konrad

May I ask where you got that design? Was it done by an A.I. chatbot?

Yes, but I would advise caution. Pin 22 is driven by a component (Rohm SP8K22 dual N-channel MOSFET) known to have failed on at least 3 Explorers. This renders the ECU useless. I don't know of any trials model to which this has happened. I assume there is something about the Explorer wiring harness/easy start that's causing the failure, but I don't have one to investigate.

From my notes... There is a symbol on the initial 2011 wiring diagram called "Testigo Averia". That translates as “Fault Witness”. I called it the CEL (Check Engine Light) in my notebook. Another name is the MIL (Malfunction Indicator Lamp). Looks like OSSA made it part of an instrument panel in the 2014 wiring diagram. Reverse engineered it a bit. It sources 5 volts at only 5 mA, so not too useful to drive a lamp. Even an LED is pretty dim. But, you could easily read it with a voltmeter. If your bike does not start, see if ECU pin 22 is at 5 volts (with the bike powered by a battery). This would indicate the ECU thinks there is a problem, versus the bike just being recalcitrant. Wiring diagrams are here: https://www.ossa-efi.com/home/electrics/wiring-diagrams

The write-ups are quite technical, but maybe some here will be interested. This link is the actual retrofit process: https://www.electricmotiontech.com/home/em-5-7/sx-controller-retrofit This link describes some preliminary work to familiarize myself with the SX controller: https://www.electricmotiontech.com/home/em-5-7/sx-controller-experiments

The trials model definitely had superior suspension to the Explorer. But I think going forward, the Explorer will be a very desirable bike. I expect some trials models will get sacrificed to keep Explorers running. I'd suggest buying a ratty trials model to use as a donor.

Here's my analysis of that dyno comparison: https://www.electricmotiontech.com/home/what-makes-a-good-trials-motor/zero-loss-gearbox-anlaysis

Beta has a 6-speed box. I'll let you do the calculations.

I think you want something with a 6-speed. Here are overall ratios for two "obsolete" bikes. OSSA TRi 36.93, 29.99, 24.78, 20.73, 14.2, 8.45 Aprilia Climber 37.81, 29.65, 21.5, 15.45, 12.18, 8.45 Plus, one current bike (but it uses GG's 4/6 system and shifting will be more clunky than a true 6-speed). GagGas Pro (all) 31.77, 27.27, 23.19, 19.91, 11.93, 8.7 Here's the Montesa 4RT for reference 36.36, 30.97, 25.97, 16.53, 10.58

Fully extended. The air trapped inside acts as a spring. Although the pressure would probably eventually equalize itself either way. Longer travel forks often have bleed-screws to release excess air pressure when the forks are fully extended.

This is a topic near and dear to me. I keep spreadsheets with gear ratios for a variety of bikes. Modern trials bikes will all have the same problem, a wide gap between the "section" ratios and the "loop" ratios. The most even spacing I've measured among trials bikes was my old TXT321. Never had that gearbox apart, but counted motor revs per wheel rev as: 39.25, 33.75, 26.50, 20.75, 13.25, 9.00. Typically, a 6-speed box will offer a slight improvement over your Sherco's 5-speed. FWIW, I've discovered that single-speed electric trials bikes work really well as a technical trail bike.

Fill and drain bolts are both M12 x 1.5

Clearly, someone before you has had it apart. Is the top end getting sufficient oil? IIRC, there is an oil pressure check bolt in the head. There's no oil filter but, there is an oil screen that can be cleaned if you remove the clutch cover.

TT-R125 manuals are available online. Valve clearance (cold) IN: 0.08 ~ 0.12 mm (0.0031 ~ 0.0047 in) EX: 0.10 ~ 0.14 mm (0.0039 ~ 0.0055 in) Check the cam chain tensioner too.

Regarding ticking, have you checked the valve clearance? Regarding low-rpm hesitation...

I'd strongly suggest borrowing a bike to see if you even enjoy the sport. You could easily spend far more time tinkering than riding. Which is fine if that's what you want, just understand what you are getting yourself into. You'll need well-developed mechanical skills from some other endeavor.