RPM shooting up after 7-8rpm

NS125RK · Nova Slayer Joined: 26 Apr 2004 Karma :

Hi, For the short time I had my bike back form having some work done to the clutch I took it out to wear it back in. But when the bike hit about 7500rpm it shot up to about 10000rpm pretty quickly, i've hear of people talking about power bands but I don't think that this is the case as it doesn't feel like the bike was getting any quicker. Does anyone have any ideas what could be causing this?

Mattastic · Trackday Trickster Joined: 03 Aug 2003 Karma :

My GS125's revs fly up from 7.5k to the 10k redline, i think it may be a powerband but due to the bike having hardly any power it doesn't seem to make much difference!
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dainesefreak · World Chat Champion Joined: 04 Apr 2003 Karma :

Is the bike restricted? If it is it's probably the way the power is delivered in the power band. It won't stun you with the acceleration! Wink

Keith · World Chat Champion Joined: 24 Mar 2004 Karma :

does it do this in all gears?
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ShaggyD · Derestricted Danger Joined: 25 May 2004 Karma :

Is the clutch definitely sorted?

It sounds to me like when you hit the power band the clutch can't cope, slips & lets the engine rev its head off.
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NS125RK · Nova Slayer Joined: 26 Apr 2004 Karma :

Kickstart · The Oracle Joined: 04 Feb 2002 Karma :

Hi

That is pretty much the effect of the power band. Nice sharp increase in power. However I would doubt that it would go from 7000 to 10000 in a second (well, maybe in first). Sorry, but it probably is the clutch slipping.

All the best

Keith
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NS125RK · Nova Slayer Joined: 26 Apr 2004 Karma :

OK, thanks again for your help. I'll ask the garage when I take it in to have the front wheel fitted, would try myself but with the luck i'm having at the moment i'd better leave it well alone. I'd also like to add that it doesn't just stop at 10000rpm it's just that i've not let it go over that as I don't want my bike to blow up on me.

ShaggyD · Derestricted Danger Joined: 25 May 2004 Karma :

If its the clutch slipping, when the revs shoot up you won't feel any acceleration.

If its the powerband doing its thing, when the revs shoot up you should accelerate like hell - the speedo should shoot up with the revs.

Hope this helps you pin it down
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NS125RK · Nova Slayer Joined: 26 Apr 2004 Karma :

Yeah it does look like it must be the clutch as I thought the speed of the bike should be relative to the engines RPM and for it to increase by 40% in about a second the bikes speed should also increase which I doubt its going to go from 60mph to about 90mph in the same amount of time, wish it would though.

Like I said i'll have a word with George at the garage and see if it can be sorted, do you reckon it will be just a case of adjusting it or will it have to be taken apart?

tony532 · World Chat Champion Joined: 29 May 2004 Karma :

sound like a problem i had on my rs125

turned out the clutch plates were worn out

new clutch plates and it was sorted

G · The Voice of Reason Joined: 02 Feb 2002 Karma :

Sounds like it is the clutch, could be the plates or the springs.

Try adjusting the biting point so that it's further in, if it's pretty near to the bar. Ideally so there's a little bit of slack on the cable when it's not held in.

If that doesn't work, clutch plates/springs should be pretty easy to sort out yourself if you want to fiddle.

clemsta · Scooby Slapper Joined: 29 Apr 2004 Karma :

Sounds more like the springs to me, if it were worn clutch plates then the clutch would slip when letting it out.

NS125RK · Nova Slayer Joined: 26 Apr 2004 Karma :

I've got it sorted now, when I took the side panel off to see if adjusting it would help I noticed that the mechanic had put nearly no oil in. Topped it up and now when it hits it's power band you can really feel it and it's not jumping up as quickly. Only problem now is that the clutch is biting a bit early but that should be easy to get sorted. Thanks for all your help.