Honda CB750 - Feels like slipping Clutch... but its not...

[Tom928]

Hello,

Wonder if anybody can help me, Bike details as follows:

Honda CB750 F2
1992 REG
29K Miles

Recently took the Motorbike to a Garage because when im out riding and i accelerate and go over 7k Revs in gears 1-4 the Revs just fly up to like 12k..... When in 5th gear it sometimes flies up, but then sometimes doesn't. I have to reduce the throttle to bring the Revs down back to Normal, the motorbike feels like its going to blow up lol....

I took the Bike to the Garage and explained, he thought it could be the Clutch that was slipping, so he went away and changed the Clutch and the Oil.

The problem still is occurring, its really annoying!

Has anybody got any idea what it could be?

*Recently had a New chain and Sprocket and New Plugs whilst the Clutch was being fit.

Look forward to your replies,

Tom

[MaybeGuy]

just because some "mech" changed your clutch, doesn't mean he did it right. He probably didn't change the springs.
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Blue_SV650S wrote: it was a sh1te wheelie, but it proves that he can get it up in 3rd and can do angles. In summery, mattsprattuk is a gobby little sh1tebag, dopehead tw4t, but sadly for all of us, he probably isn't THAT full of sh1te!!
Kickstart wrote: Hi I tend to agree with Matt. All the best Keith

[Teflon-Mike]

The wrong oil can shag the clutches on these. The Hydraulic tappets don't like the wrong oil much ether; so make sure that it's the right stuff.

Symptoms sound like it's clutch slip; ish.. but when mechanic says they have 'done the clutch' that could mean almost anything from adjusting the cable to replacing the plates....

Small niggle on the CBX750 engine is that it has a 'weird' castle nut on the clutch.. finally got round to swapping the plates on mine that have been in the ready spares box for three years this summer; that nut is nie on impossible to get off without the 'official' Honda tool, which is something like £50 at DSS, and on 'special order', and not to be found on e-bay. ended up buying, think it was a deep 32mm impact socket, and the painstakingly grinding out the castle profile on the face to fit the nut with a chuffing dremmel!

This suggests that there is MORE than a small chance that your mechanic, lacking the Honda special tool, and finding it rather ore than difficult to try chisel the thing off, HASN'T done any more than take the clutch cover off, look at it; the put t back together, bung in some thicker oil and wind the cable adjuster off a bit ad give it you back!

From memory, I think there are seven friction plates, two their ones on the ends and five thicker in the middle; priced according to CSML at approx £10-£15 each which implies that a full pack would be about £70, Clutch springs are approx £4 and I OUGHT to remember if there were 4 or 6 but I cant! Think there are 6, which would bring parts total up near £100 with a gasket; With the castle socket? Probably about an hour's labour; it's NOT a big job.

So, I'd look at the invoice; if you weren't charged £150-£200, good bet that clutch ENT been replaced. If you WERE charged that sort of money, look at the receipt, see if they have listed parts used, and hours of labour.. cos my bet is mechanic hasn't got past that bludy castle nut.....
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My Webby'Tef's-tQ, loads of stuff about my bikes, my Land-Rovers, and the stuff I do with them!
Current Bikes:'Honda VF1000F' ;'CB750F2N' ;'CB125TD ( 6 3 of em!)'; 'Montesa Cota 248'. Learner FAQ's:= 'U want to Ride a Motorbike! Where Do U start?'

[Tom928]

Thanks for prompt replies....

On the invoice it looks like everything has been changed;

'Engine oil 10/40 semi syn'
'Clutch plate gasket'
'Clutch kit plate and Springs'

To be honest to the Garage, I quite do trust them. However as you say, he could be missing that special tool!

So I'm guessing normally a Motorbike which Revs shoot up is caused by a Worn clutch - can't be anything else?

Thanks,
Tom

[stinkwheel]

I can think of only three possible causes of the revs increasing but the speed remaining the same on a motorcycle with a conventional manual gearbox.

1) Clutch slip.

2) Rear wheel spinning up.

3) Teeth totally worn off front sprocket.

I would hope you'd have noticed items 2 and 3.
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“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.

[Teflon-Mike]

[doggone]

There is a chance it's badly adjusted or cable is sticky so does not fully release.
Should have been checked by mechanic really.