I have posted this earlier as part of another thread and thank you for the suggestions however I have now serviced the bike and tightened all that needs to be secure and correct except the valve clearance which will be done by a mechanic who is far more proffesional and way better than me and also has the right tools.

He however is an hours drive away and is so busy it won't be till the end of May.

What I have is an engine that starts and sounds perfect, engages gear 1st and 2nd with no problems, once into 3rd there is a "slapping" noise from within it is like a loose chain flapping. into 4th it isn't too bad all though still in the background.

I haven't travelled further as I don't want to risk the higher rev's/speed.

Could it be low rev noise, a damaged gear selector?

The sump plug was removed and the sump totally wiped out with a rag and magnet with no metal fragments found- it was also clear that the plug had been on for some considerable time before my removal.

At some time in the past there had been a drive chain snap on the bike - the present one is worn but still very usable so bike has been ridden for some distance after the chain broke.

Mileage is 30,000 UK miles.

Any ideas to maybe put my mind at rest before pushng me into actually stripping the engine would be appreciated as assuming I get the MOT (the British road test) today this is going to be (hopefully ?????) a rolling restoration.

thanks

Stiv

I think you may have answered your own question. To test if the chain and sprockets are worn. First make a visual inspection of the front and back sprockets, the teeth should look even, not hooked on one side. The engine sprocket is particularly prone to wearing, if this is ok try to lift the chain from the rear sprocket about half way round, if you can lift it at all it is worn. The chain and sprockets should be renewed together.

Mike

Put the bike on the main stand, and make sure it is very stable, with plenty of clearance under the rear wheel. If there is less than an inch clearance, add chocks under the main stand. Start her up and let her idle, standing next to the bike. Pull in the clutch, select first gear, and gently release the clutch. Continue through to third gear. The rear wheel will be spinning pretty fast, but if there is plenty of clearance under it, she'll be OK. You can hold the bars to steady her. Listen carefully to locate the source of the noise.

You could perform a similar test (without the noise of the motor) by removing the spark plugs and turning the rear wheel by hand.

I have already checked the chain an there is no problem with the sprockets or line up etc.

This noise is from the Gearbox area. I shall try running on the stand tomorrow.

The bike passed the UK test so I have done about 12 miles today locally trying out the full range of gears and third is the noisy gear whatever the speed.

One thought on my other thread was compression if any one could explain this further I would appreciate it.

no specific ideas (per se) but a little advice...

if it makes awful noises something is wrong - and its probably not going to self-fix.
It might be OK to run it for a while but think about how you'll feel if you put a shaft thru the case...

I know we have all heard noises and eventually found that they weren't much BUT you're probably going to have to fix it eventually - don't risk further damage.
most likely it is the selector - but I dunno...sometimes you can feel a difference in pedal throw length when changing.
if it is a selector the gear dogs may not be fully engaged - which can develop into a problem - eventually popping out of gear under load.
this happened to 2nd gear on my XS1100.
the gears need to be replaced if the dogs get damaged.

picking up a bike that has been mistreated could leave you all sorts of surprises...
some guys do clutchless changes - no probs if you have mastered the art, a little less positive if you get it wrong gearing down 4th to 3rd...

the box is probably full of high quality synthetic oil - so if you can hear noises there is a fair bit of pressure, misalignment and associated rough play going on...

if it only happens in 3rd gear - avoid 3rd gear...
I drove a 3 speed Chrysler for 2 years with no synchro in 2nd - I just didn't use 2nd gear...you have 5 more to chose from...lol

bite the bullet and split the cases...

or get some 80 weight gear oil into it and squint while you ride...

I have run it again and the result.............................?





Stripping it down and a getting it sorted didn't want to but hell who wants blow a unique engine - certainly not me.

Will let you know the result of what bits are broke but it sounds like a tooth is a miss somewhere

IIRC,
if you strip clutch side totally I think you can see a small bit of gearbox.
Maybe a possibility to see missing teeth?

Will try that but resigned to spliting the engine.