top end rattle..

ZZR 600.

Thrashed well into red zone, thru gears. rattle started as a buzz at about 4-5K revs. after about 50 miles it is overwelming throughout the rev range. stopped riding bike. have removed rocker and cams. All in good shape. Cam chain is at it max tolerance but still ok - rubber pad on underside of rocker cover is unmarked and cam chain tensioner not fully extended. Next off is the head, i think it might be a bust spring - any other ideas?

thanks

I don't know anything about your particular bike but I had an older honda that started to "rattle" at about 2500-2800 rpm and I thought it was the top end at first cos I couldn't hear it unless I was riding it and after quite a bit of searching it turned out to be a big end, it didn't seem to me to be the sort of noise I would have expected from the crank and the rattle didn't come in until the revs were a lot higher than I would have expected , hope I'm wrong in your problem but it could be worth considering

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TIT#79A

If you have had the rocker cover off, sorry cam cover showing me age, you would have seen a busted spring. Would be unusual on a newish bike to have a weak spring, it should have duplex springs to prevent bounce. Check the clearences, balance the carbs and see if it goes.

valves are well hidden in the guides, removing the lifters (covers that the cam shaft lobes press on to open the valves) only reveals the top of the valve - not enuff to see the springs.
Bike has two springs per valve according to Haynes.
Will derust my feller gauges and try to check the clearances. If these were well out could this cause a loud rattle?

Never seen a broken valve spring in my life, I'd be very surprised if its that. More likely you have damaged a valve eif you have overreved it.

Have you checked carefully for anything astry. Are all the shims/adjusters in place, are the camsprocket screws accounted for. Turn the motor over and check the camchain is ok.

What was the oil like when you dropped it? Any bits in it? Where the plugs ok, any white spots are oil and are
bad news, usually damaged piston/rings.

Whats the compression test figures like?

Try and delay pulling the head as the head gaskit is always expensive.

Kev

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DISCLAIMER:
Application of the procedures described herein is at your own risk. Myself or other Visordown members have submitted this information in good faith, without charge but neither myself, members nor admin will be held responsible for any injury, damage or loss whosoever caused resulting from your use of these procedures or Information. This infomation is not intended to replace your repair manuals, your common sense, or your responsibility for your choices and actions.

http://www.eddnet.com/kev

thanks for all the advice,

demon u.k - crack on with the bottom end diagnosis. Removed the cylinder head and inspected the valves - didn't look to bad. Span the crank around a little to watch the pistons bob up and down (small things - small mind) and tapped each piston top - one bugger moved downwards when pushed (about 3 mm). Off with the barrel to reveal that a big end bearing had bitten the dust!

Bugger!

Whats it done spun the bearing in the rod?

Has it damaged the Rod or Crank? Im not sure you can Identify what shell thickness it is without a plastigauge.

Nightmare!!!

Might be easier to get another motor?

KFZ

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DISCLAIMER:
Application of the procedures described herein is at your own risk. Myself or other Visordown members have submitted this information in good faith, without charge but neither myself, members nor admin will be held responsible for any injury, damage or loss whosoever caused resulting from your use of these procedures or Information. This infomation is not intended to replace your repair manuals, your common sense, or your responsibility for your choices and actions.

http://www.eddnet.com/kev

Sorry to hear that mate
but hopefully this might be of help it's old so some of the area codes will be out of date but worth a try for parts.
www.all4bikers.com/breakers/index.asp
a trick I used to pull occasionally with the older hondas was putting second hand cranks into rebuilds complete with the cranks shells (mains) and honda were notorious for having individual size journals and seats, all I did was fit the shells into the cases in the seat corresponding to the journal that they came from then lubed them with nice new oil before torqueing them down, whilst torqueing I would rotate the crank to "feel" if they were going tight (I never had any probs) and I was never known for being kind to my engines and just pottering around, cranks and big ends "float" on a cushion of oil so unless it is tight or your oil pressure is iffy you should get away with it but if you do this you MUST see the engine being split and TAPE the shells to the journals to avoid them being put back in the wrong places.
I AM NOT GOING TO GUARANTEE THIS OK AS YOUR BIKE IS DIFFERENT TO MINE AND YOUR RIDING STYLE MAY BE DIFFERENT ALSO YOU MUST TREAT THE ENGINE AS A REBUILD AS WITH NEW PARTS.
oh p.s. your crank is buggered with 3 mill' of movement

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TIT#79A

thanks for all the advice,

think i'll get a 2nd hand motor as the the cost of the repair will be too costly to justify. (piston had made contact with 2 of the valves). What with the price of gaskets etc and the risk of me screwing up the rebuild I may as well fork out for another mill and fit that. (ill get one with a 30 day guarentee).

thanks again

jjones

ok mate just don't throw ANYTHING away out of your old motor cos it's ALL useful spares should you need them in the future

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TIT#79A