konrad

Dan, I can add some detail about variable-reluctance pickups. The one shown here is from a Chinese pitbike, but it's representative of what's commonly used. The coil has a DC resistance of 145 ohms. Inductance is 63 mH in air. Inductance is 61 mH when contacting steel. (Both measured at 1 kHz.) The magnet has its North pole facing out. The oscilloscope capture shows the waveform when a block of steel is repeatedly brought into contact with the pickup magnet and withdrawn (by hand). Each positive pulse is contact, each negative pulse is the withdrawal. The waveform is asymmetric because the rate of change in the magnetic flux is faster when making contact (magnet pulls on the steel) than when moving the steel away. EDIT: Just noticed that the scope probe I used did not automatically change the display settings. So the vertical axis is 2 volts per division, not 0.2V per division.

Is a bicycle helmet as safe as a motorcycle helmet? Probably not. But modern MIPS-rated helmets are pretty good. See: https://www.helmet.beam.vt.edu/bicycle-helmet-ratings.html It may partly depend on the ambient temperate at which you ride. I know that if my brain gets overheated I don't make good decisions, and am more likely to actually need a helmet. Assumption of personal risk is a very personal decision.

Probably the best-ventilated helmets are for mountain biking (MTB). Might be worth a look if your club does not require a motorcycle-specific helmet. Probably easier to find a vendor to try something on as well. My wife wears a full-face MTB helmet all season for trials.

If there is any way for you to try on a prospective helmet before buying, I strongly suggest you do so. I bought a GasGas-branded Hebo Z4 Carbotech by mail because it was a fabulous price. The Carbotech is a top-of-the-line helmet with two annoying (to me) "features". 1. The cheek pads were far too tight, despite the helmet otherwise fitting perfectly. I figured they would eventually "pack out", but did not. I ended up removing them completely. 2. The buckle hit my Adam's apple, which was most uncomfortable. I eventually improved that somewhat, but it's far from perfect.

You can take stator resistance reading as woody suggested. Although that does not guarantee functionality, you can find some definitely-bad components that way. A peak-reading voltmeter is better, but again will not guarantee proper function. https://www.thumpertalk.com/forums/topic/1034259-build-your-own-peak-voltage-adapter/ I have used a drill motor and socket on the flywheel nut (or primary gear nut) to spin the motor for stator testing. This is best done with the head removed for easiest cranking, but just removing the spark plug may be adequate.

I think all those red Motoplat "ignition coils" contain other CDI components too. Best source of Motoplat information I have found: https://motelek.net/motoplat/

What is "semi-seized" on your old engine? Can you make one good engine out of old and new parts?

Those engine brackets already look pretty insubstantial by modern standards. I would not want to thin them. How much material do you think needs to be removed? Make some measurements. P.S. It may be preferable to heat and bend the frame mounting points. In general, I try not to make modifications that can't readily be undone.

I don't see that you have anything to lose by plugging a hole that should not exist. Personally, I would try something quick and dirty like hot-melt glue. If that was successful, I'd use epoxy.

Typically, the unused side would not have been machined. If it was like that from Day-1, the engine would have had a massive air leak and never worked properly.

Yes. Yamaha used that on some conventional carbs. Could be a torn diaphragm or gummed up. Suggest you disassemble and inspect/clean.

I'm used to the PHBL, but your VHST looks like this photo: https://www.speed-parts.nl/carburateur-dellorto-vhst-26-mm-bd-flat-slide.html The casting probably was made that way so it could have mixture and idle screws on either side. You could test with compressed air.

Likely true. In roadracing, tech (scrutineering) is about safety. Illegal modifications must be protested by other competitors.

How old is the battery? How many charge cycles? Conduct your experiment again while measuring voltage across the battery. If the battery voltage drops precipitously just as the wheel touches the ground, the battery is probably bad. You will have to be quick to observe the drop because the controller will be likely to cut the power due to an "under voltage" condition (and the battery voltage will bounce back immediately).