The one thing i don't like about my ST4 is the tingling through the bars at sustained motorway speeds. In normal riding it's not really a problem as I tend to avoid motorways, but a recent tour to the north west coast of Scotland meant going up the motorway at high speed and this highlighted a problem with vibes through the 'bars. It made my hands go numb after an hour or so, forcing a break at a services to bring back some feeling to my hands. I've heard about foam overgrips such as Grip Puppies, but do they actually help? Any other suggestions?
Another route to eliminating this is to add weight to the bar ends, I’ve used this method before on large capacity singles with great success. You can wrap plumbing solder round the bar ends or add wheel weights inside the bar ends, the trick is to find the right weight to eliminate the tingle at the revs you normally cruise at.
Foam grips can only help with symptoms , and don't do a thing about the root causes . For what it's worth ..... I've had my ST4 for over 20 years and I've put about eighty thousand miles on it , most of it being high-speed , long-distance touring ( it's the reason that I bought it ! ) I've never experienced any handlebar vibrations at all ..... even with loaded panniers , a tent-roll and gf on the back ! My personal opinion is that it was a pretty much perfect design , straight out of the crate , although I did tweak my front suspension settings a wee bit . Assuming that you have the standard OEM bar-end weights fitted ( they are quite hefty ) , I'd be looking at how these " bad vibes " are being fed to your handlebars , and the possible culprits. 1] the front wheel - check for any play or wear in the bearings , and also look for any signs of balance weights having been thrown off the rim . 2] possibly a slight out-of-balance between the injectors .... .... this is set by a white plastic adjuster , on a threaded rod linking the two throttle bodies . A set of vacuum gauges is the best way to be certain , but TBH , I can tell by ear now ( and by " gut-feeling" ..... whatever that is ? ) But that's only my two Chetrums worth ....
Well, I fitted the foam grips so will have to see what effect they have. I'm pretty sure my bike doesn't have any underlying issues and it's only covered 9000 miles from new. My feeling is that the tingling through the bars is a product of an internal combustion engine mounted rigidly in a steel frame. I have Brit twins and singles so I'm familiar with proper engine vibration! The issue only arises at sustained high speeds (90-100mph), and at these speeds the rider has to grip the bars tighter because of the wind pressure, which would probably aggravate the problem. Interestingly, I rode 350 miles from Mallaig to Cumbria at varying speeds on A roads recently and did not suffer the same problem, so it does seem to be specific to the revs at 90-100 in top gear. Maybe the answer is to slow down a bit!
Have you tried a lower gear at these speeds? I found the ST is quite sensitive to front tyre pressure , I run about 32psi
You might still be able to get these (FleaBay, etc.). I used them on a Gixxer 750 and they seemed to help. The idea is the mass inside the bar is free to resonate at the opposite frequency (hopefully) and offset the vibration. https://en.wikipedia.org/wiki/Tuned_mass_damper
