Nasty low frequency vibration

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Binetta Steve
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Nasty low frequency vibration

Post by Binetta Steve »

Took the Kr1s last friday , best day of the year , that ended in tears!
After appx 6 miles engine realy warm gave it full throttle , fine in 3rd 4th power dropped , pulled clutch in , but not seized just vibrating! Realy low frequency "drumming" feeling through bars and footrests. Limped home. Power down but ran ok and started and stopped, but tickover lumpy with revs holding at 3k
Got it home checked following
Plugs fine , rich tea biscuit colour
Dropped gearbox oil , clean no swarf
Small spots of oil on spannies, lube is getting through.
Took stator/ alternator cover off, flywheel really hot, like twice as hot as exhausts after 30 mins, strong smell of burning
No play on flywheel

Next step to remove flywheel and look for any damage.

Then barrels off and look to see if a ring has nipped up

Any thoughts what this could be
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Garry
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Post by Garry »

Sounds like a bearing in the crank

Is there any play if you try lifting the flywheel
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Binetta Steve
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Post by Binetta Steve »

Garry thanks for reply, in short no, the flywheel feels solid no up or down or side to side. It baffles me. Even today 2 days on the plastic alterator cover smells of burning. My pal thinks it maybe a bearing, maybe its the post winter strip!
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martin
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Post by martin »

if top end ok, could be as gary says, bottom end, bearing
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Binetta Steve
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Post by Binetta Steve »

Plan is over next week , have a good look at everything , including top end. Ill post news on here Martin


Any other ideas as to what my woes are shout up!

Steve
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Post by Cliff »

Engine to frame bolts tight?
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ScottaKR
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Post by ScottaKR »

I'm thinking crank bearings too. Maybe conrod big-end bearing.
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daz680
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Post by daz680 »

The strong smell of burning could be the stator windings on the way out, Ideally you need a mega to test it. as for the vibration have you checked the balance shaft is aligned correctly. If the stator is on the way out or has actually burnt out it could affect a lot of electrical components including the CDI and regulator which in turn would effect the running.
Currently building RC30 lookalike
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Binetta Steve
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Post by Binetta Steve »

Cheers guys for the suggestions. No news yet as bike is in the shed awaiting my pal who has more confidence than me to start to pull it to bits.

I hope it could be loose engine mounts, but in my heart of hearts doubt it.

Stator damage maybe visible and could explain the realy hot flywheel but the £££££ imact on that is awful to think of.

Bearings will be our first port of call

Positivly the weather in lancashire is awfull so im not pining to be out on the roads.

I will update and probably ask for more guidance as the motor dissembly starts.
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Post by SP_BOTT »

Luckily I didn't find it with mine, but could the vibration be the infamous broken frame lug/bracket? Easier to check before removing the engine, otherwise the crack closes when tensions removed.
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Binetta Steve
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Post by Binetta Steve »

Hi good point which bracket fails , i had a quick look under the motor the other day when i read about Wills problems. Sorry for the ignorance but putting it simple is it rear right front left , by sidestand etc.

Thanks in advance

Steve
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ScottaKR
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Post by ScottaKR »

It's the rear ones that crack Steve. Although I doubt that this would be the source of any vibration whatsoever, it's still an issue you want to keep an eye out for all the same.
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dave32
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Post by dave32 »

I had a hairline crack in the left side lower bracket,it felt like the main bearings had gone,lots of vibration when riding through bars and pegs.
You should be able to see the crack,normally go on the left side and its where the bracket meets the frame.It will be harder to see when its NOT in tension as it will close up again.
Stator getting hot wont have anything to do with it,left side mains could have been running dry and transmitting heat outwards or the stator windings are overheating,but they normally pack up on KRs and just dont work.
dave
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Binetta Steve
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Post by Binetta Steve »

Well been cleaning under the bike today, didnt realise how many nooks and crannies there were. No signs of hairline cracks , unless i use dye penetrant i dont think im missing anything. Orderd puller for flywheel, first step, is to try and work out where heat came from

Ill post updates as i go along, unlike all the builds on here that get better and shiny (Teerex & Bernie) i seem to be digging a blo..y big hole !
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daz680
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Post by daz680 »

Hi Steve
hope you've got something to hold the flywheel while you take the bolt out

http://www.ebay.co.uk/itm/380454027221? ... 1439.l2649
Currently building RC30 lookalike
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