Balancer shaft adjustment confusion

StabEDealin said:
First time posting on this site, been lurking for a while. So hello all! I love this bike and am very sad it’s not still in production.

On topic though, this is such a maddening subject for me. I like to keep things mechanically sound, but this adjustment seems so subjective that I can’t even parse out if I need to do it.

Others say this engine is buttery smooth and can’t even tell the bike is running. To me, it’s not that smooth…and my last bike was an old Harley. In my best description the engine is incredibly smooth up to about 4,000rpm and then I start to feel some vibration coinciding with engine speed and throttle increase. Not alarming, just hard to know when it’s actually out of spec.

Sorry for the ranting and raving, and it’s good to see this community is still busy.
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Would not have anything to do with the balance shaft adj...

Likely it's wheels/tires (bad tire or missing wheel weights) or possibly a u-joint going bad.

Put your bike on the centerstand and in neutral, spin the tire. Other than brake pad noise, do you hear anything that might sound like thumping or once the tire stops, does it spin back the other direction, just a few millimeters? That's usually the u-joint binding and getting ready to fail.
 
Sorry, I should say it’s only with the application of throttle. For example, say I rev it out to 8k and let off the throttle it won’t do it.

I actually had done all of the above to find a cracked rear disc, wheel does spin freely.

This bike only has 20,000 miles on it and could still be breaking in for all I know lol
 
StabEDealin said:
Sorry, I should say it’s only with the application of throttle. For example, say I rev it out to 8k and let off the throttle it won’t do it.

I actually had done all of the above to find a cracked rear disc, wheel does spin freely.

This bike only has 20,000 miles on it and could still be breaking in for all I know lol
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In that case, it's possibly spark related so check your plug wires and plugs.
 
I can't say tha I have felt additional vibration when the balance shafts are out. The adjustment doesn't really affect the weights that are spinning round to conteract the crank shaft. The adjustment is just to make the gears mesh more closely or less closely. Too close, they whine a bit. Too far away and they rattle a bit.

Our brains hear a rattle and feel a vibration and they put two and two together, link the sound with the vibration and and come up with a very expensive solution. Put earplugs in and see what you feel then !

This is throwing solutions at a problem - but that isn't my intention. Just little anecdotes which may or may not be relevant, listed in order of cost to fix. I have had vibration caused by:
  • Moving my exhaust pipe out of the way and breaking the seal (3rd party downpipes/collector, sealed with exhaust paste. The escaping gasses casued vibration through the pegs and the bars as one side of the engine had more back pressure than the other. (Free to fix).
  • House keys rattling in the fairing pocket. My brain decided that the noise had to have vibration with it, and that is what I described when I asked for ideas. Free to fix.
  • ST1300 Starter Valve balance. Dealer said there was no need to adjust them, the ECU takes care of it all. Wrong ! When I eventually got round to balancing them, the difference in smoothness and in acceleration and fuel economy was VERY noticeable. (Free to fix if you already have a Morgan Carbtune).
  • Spark plugs not fitted properly. Well - they were torqued to the correct value, but engine was rough, resulting in vibration. It turned out to be the new spark plugs. The captive compression washer had been at a slight angle - caught on the threads, so it prevented the plug from sealing properly. As a result, there was an air and exhaust leak and a small loss of compression in one cylinder. Free to fix. Took plugs out. Found one with the slightly skewed compression washer. Refitted. Fixed.
  • Plug leads. Poor ignition caused by faulty leads and plug caps. Lumpy riding like riding a rough road surface. Got worse and would not pull smoothly unless high revs were used. Cost quite a bit replacing all plug caps and all leads.
    If you are thinking it may be this, I wrote something about my experience here - I've just checked the link and it is not working at present. I'll check back later. If it is still not there, I'll put it in a new thread.
 
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