being the proud owner of 3 bikes and 4 motors of the 400fs 76, i've had a lot of valve adjustment experience and usually it has it's peculiar lock nut's ability to change the gap so that a stab in the dark is usually the way i end up doing it.
i have a xr650r 2000 that is a breeze to adjust by first they give you a target torque 18ft lbs, i shoot for 17ft lbs for the lock nut, but second cool part is to adjust valve clearance is simply putting the crankshaft where it should be and loosening the adjuster screw and place the feeler ga, under it and tighten the screw until it's snug then torque the nut and the clearance is the same as it was before tightening the nut.
the 400fs i've had 2 nuts fall off within a few minutes of running, so i'm kind of spooked, because of it being not tight enough. the trouble arises when using a feeler ga under the adjuster screw tightened by hand and then tightening the lock nut goes well for a brief moment, and then it goes from turning the screw into the now too tight feeler gauge, so you back it out and then try holding the screw while tightening. and then a unique and regular occurrence of gap happens, the tighter the nut is turned and even following with turning the screw intentionally, the gap gets wider on it's own to where a .006 walks through. so does anyone know a ball park torque on that screw/nut, i'm assuming close to the 18ft lbs maybe 15ft lbs, but what seems to be happening, other than worrying about it, but as it gets tight while there's a feeler ga taking up the gap, the nut bears on the rocker while pulling the screw into the rocker and away from the valve stem? it sounds far fetched but what else is happening there. and not every valve, nor any respond like the others. they are completely a separate nightmare all of their own. 8 nightmares in each head.
still working on the project in the living room, i thought i had taken pictures of the motor removal using 2 couch cushions but apparently i was in too much of a hurry to get it out and finish stripping the frame of all the accessories to start painting it. (i'll get pictures of installing it with the 2 cushions,) which is the first set back, as nowhere not even phone calls to rustoleum could get anyone that could sell it's appliance epoxy so i ended up using a rustoleum automotive primer in just the bare metal spots, then rustoleum gloss enamel. and other parts i used the semi gloss and satin gloss, and after that defeat, and the primer was shot, within an hour the sun was already set and i figured might as well finish it in the dark that way i'd have an excuse of it looking now just painted getto. it came out better than i thought it would. only had some light spots, i hung it in tree with some wind blowing and started painting. i know it's probably not gonna last long but either am i so i didn't care. the top of the motor is so missing the silver paint and it's kind of corrosion so i'll hold some cardboard over spots and paint it one coverage, tape some chrome nuts or rusted nuts. i don't think i'm even gonna take the valve cover off, the valves had excessive clearances, the cam chain adjust bolt lock broke free, i didn't unscrew it but i did back it out a 1/4 turn and put it back where it was. it's still loose. i might just try connecting the ign and other electricals and a battery and see if it'll start on the floor, if it fired up, i wonder if it'd bounce around a lot. i started 16 hp Koehler electric start that had the balance gear and shaft out, on the concrete floor, it was bouncing off the floor.
