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What is the best way to gain more powerband thrust !! Carb mods or Topend Mods ?

Well if the bike is stock I would start with a pipe.

Yes there is search for "RB head mod"

As far as I know only the 220's qualify...someone will have to confirm that but you can find lots of info with the search box in the top right corner

KDXrider32,

You are not giving anyone a whole lot of information to go on.

Do you have a 200, or 220 ???

You approach each bike from different angles.

Please disclose the year and cc of your bike and any modifications done to the bike, i.e, pipe, etc...

You will get better feedback with more and better information.

Michael

Sorry guys ! Its a 1997 KDX 220 r it has alot of mods already fmf knarly woods pipe and turbocore 2 silencer, moose open air , re-jetted carb , boysen power reeds and power flow , the bottom end and top end has been completely rebuilt all new bottom end gears and input and output shafts, new seals and bearings ! Was trying to find more thrust and zip when the powerband kicks in like a kx 250 ! It is also on a 97 Kx 250 frame! would love to post pics but cant figure out how ! Also gearing is still stock 13 / 47 and running oil gas mix alittle rich 40:1 . I have a youtube GoPro page at Chris Blackburn KDX rebuild ! So any help with some more mods ideas please feel free to let me Know !!!

Bored carb, the small carb on the 220 helps lowend but hurts hit and top end.
Then ditch the woods pipe for the rev, or a PC pipe.

After those two mods are done, I'd say porting and head rework next.

"Was trying to find more thrust and zip when the powerband kicks in like a kx 250 !"

Not gonna happen.

A Gnarly Desert (rev) pipe may help. Porting and head work always helps for more power.

Nothing wrong with the mods you are already running.....if you are looking for a little more umph on your 220 then simply fit the 35mm carb off a kdx 200 & jet to suit, you wont loose any bottom end at all & you will gain in the mid rpm range right through to the top...but it will fall flat quicker!, what you could do is advance the timing on the stator 1 mark ( they are clearly marked on the stator & crank case behind the flywheel, not many do this simple mod but it does work ) this will give the 220 a little more over rev ( retarding it on the 200 should give it more bottom end for a slight sacrifice on the top )...if you still want more then you have to go down the `porting & head ` road, these mods will really wake the bike up but will cost $$$.

cornishwrecker220 wrote:Nothing wrong with the mods you are already running.....if you are looking for a little more umph on your 220 then simply fit the 35mm carb off a kdx 200 & jet to suit, you wont loose any bottom end at all & you will gain in the mid rpm range right through to the top...but it will fall flat quicker!, what you could do is advance the timing on the stator 1 mark ( they are clearly marked on the stator & crank case behind the flywheel, not many do this simple mod but it does work ) this will give the 220 a little more over rev ( retarding it on the 200 should give it more bottom end for a slight sacrifice on the top )...if you still want more then you have to go down the `porting & head ` road, these mods will really wake the bike up but will cost $$$.

Advancing the timing gives more bottom end and retarding gives more top end.

The PC pipe is good for all around power . If you want top end , go with the FMF rev pipe.

FMF rev pipe is great for upper mid to topend. Had a rev on my YZ250 before the gnarly. Bike had great mid and just stupid unstopable topend. The gnarly took the topend off ,but gave me the low to mid I was looking for.

I just installed a pro circuit platinum 2 pipe. It's perfect for all around power.

might be more cost effective jusst to buy kx 250?

Head and carb mods work wonders on the 220. If you're after more top end snap, definitely ditch the woods pipe. It's a terrible match for the 220 unless you are looking for strictly low end grunt. As mentioned, you are never going to get the snap that a 250mx bike has. Totally different animal designed for a totally different purpose.

Well My 220 has some snap and I had a pro circuit pipe on it and it was so damaged I had to pull it ! I can tell a major difference in the power with the fmf pipe seems faster with alot more bottom end all around but just trying to figure out if changing the gearing around would help by dropping to the 12 on the front sprocket or up to a 49 / 50 in the back ? But what would be more cost effective the CARB or the TOPEND ported and bored to a 250 ?

You can go to a 240, but that's not gonna get you more top end "hit". You have already gotten the best advice in this thread according to your description of what you are looking for. Open up the carb, do the head mod, ditch the woods pipe. Carb and head mods will be much more cost effective than boring and porting, and with much more predictable and reliable results.

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Thanks Guys

I think im running a 13/51 on one of my bikes and it is a wheelie machine, first 4 gears all it takes is a twist of the throttle, 5th gear a little compression of the forks (or a good railroad crossing)

kinda rough on the tarmac though, since you cant spin the rear tire and have to be carefull not to get thrown off

The very best thing you can do is tighten up the head and have a good port job. The 220 loves compression and really needs it. The other is porting. They are ported for torque, almost too much. Have some one clean the castings out of the ports and open up the boost port. Did wonders for mine. And although you are gonna hear a million say it loses its lug, lighten the flywheel. Have someone with knowledge do the work. The best I could get off of mine was 8.3oz. Doesn't sound like alot, but it's half a pound. To put it into perspective, on my scale a factory KDX flywheel is 43.3oz, a factory KX is 26.6oz, thats alot. I would like more but it's just too hard to get.