its time for a new chain the factory one is stretched to the max right now and i think im going to change my rear sprocket while im at it. i read on thumper talk somewhere about a woods set-up and they said to use a 50 rear sprocket with a 520 o-ring chain. i need to know how many links i will need in the chain? it comes from the factory wtih 112 right, so do i need a 114 for the extra 2 teeth that i will have on the new rear sprocket? also should i mess around with the front sprocket or should i leave it alone?
changing gearing for woods riding please help
- Thread starter Lonewolf
- Start date
I would go with more than the 50 tooth(its only 1 more than stock). I went to the same size, and honestly can notice very little difference. I would go to a 51-52. That should allow you to use 2nd a little more efficiently, and make 1st a grunt gear. As far as the front sprocket, honestly I don't know. I have heard that if you go down too small on the front it causes accelerated sprocket wear, but again I'm not certain.
Yeah I change my front sprockts, I have a 15, a 14, and a 13. Ive been running the 13 T on the front and it dose not appear to be wearing any faster than the 14 wich I use alot too. Dropping a tooth in the front is like adding 4 in the back but its alot faster to do than removing the wheel to change rear sprockets thats why I do the fronts, they are cheaper too. I use the 13 in tight woods and Paragon so I keep it on most of the time, 1st gear is a put put gear that helps keep the bike and clutch cool in tight slow group riding, second is great for about 80% of woods riding. The 14 makes 1st more usable on my WR but leaves an uncomfortable space between 1st and 2nd that requires more shifting between the two in the woods. the 15 T makes first more like 2nd with the 13 T but the gap between 1st and 2nd is now like skipping a gear when shifting in the woods unless you wind the motor up alot and using 1st in tight woods and rocks with the 15T gives you arm pump from feathering the clutch but the bike dose 105 MPH in 5th :) .
Some say putting a smaller front sprocket on increases the sheeth resistance wich it true to a point, I guese the smaller radius adds more drive resistance and works the chain harder by the % differance of the diameter, but IMHO its not worth worrying about. There is a 12 T that I have herd of available for the WR YZ to make it more of a better woods bike and I have herd thats as small as you would want to go.
Also, a bigger rear sprocket besieds being more expensive and harder to install will be heavier and have a larger radius, the weight may not seem like alot to you when you first think of it but the rear sprocket is unsuspended Rotating mass and thats the worst kind you can have so the mass becomes multiplied by the speed and the factor that its spinning at the end of you swing arm and you now have more to consider as well as the weight of the extra chain links wich are for the most part also unsuspended rotating mass.
Some say putting a smaller front sprocket on increases the sheeth resistance wich it true to a point, I guese the smaller radius adds more drive resistance and works the chain harder by the % differance of the diameter, but IMHO its not worth worrying about. There is a 12 T that I have herd of available for the WR YZ to make it more of a better woods bike and I have herd thats as small as you would want to go.
Also, a bigger rear sprocket besieds being more expensive and harder to install will be heavier and have a larger radius, the weight may not seem like alot to you when you first think of it but the rear sprocket is unsuspended Rotating mass and thats the worst kind you can have so the mass becomes multiplied by the speed and the factor that its spinning at the end of you swing arm and you now have more to consider as well as the weight of the extra chain links wich are for the most part also unsuspended rotating mass.
Excellent points Jason. :thumb: The only thing I'm uncertain of is the ratio of the front sprocket. I've always heard that changing 1 tooth in the front was like changing 2_1/2 in the rear, not 4. :eek: I may be wrong, but this has been accurate to me thus far.
I have herd on a dirt bike its like 1 to 4 and if its dependant on the ratio of # of teeth I took 51 and devided it by 14 and got 3.64 to 1 as the differance. On a street bike you often have closer final gearing so that may be more accurate for street bikes.
Im my experiance with messing with sprockets dropping a tooth on the counter sprocket makes a much larger differance than the rear wheel, wich can be a draw back if your looking for more subtel massageing. I can tell distinct differances between my 3 WR sprocktes as soon as I let the clutch out. The other nice thing is that all 3 of my counter sprocktes can be run with the same chain, no links need to be dropped or added, the only bad thing about that is with the small 13T it puts the rear wheel adjuster so that the wheel base is longer wich is not ideal for tight trails but Ive never really been able to notice the differance in tight cornering with a few mm either way of wheel adjustment all though the pros claim to :) it seems to turns just the same when the rear wheel is power sliding into the ruts and berms :) .
Im my experiance with messing with sprockets dropping a tooth on the counter sprocket makes a much larger differance than the rear wheel, wich can be a draw back if your looking for more subtel massageing. I can tell distinct differances between my 3 WR sprocktes as soon as I let the clutch out. The other nice thing is that all 3 of my counter sprocktes can be run with the same chain, no links need to be dropped or added, the only bad thing about that is with the small 13T it puts the rear wheel adjuster so that the wheel base is longer wich is not ideal for tight trails but Ive never really been able to notice the differance in tight cornering with a few mm either way of wheel adjustment all though the pros claim to :) it seems to turns just the same when the rear wheel is power sliding into the ruts and berms :) .
stock rear sprocket on a YZ250F is a 48 tooth. 50 tooth did the trick for me. 51 would probably work just as well, just figure out want you want to accomplish, although the difference b/t a 50 or 51 is probably minimal. Maybe a 3-4 MPH loss on top, but a tad more low end pull. I know a lot people just put a 12 tooth front on and go. Either way, lowering the gear ratio will help the YZ250F in the woods big time.
High Lord Gomer
Poked with Sticks
- Sep 26, 1999
- 11,790
- 34
If you were asking if you should replace the front when you replace the chain and rear sprocket...yes! Besides, they're fairly cheap.
As far as getting a longer chain...for every 2 teeth you add to the rear sprocket, you only need to add 1 link (roughly) because the chain is only contacting half of the teeth at any one time, anyway.
As far as getting a longer chain...for every 2 teeth you add to the rear sprocket, you only need to add 1 link (roughly) because the chain is only contacting half of the teeth at any one time, anyway.
I don't know about YZ250fs, but I have a spreadsheet that calculates the effect of changing sprockets and 1 tooth on a CR250 rear sprocket will make a 1 mph difference at 10,000 rpm in 4th gear. I personally can't tell a whole lot of difference between 1 or two teeth on the back....but one tooth on the front will be noticeable (about 4 mph @10,000 rpm in 4th on the CR)
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