2018 KTM 150 XCW First Impressions

I’ve been riding and racing a KTM 300XC.  I’ve tried and owned a number of bikes, and the 300XC is the bike I was fastest on in gnarly terrain, open areas, and single track.  But when racing enduro or Hare Scrambles, corners are my Achilles heel.  So I purchased a KTM 150 XC-W on the theory that it has less power,  will carry less speed into the corner, and will therefore require me to fix my cornering problems to go fast.  Also, I’m a small guy – 5’4, 155lb.

At the time of this writing, I’ve had the bike for about two weeks.  I put two hours on it in initial setup, 4 hours on it at the 2018 Zinc National Enduro, and another two hours working on setup.  The stock front and rear tires provided great traction but I wore out both the front and rear tire in only two hours of riding (but on very rocky rough terrain that’s super hard on tires).  When I say “wore out”, I mean the fronts of the rear tire blocks rounded enough that acceleration traction was substantially lessened, and the backs of the front tire blocks rounded enough that braking traction was substantially lessened.

I replaced the front with a GoldenTyre GT216 80/100-21.  After six hours of riding it looks like it has another 10-15 hours of life.  I replaced the rear with a Michelin Starcross 5 soft 120/90-18.  The Starcross 5 is just about wore out after 6 hours.  This is very unusual for me, the Starcross 5 soft rears usually last me 15-25 hours.  I think this is directly attributable to the fact that the 150 spends most of it’s time crazily spinning the rear.

Jetting

As delivered, the bike’s jetting table says that it’s set up for 80 degrees and sea level.  I did my test riding at 80 degrees and 2000′, so the bike should theoretically have been a bit rich.  My actual experience was that the bottom end was very lean.  Idle started low then gradually rose as the bike leaned out.  Gassing the bike at all hard would result in a lean stall, and the bike had a bad flat spot just before it came on the pipe.  I was unsure whether the flat spot was a jetting problem, a pipe issue, or a powervalve setup issue.

With a little experimentation, I replaced the 30 idle jet with a 32.5 and then a 35 (the largest supplied). The low end was still too lean even with the air screw screwed so far in the bike wouldn’t idle properly.  So I also raised the jet (dropped the clip) two clip positions.  At this point it was getting very dark.  I rode it a bit and it seemed much better.  I was heading to an enduro where it’d be 2-30 degrees colder and 2000′ lower so I thought it would be OK.

I was wrong.  At Zinc, my first two tests sucked.  Every time I let off the gas, the engine would load up.  I couldn’t power out of turns and it took the engine halfway to the next turn to clear out and get up on the pipe.  After test two I took a 37 minute penalty to install a 32.5 idle jet and lower the needle to the stock clip position.  This really woke the bike up and it ran great for the rest of Zinc.  I was able to find out that the bike absolutely loved going into a tight tree corner laid over as far as would fit (in some cases with a good rut and trees 4-5′ apart, this meant the bars were almost on the ground and the bike rolling the rut).  Just after corner entry I’d smoothly add throttle until I was at full throttle and on the pipe coming out of the corner.  I was instantly faster than I’d ever been on any other dirtbike.  Period.  Ever.  I race B for the long course but many C riders are (were) faster than me.  Not so much on this bike.  For the first time ever, I passed about the same number of people as passed me in an enduro.

Back at my regular riding spot, I found the engine was still very lean on the bottom.  I moved back to a 35 idle jet, but it’s not big enough.  I still have to keep the air screw so far in (about 1 turn out) that it causes idle problems.  I plan to try a 37.5 idle jet but I had to order one as I didn’t have one handy.

Suspension

I’d heard a lot about the XPLOR forks being bad.  Too soft.  No damping.  Clickers don’t do anything.  I figured I’d have to replace them.  On every other KTM I’ve ever owned (ones with 4cs forks and AER forks as standard), I’ve replaced them with Ohlins TTX forks and gotten much better results.  I ordered a set for this bike.

Well, much to my surprise, these forks are (for me, a fast C/slow B rider who does lots of rough central Texas terrain), the very best forks I’ve ever ridden.  By a long shot.  The only problem I have with them is that they have zero bottoming resistance.   That’s OK for almost everything I ride.  I never get more than 5′ of air and the bike has plenty of bottoming resistance to land that flat.  But I’ve bottomed the forks once in a g-out (not a good place for fork dive) and once on a high speed square edge.

What these forks do very, very well is a) work in a balanced way with the rear suspension to keep the rear of the bike from kicking, b) absorb enough bumps that even in very rocky terrain at pretty high speeds you can stay on the tank without fear, and c) help the front tire stick like glue.  Especially in situations where you have very tight right and left 90 degree turns linked together, the suspension is magical.  Coming into the corner the forks put just enough resistance into the turn that you quickly get to your traction limit as you lay the bike down, then they set in, grab on, and beg you get on the gas – hard – on the way out.

I’ve heard the fork clickers don’t do anything and I haven’t tested this theory.  This the first bike I didn’t start changing fork clickers on immediately.  I will at some point spin the dials and see if anything gets better, but it’ll be hard to beat.

In addition to the lack of bottoming resistance, the forks have one other downside.  They seem to harden up after a lot of heat builds up.  Since I got 27 minutes behind in the Zinc enduro I had to do two tests and two transfers with no wait, and I only got a 90 second stop for the third test.  About 1/3 of the way through the third test (about 25 miles virtually nonstop), the forks firmed up and started beating me up.  Makes no sense to me, I’d think hot oil would be thinner.  But it’s what I experienced.  The next time I rode after giving the forks time to cool down, they were back to their fabulous normal.

Rear suspension

I wasn’t sure what I’d think of the non-linkage rear, but it’s been great.  After a little experimenting, I’m running the rear suspension at the manual’s most aggressive settings, which if I recall is 12 clicks out on LS compression, 12 out on Rebound, and 1 turn out on HS comp.  I went as far in as half a turn out on HS comp, but it was too much.  The rear end started kicking badly on square edges.

So How Fast is it?

I have three test loops that I run.  After getting the bike set up, I did a 6.5 mile loop (Hidden Falls Ridge Trail).  I have this loop memorized, dialed, and I’m faster than anyone I know on this loop.  My fastest time was set on my 300XC at 19 minutes 45 seconds.  However, my recent best was 20 minutes 20 seconds.  This is mostly due to the fact that there are some sections of the trail that have been boogered up by the landowner and have added 35 seconds to my time.

My first attempt on the 150 XC-W?  19 minutes 28 seconds.  52 seconds faster than my recent best and 23 seconds faster than my record.  And when I set my record I had zero errors.  I actually made three errors that cost me a total of about 15 seconds on this run and still beat my record.  All three errors were the same — I came into areas with more speed than I realized and ended up either clipping trees or having to jam on the brakes to avoid trees because I was just coming in too hot.

Strengths and Weaknesses

Weaknesses?  It has ’em.

First up, extreme terrain traction.  Or more specifically the lack thereof.  Especially on steep, slick hill climbs and technical climbs with ledges.  I just can’t get it to grip.  I’m significantly faster on my 300XC in rocky, ledgy streambeds and rocky technical climbs.  I also make less errors and fall less.

Second, no torque.  With the 300XC you have your choice of great torque for technicals by staying anywhere between 2500 and 6500 RPM or great power by getting over 7K.  A huge range of great traction, and a huge range of great power.  And both low and high power ranges are very easily modulated.  As an aside, I run the red spring at the stock preload and the aggressive (stock) ignition map).   But the 150?  The good news is the power is easily modulated when the bike is on the pipe.  Also, there’s a TON of power when the bike is on the pipe.  The bad news is that under about 8500 RPM there is no torque.  A Smart Car surely has more torque than this thing.  I’m hoping to improve that somewhat with jetting, but my feeling is that the only way to improve torque will be to trade off top end power by going to a pipe with a shorter expansion chamber tuned to deliver torque down low.  I don’t think this will be worth it, as I expect you’ll get maybe 1,000 more RPMs of torque and you’ll trade it off by losing the same amount out of the meaty power band.

Third, shifting and top speed.   Expect to shift twice for every shift you’d make on a 300 or 350.  And the top speed at redline is theoretically about 71.  In reality, I topped out at about 65 due to wheelspin.  On a positive note, the bike is very happy at 60 MPH and you can cruise there for a decent span before the vibration starts making your bits go numb.

And fourth, the starter(s).  The electric starter has a really hard time turning the bike over.  Even in neutral, it often takes several seconds to start and it usually hangs up the first time it hits the compression stroke (probably depending in where it started in the stroke).  With the bike in gear it’s almost impossible to start.   The starter motor just can’t overcome the significant clutch drag.  Perhaps this will get better as the clutch wears in.  The weakness could be a super small starter motor, but I have a second theory too.  It could be insufficient wiring.  I haven’t measured it yet, but it looks like the starter motor may be wired with 10 gauge wire.  I’m going to do a voltage drop test and, if that looks like the problem, I will try rewiring with heavier gauge wire.

Why did I say starter(s).

Strengths?  Where do I start?

First, the bike wears you out less.  Way less. That means that I still have good form and good speed way later in the race.

Second, flickable?  Look in the dictionary.  Flickable (n) : KTM 150 XC-W.   You can push the bike into the ground for a left turn, pop up so fast the suspension almost lifts you off the ground, and shove it down hard for a right hander.  And the suspension and tires just dig in and grip as you lay it over.

And third, fourth, and fifth are suspension.  Superb.  Stupendous.  Supremely Satisfying.

I will post updates or write a followup article as I continue to work on tuning and race it a few more times.

Update : Starter Motor

I still don’t have the problem solved, but I did some tests to help determine whether it was a starter, battery, or wiring problem.  All I know so far is that there is a problem…

First, a look at the battery voltage when cranking :

This is 5V/division with zero at the center.  This shows two start attempts.  The first attempt, the starter motor stalled and there is a steady droop.  The second attempt, it didn’t and you can see the variable current draw as the motor turns the engine over about 5 times.

This shows a drop to 10v at the battery when the starter is locked and about 11v when it’s not.

Now for a look at the voltage at the starter terminal :

Here you see one full attempt.  This time, the starter locked but after just a bit started turning the motor over.  You see that voltage when locked was about 9v and a minimum of about 10v when turning over.  These voltages are both 1 volt less than seen at the battery terminal.  These graphs tell us that either the starter motor is drawing more current than designed or the wiring is insufficient – a 10% voltage loss in the wiring harness is considered too much for a starting system.

More to come…