Right then, a few years ago I rebuilt the rear cylinder with a new barrel and piston after it blew from overheating (put a hole in the piston whilst doing 130mph).
The rebuild was successful, bike fired up first time and ran as per norm. However, after doing about 1,500 miles the rear cylinder has developed some noise which sounds like something is loose and is rattling, giving an intermittent high pitched "pinging" noise.
The bike runs fine though with no lose of power.

I've removed the rocker covers (all three), and everything looks OK (didn't find anything loose, no sign of wear or damage and no metal filings). However, despite having the rear piston at TDC, i noticed that as i slackened and loosened the last few bolts on the last rocker cover, the one with the rockers mounted in it, the push rods where pushing against the rocker cover forcing it up by a few millimeters. Is that to be expected? Could that be cause of the noise?

My next stage in problem finding and solving is to remove the cylinder head, which entails removing the exhaust and carb. So. I'd thought I'd better check first with those who might know better. Perhaps someone has done a rebuild before and experienced the same problem?!

Thanks in advance for any help,

Cheers,
fred.

How do Fred, what bike?

And err how the hell do you do 130 on Jersy?

Nate.

have a look at his signature

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I intend to live forever.....................................so far, so good!

Same way that you do elsewhere...

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Oooops, sorry Fred

n.

No worries Nate. Yup it's a S1WL 1998.
And, no, I wasn't in Jersey when it blew.

You need to ask Maz dude.

Nate

are you sure you was on the compression stroke when you had the piston at TDC?

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Yup, both valves where shut. I was watching the rocker arms and poking a pen down the spark plug hole to make sure that the piston was at TDC, whilst turning the rear wheel with the bike in gear. Ain't it hard work though, turning the rear wheel! I was half lifting the rear end up, bit of a struggle. (obviously the rear of the bike is raised off the floor, and i have removed the spark plug from the front cylinder as well!)

Come on then, have I got a problem with the push rods, or do i have to remove the head and inspect the piston?

When you refitted the rockers did you follow the correct procedure as in the manual or just bolt them down? Unless it's done very slowly, you'll bend valves, break guides etc etc. I've even known dealer serviced bikes suffer from this.

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I intend to live forever.....................................so far, so good!

No ......you did have the bike in 5th gear didn't you ?.......my 13 year old son can do this with one hand, no probs

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No I didn't! Didn't know about that little trick. Makes sense now when i think about it! Engine revolutions v wheel revolutions.

Might be a good idea to put it in 5th now and give the wheel a slight turn to see if the rods drop down a bit? But should they be putting pressure on the rockers when assembled? And is there a set measurement for the amount of push rod proud of the cylinder head when the piston is at TDC?

Assuming that you have the pushrods the right way round (they are different lengths) you need to follow the manual advice on re-assembly, so that the hydraulic lifters bleed down properly. When the pushrods are located correctly and the rockerbox is torqued down, you should still be able to rotate the pushrods by hand.

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I started out with nothing and still got most of it left.