KDXRIDER.NET

Hey guys, so lately I've been wanting more power, specifically low end power. I've even thought about selling the 220 and getting a used ktm300(ridden one before and love the grunt). But with a baby almost here the wife frowns heavily on spending a bunch on a different bike, especially since she wants a bike again after the baby is born. The single track we ride is super technical and tight 1-2 gear stuff with steep hills and downed logs. Having some extra grunt to loft the front off idle easier would be awesome so I was wondering if doing the head mod would help. I've got boysen reeds fmf woods pipe and silencer and modded air box. The kdx honestly does everything I need it to and has more than enough top end power for me, I just want more low end to help calm the ktm itch. Is the head mod the cure for my issue?

Proper squish clearance and shape never hurt power anywhere.

Now maybe you could request that it be modded differentlt for an concentration on low end. Typically a little tighter squish, and a larger squish area vs total head area.

Thoughts outside that area:
Suspension. What springs and sag? The stock fork/shock imbalance adds a little to keeping the front down. Once the forks are properly sprung it wheelies more easily. Same goes for rear sag, not enough and the stink bug makes the front harder to pull up.

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never knew that about the suspension, but I did notice my plated KDX (best I know its on its stock piston) will pop wheelies effortlessly in first second and third and with a little compression of the forks in fourth while my woods KDX which has a fresh top end and the front end feels heavier

only difference?
the woods bike has the stock front end, the plated a KX 125 USD unit

before you start spending the big buck though, do you ever run the bike full bore in 6th gear?
if you don't you can try going down one tooth on your countersprocket and see how you like that
it will shave some top end speed but give you low end grunt in return

I hadn't thought about suspension helping out. I have a usd kx125 front end. So maybe ill play with how it sits. The problem with doing the ole compression hop to get the front end up is there's no time for it usually. You turn the corner and bam! Log or rocks to get over. Just enough time to grab a fist full of throttle to get over it. I have 13/48 gearing and use every bit of it at times. I ride a varying terrain, its tight on the west side and open on the east side of the state and the current gearing setup works good for both. So what your saying is the head mod isn't noticeable?

RB carb and head is a great modification but depending on your riding style maybe a 12t front sprocket is what you need and is only a $20 mod.

I've often wondered about a LIGHTER flywheel on these bikes. Sounds backwards, I know.

Since a flywheel weight works by adding rotating mass to the engine it slows the rate at which rpm can change. This is good (reduced stalling, smoother power application), but can also be bad (slower to gain revs). On my YZ I hated an 11 oz flywheel. They don't add low end, as many claim, they just smooth it out. I found that there were corners I could take in say, 3rd gear, and roll on the gas with pletny of acceleration despite being a gear high. Same ride with the FWW and the bike pulled those off-pipe revs much more slowly, and that same corner required either a downshift or some clutch work to get the same drive out of. The other minus was just as this thread discusses, needing to pull the front end with a flick of the wrist. Since it tamed the rate at which revs could be built, I again needed a flick of the clutch, a downshift, or just more body english. It made riding more work. I went back and forth many times, and ended up selling the FWW and sticking with a stock flywheel on that bike. I didn't have throttle control problems, and the weight seemed to be a solution for a problem I didn't have.

The stock KDX flywheel is pretty heavy if I remember correctly. I'll try and pull mine this week and weight it in comparison with the YZ250 one I have laying around. Granted, leaves out tons of other factors like crank weight, clutch weight, etc etc etc.

Suspension will help some, a 12T CS would help a bunch. When I made the switch to my hybrid, the change in suspension was immediately noticeable, not just in the high speed whoops but also in the slow and tight...the bike was much more planted feeling and more point and shoot rather than steering a barge. I have the same problem up here in WA as far as riding areas, west side of the state lots of slow, tight single track with lots of logs and small creeks, east side desert and fast whoops (hate those f*&@#* whoops lol). I have a 12T CS and chain for the west side, and a 14T and chain for the east side. Also have the stock 13T. RUn a stock 47T rear. For the 15 minutes it takes to swap it's the best solution for me, and I have no problem with the KTM itch as I have lots of buddies who ride orange...well actually lots of buddies who ride orange for a little while, then wrench on orange a bunch.

I havn't heard anything but positive when you have the 220 head done by Ron Black.

I'm sending in mine this winter.