The following is an email I just sent to Shadetree. I thought you all might find it intellectually stimulating.
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KLX300 header and muffler now installed. Need to quieten it a bit more, as the muffler I got off eBay was lacking the baffle. I'll have to make it. My TIG welder won't be in place in time, but I did decide last week to pop for a latest-greatest plasma cutter ($1,600) that'll make parts fab easy, then I'll braze together and install via the 2X M6 threads.

The 330 cylinder is going on this weekend to give time to break-in for the big ride next weekend. Be interesting to see why this bike is so powerful compared to the old KLR. Be a real surprise to find a 300 cylinder in there. I suspect it's just jetted right.

Did some extensive frame and shock measuring and ride experimentation. I did not like the KLX's skittishness and tucking-oversteer-plowing in the soft stuff. The `09 KLX (I believe the DSN article on the `09 has it backwards) has 1 degree more, not less, rake. That's an improvement and I think they did it with a shorter shock (love to confirm this)

So, I suspected lowering the too-tall rear end (and I'm tall) might calm the handling and make the bike feel more like the wonderfully-neutral, old-tech KLR250 that was surprisingly so easy for me to fly confidently at last-year's Rideok Clayton Lake ride.

At zero shock preload I had 47% travel sag and the front end stopped plowing. I'm going to lower the rear end and then bring it back up some with spring preload. The end result is I've ordered some 2" lowering links off eBay. Weird, huh?

Hope I'll get the parts before I leave. The dynamics are complex and what I'm saying is backwards to some assumptions. Given rake and trail are fixed by design, we can affect handling only by all of the variables affecting ride height (pitch) and the moments (torques) resulting from where the centroid of tire ground contact is with respect to the center line plane of the bike at various bike pitch-roll-lean-steering degree angles. A high rear end on this bike results in less rake and an oversteer moment (tuck-push) earlier in the lean and steering degrees. My shock spring preload experiment resulted in a zero oversteer moment at full lock when plunging into a high lean and steering angle turn in loose sand. Yes!

I'll lose a little ground clearance with the lowering, and affect the rising rate curve a bit. Riding technique and my Utah skid plate will compensate. A big design step forward in modern observed trials bikes (early `90s) was abandoning the idea that high ground clearance was best. Thereafter followed the major lowering of the engine in the frame with ground clearance compensation from improved riding technique. I'll do the same.

I'm sure I've confused you thoroughly (and maybe me too).... Oh well. The proof shall be in the end result, no?

-Chris

 

Drop the forks in the clamps 5mm.
Calms it down a tad. Simple but effective.

 

+1. That also gets rid of the high speed wobble.

 

Before just doing that, I'd recommend first properly setting the rear sag if not already dialed in and put some proper springs in the front and possible the rear too. Improper sag, front or rear, changes the bike's geometry and handling. Set it up correctly, and you ride with the geometry it was engineered to have. If you need to tweak it after that, then at least you are starting from the "factory" geometry.

 

Ya do what nobrakes said.

 

Yeah, yeah, what he said! I guess I'm assuming that Einfahrt already knows how to set sag and has done so...he seems pretty knowledgeable to me.

I know that going with more suitable spring rates and valving on mine worked wonders for stability (sag properly set in both cases).

 

The mod was not a tweak but a workaround for a weakeness (in my opinion) in the design. The steering characteristic I was after was achieved at 47% sag, not the recommended 30-35%. That's why I opted for lowering links, to lower the butt end so I could add spring preload back in. This retains all the useable factory suspension travel (lots of clearance room is available) while getting back to the recommended 30-35% sag. Yes, I'll be up a tad farther on the rising rate linkage curve, but that's a minor detail for me compared to getting rid of the slight skiddishness of this able steed.

Raking out the front end is directly linked to bike pitch (rear and front ride height). Correct on dropping the forks in the trip clamps, but 5mm (.19 in.) is a micro change. Stiffer fork springs do help, but I like to run those at zero preload, so ride height will come up in the front only a bit. But if after the others mods, stiff springs slow the steering too much, I can increase rear shock preload to quicken the rebound. I hate slow suspension and right now all the adjustments are at full miminum and she's still too slow. When the weather cools that will be worse, so I will be screwing around with forks and shock to speed them up significantly.

Much of what I like has been influenced by 20 years in observed trials competition, so it's a bit unusual. It's very hard to describe to you all what I could feel on a modern trials bike, but I do know what I want and it is effective for the type of rising I do, which is I love picking over rough terrain, and I'll go just fast enough to not break into the expert cross country speeds I did 25 years ago. Getting a bit old for that foolishness.

The suspension on the KLX bike really is pretty good to start with. A bit harsh on the choppy stuff, but it handles the big hits all right. A big improvement over my previous (and oddly loved) KLR250. The KLR did have it over the KLX in one way. The softer suspension really soaked up choppy stuff well. The handling was so good - so precisely neutral - I was able to thread through rocks and other big-hit impediments when cutting a fast line on the trail. The plush general ride allowed me to stay on my line, helping me keep up with the fellows on thoroughbreds, causing a few eye-poppers from them when we'd stop. Now hitting something big was to be avoided on the KLR, but I loved that bike and thought very seriously about making it a 330 and my project bike. Sticking with the old tech was fun for me and it had the side benefit of lowering expectations by others with their big-money machines and cockroack outfits. Avoiding being marketed to effectively and exceeding expectations is a fun way to mess with people :-)

But I went modern and bought the KLX to make it the basis of fun. Thankfully, it is still a humble mount with low expectations. The fun continues!

The below is me on Pukey the venerable $1,000 KLR.