From Caspar Milquetoast to The Green Beast


Written by "Marty", Global Moderator, The KLRWorld.com Forums

I became interested in dualsport motorcycles about 5 years ago.  Up until then, I was a cruiser rider.  However, my right hip degenerated and had to be replaced.  One day, after my surgeon gave me clearance to drive, which to me was the same as riding, I rode my Vulcan Classic 1500 to a follow up appointment.  How did that go over you ask?  Not too good.

My doctor told me that I had to give up riding motorcycles because of the new hip.  I immediately informed him that he should schedule another surgery to re-install the old hip as I could ride a motorcycle with that hip in place.  Then I told him that prior to the surgery, I asked, "What limitations would I have with the new hip in place?" and was not told anything about having to give up riding.  We came to a compromise, he gave me a set of rules for the position of my hip and knee when riding that I needed to follow to avoid dislocation of the new joint.  When I looked at those requirements, it was obvious that I needed a new style of motorcycle to ride.  The position of the legs directly under the rider and the knee below the hip brought me into the dualsport world.  Little did I know what I was missing!  No longer do I have to ride down a rural road, see a dirt road leading off into the distance and have to say to myself, "Hmmm, I wonder where that roads leads to?"

I went out and bought a KLR650.  What a bike!  I loved it.  However where I live, we have a thing called "Sugar Sand",  where the sand is deep, has no traction in any direction and is quite a chore riding through with a heavy bike.  The KLR650, in the "Ready to Ride Mode", not the "Japanese Dry Weight" weighs 400 pounds.  I could ride it, but at the end of the day I was plum tuckered out and I found it rather hard to pick it back up at times.  So I went in search of a smaller dualsport bike.

Next came my 1985 KLR250.  A great running bike, but one without electric start.  I found out very soon that it and my new hip were rather non-compatible.  I needed something with electric start.  I went in search of the elusive Super Sherpa.  I was getting close, but could not get to one soon enough.  Seems as though they sold quicker than you could find them.

Well my search had ended.  Kawasaki introduced a new for 2006 model, the KLX250S.  I saw the bike and knew that was what I was looking for.  A nice lightweight bike with electric start and was still for a tall person.  I went down to my local dealership and told them the first KLX250S in was mine.  I got a call in November of 2006 to come down and pick up my KLX250S, so I did and brought it home.



So why did I call my bike "Caspar Milquetoast"?  Here's the reason: It's an eponym, named after a fictional cartoon character named Caspar Milquetoast, invented by the American illustrator Harold T Webster in 1924. The strip was called The Timid Soul and appeared every Sunday in the New York Herald Tribune up to his death in 1953. Mr Webster said that his character was the man who speaks softly and gets hit with a big stick.

Well my KLX250S as delivered by Kawasaki surely did fit this description.  It was quiet - kind of sounded like a Briggs and Stratton powered lawn mower, not a fierce motorcycle!  It was fun to ride, but kind of lacked in the power department.  But there were a lot of things to like really good suspension, light weight and great handling off road.  I really liked the bike, so I decided to make it into what I wanted and set off down a long path.

I guess you could call it "Phase-I" of the change.  I did a bafflectomy on the exhaust can, drilled the slide, put in a #40 pilot jet, a #128 main jet, removed the smog plumbing, uncovered the pilot jet adjustment screw and set it to 2 1/8 turns out and went to a 13 tooth countershaft sprocket.  The bike really woke up and it was so much more fun to ride.  What sort of power increase did this give me?  I found a site, www.hmfengineering.com where they did basically the same modifications and found the power output went from 18.3 rwhp to 20.8 rwhp.  Well, that 2.5 more horses at the rear wheel sure felt a whole lot stronger!  Mathmatically it's about 14%, but in real life it felt a whole lot more.  The bike was now responsive and sure did feel a whole lot quicker.

Here's a picture that shows the HMF slip-on probably does flow more air than the stock muffler.



There was an opportunity to race a friend's box stock KLX250S one day.  We were out riding and came to a stop sign that lead to a long, lightly traveled road.  My friend looked at me, smiled and took off.  I did the same and by the time we were in 3rd gear, he was but a small, bright light in my rear view mirror.  Well, I immediately was asked 2 questions.  "What did you do to your bike? and Will you do the same thing to my bike?"

I was having a ball with the bike, but there was just something calling to me and I listened.  Here's where Phase-II starts.

The carb on the KLX250S was the next thing to undergo a bit of massaging.  The CVK34 carb is a good design for a smooth running motor that is not altitude sensitive.  However, it does not have an accelerator pump and that is what gives a bike immediate throttle response.  I contacted Bill Blue, whom I had met over on another forum and had him build me a drop in Mikuni TM33 pumper carb for the KLX.  When I got the carb, it was jetted a little lean, but the difference was immediately noticeable.  I upped the jetting several sizes and the bike was running very strong.  Once again, my friend with the now modified by me KLX250S challenged me to a race.  Once again I just walked away from him.  For an old drag racer, that is a very satisfying thing to do.

The CVK34 carb operates on airflow.  When you open the throttle on the CVK, the carb senses a need for fuel, then it opens the throttle plate, not the throttle.  On the Mikuni carb, when you open the throttle, it is directly coupled to the throttle plate.  It opens right up and squirts a small amount of raw fuel into the intake tract.  Makes the bike very responsive to throttle movements.

Here's a picture that shows the business end of the Mikuni TM33 carb.  If you look at it, you will notice a tube sticking up from the bottom of the carb.  This is the squirter that, when you open the throttle, adds a bit of raw fuel to the intake tract to make the motor immediately respond to your desire to go faster.



Well now I had a bike that was running quite respectable, but the stock 1.9 gallon tank kind of left a bit to be desired.  I live next to 400,000 acres of national forest and there are not a lot of gas stations to be found when out riding.  I needed at least another gallon of capacity.  I found Acerbis made a 3.7 gallon tank for the KLX300 and the earlier KLX250.  I contacted MotoSport and asked them if I bought it and it did not fit, would there be any restocking fee.  I explained what I was going to do and they told me I would only need to pay for shipping the product back to them.  I ordered it, got it in and tried to fit it to the bike.  It fell right into place.  As a matter of fact, the Acerbis tank is easier to put on than the stock tank.  I did have a bit of interference with the choke and the fuel supply valve, but that was a minor irritant.  I now had almost 200 miles of range on my bike and loved it. 

When I ordered the tank, I also ordered a new front fender.  The stock green fender just did not do a thing for me.  So I ordered a black Acerbis SuperMoto front fender for the bike.  I love the way it looked.

Since the bike spends the best part of it's life riding in the sand of the Ocala National Forest, I decided the stock handguards had to go and replaced them with a set of Moose Barkbuster Handguards.  Since I spend a lot of time standing up when riding, I wanted a taller set of bars, so I have a set of Moose ATV Raptor Aluminum Competition handlebars on the bike.

To accommodate a size 14 MX boot a bit more comfortably, I also added some IMS supersport footpegs to the bike.



After riding the bike for sometime, I felt I needed a bit more power.  So once again, I went in search of.  Got a hold of Bill Blue once again and started talking with him about a few things.  I was going to order a KLX300 cylinder and just install that.  I thought taking the bike to 292 cc's would give me what I wanted.  However Bill Blue said that he could bore my stock cylinder out to 331 cc's for less than buying the parts for the 292 cc version would cost.  A good friend needed a set of shrouds, which I had.  He had a spare 250 cylinder, which we swapped for and Bill Blue was sent the cylinder to modify.  When I got it back and installed it, I knew right away . . . . . this is what I wanted all along!

Enter Stage-III!



This shot shows very graphically how much larger the big bore kit really is.  This photo shows the old piston sitting in the new bored cylinder!  There's a 9 mm difference in size. 

Yes, size is everything!



Well, after building a bike that will now get with the program, I needed a bit more protection for it.  So I added a skidplate from Utah Sports Cycle Products.  I do believe that make most of the aftermarket skidplates you buy from various sources.  They are the only ones that were interested in making one for the KLX250, and I've very glad to have one. 

I have bounced a few hard objects off of the skidplate thus far!



So, what did I wind up with?  Well, I started with a KLX250S - "Caspar Milquetoast" from Kawasaki and created my "Green Beast".  I have not had the chance yet to put the bike on a dyno.  However another fellow that I know with a 331 displacement bike, but without the Yosh cams has produced 29 rwhp on his bike.  The Yosh cams are supposedly good for another 2 rwhp.  That is what the DRZ400S produces on the dyno with a jet kit installed!

The final version contains:

  • Acerbis SuperMoto Front Fender
  • Acerbis 3.7 Gallon Gas Tank
  • Bill Blue's modified Mikuni TM33 pumper carb
  • Bill Blue's 331 cc Big Bore Kit - Uses LA Sleeves "Dry" Sleeve and J&E Piston
  • HMF Slip-on Exhaust
  • IMS Superstock Footpegs
  • Moose ATV "Raptor" Aluminum Handlebars
  • Moose Barkbuster handguards
  • PerCiVal Mod
  • Pro-Moto Fork Springs
  • Pro-Moto Rear Spring
  • Utah Sport Cycles Bashplate
  • Yoshimura D-Tracker Camshafts



The bike is awesome to ride. 

It's lightweight has plenty of power and the power is right now!  If you hit the throttle hard in 1st gear, you're going to see sky and lots of it.  If you take it to redline in 1st gear and shift hard, you're going to see sky once again.  The bike just pulls very hard from off idle right up to the rev limiter.  I had a chance to race a guy on a DRZ400S the other day.  I kind of embarrassed him.  I got a call from my buddy, the service manager at the local Suzuki dealer, asking me to not do that any more.  Seems as though the guy brought his bike back and started telling the service manager how a big guy riding a KLX250 just walked all over him.  My friend then explained my KLX was NOT a 250, but a 331 and had lots of stuff done to it.  It didn't help, but I thought it was funny!

After putting in the big bore kit, I replaced the 13 tooth sprocket with the stock 14 tooth one.  When I first got the bike, to get it over 60 mph in 6th gear, you had to do the Daytona Tuck and make the bike very aerodynamic.  A few weeks ago, I was out riding the bike and was coming back from a trip to the forest.  I was heading down some freshly paved asphalt that was very straight and no traffic.  I was cruising along at 75 mph sitting straight up in the seat.  The engine was loafing along at 7500 rpm.  I decided to open the throttle and see if there was anything left.  Well, as the speedo climbed over 85 mph indicated, I said to myself, "Self, there is 12 psi in the front tire and 15 psi in the rear tire.  Do you really want to be riding this fast?" and immediately started to slow down.  I feel that the bike will hit 100 mph, or as our friends across the pond say, "The Ton"!



If you're ever in the area, just ask . . . . I'll let you ride it!

And yes, I would do it all over again.  It's that much fun!

Marty can be reached at The KLRWorld.com Forums for further discussion.

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