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Hi,

1987 GSXR 1100 - Engine has Wiseco pistons bored out to 1109. Done maybe 6000 kms since rebuild.

Std Cam and springs. Head had a bit of work with ports cleaned up. Idles fine, performs fine. But a bit of a rattle with revs, sounds like top end, maybe cams?

Popped rocket cover and checked and set valve clearances, all good.

Any clue on the noise?

Plan on doing a compression test later this week.

 

 

Edited by kiwisuzuki1100nz
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As said above but when you removed the cam cover did you also check the bolts that hold the cam sprockets to the cams? I am guessing these are probably fine as you checked the valve clearances but if these work loose/fail it can all end in tears:(

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Thanks for all the suggestions, appreciated. The rattle is easier to hear with the 2 revs at 32 33 secs.

Ill do the compression test rule out ring and values, drop the oil and check,, pop the cam cover again and check cam chain tension and cam bolts.

I think this time ill actually pull the cams out checking the bolts and the bearing surfaces. Typical as  I have a race in 4 weeks.

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Compression Test Results:

Manual Std Compression: 142 - 199 psi

Min: 114 psi

Max Variable: 28 psi

Bike Results       Initial psi / Final psi

Cylinder 1: 140 / 178

Cylinder 2: 140 / 180

Cylinder 3: 140 / 170

Cylinder 4: 140 / 175

Keeping in mind it is an 1109 with high compression wiseco pistons. Also I haven't ever done a compression test on a slabbie but followed manual instructions

Diagnoses:  Initial of 140 psi I will assume is great on first crank? If so valves are sealing well . Built to max pressure quickly so rings good. Variation within 10 psi so within spec and less than 10% variation.

So looks like rings and pistons fine and values sealing which leaves the possible noise source as maybe

  • Cam shafts loose in caps - cap bolt loose or snapped
  • Cam chain - Probably not - wrong noise

I'll drop the oil out of the engine next and then tear down the top and and check camshafts and cap journals etc...

Sweating that I have buggered cam journals

Anything else to check or consider?

 

Edited by kiwisuzuki1100nz
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The tappets are fine, compression is good and it performs fine. You can hear it is not running smooth at low revs so balance the carbs, check the cam chain tensioner is working properly and you have no exhaust leaks. With the carbs out of balance the load will cycle as it runs through the firing order and everything will "chatter". Even if it doesn't stop all the noise, at least you will be left with what is causing it and got rid of the background noise. Do the basics first before you go looking for doom and gloom ( I think we've all heard the one about the full engine rebuild when it was the keys rattling on the top yoke all the time ).

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4 hours ago, bluedog59 said:

The tappets are fine, compression is good and it performs fine. You can hear it is not running smooth at low revs so balance the carbs, check the cam chain tensioner is working properly and you have no exhaust leaks. With the carbs out of balance the load will cycle as it runs through the firing order and everything will "chatter". Even if it doesn't stop all the noise, at least you will be left with what is causing it and got rid of the background noise. Do the basics first before you go looking for doom and gloom ( I think we've all heard the one about the full engine rebuild when it was the keys rattling on the top yoke all the time ).

@bluedog59Thanks good advice. The carbs are flat sliders and chatter at idle, they have been balanced but will check again

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Cam chain was tight and not loose. Idler sprocket bearings fine. All cam caps still tight no bolts broken. 1 cam bearing showing some blue so possibly a bit tight wit cam cap and binding and overheating.

No major galling on cam surfaces. Bit at a loss.

Any concerns looking at the photos?

Will look to spruce the cam chain tensioner.

Have a few cam caps to helicoil as cylinder head cover threads stripped on a few.

 

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Edited by kiwisuzuki1100nz
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