KDX wont turn in mud

[budpat105]

I'm a newbie to dirt riding and hare scrambles, just rode my first 2 in the mud in central IL. I have KDX2 lowering links on my bike (2002 KDX200)and the forks slid up in triple trees about 1". It seems when I'm turning in muddy areas the front end wants to go straight, may be just me or the conditions but didn't know if the front not being lower as much as the rear end would have any effect on this. I'm really thinking I just need more riding time. Whats everyone's thoughts on this. Thank you

 

[mechanos]

Had the same problem with the stock tires on my KDX. Replaced stock tires with more agressive mx tires and it made a world of difference, much more stable thru mud. You could start with just the front as I did (I quickly changed the back also).

 

[budpat105]

I'll try a new tire, whats everyone's favorite tire? Thanks

 

[reepicheep]

That's a pretty radical geometry change, FWIW. Maybe that's a proven mod, so see what others running it have experienced. I haven't heard of it, but I'm no expert.

On the other hand, its hard to ride mud under any circumstances. I can usually get decent grip with the front if it is really just mud, when it hits the first diagonal rock or tree root or rut, wham, down I go. Or if it gets completely clogged with that sticky and thick Ohio clay, its point the bike, whack the throttle, and hope it works out...

 

[reepicheep]

Oh, and for tires, I put a Continental GS on the back of my KDX. It was the biggest widest spaced knob tire I could find. Doing great and lasting longer then I expected. When I had my KLR-250 dual sport (and was doing street), Kenda Trackmaster II's were pretty nice, but clogged in the mud. I put a Pirelli Scorpion on my kid's KX-60, and that looks like a really nice tire as well. My buddy managed to scare up a Tera-Flex (Terror Flex?) rear and is running it on his KDX, working well, and did half a days ride with NO air in the back (we must have forgot to tighten the bead lock and he ripped the stem right out). We just tightened up the bead lock and he kept riding. Worked fine, they have really stiff sidewalls. Kind of a poor man's "run flat" tire. Though he did rip off a few knobs in it doing 40mph power slides.

I got the uber-cheap IRC tire for my kids Kx-60, it was beyond junk. Maybe other IRC tires are good, but that one wasn't, and with so many other good tire brands out there, I don't feel the need to blow any more money on them.

Anyway, those are a few data points. Lots of good tires out there.

 

[sr5bidder]

if you have a cycle gear in your area they have the dunlop 745's on clearance for 39 bucks front and 49 bucks rear I bought them and put them on my kx125 project

friday I got the engine all bolted up and hit the back yard, it had rained thurs. and friday and was muddier than I expected and the front end dug right in..if I had money enough to spread freely between my 4 bikes I'd give the pirelli line a try they seem to have aggressive front patterns....

stay away from the dunlop 756 front though they are crap from the get go, I have had them on my kdx for over a year and washed out many many times, I have the kdx 1 lowering link, forks run up 12mm in the trees and the shim stack mod

 

[mudpack]

Turning in mud is not easy, even harder when its rutted as in on a track. Best is to steer with the rear end. If you want to ride in the slop, Bridgestone's M101 is a very good front mud tire.

 

[dirt bike dave]

The Michelin S12 is a very good mud and soft terrain tire. You'll see a huge improvement over stock rubber.

 

[Joburble]

Lowering the back end flattens out the rake of the front forks and will make the bike want to push and go straight on in the corners. The problem will be even worse if you have the rear suspension too soft. Another common mistake that new dirtbike riders make is not moving about on the bike enough. If you are sitting too far back on the bike combined with the flatter fork angle it sure will not want to turn. If you have lowered the back end by an inch and dropped the front end by an inch you are still only at the standard geometry of the bike (nothing too radical there).

All the tire talk is important but it is only a small part of how to fix it.

How to fix it.
1. Make sure the front end is lowered at least the same amount as the back end (back end lowered by an inch - front end lowered by and inch)

2. Get a decent front tire.

3. Tire pressure. Depending on how slippery and muddy it is and how many rocks there are about you can run the front tire quite flat and have the rear a couple of pounds harder. Try 7 - 9lbs in the front and 9 - 11lbs in the rear (don't run it any flatter if there are rocks or gnarly hard tree roots to hit), and make sure the tire bead is seated properly and that the rimlocks are tight.
I bet I get slated for this but, (don't try this at home)
In the past when racing MX on incredibly slippery ground with no rocks and only smallish jumps I have actually run my front tire flat and 4lbs in the rear. I had no issues at all and beat many of the "fast" guys because they couldn't stay upright on their hard tires. A few weeks ago I ran 2lbs in the front and 7 in the rear, and that was in a 2hr ride with no broblems on very slippery ground.

4. Set your suspension sag properly, here is a link about that >>HERE<<

5. When turning in mud get your crotch right up to the gas tank to get the weight forward and onto the front wheel, this also compresses the forks and steepens up the rake, then you will be able to steer it with the rear wheel like Mudpack suggested if need be.

6. Standing. (On slippery trails) Standing in wet slippery conditions gives your bike a lower centre of gravity and makes it easier to control. When you are sitting your weight is on the top of the seat (quite high) when you stand your weight is on the footpegs (quite low). That's why you see a lot of guys sitting and paddling away with their feet in slippery conditions while getting nowhere and the bike going in all directions, then some other guy who's standing not sitting passes them all with seemingly more grip and a controlled bike. You don't have to stand all the way, just put all your weight on the pegs and you will notice the difference.

7. Weight the outside footpeg in the turns. When turning put your weight on the outside footpeg. This combined with all the other stuff should see that bike turning pretty good.

All of this is just my opinion. (Disclaimer so I don't get hassled about those low tire pressures).

 

[budpat105]

Thanks for the answers, I am going to get my rake back like it was stock, change my tire, and get in shape, I was the guy on the seat and noticed when I got off the seat I was up shifting but fatigue( from falling) kept putting me back on the seat so I need a little conditioning also. This thread really helped me. Thanks again

 

[mudpack]

Standing... gives your bike a lower centre of gravity...

You'll see this advice many, many times. Standing will often give you more control, but it raises the CG of the rider. The bike's CG stays the same.
In other words, raise part of the mass of an object (in this case, the object is the bike/rider) and you raise the CG of the entire object.
I know where this standing-gives-lower-CG comes from; logic would tell you having the rider's weight on the pegs instead of the seat would place the weight of the entire object lower. It doesn't. The bike's CG is unchanged, and the rider's CG is raised slightly. The "attachment point" of a component to the whole does not effect the CG. Only the positioning of the component affects CG...and when you raise the component, you raise the CG of the whole.
Standing gives you more control because you can move more easily and you can allow the bike to more more easily beneath you. That's why telling you to stand is good advice.
Stand up! :nod:

 

[reepicheep]

Nice writeup Jo. Wouldn't lowering the front and rear by an equal amount significantly shorten the wheelbase?

I have no idea what that means on a dirt bike with 8 inches of travel, but it would be a huge (like maybe kill you huge) on a modern sportbike. I suspect it would have *some* handling impact on a dirt bike. Perhaps making it able to turn tighter, but at the cost of higher effort, and maybe with a slighter highly tendency towards tank slappers... but that's a guess.

That being said, back to the original question, the reason the KDX doesn't turn on mud is because nothing turns on mud. It's more like driving a boat, the more it's pointed the direction you want to go, the more throttle you give it, then hang on and hope. :)

 

[Joburble]

You'll see this advice many, many times. Standing will often give you more control, but it raises the CG of the rider. The bike's CG stays the same.
In other words, raise part of the mass of an object (in this case, the object is the bike/rider) and you raise the CG of the entire object.
I know where this standing-gives-lower-CG comes from; logic would tell you having the rider's weight on the pegs instead of the seat would place the weight of the entire object lower. It doesn't. The bike's CG is unchanged, and the rider's CG is raised slightly. The "attachment point" of a component to the whole does not effect the CG. Only the positioning of the component affects CG...and when you raise the component, you raise the CG of the whole.
Standing gives you more control because you can move more easily and you can allow the bike to more more easily beneath you. That's why telling you to stand is good advice.
Stand up! :nod:

Okay point taken, poor wording on my part. Standing lowers the weight distribution on the bike and allows the bike to be more responsive and easier to ride.

Wouldn't lowering the front and rear by an equal amount significantly shorten the wheelbase?

Yup, the standard fork rake is 26.5 degrees, then set 1 inch (25.4mm) down in the clamps will shorten the bike by just under half an inch (11.33mm) to be exact, that's if the rear is lowered by the same amount. Shorter bike will turn quicker and will be less stable at high speeds, but it shouldn't be a problem unless you are going real quick on the beach or a field or something. Through trails I would think it would be fine, I'd ride it. Don't forget almost all bikes have some tolerance in the design for wheelbase changes caused by chain adjustment and the shorter wheelbase caused by full suspension compression.

It's more like driving a boat, the more it's pointed the direction you want to go, the more throttle you give it, then hang on and hope.

If I ever get to go riding in the US warn me where you are riding so I can stay at least 10 feet away from the guy hanging on and hoping WFO in the mud :)

 

[reepicheep]

Don't worry, based on my riding, you would be ahead of me anyway. :)