and clean, you could almost do it on the living room carpet. And it doesn't pick up crap and junk, have a lot of fling, etc. Takes maybe five minutes total.

I can't say that I notice my bike runs faster immediately after lubing the chain.

Jäger wrote:

.....I don't think wiping and rubbing is going to get at the dirt that matters down around the O-rings anyway,......

Ah, but a gold chain looks SOOOOOO much nicer when its cleaned & polished - especially with wax!!! Bling...

ssauer2004 wrote:

I purchased an 08 WRX about two months ago. The other day I accelerated and the rear end began to hop. I'm thinking the chain might be loose, but I didn't have time to check it. Anyone else expierence this?

Before i had my shock revalved the bike would "hop" up and down under hard acceleration,usualy on exit of the corner. And i do mean hard,WOT.
The chains would slip easy on these things,but not hop.

ssauer2004 wrote:

I purchased an 08 WRX about two months ago. The other day I accelerated and the rear end began to hop. I'm thinking the chain might be loose, but I didn't have time to check it. Anyone else expierence this?

I would imagine that for your chain to be jumping teeth on the rear sprocket your chain would have to be SOOOOOOOOOO loose you could see it from over 10 feet away as you walk up towards bike.

If I were you I'd remove the front sprocket cover and inspect both the front and rear sprocket for missing teeth.

When I think of the rear wheel hopping I think of one too many downshifts while braking hard and that causing the rear to hop around a bit.

It's very hard for me to picture how a street bike can hop the rear under acceleration. You'll either loft the front, or spin the rear.

Since our dinky little 250cc can't really power wheelie .... and doing a rolling burnout isn't really in the cards either.....I just wonder if you could describe exactly what was going on at the time you felt something "not right"?

Any chance you were on some gravel, sticks, unstable ground of some sort????

Can you re-create the problem?
Has it happened more than once?
One time fluky thing that's never happened again?

Since you posted this have you had time to at least inspect chain and sprockets?

Jäger wrote:

Yamaha made a serious error in assuming people would actually regularly check and lube their chains when they came out with those sprockies. Most people don't of course.

Jager, in your opinion, what's the design intent of the rubber gasket on the rear sprocket?
Why would Yamaha put it there? What's the theoretical advantage of that "system"?

To me it appears that the intent was to deaden the chain/sprocket noise. Which if all things are adjusted properly may do just that. The big IF is the pivot point though. Best laid plans.

I've never seen such a thing on a street bike. Is it something that's more common on dirt bikes or dual sports?

Sorry for taking so long to repost. I inspected the chain it didn't appear to have too much play in it. I cleaned and lubed it up and rode it to the dealership. I could not duplicate the hopping rear end today. A good friend works at the dealership and he inspected the bike. Without really going through it (going to look at it in the morning), he stated that the chain seemed to have the proper slack, and the rear sprocket looked a little worn for a bike with only 1800 miles. He believes that the chain could have a bad link in it causing it to get hung up on the sprockets, causing the slight wear and hopping. I'll know more tomorrow afternoon. I post tomorrow. Thanks for all of the replies and interest.

motokid wrote:

Jager, in your opinion, what's the design intent of the rubber gasket on the rear sprocket?
Why would Yamaha put it there? What's the theoretical advantage of that "system"?

I don't know and I'm only guessing, but I think it was a system intended to extract every possible bit of sound deadening throughout the bike. A crazy idea is that some perfectionist engineers thought "When this thing squeaks, the owner will lube the chain: improved chain/sprocket life".

They couldn't have been that married to the idea as they certainly abandoned it pretty fast. I wonder if those sprockets are still an available replacement part for bikes - and if they are, if they're only there until they can flog them.

I found the rubber ring mildly useful for reminding me my chain was getting dry. Other than that, I can't discern any difference in noise while riding. But the original sprocket WAS quieter when I had the bike up on a stand and was rotating the rear wheel while spraying lube than when I did that afterwards with the new sprockets. Of course, the engine wasn't running then...

Hey! There's an idea! Start the bike on the stand, run it up into 6th gear, and then spray lube on the chain....

... maybe not.