My 09' kx450 could use more bottem to mid power

macchiavelli450
Edited Date/Time 7/31/2013 5:47am
Whats up everybody...Im trying to find out what will make efficient and noticeable power gains from bottom to mid range on my bike. Im a bigger dude @ 6'1'' 275, but my buddies 08' crf450 has way more bottom to mid power than my bike and feels and great. Im still running stock exhaust and he's got a full FMF set-up, but will the exhaust really make THAT big of a difference!?!? does it have anything to do with him having a carb and mine being FI?
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Travis_Hudson 7/14/2013 11:29pm
7/14/2013 11:29pm
I'm not sure man.....my 09 kx 450 felt like it had a ton of bottom, I'm 6'3 and 245 but when I put a full pro circuit on it I actually lost a little bit and got a ton more over rev. That bike has a lot of bottom end. Try one tooth bigger on the rear.
partialperson
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partialperson 7/15/2013 7:58am
7/15/2013 7:58am
Save yourself a ton of money and add a tooth or two to the back sprocket. A pipe will probably not make near the difference in feeling of pull down low and may only increase your over rev.
partialperson
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partialperson 7/15/2013 8:00am
7/15/2013 8:00am
Sorry, I responded before reading Travis' post, oops.
macchiavelli450 7/24/2013 2:42pm
7/24/2013 2:42pm
Thanks for the input guys!!! I have already put a 51 tooth sprocket on there and it still don't have the bottom end pull like my friends 450. I also forgot to mention that I've got an aftermarket ignition on it that another friend pulled off his JGR bike and I'm thinking that is actually smoothing it out since he was always talking about how smooth his bike was, but I don't know? I also checked my clutch the other day and with the accept ion of the basket being notched out some....the plates all looked good. I'm not sure if the frictions are worn to the point of replacement though.

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enginedr
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enginedr 7/25/2013 9:23am
7/25/2013 9:23am
macchiavelli450 wrote:
Thanks for the input guys!!! I have already put a 51 tooth sprocket on there and it still don't have the bottom end pull like my...
Thanks for the input guys!!! I have already put a 51 tooth sprocket on there and it still don't have the bottom end pull like my friends 450. I also forgot to mention that I've got an aftermarket ignition on it that another friend pulled off his JGR bike and I'm thinking that is actually smoothing it out since he was always talking about how smooth his bike was, but I don't know? I also checked my clutch the other day and with the accept ion of the basket being notched out some....the plates all looked good. I'm not sure if the frictions are worn to the point of replacement though.
do the intake cam and stock pipe , should be able to pull a 48 / 49 when its right , we have a few of these set up that way with very good results on pump gas.
the degreed intake cam will make you happy camper
mynewcr250 7/25/2013 3:36pm
7/25/2013 3:36pm
People seriously complain about lack of bottom end torque from a 450? You gotta be kidding
Paw Paw 271
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Paw Paw 271 7/30/2013 6:27am
7/30/2013 6:27am
Your bike should not need a 51 tooth rear sprocket. You need a 47 or 48 on the rear to get the correct torque.
joeellis
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joeellis 7/31/2013 5:31am
7/31/2013 5:31am Edited Date/Time 7/31/2013 5:42am
Paw Paw 271 wrote:
Your bike should not need a 51 tooth rear sprocket. You need a 47 or 48 on the rear to get the correct torque.
The increase or decrease in the number of teeth and its effect is somewhat confusing to me. Let me try and explain.

I also want to increase the torque which should decrease the top end slightly. I come from bicycle racing in which the gearing is very similar. What I know about gearing is that the greater the difference between the 2 gears, the higher attainable speed. But, with that said, if there isn't an increase in hp, there will not be an increase in speed.

So, going to less teeth in the rear should allow the engine to turn the rear wheel at a faster rate. This appears to me thai it would create a situation in which you will get up to speed quicker in each gear, but the max speed in each gear would decrease with all other things being equal.

In other words, going with less teeth should create greater torque but less top end speed. Am I thinking correctly?

Update: It has been explained to me that in order to create this scenario, you would either need to increase the nuber of teeth in the rear sprocket or decrease the number of teeth in the front sprocket. Obviously you could also do both to get a greater ratio. Very confusing to my pea brain. Smile
BRMX
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BRMX 7/31/2013 5:47am
7/31/2013 5:47am
the kx 09 is definitely smoother than the crf 08 ( already had both of them ).
Most because of the FI.
If i was you, before spend any more money i would just work on some different maps.
The results that you can get working on maps are amazing...

About sprocket. I always prefer to run +1 tooth in all of KX 450 i owned so far.

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