I just recently had some engine work done on my 400ex and it still has plenty of bottom end so I was thinking about gearing up one tooth on the counter sprocket. Has anyone done this and what benefits did you see? Also since I don't have the info handy, does anyone know what is OEM on the Front and Back sprocket. I think it is 13/38 just not 100%. Thanks for your feed back.

 

Stock is 38/15. I run a 14 on the front, but I am willing to give up some top end for more low end grunt.

 

YZGUY,
Do you notice any difference with the 14? I am thinking about getting one but I can't see how one tooth makes that much difference.

 

I put a switched to a 14 tooth sprocket, and love it... you do loose some top end speed, but I do mostly tight trail/woods riding and rarely get the bike wound out in 5th.

Leo

 

I have a stock engineand went to a 39 tooth rear. I also run a smaller tire in the rear though (18's) The gear helped get me off the line quicker and I don't have to shift as much on most tracks.

 

400exrydr-I put on taller tires (22" Holeshot XCT), so with the smaller sprocket I'm probably getting back close to stock gearing. Anyway, the thing climbs the worst hill I know (long, steep and with a bunch of overhangs) easily in second gear!

 

What do you want to do? More bottom or top end. The EX has plenty of bottom end. The stock gearing is 15/38 this give you a ratio of 1:.39 In other words 1 revolution of the front sprocket equals .39 revolutions of the rear sprocket. If you go with a 16 tooth front you get a ratio of 1:.42 which gives you more top end. Or you could go with a 37 rear which gives you a ratio of 1:.405, not as much top end. Or you could go with a 16 fr and 37 rear and get a ratio of 1:.432 which is heller top end. If you have more hp and torque than stock,you should have no problems pulling these ratios. If you used the 16/37 combo, for every 100 revolutions of the rear tire you would be 27 feet further down the track than with the stock gearing. Now, if your engine can pull this kind of gearing, you would be smokin some ***.!!!!! I am just giving you the numbers, do with them what you want.

 

SeaDooMan - and others, Thanks for the input. Your right in that the 400Ex has plenty of bottom end and I do want more on the top. I ride mainly in the sand but in a motor x fashion, and the two bikes I'm up against are 250r's and Raptor. I now have somewhat of an advantage with the motor work, but on a straight drag, the Raptor has me by a few bike lengths. I love the ride on the 400Ex so I don't want to trade it till Honda comes out with a bigger EX. Yet I'm tired of being lost on the straight away's. So with all your advise, I think I'll go to the 16 tooth front, I'm just having some problems finding one. Any suggestions on a good sight to pick one up? Thanks again.

 

With your engine mods listed the 16 tooth will kill you in a drag, especially in sand. If you have enough power, you may gain a couple MPH's at very top end. I went through the same thing before trying to out-drag a stock Banshee. With the 16 tooth sprocket on the slightly modded (comparable to yours) 400ex I had, I would get beat out of the hole and top end did'nt matter, because the Banshee was in the next county (seemingly-and this was on pavement). In my opinion, get a 13 tooth front sprocket and enjoy being in the race for 3 or 4 gears. Good luck!

 

EXlarge, you should be able to get sprockets at your local dealer. Get them out of the Parts Unlimited Catalog. Or you could get them from anyone who sells parts in these magazines. You may want to get both the 16 front and the 37 rear. You don't have to use both, but you can vary your ratio by using one or the other. Look at my previous posting. If the front sprocket takes away too much bottom end, put the 15 back on and put the 37 rear on. Since the 37 rear has a lower ratio, it won't hurt the bottom end as much. Play around with it, you will figure it out. By the way, you can't be getting beat that bad by the Raptor, all I have is a 440 kit with stock pipe and I only got beat by 1 quad length.