125 Riding Technique

[NM_KDX200]

YES!!! I still have a 125!!! :)

My question....when people say "pin it and just shift" are they serious?? I've been riding for about 30 years off/on, and I've been riding my KX125 for about a year (prior to this I raced a 125 in 78-79, but that was then). In this time, I've learned to work the clutch, keep the revs up, and am doing much, much better than I was when I started last year (coming off a 250 and a KDX200).

However, jumps are still a little bit of an issue. If I hit a jump literally wide-open, there's no "push" and the bike will usually nose-dive a little. It works so much better to let off a little and then accelerate up the slope. Likewise, on whoops and small doubles- I need that acceleration factor to really clear them. If I really, literally, "pin it", I don't have that acceleration and the bike runs in the over-rev portion of the powerband.

So...any 125 specific tips for jumping?

 

[High Lord Gomer]

"Pin it and shift" leaves out the most important aspect of riding a 125 ... slipping the clutch to keep the RPMs up where the power is while providing drive.

Over-revving on a jump face is a bad thing on any bike. Because the 125 has a narrower powerband than 250s (or any 4 stroke), I would try using one more gear and the clutch to keep the power up.

 

[NM_KDX200]

I would try using one more gear and the clutch to keep the power up.

What happens when you're approaching the jump face and realize you're not quite as high as you'd like to be in the powerband?

I'll work on clutching on a jump face and see what happens.... :ride:

Are you the same High Lord Gomer what used to hang out on RMD? I seem to recall a picture of you and a sheep..... :nod: :nod:

 

[adam728]

It sounds to me like you are running the jumps a gear too low. If the next gear is too high then it may be time to think about a sprocket change to keep you in the meat of the power band.

 

[NM_KDX200]

It sounds to me like you are running the jumps a gear too low.

I didn't say that I am hitting them wide-open, I was just saying that if you DO, it doesn't work right. I'm questioning this saying about "pin it and shift" that I read every so often regarding 125's. I just haven't found that to be true. I've found it to be more of a "hold it 3/4 throttle, shift, use the clutch". Just for fun I tried riding the entire track in 3rd gear- Bubba did that an earlier SX when his bike got stuck there. It sure teaches you to maintain momentum!

 

[High Lord Gomer]

What happens when you're approaching the jump face and realize you're not quite as high as you'd like to be in the powerband?

I'll work on clutching on a jump face and see what happens.... :ride:

Better riders may be able to slip the clutch all the way up and off a jump but I slip it on the approach with the intent of getting/keeping the power where it should be in the correct gear so it's pulling for the takeoff without needing the clutch or a gear change on the face of the jump.

Are you the same High Lord Gomer what used to hang out on RMD? I seem to recall a picture of you and a sheep..... :nod: :nod:

(in my best Bill Clinton voice)

I did not have motocross relations with that sheep.

 

[adam728]

I guess I'm still trying to understand what is happening here.

It sounds to me like you are saying in the first post that when you try to be wide open you aren't accelerating, and you have to slow down and get back on it. That tells me that when you are wide open you are past the powerband and need to be up another gear.

In your third post it sounds to me like something maybe setup wrong with your jetting if your bike accelerates better at 3/4 throttle than wide open.

I used to race 125's and definitly used the pin-it theory. I really never used the clutch that much either, until a clutchless wide open upshift caused 3rd gear to frag, while going up the face of a double. Hitting a new found neutral gear as your front tire leaves the lip is not where you want to be. After that I still rode the same, but would slightly slip the clutched as shifting.

 

[NM_KDX200]

I'm looking at a dyno chart of a CR125 and peak power is at 11,000 rpm. Past that, it falls away fast (up to 12.5k). There's a definite hump from 10k to 11 k and that's the upper hit "hit". 8k to 10k is the meat of the powerband. Assuming 12.5K as the limit, 3/4 throttle is 12.5k * .75 = 9.5 k. That corresponds with my seat of the pants where I'm working the throttle from 3/4 to just under wide open. Actual, literal, wide-open makes a lot of noise, but I'm out of the powerband and I've lost acceleration.

But whatever throttle you ride at, if you just leave it there, you're not really accelerating. For instance, I've also ridden around the track with a constant 1/2 throttle and it's hard to do anything. The power and speed have hit equilibrium and you're going fast, sure, but there's no forward acceleration anymore. It's like riding an electric cart or something. I guess that's where you'd use the clutch to slip the power, then reapply it to get acceleration again?

Next question- how do you slow down for approaching jumps? I can pretty much over-jump all the jumps on our track, except the 90' tabletop, if I literally keep it wide-open. There's one small table top (40'?) in the middle of a gently curved straight. By the time I hit the jump, I'm in 5th gear. If I hit that sucker in 5th, I'm going to overjump it by 20' and flat-land. Plus the jump face is steep and the impact on the face at that speed is harsh. It's too steep and too fast for ME to scrub- maybe you can, but I'm 44 and I'm not gonna scrub that puppy at that speed. What I've been doing is braking a little about 20' or so from the face- this then throws me out of the powerband, so I d/s to 4th for the jump, then click it back to 5th in the air and use the lack of traction to get the revs back up for the landing. I only get to use 5th for about 100' then there's a sweeping 90 deg right hand hand and an upcoming table top that I need 4th for. However, if I just leave it in 4th after the smaller tabletop, I'm over-revved when I hit the corner. I know that when I click up to 5th that I have to brake harder, therefore I think I do go faster when I up shift.

These things are hard to describe- maybe I'll just go practice and try things out some more.... :nod: