I recently replaced a badly worn d606 front tire, the double lug in the center of the tire had worn almost completely down leaving the single lug intact. The effect was a very noticable bump at low speed, and a serious hop at around 60km/h.

After replacing the d606 with a new MOTOZ The hop is gone, but there is still an odd feeling like I'm going over small invisible bumps. I'm guessing the uneven tread was transferring up through the forks for some reason.

I took a closer look this evening, and the forks are not operating smoothly. They preload to a certain point, and stiffen right up. There is no compression happening when I go over small bumps or imperfections on the road. High speed is no issue, and low speed doesn't seem to bother me. It happens right at cruising speed, in traffic mostly. Annoying as hell, feels like the bike has no suspension right at the speed I spend the most time

Fork oil is low, 85mm.. No sign of leakage or bad seals. I can't tell if the springs are oem or aftermarket, but there was some nice rust right at the top of the spring. I also couldn't see a "spacer". The service manual shows a spacer tube, and I've seen other forum members make some... but mine has none?

I was planning to do a respring and all that jazz, but not this soon. Bike has 15000km, barely broken in.

Hopefully someone can chime in about their forks feeling like they are sticking.

 

I haven't tore into the forks yet on this bike. But you said the oil is low at 85mm? If the fork oil is low, you may not be in the oil when fully extended, and as the dampning valves hit the oil, they stiffen up. This "may" be what your feeling. Like I said, don't know these forks yet, but its just a thought. I would top off the oil level to spec, then give it a try.

 

Put the bike on a stand and with the fork caps off, see if the forks bind when you compress them.......the forks may be twisted. Oh yeh, don't pump the fluid out of the forks when you compress them, messy.

Ride on
Brewster

 

Verify your tire is fully seated around the bead. A constant "bump" sounds like a tire not seated or severely out of balance.

 

I was wondering about this too when he mentioned pulling the wheel to change the front tire. I think a lot of people overlook that "stroking" of the fork when reinstalling/torqueing the wheel/axle. Twisting from a small fall or impact and/or removing/installing the front wheel...always good to insure the forks aren't in a bind at the axle or triple clamps.

OP, the forks on the '06/'07 bikes have really soft initial compression damping but then deliver a pretty good compression spike into the travel. Most will agree that the damping is not so hot for off road and really benefits from a revalve and proper spring rate.

 

Thanks for the feedback.

After thinking about it, the oil level is perfect. (97mm from the top of the tube.. I measured from the inner tube.) I can rule out too much air cushion as a reason for the compression dampening to be soo odd.

The wheels have been re-shod with fresh Kenda k761 tires. (80/20) I have all my tires installed by a reputable shop, and I watch them mount and balance the skins to the rims. Wheels are true, rubber is brand new and balanced.

The forks compress smoothly with the caps off. I had to remove cap and spring to check the oil level. I too thought they might be twisted, especially since the bike took a dirt nap one night on soft ground. As far as I can tell, they are straight. I also undid the pinch bolts and moved the wheel left and right then centered it, to ensure the forks were lining up with the wheel, not twisting to make the wheel fit.

My wr250r had a procedure in the manual to unbind the forks, something to do with pumping the shocks and tightening the clamps in a certain order. I couldn't find anything in the klx250s manual that describes anything like this.

The fork install procedure just says to do "everything in reverse to disassembly" :/ If anyone has a set of magic words and strange arm movements to remedy a bound up fork, I would appreciate it.

To reiterate, the same thing is still happening. Front forks won't compress over small bumps and imperfections. Brand new balanced tires and verified to be true and straight wheels. Oil level is to spec. Forks move freely with caps off. Wheels was installed by tightening the axle first, then right side clamp, in a criss-cross pattern.

I'm starting to wonder if it's the fork bushings....

 

Your mention of fork bushings is something to consider, but I usually see more looseness and "fork knock" when bushings get worn. If yours are worn enough to cause binding, I'd suspect you'd get more noticeable looseness when you rock the bike on a flat surface with the front brake applied. It's hard to predict bushing wear as abusive use and environmental conditions...mud etc...aren't the same for everyone. My best guess is that unless your bike has been hammered roughly and consistently off road in those miles you mention, your bushings are probably not worn out.

I would suggest that if you break your fork down for a revalve, go ahead and install new bushings as they're relatively cheap and super easy to install at that point. In the long run I'd really suggest revalving the fork. The change is pleasantly dramatic...and of course springs that fit your weight and riding style.

 

This was the whole plan from day one, even before purchasing the bike. When I took if for it's first ride off road, I changed my mind. The suspension surprised me, and I felt confident riding hard off road without making any changes aside from rear preload and compression/rebound adjustment. I say this all from the perspective of "it's worked for me so far". I'm not saying firmer springs and a revalve wouldn't be better for someone else, or perhaps even my self!

For conversation sake the previous owner was a bigger guy, and could very well have respringed the front...thicker fork oil... or even the guy before him. Front end doesn't dive as bad as most people say, and I remember my klx250sf diving like mad on heavy braking.

However, the compression dampening was maxed out when I pried the covers off and started clicking about for myself. Seems weird to max out comp. dampening with stiffer springs. I can notice a very small difference between max compression dampening and say 16 clicks. With gear on and full backpack, I notice slightly more dive. I weigh about 145lbs.

I'm going to take another shot at the front end. This time, pull wheel off... drop tubes... pop the caps and yank the whole inside out. Maybe a thorough reassembly by the book will do the trick.

 

Use the same procedure on your KLX as described in the WR manual.
It's just to ensure that everything is seated properly when reassembling the forks/wheel so there is nothing binding.

Here's a video of the process. It's a road bike in the video but the process is the same for all bikes.


Doug

 

Thanks for the advice, everyone. I went over all the suggestions and applied as much information as I could to my method.

After a grueling week of troubleshooting, I was at my wit's end. Almost in the headspace that is quickly followed by a "for sale" ad on the local craigslist... Done with it.

Saturday was no luck. Sunday was a ride in the mud on my tw200. Having a day to relax, forget about the KLX and ride a steel donkey around for a couple hours really helped me get back into the zone. Monday was monday, a cruel mistress. KLX wasn't giving me anything to work with, nor was the day giving me time to address it.

Today being Tuesday- things are looking good. I ride my bike to work, and commute between job locations during the day. Plenty of time to make adjustments, ride and adjust. Spent some time re-reading the suspension section of the Manual, and decided to set everything back to stock.

Compression Dampening 16 clicks out. Top adjuster on rear shock.
Rebound Dampening. 12 clicks out. Bottom " " "

Fork Compression Dampening. 8 clicks out, bottom of each fork.

Voila. It's fixed. Front end still shows is flaws, but I'm not getting a helmet jolt over invisible bumps in the road. My guess is that the settings were either too firm, or I had mixed up the compression for the rebound on the rear shock.

This was a "wag the dog" situation. Rear shock made it feel as though the front was too stiff. Focus of everyone's attention was on the front fork, especially as that was what I was specifically asking about.

What a relief, and a learning lesson. Chasing this gremlin got me doing things I hadn't done to a bike yet. Fork service being the biggest one, as I hadn't needed to take that plunge on any previous bikes. Now I'm encouraged to address the front forks on the tw200!