got the g2 throttle tube today. i had also purchased some thicker grips, the sunline grand touring grips, and was just waiting on the g2 tube to get back in stock to get delivered to do the whole mod at once.
got everything off and on without too much of an issue. the dude that assembled my fjr, that didn't tighten the frame bolts where skyway's sliders are now, made up for it with the two bolts holding the throttle assembly. those bitches were on tight, took a few whacks with a hammer on the allen wrench to get them off.
i did have an issue once i got the g2 tube back on, the throttle wouldn't return closed. i called sam up, as he suggested i do so if i had _any_ problems (quoting him) whatsoever. mind you, this was about 5p on a saturday, eastern time. sam answered, and gladly solved my issue. the g/t grips have closed ends, and that was causing the throttle to hang up and not snap closed. so i cut off the end, and viola, nice and snappy.
i can't comment on high speed performance, but just taking the fjr for a quick 20mph ride to the end of our street and back, i could notice the difference, and this is what immediately came to mind: you know when you took the motorcycle safety foundation course beginners course (you _have_ taken that course, haven't you?), and you used their little 250 bikes, you know how if you cranked on the throttle too hard, it would just sort of cut off the engine, not stall it, but just hold it at idle or just over? that's what the mod reminded me off, except when i would just give it mild throttle, it was nice and smooth, like it was on the msf bikes. crank it, and you get the full fjr13 punch, but in nice easy throttle twists, you get nice easy power delivery. i'm very happy so far, but again, will have to test it in high-speed corner operation.
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EDIT
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as i posted somewhere else on the forum, after a weekend trip to the motorcycle playground, little switzerland, and other lovely roads where i could appropriately test minute throttle adjustments in twisties, the g2 mod did not satisfactorily tame the abrupt throttle herky-jerkiness; nor did adjusting the throttle cable. a buddy of mine, a suspension whiz, took it for a ride to get the feel of my suspension, and about tore my head off when he returned and said it was downright dangerous. i agreed. the throttle spring mod did tame it to a 90% satisfaction, however.