I have two XR100s and am picking up an XR80 for my daughter. All of the bikes need chains and sprockets in some fashion (the 80 has no actual chain, for starters...). Here's my dilemma - Do I get three sets of 80's chain and sprockets, or do I get three sets of 100's chain and sprockets? I'm (over)thinking that why not have some commonality between the machines, just because? Plus it's easier to click the button three times when ordering, and 80 chain/sprockets are cheaper (by like $5 a set). I use the 100's for flat track, and the 80 will be for my daughter to learn to ride. (I'm serious, I won't take the 80 out unless I really have to. Really.) Will I lose strength/life by having the 80 set up on the 100's? Will the smaller chain withstand the flat track abuse? Will the 100 chain/sprocket combo slow down or otherwise impede the 80? I know, just get two 100 combos and one 80 combo, but I like to completely overthink what I'm doing, and thereby reach paralysis by analysis and do nothing. Whatchu think?
Should I get the same ratio for both engine sizes? I'm not really worried about performance on the 80, but I am with the 100. And what's the conversion factor between the 100 and the 80 sizing? Or is the tooth count the same between the two models? I'm easily confused, as you can tell. And easily influenced as well.
I think my 1 bike has 14/46. Maybe get a couple 14 and 15 counter front & 47 48 and 49 rear since youre buying 3 sets.
Okay, I just read up on the differences. XR80 is 420 at 14/46, which is smaller diameter and narrow rollers. XR100 is 428 at 14/50, wider and bigger diameter rollers. Link distance is the same, so the ratios are the same. I assume that the XR100 transmission ratio or the primary ratio is different, therefore final sprocket ratio is different. I'm not going to get different sprocket sizes, I'll just get the stock 100 ratio for all three bikes. It will make the 80 a bit faster on top end, but it will tame the initial throttle response for my daughter. I think.
I would order whatever gearing comes stock on both bikes and call it a day. Also, you should get a whole 420 chain and break it down for the 100. I remember something about having to only take one link out of the chain I ordered, but I can't remember how many links it was total. Looked it up...I was either running 15 or 16/46 gearing and purchased a 120 link 420 chain for the 100.
I finally had the epiphany that saved me headaches and money. The 80 has a shorter swingarm than the 100, so I can't buy three sets of any one thing. I know, I could have bought three sets of 80 sprockets, then 15' of 420 chain, but it was cheaper to buy kits instead of single items. So, I got a stock 80 kit, then I'll figure out the 100's when I have some brain cells available.
