MX Gearing

[Co_Racer]

What are the MX guys running for gear stock is 14/42 just thinking that is a little high 3 to 1 ? on the YZ Hybrids ran 14/39
like 2.78 to 1 any input?

[ml450r]

I am running stock gearing, I think it is to low for 2nd gear but fine for 3rd and 4th. The trans gearing is different and seems to let the stock gearing be ok. I definately would not lower the gearing.

By lower I am saying do not make a higher ratio.

[TNT]

Just depends on the rider, heres some general rules,

Smaller front sprocket: more bottom end, less top speed
Smaller rear sprocket: less bottom end, more top speed
Smaller rear tires: more bottom end, less top speed

My 09 DS450 comes with a 13-38 and we noticed a dip in torque at 1st to low third. A 5-6% change down would be good for torque but not as much speed in each gear,

38/13= 2.92 stock sprocket ratio

40/13 = 3.07 new sprocket ratio

(new ratio / old Ratio) - 1) * 100 = change as a percentage.

(3.07/2.92) - 1) x 100 = (+ 1.0513 -1) x 100 = 5.13 % change from stock down.

Positive % trade top for bottom, negative bottom for top.

I could figure this out better if I knew what rpm I had at 1, 2, 3 but I can try this and experiment without a dyno. 5-6% changes are good to try at a time, any less wont be felt, any more might be too much.

Actually to change the torque or rpms for a given mph up or down its better to change the rear sprocket since going to a smaller front sprocket requires the chain to turn at a smaller radius causing more friction and wear. Its always a good idea to change the chain if it's not new when changing sprockets and visa versa since these surfaces are made to wear together with respect to the chain roller.

[ml450r]

My 09 ds 450 mx has a 14 tooth sprocket on the front.

[TNT]

Thats what DGS said, I'm going to see the eye doc now! Im old! Well you get the idea anyway.

[jlrenken]

tnt1 check your pm

[andiboy123]

this is my experience and point of view
When I start messing with the gear there was a lot of theory but actually on the track is where you get that result. First thing I did was compare all ratios gearing on a chart I found on the internet ( http://pinnedoutracing.com/gearratiochart.aspx ). My ride is a 08 it’s come stock 14t front, 42t on the rear, giving me a 3.0 ratio plus considers a 20 inch tire. Now first thing you should do on your mind is forget about other atv’s Yamaha , Honda, kawi, LTR they are all different, trany’s are different start by knowing your starting ration and going from there. Lowering 1 tooth to a 41t giving you a .07 lower on your ratio giving me a 2.93. Now as we all know DS come low on the very low end but once you hit that 3 gear it goes good. And when I put that 41t it was good for the off road but no good for race. NOW THIS IS WHAT MY TEST GAVE ME RESULT!!!!!!!
Thinking on how to get that low end first thing you think is lowering the front sprocket to a 13t but that affect the top end keeping the 42t on the back. Ds comes with a 3.0 ratio stock so I put 13t on the front and a 39 t on the back, same ratio buttttt different spin on the engine and rear axle giving more spin on the engine and compensating that on the rear. First test was great, dragging and starting my race on 2nd gear and it was a beast against VS my brother YFZ, it was a real good improvement, nowwwwwww remember I’m still going with the 20” tires so we change to a 18” wheel and there was when it woke up hehe out of the hole I jump easy 1 ATV or 1 ½ and keep it that way until 5th gear.
So, like I said my personal opinion and my experience, my test, and my result on my ride hehehehe, at can am the spend real time searching for the right gear based on the transmission they design, out of the box, stock, you get the fastest ATV on the market (I never race a KTM) but all ATV has to spend real good amount of money or open their engines (yfz) to do cam mod,s to run side by side with you and with a few test you get results……..
Also remember http://www.marineworld.com/aboutus.asp THEY REALLY HOOK YOU UP THANKS TNT1

[X400EX]

Thanks for the info, but anyone can confirm me that the MX 09 has 14 front? Then I would order a 13...

[X400EX]

No one? I'm not at home right now and would need to order ASAP.

[ml450r]

It is definately a 14 tooth on my 09 ds450mx.

[X400EX]

Ok, thanks!

[Co_Racer]

Thank You everyone for the info.

andiboy123 liked yours coming from testing so I'm going to order Siderwinder T2 13/39 with there Smart Chain have had good luck with Siderwinder in the passed.