Vibrations at hig revs

[Satoru]

My TRX has 66.000km on the clock and about 10-12.000 ago (3 years) I had it serviced for valve clearance, carb synch and the likes.
Since then I have only made regular service (oil and filter) and had no significant problem.

In July, in a very hot day (32C), I took a relaxed ride here http://www.cremonacircuit.it/shop/en/ when I started to notice a significant increase in vibration from 3500rpm up to the limiter.
This was accompained with the feeling of the motorbike not pulling hard as usual: top speed on the long straight was 185km/h (GPS) near redline in 4th.
The vibration is worse when the throttle is fully open and almost non-existant when it is closed.
During one of the sessions the welded attach of the left exhaust can broke, potentially because of this vibration; after fixing it to the frame again with some straps I completed the day.
Vibration is tied to RPMs not to speed.

I have washed and re-oiled the K&N air filter, but the problem did not improve.
Temperature now is down to a fresher 18C, but the problem is still there.
The oil is Shell 10W40 fully synthetic, the same type I've used since my purchase in 2012.

What should I check in order of likelyhood?
Spark plugs? Synchronization?

[dandywarhol]

Check all the engine mountings are tight and that there are no cracks.

Is there any noise to accompany the vibration?

It won't be the chain as you say it is rpm related.

[Satoru]

Ok, I'll check the mountings and report back.

I don't notice new noises: my TRX has never been very quiet since I purchased it.
At least not compared to my former 1999 GPZ500S (aka EX500).

I did a bit of highway coming back home a couple of hours ago and I can confirm it is throttle related almost no vibration if i pull the clutch and let the revs go down.

Idles well.
Vibration is there both with cold and warm engine.

I might have to change the steering bearings, but I have to wait at least until I get to change the real wheel bearings of the other motorbike.

Too bad the mechanic that did the job in the past has moved to another country!

[cobbadiggabuddyblooo]

Did you fill up your motorcycle with fuel before you went for the ride??
What fuel do you run in your bike???
If you got bad fuel with a low octane rating you may be going into detonation.

[dandywarhol]

You would need to be running on kerosene to have a stock TRX motor to detonate Cobba. Not even Italian fuel is that bad

[Satoru]

Did you fill up your motorcycle with fuel before you went for the ride??
What fuel do you run in your bike???
If you got bad fuel with a low octane rating you may be going into detonation.

I have filled the thank a few times always in different places since I started having the issue and the situation didn't change: vibration is with me for at least 500km now.
The base petrol in Italy is 95 octanes.
Anyway I can give a try at premium (100) or with an octane booster.

Check all the engine mountings are tight and that there are no cracks.

Just checked: I see no cracks nor culd find any loose mounting bolt.

Releasing the gas at high revs (with the clutch engaged so they don't drop immediately) gets rid of the new vibrations.

stock TRX motor

Engine is stock, exhaust is stock. Only different from factory shipping engine wise is the air filter. The filter has been there since I purchased the bike.

[dandywarhol]

I'm hoping it isn't the start of a crank big end failure
That's why I asked if it is accompanied by noise. Big end failure tends to start as a vibration and a "heavy " rumble noise and happens under engine load.
Sorry to worry you but I feel it is worth mentioning it.

[Satoru]

crank big end failure

My mechanical english is not good enough to understand exactly what this failure is (and hence what it implies).
Could you elaborate a bit?

Sorry to worry you but I feel it is worth mentioning it

I can confirm I'm worried now!

[dandywarhol]

The TRX/TDM engine is known for the left crank bearing to fail if the oil level gets low.
Search TDM Italia for the problem

[Overlord Neil]

Following on from Cobba's suggestion of fueling, could it be ignition related? Does the standard ECU get gremlins in later life, assuming Satoru's bike is running the stock ECU.

Only reason I pose the theory is that I've been 'tinkering' (aka meddling with more enthusiasm than knowledge) with the ignitech box on my bike. I've heavily advanced the ignition and it purrs like a kitten at low engine speed and will happily sit at 70mph (110Km ish) at 3,500rpm on the highway. However this morning I took a twisty road in and the thing rides like a dog in the higher rev range (4k+) theres no actual vibration but it struggles to reach the redline ad rides really lumpy and anemic.

The problem does sound mechanical to me, but it might be a collection of minor problems that produce a big effect, rather than a single big problem?

[cobbadiggabuddyblooo]

That's because you over advanced the ignition..
Your base curve should stay pretty close to default but your advance is usually in the percentages of throttle.
you may get by with a little more advance down low but again this may just be because of an over rich fuel mix.
http://www.trx850.com/phpBB_forum/viewt ... 7&start=45



As for detonation, there was a photo of a std TRX posted a couple of years ago with a rod split down the middle with the top snapped off due to detonation.
Bad fuel with a Lower octane will preignite earlier plus it will burn faster.

The std ECU timing is retarded till around the 4-4500rpm mark so if you have bad fuel it will be masked a little until you start to open the bike up and if the carby is also running richer due to worn needles, the major problems would really start until your starting to rev and load the motor higher up in the rev range.

Any pre ignition from over advanced ignition or bad fuel will only stress the crank bearings and good oil pressure is dependent on minimum wear on the crank bearings.

[Overlord Neil]

'tinkering' (aka meddling with more enthusiasm than knowledge)?

Amen to that Cobba, fortunately I haven't managed to blow it up... yet! As a double kick in the pants my economy dropped as well.

[Satoru]

assuming Satoru's bike is running the stock ECU.

Definetely stock ECU

Search TDM Italia for the problem

!
I got registered on the site. There are a few references, but is hard to tell if it is the issue.
I'll try and ask if anyone in my area has had the problem and can check riding my bike.

over advanced ignition

Did not touch anything in that area.
And had a few sessions (albeit at a different slower track) earlier in the year with no problem.
After each session I check the oil level and refill as/if needed.
Italy is not famous for problematic petrol, anyway I have filled up from different places with no change in throttle behavior.

[Satoru]

There it is any check or test I can conduct without opening the engine?
Sharing a recording of the engine noise when running in neutral (at different revs) might help you guys tell if it is the bearing or something else?
Bearing failure would be progressive (in how many km?) or should I expect a sudden fail?
If so what kind of behavior should I expect from the engine?

[Satoru]

The videos here can help in the diagnosis?
https://www.youtube.com/watch?v=cVhOtMToVw4
https://www.youtube.com/watch?v=LAj8FUAxRh4
https://www.youtube.com/watch?v=Ljj_G8zztT8

While I was fiddling with the bike I changed the spark plugs.
Old ones (turns out they were NGK DPR8EA-9)had a gap of about .88/.89 (.85 had some play while .90 gauge would need a bit of forcing)
Recording is already with the new ones (NGK DPR9EA-9).