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Author Topic: How can I tell if clutch or rear wheel is slipping - CB750???  (Read 4509 times)

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Offline mycb750k6

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How can I tell if clutch or rear wheel is slipping - CB750???
« on: April 17, 2012, 05:37:28 PM »
I have a sorta fast CB750 836 geared 17-48. If I'm running at about 4800rpm and nail it in fifth, it feels like the engine is revving slightly as the bike lunges forward. I'm familiar with slipping clutches as the tach needle will jump when that happens with accompanying noise and no acceleration so it doesn't behave like a slipping clutch. It is like the rear wheel is breaking loose but that's what sport bikes do - right? Not 40 year old Honda's. It's kinda a hard to believe that's what's happening but I thought I'd ask the hot-rodders in the group. Or maybe someone can provide some insight.
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Offline GammaFlat

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Re: How can I tell if clutch or rear wheel is slipping - CB750???
« Reply #1 on: April 17, 2012, 05:48:18 PM »
Are you asking a question or just trying to make folks with less horespower feel bad? 

In any case, it seems that you're making a lot of power.  Is that correct?  Is that a bad thing?  Yee Ha!

Keep us posted :)
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Offline TwoTired

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Re: How can I tell if clutch or rear wheel is slipping - CB750???
« Reply #2 on: April 17, 2012, 05:49:52 PM »
Loud exhaust?
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Offline mycb750k6

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Re: How can I tell if clutch or rear wheel is slipping - CB750???
« Reply #3 on: April 17, 2012, 07:05:55 PM »
Ahhh, no. Stock HM300s. And I really don't know what's going on but would like to know if I have a clutch problem or not. Oil is Castrol 20/50 4T motorcycle oil and clutch adjusted 1/8, 1/4 and everything in between. So is spinning the tire really possible in this scenario? Seems unlikely.
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Offline the technological J

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Re: How can I tell if clutch or rear wheel is slipping - CB750???
« Reply #4 on: April 17, 2012, 07:15:36 PM »
my money is on clutch slippage.. maybe  pull the clutch and scatch up the sufaces a little... maybe through some hd springs for good measure
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Offline Frostyboy

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Re: How can I tell if clutch or rear wheel is slipping - CB750???
« Reply #5 on: April 18, 2012, 12:48:23 AM »
I often see Motogp bikes leaving a black trail of rubber in high gears when I'm watching the telecast, but these machines of upwards of 200 horsepower.
I think really that if your bike is capable of wheelspin in 5th you would be lighting the back tyre up every time you hammered it in the lower gears as well.
Time to think clutch methinks.  ;)
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Offline Retro Rocket

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Re: How can I tell if clutch or rear wheel is slipping - CB750???
« Reply #6 on: April 18, 2012, 01:22:52 AM »
Quote from: Frostyboy on April 18, 2012, 12:48:23 AM
I often see Motogp bikes leaving a black trail of rubber in high gears when I'm watching the telecast, but these machines of upwards of 200 horsepower.
I think really that if your bike is capable of wheelspin in 5th you would be lighting the back tyre up every time you hammered it in the lower gears as well.
Time to think clutch methinks.  ;)

+ 1 Frosty, if that bike spins the tires in 5th then i want it...... ;D
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Offline Terry in Australia

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Re: How can I tell if clutch or rear wheel is slipping - CB750???
« Reply #7 on: April 18, 2012, 03:47:32 AM »
Either your clutch is slipping mate, or there's oil all over the road. (you're not riding on loose gravel are you?) There's a right way and a wrong way to reassemble a clutch assembly, if you don't get it right, it doesn't matter how well adjusted it is, it'll slip. Did you reassemble the clutch, or was it a PO?

Anyway, short of your clutch discs being worn out, I'll bet it's been put back together incorrectly. The only bike I've had that will spin the back wheel in top gear at 60+ MPH is my Triumph Rocket III, but it's got 3 times the rear wheel BHP and 4 times the torque of a CB750. Cheers, Terry. ;D 
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Offline KJ790

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Re: How can I tell if clutch or rear wheel is slipping - CB750???
« Reply #8 on: April 18, 2012, 04:25:29 AM »
Hit your back brake while you peg the throttle in 5th gear. If it still feels like it is slipping then it is your clutch.
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Offline mycb750k6

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Re: How can I tell if clutch or rear wheel is slipping - CB750???
« Reply #9 on: April 18, 2012, 08:02:04 AM »
OK thks. I'll do some more informative and useful tests. 
Terry, is it true that the wheels spin clockwise in OZ?         
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Offline Dyrden

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Re: How can I tell if clutch or rear wheel is slipping - CB750???
« Reply #10 on: April 18, 2012, 08:30:48 AM »
+6 on slipping clutch.
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Offline Duke McDukiedook

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Re: How can I tell if clutch or rear wheel is slipping - CB750???
« Reply #11 on: April 18, 2012, 10:11:57 AM »
clutch
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Offline mec

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Re: How can I tell if clutch or rear wheel is slipping - CB750???
« Reply #12 on: April 18, 2012, 03:10:25 PM »
you are riding on snow or ice? then its the rear wheel (836, CR, hot cam,....)

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Offline zzpete

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Re: How can I tell if clutch or rear wheel is slipping - CB750???
« Reply #13 on: April 18, 2012, 07:10:44 PM »
Had a similar problem. I fixed it by installing new clutch springs.  8)
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Re: How can I tell if clutch or rear wheel is slipping - CB750???
« Reply #14 on: April 18, 2012, 08:11:03 PM »
Put the front tire against a tree in gear and see if you can make it slip. Rear tire must be on hard surface.
« Last Edit: April 20, 2012, 03:51:01 AM by bollingball »
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Offline Terry in Australia

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Re: How can I tell if clutch or rear wheel is slipping - CB750???
« Reply #15 on: April 19, 2012, 12:29:24 AM »
Quote from: mycb750k6 on April 18, 2012, 08:02:04 AM

Terry, is it true that the wheels spin clockwise in OZ?         

Hmmnn, that's an intriguing question mate, I'm glad you asked. If I look at my front wheel as I'm riding along it turns clockwise if I look from the points cover side, but anti-clockwise if I view it from the alternator cover side? I've got no idea what the back wheel is doing, because my tiny brain can't cope with me looking backwards as I go forwards, so I avoid trying at all costs!  :o  :)

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I was feeling sorry for myself because I couldn't afford new bike boots, until I met a man with no legs.

So I said, "Hey mate, you haven't got any bike boots you don't need, do you?"

"Crazy is a very misunderstood term, it's a fine line that some of us can lean over and still keep our balance" (thanks RB550Four)

Offline hockeyteeth

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Re: How can I tell if clutch or rear wheel is slipping - CB750???
« Reply #16 on: April 19, 2012, 08:17:21 AM »
Quote from: zzpete on April 18, 2012, 07:10:44 PM
Had a similar problem. I fixed it by installing new clutch springs.  8)

Yeah, I once bought new fiber plates for a slipping clutch only to notice how weak the original springs were when I replaced them. The original fiber plates didn't look burnt at all, so I bet it was just the springs in my case...
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Offline phil71

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Re: How can I tell if clutch or rear wheel is slipping - CB750???
« Reply #17 on: April 19, 2012, 08:27:10 AM »
Breaking the rear wheel loose in 5th? I'd say the thing that's slipping most is the grip on reality. Check that first.
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Offline Terry in Australia

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Re: How can I tell if clutch or rear wheel is slipping - CB750???
« Reply #18 on: April 20, 2012, 12:49:17 AM »
Quote from: phil71 on April 19, 2012, 08:27:10 AM
Breaking the rear wheel loose in 5th? I'd say the thing that's slipping most is the grip on reality. Check that first.

Will stronger springs improve your grip on reality Phil? ;D
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I was feeling sorry for myself because I couldn't afford new bike boots, until I met a man with no legs.

So I said, "Hey mate, you haven't got any bike boots you don't need, do you?"

"Crazy is a very misunderstood term, it's a fine line that some of us can lean over and still keep our balance" (thanks RB550Four)

Offline trueblue

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Re: How can I tell if clutch or rear wheel is slipping - CB750???
« Reply #19 on: April 20, 2012, 01:33:59 AM »
Quote from: Terry in Australia on April 20, 2012, 12:49:17 AM
Quote from: phil71 on April 19, 2012, 08:27:10 AM
Breaking the rear wheel loose in 5th? I'd say the thing that's slipping most is the grip on reality. Check that first.

Will stronger springs improve your grip on reality Phil? ;D
I can verify that changing to a non-synthetic oil improved my grip on reality, but I could still use some stronger springs I think.
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Offline dave500

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Re: How can I tell if clutch or rear wheel is slipping - CB750???
« Reply #20 on: April 20, 2012, 01:59:21 AM »
i would expect easy front wheel lift in first/second and third if you can spin it in top gear?
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Offline excellrec

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Re: How can I tell if clutch or rear wheel is slipping - CB750???
« Reply #21 on: April 20, 2012, 10:48:59 AM »
If your clutch springs are old maybe just get new ones.  Heavy duty springs will work but it comes at great cost in the feel of your clutch.
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