howie333 Posted February 9, 2023 Share Posted February 9, 2023 (edited) 2017 Yamaha FJ-09 The Yamaha FJ-09 Service Manual states the Drive chain slack to be @ 5mm-15mm measured while bike is on center stand while wheel is elevated. I was surprised. My chain was @45mm. I looked over all discussions to this subject, and seems majority are not using manual's specs; but anywhere from 25mm to 45mm. When I set chain slack @ 32mm on center stand; then I put bike in front wheel chock to put weight on rear wheel; and found setting tightened up 10mm to a setting @ 22mm. I cant imagine setting slack to manual specs ! Please help me w/ correct way to set this Drive chain slack. Thank You... Edited February 9, 2023 by howie333 Link to comment Share on other sites More sharing options...
Supporting Member betoney Posted February 9, 2023 Supporting Member Share Posted February 9, 2023 30-35mm or - if it seems too tight, loosen it. Honestly, I don't remember the last time I actually measured the slack, I make sure the wheel is even side to side, flick the chain up and down to make sure its not tight and forget about it. 5 ***2015 Candy Red FJ-09*** Link to comment Share on other sites More sharing options...
howie333 Posted February 9, 2023 Author Share Posted February 9, 2023 where the chain slack feels right w/ wheel raised and then bike dropped to floor is very different. Link to comment Share on other sites More sharing options...
Lone Wolf Posted February 9, 2023 Share Posted February 9, 2023 (edited) 9 hours ago, howie333 said: where the chain slack feels right w/ wheel raised and then bike dropped to floor is very different. Don't focus on that. Keep it simple, the tightest spot will be when this stuff lines up - whatever stand you use to achieve that. The center stand is going to let the suspension fully extend vs. side stand vs. rear stand (Pit Bull) The settings noted in the manual are too tight. If you have had other motorcycles and adjusted their chain, the slack on this one will be similar and you don't want it too tight. Edited February 9, 2023 by Lone Wolf 2 1980 Yamaha 850 Triple (sold). Too many bikes to list, FJ-09 is next on my list Link to comment Share on other sites More sharing options...
KrustyKush Posted February 9, 2023 Share Posted February 9, 2023 5mm to 15mm sounds way tight. My 2021 T9GT book says 40-45mm. Bike on center stand, in neutral. Different bike, longer swingarm probably explains the diff. Link to comment Share on other sites More sharing options...
howie333 Posted February 9, 2023 Author Share Posted February 9, 2023 (edited) 2 hours ago, Lone Wolf said: Don't focus on that. Keep it simple, the tightest spot will be when this stuff lines up - whatever stand you use to achieve that. The center stand is going to let the suspension fully extend vs. side stand vs. rear stand (Pit Bull) The settings noted in the manual are too tight. If you have had other motorcycles and adjusted their chain, the slack on this one will be similar and you don't want it too tight. OK; so basically it seems the best way to set chain slack w/ be to put front wheel in chock to achieve that rear assembly lineup shown in diagram; but id have to either pull rear shock bolt out or compress shock to align swingarm as shown in diagram, and then I guess set drive chain slack 35-40mm ? Thanks for reply... Edited February 9, 2023 by howie333 Link to comment Share on other sites More sharing options...
Lone Wolf Posted February 9, 2023 Share Posted February 9, 2023 (edited) 45 minutes ago, howie333 said: ... but id have to either pull rear shock bolt out or compress shock to align swingarm as shown in diagram I suppose you could have someone sit on the bike while the front wheel is in a stand. Or you could do what betony said "flick the chain up and down to make sure its not tight and forget about it." If you watch Dave Moss videos when he is checking the chain on various bikes, that is EXACTLY what he does. It is not like measuring the clearance of a bearing to the thousandths of an inch, there is an acceptable range and you generally want it on the looser end of the spectrum because as the suspension compresses it will hit that tightest part of the range. Notice that there is no tape measure being used in this video. With experience, you can tell if it is tighter than a 12 year old, or way too loose. Edited February 9, 2023 by Lone Wolf 1980 Yamaha 850 Triple (sold). Too many bikes to list, FJ-09 is next on my list Link to comment Share on other sites More sharing options...
Premium Member fddriver2 Posted February 9, 2023 Premium Member Share Posted February 9, 2023 ~1" on streetbikes since 1974. YMMV 3 "It doesn't matter who walks in, you know the joke is still the same" Ft. Lauderdale, Florida. USA Link to comment Share on other sites More sharing options...
howie333 Posted February 9, 2023 Author Share Posted February 9, 2023 (edited) 9 hours ago, Lone Wolf said: I suppose you could have someone sit on the bike while the front wheel is in a stand. Or you could do what betony said "flick the chain up and down to make sure its not tight and forget about it." If you watch Dave Moss videos when he is checking the chain on various bikes, that is EXACTLY what he does. It is not like measuring the clearance of a bearing to the thousandths of an inch, there is an acceptable range and you generally want it on the looser end of the spectrum because as the suspension compresses it will hit that tightest part of the range. Notice that there is no tape measure being used in this video. With experience, you can tell if it is tighter than a 12 year old, or way too loose. I Just talked w/ a bike tech in my town; said best is to set slack @ approx. 1-1.25 inch or ~30+mm w/ rider on bike just as you said. I'll set my Motool suspension tool to measure sag, and preload bike to match my weight, then I'll set drive chain slack. Also, as setting chain slack; not to see upper part of chain move as lower is measured to be accurate; either way, Service manual is dangerously wrong on setting drive Chain Slack ! Thank you... Edited February 10, 2023 by howie333 2 Link to comment Share on other sites More sharing options...
peteinpa Posted February 10, 2023 Share Posted February 10, 2023 I'm going to say if your rear suspension is compressing at all under bike weight alone, the shock preload is too loose. The factory spec. IS wrong. FACT. I go for 1.5 inches. Link to comment Share on other sites More sharing options...
howie333 Posted February 10, 2023 Author Share Posted February 10, 2023 (edited) Well I installed the Motool suspension sag meter to set my weight w/ tie downs to simulate my weight. I set chain slack as not to move upper chain. Worked well. I set chain @25mm(~1 inch) slack. When on side stand; measures 30-35mm and on centerstand 40-45mm. hopefully done correctly; I'd want the most accurate slack to be w/ my weight on the bike. Edited February 11, 2023 by howie333 Link to comment Share on other sites More sharing options...
kilo3 Posted February 10, 2023 Share Posted February 10, 2023 I like to adjust my chain slack on the fly while I'm riding, that way as the chain warms up I can tighten it to exacting specifications. Sure it takes an hour extra stopping every 10 miles to adjust, but man do I feel better about it being right in the sweet zone. 2 Link to comment Share on other sites More sharing options...
Supporting Member piotrek Posted February 10, 2023 Supporting Member Share Posted February 10, 2023 5 hours ago, peteinpa said: I'm going to say if your rear suspension is compressing at all under bike weight alone, the shock preload is too loose. Hmm... I suppose YMMV, but you should be able to set your rider sag AND still have 10-15mm of free sag. 1 Link to comment Share on other sites More sharing options...
manimal Posted February 21, 2023 Share Posted February 21, 2023 There's a variable I didn't see mentioned in this conversation; the chain slack varies as you rotate the wheel. The best theory I've heard regarding this phenomenon is that the rear sprocket is off-center, creating a high spot, and a low spot 180deg opposite (with some variation due to tolerances in the chain bushings/pins). If you rotate the rear wheel so the high spot points aft, the chain will exhibit the least slack/greatest tension. When I adjust the chain slack to 5mm with the high spot pointed aft (least slack/greatest tension}, and then rotate until I get the greatest slack and measure I get 30mm+ of slack. It's always seemed logical to measure your slack at the point of highest tension, to ensure you don't over-tension the chain. But, I've always wondered, how much variation between minimum and maximum slack is acceptable? Link to comment Share on other sites More sharing options...
Suzukiguy Posted February 21, 2023 Share Posted February 21, 2023 I believe you're over-thinking this! Really,..........how much is your sprocket off-center??? I'll never use a dial indicator to adjust my chain! The old way has been working just fine for a long time, for a multitude of bikes and bikers. Just my .02! 2 1 2020 Tracer 900GT /1978 Suzuki GS750E /1978 Suzuki GS1000 /1982 Suzuki GS1100E /1999 Honda GL1500SE Link to comment Share on other sites More sharing options...
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