Can HIGHLY recommend theese. You need an adaptorring for the stock headlight
The light will flicker a bit at low idling.
https://www.ebay.com/itm/Nighteye-H4-9003-HB2-8000LM-Car-LED-Headlight-Kit-Hi-Lo-Beam-Bulbs-6500K-White/391600374998?epid=907124270&hash=item5b2d3384d6%3Ag%3AqOYAAOSwlCdbGfEK&_sacat=0&_nkw=Nighteye+H4+9003+HB2+8000LM+Car+LED+Headlight+Kit+Hi%2FLo+Beam+Bulbs+6500K+White&LH_BIN=1&_from=R40&rt=nc
Adaptor:
Yes a 428 is lighter per link, but you also need more liks than a 520 because a 428 is smaller.
We've talked about the supersmall weight difference in another thread, so please, lets not go there again 
Jt sprockets from an old YZ125, and a quality 520 chain of your choice will last about forever on this bike. I used a Did vx2 chain for all my bikes.
The air is regulated over the entire throttle range, however, it doesnt matter much/signifianly up top. Its primarily used to finetune from idle up to where the idle curcuit is beeing overlapped by the needle, at around 1/4 throttle.
Found one on ebay that said 1,1 and listed as beeing for a dt125r
Just aout all hubs are aluminium, no surprice there.
Next time add heat, if that doesnt do it, drill the head of.
Btw, isnt our stock cap a 1,1? Thats what I recall anyway.
Normal, what is normal? Outside temps vary by 20c theese days where im located. You'll have a hard time to reach 70c at the cap in the morning just cruising around, and having a hard time not to exceed 110c at the head in the afternoon on a tight track. Some valid points to where you meassure, temps will read higher in the head, compared to on top of the radiator.
Waterless coolant boils at higher temps, but something like Evans actually remove less heat from the engine, so...whats the point of that? I've never heard of anyone damaging a radiater due to cooling preassure. 1,3 bar isnt normal running pressure, but maximum pressure, before the cap lifts and "bleeds of" the excess. If you're worried, buy a cap with less pressure.
Unless it boils, its fine. Bike is designed to function with 100c or more coolant, otherwise it wouldnt have a 1,3bar cap on. Everyday use should be less of that, ofcourse. But the thermostat isnt even fully open at 80C, come on people...
Unless something is off, its also just about impossible to get detonation in our bikes with super low compression. I've ridden mine on 20% diesel as part of a bet, no issues.
Theres always small exeptions for modified engines, which generate more power and heat, but that goes for any engine.
A 4stroke wont have more maintenance comparing to a dt125r.
My xt600 was first opened at 125.000km I check the valves at the same range where people would replace pistons/rings in a dt125r.
No liquid cooling, its just a super basic bike. Im now at 180x.000km
Any dualsport-type-bike is easy to work on, because of no fairings ect.
My wr250r has 42.000km intervals for checking the valves, 6000km oil changes, and pops wheelies in 3rd gear.
What do you want in the bike, and what do you need it to do? Is it just a commuter, or do you take it offroad, ect.