We spent the weekend testing our Raptors with the new front/rear sproket upgrades.

This is the matrix that we tested:

Front Rear Ratio
13 40 3.08 (stock configuration)
13 42 3.23
12 40 3.33
12 42 3.50

Results:

13/40, For us the stock configuration is too "tall" so obviously the need for the test in the first place.

13/42, This configuration gave us very resonable overall performance, we lost approx 5% top-end speed.

12/40, Again, very good performance with approx an 8% loss of top-end speed.

12/42, Best trail performance with approx a 14% loss of top-end speed but performance in sand dropped significantly.

Issues:

When using a 12 tooth front sprocket with a 520 chain, it appears that you will get excessive chain/sproket
wear thus affecting reliability and overall life. Probably the reason I couldn't find where any manufacturer
who actually ships this. I'd be interested in anyone's thoughts on this issue.

For now, we've settled on the 13/42 combination as it pulled us through the really nasty stuff, with minimal
clutching, and only reduced our top-end by about 5%. One nasty rock garden stalled my wife 3 times, but
she's always had problems clutching 2-strokes so this is something she just needs to learn on 4-strokes as well.

As a side note, it's actually easier for me to change the rear sproket than the front! First time for everything.
Of course I could just be slow, but removing the left front peg and shift assembly seems to take more time than
just pulling the left rear wheel.

Again, I'd be interested in all thoughts/ideas concerning long term reliability of using a 12 tooth front sproket
with a 520 chain. I actually prefered the 12/40 setup over the 13/42.

 

Sounds like you kept yourself busy! I tended to stay away from that size. I hear alot that the 12 tooth is bad for the chain and sprocket so I tend to stay away from that size. I was runnin 13/42 for a while but when I put my 22" tires on I was wayyy to high geared so I stuck on a 44 tooth rear. It made it a little better but I'm still to high so I have a 46 that I'm gonna put on. A guy with a similar Rappy had 22" tires and was running 13/46 and beatin me so I figured I'd give it a try.

 

I'm glad you went thru the pain in the a$$ part for us...I'm running a 12/40 on a 520 chain and thus far have had no problems. I am also using 22x11x10 Holeshots in the rear and find the combination to be good for dirt .I run a 21 inch paddle in the sand. I just returned from the dunes this weekend and was finally shifting into 3rd gear on my hill climbs. I smoked the guys running stock gears.Works well in the sand but am anxious to try the 13/42 if I find a wear problem.

 

I ran 12/42 since I bought the raptors. I worked very well and lasted quite a while. But, I found the 12 front would wear the chain slider alot faster than the 13.

 

Thanks for all the great feedback.

I've continued to test out the 4 combinations, and for now anyway, I'm running
the 12/42 setup and my wife is running the 12/40 setup. I really like how the
12/42 affects 1st, 2nd, and 3rd. No lugging an tons of low end torque. However,
it's REALLY easy to wheelie with this combo. That's why my wife prefers the 12/40
setup. It gives her better low end performance without so much snap. The 13/42
is a good alternative to reduce wear, but it's not quite as effective as the 12/40.

Regardless, we still feel that all three alternatives are much better than the stock
13/40 gearing. For general purpose riding, (as well as faster hole-shots), knocking
down the "tall" gearing really makes the Raptor more fun to ride!

 

If you get rid of the stock case saver and get a billet aluminum one (ProDesign), and get rid of the stock crappy shift linkage and get a direct mounting shifter (IMS), then you can just take off the front sprocket in like 2 minutes without having to unbolt anything else. That is the setup that I am running. I tried the 12/40 combo for awhile, but the 12 tooth seemed to wear out faster and stretch the chain quicker. I am now back to 13/40 with 20 inch rear tires.

RR1

 

I'm using the 12/42 setup. I find it pulls my big a$$ up the hill better. I agree, I did not like the 13/40 set up. I first went to the 12/40 and liked it so I tried the 42 and loved it. I figure I'll go with a new chain every now and again to use this setup.

 

good thread

 

I use 12 42 for the dunes right now, and I thinks it is 100x better than stock gearing