hi All,

Any advice?....

My mc28 has approx 30,000 kms on it and for the last 1000kms or so it is lurching/lumpy and seems to knock abit when off the gas in most of the gears. Feels ok when on the revs, but just when rolling off or just with a little gas it feels strange.

Is this the start of the crank going? What would it feel like? how quickly do they deteriorate? I have stopped riding it out of paranoia! Last top end was 10,000 kms ago.

If it is on the way out, does the whole crank get replaced? Or the ends?

Thanks Mark

You can normaly hear when a crank is on its way out on tick over, they tend to rumble. When the bike is riden on load the noise normaly lessens, its only off load it will really stand out.

If its the mains that are gone these can be got though the site, if its the big ends then really its a new crank job.

Try taking the gen cover off and rotating the crank by hand then pullin it up and down. There shouldnt be any movment at all. All the specs for the big ends are in the workshop part of the site.
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If I have to take the carbs off once more...

Stephen rc45,

Thank you for your advice. Any other thoughts.

Many thanks

Mark

StephenRC45 wrote:if its the big ends then really its a new crank job.

Why? Not arguing, just curious.
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Please do not PM me technical questions, if you can't find it on the Forum start a thread

Because the crank big end pins are part of the crank web so cant be replaced. You cant buy the webs on their own hence a new crank.
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If I have to take the carbs off once more...