Check out my old posting on how to torque down your rear axle after you do your chain slack adjustment.
Hint use the left side axle bolt to torque down the axle to 40-44ft/lbs, if you try to torque down using the right side which is the nut side the axle will creep forward throwing your alignment off, after doing that re-check your alignment lines to make sure both sides are on the same line than tighten the 12 nut to the plate and hold the 12mm nut while torquing down the 10mm nut, that's it. you might want to put some type of blue lockite on the tips of the expose thread or something to catch the 10-12mm nut if they come loose due to vibration. Nothing like losing your nuts when riding.
Just lost my 10mm yesterday on the right side.
I have been able to do a lot of the work on my Grom by myself without a ton of experience...but this rear wheel alignment and chain tension has me flustered at a whole new level.
From 1 day to the next my bike started shaking/wobbling ever so slightly..but enough that i noticed. This coming after a new chain, and maybe 1000 miles on the new chain with no complaints, no more weird pulling from overstretched chain etc...
Thought i had this issue fixed until after 2 days of riding i couldn't take it anymore...whipped out the sockets and wrenches and proceeded to eff up my bike more apparently.
1st attempt- Tried to do a little micro-adjustment with the tension-er screws on back ends of the swing-arm...eh, result = no change - smallest degree of improvement.
2nd try- fully loosened axle, full re-adjustment...or so i thought. result = even worse than before
3rd try- eye-balled it, knee against the tire to keep it in place. result = right side of axle moved backwards somehow...10mm nut loosened and fell off...very noticeable wobbliness and i could also feel the miss-alignment in the chain through my pegs...coasting to a stop with clutch in I can feel the chain wrapping around the front sprocket, and the tight/loose/tight grind of the chain
I am so frustrated with my rear axle and alignment and chain tension I cant take it anymore.
I thought I was a decent enough mechanic at this point to fix such a simple aspect of my Grom's maintenance, but again, like back in High school when i thought the pretty girl was flirting with me...I am wrong
I have watched many youtube videos, and they are all very good at explaining the process. But every time i have tried to adjust my rear axle/chain (with the exception of the time i replaced the chain entirely) it never seems to be perfectly aligned and I end up with a rougher ride than I expect. I want to believe its fixable, and that some day I will pull out onto that asphalt playground, and get that smooth as silk feeling as I weave back and forth, line to line...but alas it has not happened yet.
I have contemplated splurging on a new rear swingarm that has easier to use chain tension-ers