Chase

The filter is definitely damp. That explains why it felt slightly gutless afterwards.

It is the standard answer for a loose fit. Just make sure you can still get the tyre on afterwards.

Hookless rims at low pressure need a tighter bead fit than hooked ones, and 40mm at 25 psi on a 23mm internal is right at the edge where a burp is normal rather than a fault.

What actually helps, in order:

• Two wraps of tape instead of one. It increases the effective bead seat diameter slightly and dramatically reduces burping. This is the single most effective fix and it is not a bodge.
• Run two or three psi more up front until you know the setup. Twenty eight psi on a 40mm tyre is not a harsh ride.
• Check your tyre against the rim maker's compatibility list. Some casings simply sit loose on some rims.

It usually settles, but there are two causes worth separating because only one of them goes away.

If it is a low frequency howl that changes with speed and is worse when damp, that is normally bedding-in not being finished. Twenty stops from 25 km/h is fewer than most people think. I do about thirty stops from a higher speed, never coming to a complete stop, with cooling time between sets. Give it two more rides.

If it is a constant loud squeal from cold that never varies, suspect contamination. Chain lube overspray, a fingerprint, any oil at all is enough. Clean the rotor with isopropyl and a clean rag, then sand the pad faces lightly on flat coarse paper. If the pads actually soaked up brake fluid or lube they are finished and no cleaning brings them back.

Also check caliper alignment. A slightly skewed caliper makes an intermittent honk that people spend weeks blaming on pads: loosen the two mounting bolts, hold the lever hard, tighten alternately.

Then just ride it. Organic pads go quiet once they are properly in, and a week of normal use does most of the work.

I was hoping it was the hanger. Fine, both then.

Have a $12 carb kit with a float needle and gaskets on the bench before you start. On an eight year old machine you will tear a gasket coming apart.

Also confirm the fuel is genuinely fresh. March fuel in July is already halfway to being a problem again.

They almost never do. One at a time, clean the threads and the mating faces, dab of grease, torque them evenly.

Bottom bracket creaks are famous liars. In order of how often I actually find it:

• Saddle rails in the clamp. Out of the saddle you load and unload the rails and it ticks through the frame.
• Seatpost in the seat tube. Strip it, clean both surfaces, thin smear of grease or carbon paste as appropriate.
• Chainring bolts. Nine small bolts, all of which want clean threads and even torque, none of which anyone checks.
• The actual bottom bracket.

It only happens standing because that is the only time you put a real bending load through the frame. Do the cheap ones first, chainring bolts take five minutes.

Pull the muffler and look at the piston through the exhaust port while you are there. Free look at the thing you would otherwise be guessing about.

Buy two chains when they are on offer and rotate them every 500km or so. Wear spreads across both, the cassette lasts absurdly long, and you always have a spare when one gives up.

Aftermarket carburettors at that price vary a lot. Some are perfect, some need the jets cleaned out of the box. Still the right call, just do not assume plug and play.