t 3 engine noise

Hi all
I have a worrying noise coming from my right cylinder :confused: any opinions or experience of anything similar?
symptoms are as follows-
from tick over to 3 thousand rpm all is quiet and normal sounds good
however if i venture over 3 thou into the 3 to 4 thousand rev range on a neutral or lightly rising throttle i get a noise similar to tappet chatter only a good deal louder! over 4 thou less noticible but probably just lost to wind noise.

The terms i would use to describe the noise are metallic ringing resonance,clatter,or clanking pretty much like the normal tappet noise but magnified four to five times in volume! with a harsher sound to each impact!.

If i back off the throttle the noise subsides ,but can still be heard, any slow increase in throttle opening brings it back- if you accelerate harder it is less noticeable.
There is no noticeable lack of power i have no smoke from exhausts or engine breather and there has been no change in oil consumption, engine ticks over well ,ignition is electronic and spot on the tappets have been reset twice to correct values with no change, the left cylinder runs normally. both spark plugs display the same light tan on the electrode.
Being honest the noise has probably been present for a while- only at a more subdued level to which i had become accustomed
i only noticed it when i had to do a long motorway trip (something i rarely do these days) where i held the revs higher for longer and since then i guess i find it more intrusive as i am expecting to hear it!.
i will be very grateful for any feedback or ideas from the comunitty
thanks very much in advance to anyone with any info
Steve m

exhaust down pipe touching the lower frame bolt

God call on the exhaust rattling against the engine bolt.
If that looks OK, it would be worthwhile checking your tappets, make sure all is OK in the top end.
Great way that I use to set the tappets is the ICEO method:- Inlet closing exhaust opening
Remove the rocker covers and plugs and put the bike in top gear. Roll the bike forwards until an exhaust valve just starts to open. Without moving the bike, set the inlet tappet on the same side. Next roll the bike back till the inlet valve just starts to open. Now set the exhaust tappet for that same cylinder.
Then repeat for the other side.
No chance of getting your destros and sinisters mixed up.
Raceco recommend 0.20mm for the inlet and 0.25mm for the exhaust slightly wider than the factory recommended 0.10mm and 0.15mm .

First of all try finding out where the noise is coming from. Use a long screw driver and put against engine in various places and press handle to ear. Work down from the top of the engine, valve area, cylinders, cam area, distributor, alternator cover. Do it when engine at operating temp. When you have done this get back to me if you think you have found the location.
All the best Julian

Hi, i recently had a very similar issue with my fully rebuilt mk2 le mans and it was driving me up the wall!, stopping at the side of the road hitting the right revs to locate the noise as i thought it was a problem with the valve gear but in the end i located the noise and it was a loose hinge pin on the petrol flap! Which caused the flap to resonate between certain rev ranges, the noise it made really sounded like rattling valve gear, so glad it wasn’t! all the best with it, Chris.

I would check the side stand is not clattering against downpipe, i.e. put a rubber bung on resting post.
worn clutch lever can vibrate
Tappets should clatter at tick over and low revs but quieten down under load.
a more constant and loud metallic clatter could mean a worn little end - gudgeon pin
rattling from the front of the engine more likely to be timing chain.
You should also check that noise isn’t coming from the alternator, loosen the cover bolts a bit and see if it goes away.

Hopefully the noise is just something rattling, but I had a very similar noise from my Ural (also an air-cooled twin), which turned out to be a valve guide wearing out. If you have the rocker cover off, it’s easy to diagnose, as the valve and spring could be waggled about by hand. Easy enough to sort out as well. Francjul’s advice about using a screwdriver to isolate where the noise is actually coming from is sound (forgive the pun…)

Mine was doing something similar…I suspected guides and was right. Chromed bores also shagged but probably not the cause of noise.

I think small end is a good call as well as worn rings and a bit of piston slap. Does it improve marginally after about 10 miles when it is properly warmed up? Mechanics stephoscope is a useful tool if you can borrow one.

Have you done anything to it recently? Check exhaust clamp at cyl head nuts are tight, I have had them come loose then it starts blowing a bit, and sounds a bit mechanical.

Also I have set one cyl’s tappets at the wrong flywheel position, rattled like buggery and ditto I was convinced small end bush was knackered, took barrel to bits, nothing wrong with it. Mucho kicking of own arse when I worked out what i did… :smiley:

That’s why I use the Inlet closing , exhaust opening method.