crf450 sprocket change?

[Dan151]

its almost time to replace the sprockets and chain on my 07' crf450r. ive got 2 questions.

i ride all woods and mostly climbs in sandpits. what is the best gearing set up ? stock is 13/48. should i go with 13/50 or go up in the front sprocket?

if i got a bigger rear or front sprocket would i have to get a longer chain?

[polishprince]

In your case i would down 12/48. You could use one less link on the new chain and able to keep the wheel where its at. 1 tooth in the front is almost equivalent to 3 in the rear. Then this way its easier to go back to the 13 in the front than in the rear.

[Dan151]

Originally Posted by polishprince

In your case i would down 12/48. You could use one less link on the new chain and able to keep the wheel where its at. 1 tooth in the front is almost equivalent to 3 in the rear. Then this way its easier to go back to the 13 in the front than in the rear.

im looking for more torque and harder to stall. wouldnt i have to increase the number of front or rear teeth? ive hear that i can go up to a 13/51 gearing without changing to stock length of the chain.... im confused with this gearing stuff

[KKXR400R]

More torque/less top speed:smaller front sprocket or larger rear sprocket.
less torque/more top speed: Larger front sprocket or smaller rear sprocket.

It's a balance game. For me its cheaper to buy a cheap front sprocket and test it out from there then buying a rear sprocket that might "get you close".

Every tooth you +/- on the front sprocket is equivalent to +/- 3 or 3.5 teeth off the rear. there is a gear ratio chart on this site but I can't seem to find it. If I do I'll post it up for you.

My gearing stock for my bike was 13/50 leaving me at 50 to 55 MPH. In Desert racing you will easily get destroyed on the straights at that speed. More top end was in order but without losing too much low end for the hills. I ended up with a good Low end/balance at 14/48. I paced Tracy on the dry lake bed last weekend at 71 MPH.

-Kevin-

[Dan151]

this makes sense now.

so would it be easier to go to a 12/48 and remove one link in the chain

or 13/51 and keep the stock length chain?

[KKXR400R]

Originally Posted by Dan151

this makes sense now.

so would it be easier to go to a 12/48 and remove one link in the chain

or 13/51 and keep the stock length chain?

If stock gearing on your bike is 13/48 I would throw a 12 tooth front sprocket on and see if that gives you the amount of low end you want. 12/48 is pretty much the same as 13/51. As far as the chain goes just back the chain adjusters out to clean up the slack. Hope this helps

-Kevin-

[polishprince]

Well said!!!

[Dan151]

thank you polishprince and KKXR400R for your help. im gunna order the 12 tooth front sprocket with my new chain and well see how it feels.

[pjg351]

A 12 seems a little tight for my liking on a 450. I'd go the other way 14/51 maybe for a woods or trail type riding.

[Dan151]

Originally Posted by pjg351

A 12 seems a little tight for my liking on a 450. I'd go the other way 14/50 maybe for a woods or trail type riding.

what do you mean tight? like too snappy with low end?

80% of my riding is slow and technical and once in awhile i like to shoot down the road

[polishprince]

Yeah, couldnt agree more kkx! woods demands lowest grunt possible. Log jumping becomes so much easier with lower gearing.

[pjg351]

Yeh well your not going to loose the grunt, but you will be able to hold the gears longer. Putting a chain through the torture of turning around a 12 tooth sprocket, would put excess loads on the chain/sprocket/ and possibly the gear box on a 450. Anyway each to their own, this chart may help if your interested, to understand the ratios.

[Only registered and activated users can see links. ]

[Dan151]

so if a 12/48 gearing has a ratio of 4.00 and a 13/51 has a ratio of 3.92

what does this mean? will a 12/48 really damage my tranny?

[pjg351]

Originally Posted by Dan151

so if a 12/48 gearing has a ratio of 4.00 and a 13/51 has a ratio of 3.92

what does this mean? will a 12/48 really damage my tranny?

What it means is the front sprocket will turn 4 times around to one revolution of the back sprocket with a 12/48. The argument for whether it will damage your tranny is 50/50 call, some will say yes, some will say no! What it will do though is change the way the swingarm works on your suspension, tell me do you find that the gears are to far apart when your riding, that would be one of the only reasons i could see for wanting to use a 12. A 450 is a torque monster, it will pull from almost a dead stop in 3rd gear if your using it right.

[Miles711]

I don't have any advice on the gearing (I like the stock ratio on the local MX tracks), but would highly recommend a DID X-ring chain and Ironman sprockets. My setup has 43 hours on it and I haven't had to touch the adjusters since it broke in on the first ride. I don't even remember what size wrench it is anymore... That setup was more expensive that many of the others out there, but my experience has been that it definitely lives up to the hype. I honestly expect them to still be on the bike whenever I eventually sell it.

[Dan151]

Originally Posted by pjg351

What it means is the front sprocket will turn 4 times around to one revolution of the back sprocket with a 12/48. The argument for whether it will damage your tranny is