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Discussion Starter · #1 ·
My '55 T100 has developed a worrying noise from what sounds like the top end. Bit of background first:

Bike was running fine and over the winter I fitted a filter in the return line. Did about 200 miles on it and all fine. Then set off for a 300 mile weekend trip during which it developed a rattle that sounded like it was from the top end when coming to idle and when engine/oil quite hot. Still ran ok and rattle came and went. The rattle sounded like a massive clearance on a tappet.

Got home and checked all levels etc and now the idle rattle has gone but now it has developed a rattle at anything over about 3k revs. So I checked and reset the tappets, rockers have side float but not enough to let them slip off the valve, primary chain ok, can't find any loose fasteners, oil returns under pressure to tank, still rattles when fully retarded.

Basically it runs, pulls and sounds fine up till 3k ish when you start hearing a tappety noise, either under load or downhill. Can't really hear much wrong when revved in neutral. Noise is definitely revs related not speed.

Should I try it without the filter? Could it be starving the top end of oil? Any other ideas??!

Thanks in advance
 

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Have a good look at primary chain tension.The chain will rattle if too slack as it beats into the cases.Just a quick check.This noise happened when my primary adjustment rod snapped.Bear in mind i have a unit 650 engine though so may not be that at all.
 

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This is probably a shot in the dark and may seem silly.

My bike developed what sounded like a top end rattle at high RPMs that turned out to be a loose tank badge. Tightened two screws that had backed out slightly on one side and the noise went away.

Just a suggestion...
 

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Bikeman, interesting comment to which I can relate. I also had/have hi revs rattle which I located inadvertently though mine was the kneepad rubber (they are original and very stiff) and at high revs would vibrate. When I say I located the source inadvertently it was when I gripped the tank with my knees to get my head low to the tank for a better listen that the rattle disappeared...which pleased me no end!!

Japes, mate I hope yours is as simple also!
 

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This is probably a shot in the dark and may seem silly.

My bike developed what sounded like a top end rattle at high RPMs that turned out to be a loose tank badge. Tightened two screws that had backed out slightly on one side and the noise went away.

Just a suggestion...
The tank is a great amplifier.

The tank may be touching the frame somewhere it shouldn't, or a throttle cable may be vibrating against the bottom of the tank.
 

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Are you sure you aren't experiencing pinging / pre-ignition?

Sounds like it to me. (hee hee like I can hear it over the internet...)

Pre-ignition sounds like a top end rattle, and your rev range is about where I'd expect it, under load.

Coincidentally, your closing "Thanks in advance" points to the culprit of pre-ignition TOO MUCH ADVANCE! (on the timing)
 

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Are you sure you aren't experiencing pinging / pre-ignition?

Sounds like it to me. (hee hee like I can hear it over the internet...)

Pre-ignition sounds like a top end rattle, and your rev range is about where I'd expect it, under load.

Coincidentally, your closing "Thanks in advance" points to the culprit of pre-ignition TOO MUCH ADVANCE! (on the timing)
Your advice seems unlikely to be right, because:

when coming to idle
Not pinking or pre-ignition.

The rattle sounded like a massive clearance on a tappet.
Pinking and pre-ignition don't make a noise like a big valve clearance.

still rattles when fully retarded.
Not likely to be over advanced then.

either under load or downhill.
Not just under load.


Could it be starving the top end of oil? Any other ideas??!
Now I'll leave off arguing with GP. He's right you have to check timing carefully.

How do the plugs look? Much exhaust or breather smoke?

The usual obvious symptom of a dry top end is squeaking rockers. Try it without the filter if you like, but return line filters don't usually cause any problems.

Something that does make a noise like a big valve clearance is a valve sticky in its guide, but that causes a miss as well.

If you run the bike with no petrol tank and it still rattles, I think you're going to have to look into the top end.
 

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Yes, because the sound is now when running above 3KRPM.

And it's sounding (no pun intended) more like it could possibly compounding / multiple issues.

Either way, it needs a detailed inspection.
I really don't know what the problem is. If it was my bike right here, I expect I'd find the issue fairly quick.

The rattle has one cause. Every other suggestion is "wrong."
 

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Discussion Starter · #12 ·
Sorry for not replying sooner, been on a run out and trying to do some more diagnosing this noise.

Firstly, there is no such thing as a daft suggestion in this case, all are helpful and welcome!

Checked the various rattle suggestions - no luck. Not had the tank fully off though so might try that just in case, looks pretty clear though. Found the tax disc holder with loose rivets so removed it hopefully but not that.

Primary chain seems about right and oil is clean with no sign of ally particles.

The sound I'm hearing is very much like pinking but its definitely not that, I've got manual adv/ret so can experiment easily. Also it does it downhill with it hardly pulling.

Checked the plugs and both look normal and a nice light brown.

Ridden it again tonight and it seems to be slightly better (ie less noise) when cold so maybe it is oil related. Oil by the way is 20/50 and the same I've been using all the time I've had it. Oil has done about 600 miles and is remarkably clean since fitting the filter.

Having listened to it again tonight I realise it is doing it a bit when revved in neutral as well. As much as I would love it to be a rattling fastener I'm fairly sure it's something more sinister, in fact I'd probably say it's more of a tapping or light knock than a high frequency rattle.

I'll do a check with the tank off and a quick re plumb to eliminate the filter but if that doesn't work I think I'll have to start stripping the top end. The suggestion of a broken guide is a good one and I guess I could check for obvious signs of valve trouble through the ports and rocker boxes.

I'd better get reading the manuals in preparation for a possible strip down!

Thanks again for all the suggestions.
 

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IDK if a 55 tiger has exhaust spigots but if it does check for loose spigots in the head and the exhaust system in general. I had a nasty clatter below 3k RPM that would disappear with increased revs or pulling the clutch in. A primary chain adjustment fixed that. Your problem sounds like it increases with rpm.
 

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If you can hear it, even slightly, when you rev it in neutral, here's an old trick: use a piece or rubber hose as a stethoscope while a friend does the revving. With no small amount of luck, you may be able to pinpoint the area of the noise. It's worth a shot.......
From the highly "scrambled" archives of the "village idiot's" fading memories: Jim
 
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It sounds like it could be a loose guide. Get a long screw driver. Cup the handle to your ear. Move the tip around the cylinder head, and then to other places you suspect it might be coming. Do this as someone works the throttle. Better yet get a mechanics stethoscope.
 

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Discussion Starter · #18 ·
Good idea on the screwdriver or hose to the ear trick, could be a bit deafening though, it's a noisy engine at the best of times!

It's not chain or transmission related, it happens at the same revs no matter what gear you are in. Plus can be made to do it in neutral. It really does sound like the top end of the engine and more on the left side.

I checked the exhaust clamps and spigots last night as i thought it could be a noisy leak right to the head but all seemed fine.

Yes TT, it's the all alloy close finned engine (which does exaggerate all noises!) so I'm hoping it's not anything as drastic as a loose liner.

I'll be having another look tonight so I'll report back.
 
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