When upshifting above 50/60kph, after releasing the clutch and gassing it, I can feel a brief but strong shudder I'm what feels like the base of the engine. Bike (Honda Tornado 250) is under 3000k and brand new, is this just the crank or something catching up as the piston delivers the energy from the piston? Bike runs great no issues, but just curious to what this may be?

Cheers,
RTW

Probably some clutch judder. I wouldn't worry too much unless it got louder and the bike gearbox or performance starts suffering.

These small single cylinder bikes make scary sounds most of the time.

__________________
Did some trips.
Rode some bikes.
Fix them for a living.
Can't say anymore.

Thanks for getting back to me. I should have said it only lasts a second. At first I thought it was a clutch issue but if I close the throttle off and then open it half way, leaving the clutch alone, I feel the same jolt in the crankcase (feels like its there anyway) with my feet. If I roll on the throttle gently it is either not there or perhaps just not as pronounced as to be perceivable. I leant to ride on battered old Enfields and so have worked up a rather acute sense and mistrust of odd clicks, bangs, jolts and whirrings.

It's a symphony....

__________________
Did some trips.
Rode some bikes.
Fix them for a living.
Can't say anymore.

I think you found a solution (leave clutch alone). Sort of sounds to me like you may be "Lugging" your motor just a bit? Remember, these little singles like to REV ... nothing like your old Enfield.

Don't be afraid to take her up a bit before shifting. Do your shift QUICK and don't apply throttle until clutch is completely OUT. You only need pull in clutch for A SECOND for a shift. It all should happen at once, REV, clutch in, shift, clutch out. All at once, or very quick succession. NEVER slip the clutch on ANY shift other than taking off in 1st gear.
Less clutch use, the better.

This will mean LESS drive line vibes or "Jolt" you perceive. Find out where Red line is on your motor (best done in 1st or 2nd gear) Most times I'd go up to about 1500 rpm or 1000 rpm below redline for shifts ... unless just pottering in town. When you need to take off ... make sure to DOWNShift to a lower gear ... don't just wind on throttle and slip clutch when in too high of a gear. THat is pure amateur stuff. Don't do it. DOWN SHift. Rev that little monster!

Every bike has a different character. Without riding can't say for sure what is going on with your bike, but I doubt it's a problem. Lugging however is something Many Many riders do and aren't aware of ... it is VERY BAD for main bearings and can cause catastrophic failure over time and abuse.

Great response and highly appreciated; many thanks! I definitely think I lug it a little as riding high into the revs always felt 'wrong' somehow. I think I am still guilty I driving a bike like a car ie trying to get into highest gear as soon as possible. I have much to learn.