Pls can any one give me any advice on my bike that has developed a flat spot at 5500 rpm 6 th gear .....
Power just gives up and tries to kick back in but it can't .
I've changed the plugs , oil . Filter , air filter and it's still doing it !
What next ??
Bike is on a v plate 1999
Cheers guys Ben
Help flat spot
Re: Help flat spot
Have you checked the vacuum hose from the petrol tank that hold the petrol tap open this can get trapped some times
Does it run okay other wise or is it all ways on a high rev?
Does it run okay other wise or is it all ways on a high rev?
1998 black vtr (mods cbr900 fork conversion, ohlins rear shock, ohlins steering damper, prolite discs brembo master cylinder, goodridge braided lines, harris rear sets, Quick shifter,Mario Fairing, etc)
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Benjennings1981
- Posts: 3
- Joined: Sun Apr 20, 2014 2:53 pm
Re: Help flat spot
It's only under load and at high revs ... Going through 1-5 it's sweet just when it gets into 6th it's starts playing up
Re: Help flat spot
Have you had the CCT's changed or any engine work since it developed the problem?
And has it always done this or has it previously run ok?
I'm thinking that the cam timing may be out 180 degrees.
That fits with the revs at which the problem occurs exactly.
But usually affects fourth and fifth as well.
And has it always done this or has it previously run ok?
I'm thinking that the cam timing may be out 180 degrees.
That fits with the revs at which the problem occurs exactly.
But usually affects fourth and fifth as well.
It's not falling off, it's an upgrade opportunity.
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Benjennings1981
- Posts: 3
- Joined: Sun Apr 20, 2014 2:53 pm
Re: Help flat spot
The CCT's were changed by the previous owner , the bike was running perfect until last week , it's just started out of the blue ...
Thanks Ben
Thanks Ben
Re: Help flat spot
Ben, A bit of a strange one with it happening specifically at 5500revs and only in top gear, as Tony mentions.
Things that can suddenly go are, a split occur in the fuel tap diaphragm (if that happens petrol should seep out through the drain-off spout at the bottom of the fuel tap, the spout that points towards the ground). Or a split in one of the carburettor diaphragms. Even so I would have thought either of those problems would be showing up more than your problem is at 5500rpm in 6th gear, but it still may be worth checking those two out.
Highly unlikely anything to do with it, but just to remove this from the equation, if you have a mulit-meter check the charging rate at the battery terminals, it should be reading between 13.5 and 15.5 volts with the engine running, and showing 12 volts plus (12.? ) with engine off. Check battery voltage with engine off after the bike has been left un-started over night is a better test IMO.
Also check breather hoses are fitted correctly, especially the front one up underneath the air box base, and while you're there check out the fuel lines and vacuum line(s) for splits or perishes etc. If you have a take-off hose that has been fitted to the front inlet manifold for balancing the carbs, make sure the end bung is still there doing it's job of blanking off that hose whilst it's not being used.
Chris.
Things that can suddenly go are, a split occur in the fuel tap diaphragm (if that happens petrol should seep out through the drain-off spout at the bottom of the fuel tap, the spout that points towards the ground). Or a split in one of the carburettor diaphragms. Even so I would have thought either of those problems would be showing up more than your problem is at 5500rpm in 6th gear, but it still may be worth checking those two out.
Highly unlikely anything to do with it, but just to remove this from the equation, if you have a mulit-meter check the charging rate at the battery terminals, it should be reading between 13.5 and 15.5 volts with the engine running, and showing 12 volts plus (12.? ) with engine off. Check battery voltage with engine off after the bike has been left un-started over night is a better test IMO.
Also check breather hoses are fitted correctly, especially the front one up underneath the air box base, and while you're there check out the fuel lines and vacuum line(s) for splits or perishes etc. If you have a take-off hose that has been fitted to the front inlet manifold for balancing the carbs, make sure the end bung is still there doing it's job of blanking off that hose whilst it's not being used.
Chris.