Something's slipping. Any Ideas/Suggestions?

[Dave70]

Over the past couple of months, usually when travelling at 60+mph, I've felt as though something has slipped on the bike. It feels like it's something connected to the rear wheel.

Initially I thought that maybe the chain was slack but, it is absolutely fine. The sprockets look fine too and they were replaced less than 5,000 miles ago and were a decent quality branded set.

The "slip" only lasts a split second and it doesn't always happen, just now and then. It's probably something simple but, I'm not at all up to speed with the mechanical side of things, so any ideas would be helpful. I've heard of something called clutch slip but, I have no idea what the tell tale signs of that is, all I can say is that apart from this issue, everything else appears fine. Would the clutch slipping do this?

The bike is a R125 and has been well maintained and looked after since new and has done around 28,000 miles.
____________________
There ain't no devil, there's just god when he's drunk.

2012: R125 killed by white van. 2016 R125 killed by 30,000 miles of redline. Current: 2016 Kawasaki ER6f.

[DrSnoosnoo]

IIRC to test for clutch slip, at a low speed, put it in top gear and give it some welly. If the revs rise but your speed doesn't, your clutch is slipping.
____________________
I'm Sam; Northern, Ginger, Lover
Did have: '95 ZZR600 '83 CG125 '97 ZZR1100 '15 Hypermotard 821 SP Do Have: '10 ZX10R

[stinkwheel]

The only two things that CAN slip are the clutch or the back tyre. Everything else is rigidly attached together.

I doubt it's spinning up the rear wheel so you're left with clutch slip where the sandwich of metal and cork plates, held together with springs, that transmit the power from the engine to the gearbox aren't gripping together properly.

Can be because they are broken, worn, glazed or that the springs have lost some of their springiness. The only way to find out which is to dismantle the clutch. That's not a huge job but does involve draining the oil and removing one of the engine side-covers.

The friction clutch-plates and springs are a wearable componant and are relatively inexpensive to replace.

Check your clutch cable is correctly adjusted for free-play first though.
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[Dave70]

Thanks for the replies.

I'll give snoos tip a try first and see what happens.

As for taking things apart, although it's not a big job as such, I only have the back alley way to work on my bike, so will probably let someone who knows what they're doing have a look and do the job, as I wouldn't know what to look for as such, even with stinkwheels very helpful description.
____________________
There ain't no devil, there's just god when he's drunk.

2012: R125 killed by white van. 2016 R125 killed by 30,000 miles of redline. Current: 2016 Kawasaki ER6f.

[Taught2BCauti...]

If it is clutch slip, but doesn't happen all the time, can you get it to happen by gently squeezing the clutch lever gradually as you are riding normally?

Does it feel the same?

The only other thing I can think of in the drive train, is the Cush Drive Rubbers, but not sure what you might feel if they are shot.
____________________
Honda Varadero XL125(V8)
www.TheFutureIsHere.eu

[Dave70]

[Aff]

Are you trying to describe slipping, rise in revs but not in road speed.

Or are you trying to describe a momentary loss of power?
____________________
Current Bikes:Honda 929RR Fireblade, Honda CD200 Benly (Project), Stomp Z2 140
Electric Bike Project

[Dave70]

[Vincent]

If it's clutch slip, you'll find it'll happen more in high gears at low revs so get into top gear as soon as you can and open the throttle wide and see if it happens then.

Maybe you should check the rear wheel bearing too.
____________________
Space Is Deep

[el_oso]

check your sprockets for a broken tooth/loose bolts - unlikely but takes literally two mintes to whip the front sprocket cover off and then check all teeth are still there.

check rear wheel alignment. If it's massively out could casue a slight jolt when the teeth and links don't mesh nicely. Again quite unlikely given that you would probably notice other bad things first, but it's a quick check.

sprocket carrier bearing worn / blown up. Again, it's relatively easy to check if you have a centre stand or a paddock stand. Bit more time consuming though. Take off the rear wheel. Pull the sprocket from the holder. Find the bearing and give it a good feel for smoothness.
____________________
Duke 390
Previous: '05 XR125L | '96 XJ600S Diversion |'05 Suzuki GSXR1000 | '05 Honda CBR125-R | '97 YZF 600R Thundercat | '11 Honda CBR250
Car: Jeep Wrangler 4.0L