Speed specific vibration

[Smitt]

my 'as-yet-undiagnosed-paranoid-newby-sound' is a strange vibration/rattle that occurs briefly at around 60kph when in first (following a reasonably solid take off). Cuts out at around 75kph, but it is an odd rattle with a distinct vibration. One positive: it's consistent

I picked the bike up 2nd hand with 6k on it. Done 7.5k now. Thoughts??

[El Paso Joe]

Smitt,

Have you ever experienced improperly balanced tires? Does it feel like that?

[Smitt]

a long time ago and no - not tyre related

It's a distinct engine vibration (although I could almost be tempted to say a front sprocket or chain-related feel pehaps) (I've looked at the chain thread and I don't think it is chain slap).

[MacBandit]

Double check your chain adjustment many people get it wrong on these bikes. Some bikes require the rear wheel to be unloaded but the Triumph the wheel has to be on the ground and there has been more than one reported chain spec.

[amanger]

Ummmmm.... you have another 5 gears, does it do it in them as well at the same rpm. 1st isn t really designed for 60-75 km/h.

[Diego]

Good points in the two preceding messages. Since none of us can know if what we take from the description is exactly what you mean, it will be hard to offer any more specific opinions without further data. It could be a chain-related vibration as Mac says, or it could just be a normal resonance buzz at the particular RPM range. No way to distinguish right now. If you could check out other gears and speeds as amanger suggests, that would be helpful.

[Smitt]

good points and good questions.

I will check it out on the weekend (ie. different gears and chain slack) and let you know.

I must admit, I feel like a paranoid git - but I appreciate the feedback.

At the end of the day, I would prefer to be told I'm just being paranoid as opposed to finding out later it was a known problem and a dozen fellow striple riders could have told me if I had of just asked...

stay tuned

[Diego]

That's sound reasoning. Always best to learn whether something is a real problem while there's time to deal with it, than to just hope it's not and have the consequences jump up to bite you later.

[Smitt]

Update:
It appears it's not just me.... (although maybe I'm being taken for a ride...)

took it back to the shop so the rep could take it for a spin and he agreed there was a light vibration, but can't diagnose it (yet).

I now have 3 liquid paper marks on my throttle (1/4, half, 3/4) so I can pin point the rev range and throttle speed in different gears when it occurs.

I have also been told to change fuels from Shell V Ultra high octane (apparently a real 'no no' ??) to BP 95 or 98. (First I heard??)

the plot thickens...

[Diego]

From those octane numbers, I take it you're not in the U.S.