Project KLX110 - KLX110 Turns KLX150

MotoHP 150 Kit, Hydraulic Clutch, 4TH Gear Shift Drum

Jun. 01, 2005 By Eric Tabb

Let me start off by getting right to the point, our Project KLX110 has been transformed from a mild mannered pit bike into a fire-breathing KLX150 that just plain rips. Every person that I let ride this new creation brought the bike back with a stunned look on their face. They couldn't believe just how much power the bike had gained nor how mean the deep throaty exhaust note sounded after the new engine mods. Allow me to clarify a little further for you so you really comprehend the degree of change here, we aren't talking just mild improvements; we are talking more in the range of 3rd GEAR WHEELIES BABY!


Rewind to our last article where we left off with the addition of a pipe, gearing and other comfort related mods. These, along with the suspension upgrades, allowed the Project KLX110 to start to come alive and loose the pit bike status. From this point the power was improved over stock but things were still lacking in certain areas. Exiting turns is just one such area where we wished for more power. Even with the pipe and gearing mods it was tough to clear jumps that were right out of a turn and didn't offer a lot of run. In addition the bikes top speed and overall pull was lacking for the long straight-aways or desert adventures.

Since I had been reading up on the available options for engine upgrades on the 110 I knew what was available to us. The common route was either to go with one of the popular 130cc/134cc big bore kits, or go big time and combine that with a stroked crank to gain even more power. While the people I talked with that had just the bore kits seemed somewhat pleased with the improvements, it was the stroker bikes that really seemed to be the hot ticket if you really wanted to get a lot of power out of the 110. While a stroked crank combined with the big bore kit would yield a huge increase I wasn't willing to spend the mass amounts money required to make this a reality on our project bike, nor was I willing to take on the reliability risks of such mods.

 The Big Bore Kit

Enter MotoHP and their 150cc Big Bore Kit for the KLX/DRZ110. MotoHP is fairly new to the scene but they have a lot of knowledge and experience with the KLX110 and what it takes to make the bike perform to its potential. Instead of going with a typical combination of a bigger piston and stroked crank MotoHP opted to increase the displacement by strictly going with a larger piston. This provides a few key benefits over some of the other options available. First, it keeps the cost of the kit down, secondly it reduces the time and effort of installation and third it makes future rebuilds much quicker and less expensive. The MotoHP kit comes in either a regular or high-compression piston. Since our KLX110 sees a lot of desert trips we opted for the regular compression piston in order to eliminate any chance of not being able to get race gas required by the high compression setup, and also to insure we are getting the maximum durability.

MotoHP offers a couple of different kits to help match with both your engine assembly skills and your wallet size. The first option is to purchase just the "MotoHP Big Bore kit" and do the installation yourself. The basic 150cc Big Bore kit retails for $299 and comes with a new piston, rings, pin, clips, a complete gasket kit, a new spark plug and a new larger sleeve. If you choose this route you will have to do the work yourself. This means you are going to need to have the new sleeve pressed into your stock cylinder and have the cases machined to allow the room needed for the new sleeve to fit. You can also purchase the Big Bore kit with a cylinder already sleeved for $474.95, but you will still need to get the cases machined. The second option, the "MotoHP 150cc Big Bore Service Kit", is what we opted for and requires you ship MotoHP your complete engine (not the bike, just the engine). The Service Kit begins with the basic 150cc Big Bore kit and also includes the installation of the sleeve, the machining of the cylinder & cases, the complete disassembly and cleaning of the engine, the installation of all purchased parts, and finally the reassembly of the engine. In addition to the service kit we added their cylinder stud kit and inner/outer bolt kit to add to the overall reliability. The cylinder stud kit retails for $29.95 and replaces the stock tapered cylinder studs with stronger straight studs while the bolt kit, at $15.95, replaces the somewhat strip prone bolts with higher grade units.

 Other Mods

To get the most out of our 150 kit we decided to go with a few more of the common performance add-ons. In the engine department there much more power to be gained by modifying the intake. We had MotoHP install one of their Kitaco 26mm carb and air filter kits. While this takes care of getting more air and fuel past the carb adding a Kitaco camshaft ensures the mixture makes it into the engine and out to our Bill's exhaust more efficiently. This of course adds quite a bit to the cost but since the engine is already apart it is about the best time of any to do these mods. The 26mm carb kit retails for $218.90, air filter kit goes for $34.95 and the cam is $124.80.

Not wanting all of this increased power to be wasted to either a spinning rear tire, or an engine winding out in a measly third gear, we had a few final things to include in our upgrades. To control power delivery we ordered a Maverick hydraulic clutch kit and chose to remove the auto-clutch completely. To make sure the clutch gets a good grip and doesn't slip we also went with stiffer clutch springs. Finally, to combat the issue of the bike winding out and reaching top-speed so quickly on long straights and fire roads, a 4th gear shift-drum was installed to gain access to that factory 4th gear that is just waiting to be used. While all of these parts are available from MotoHP ( $319.98 for the clutch, $16.98 for the manual only adapter, $19.98 for the HD clutch springs and $78 for the shift drum) we had already purchased everything from a new online outlet for parts called, whom which carry most of the popular parts for today's bikes at very reasonable prices.

As the upgrades neared completion my anticipation was high is finding out what kind of power this bike would put out. Would the difference between the 150 and the stock bike be just so so or would the bike actually get out of its own way? The answer is undisputable; this bike produces crazy power for its size. Immediately you notice that kicking over the bike just got harder over stock, but it starts right up with an exhaust note that rivals a 250F. From the moment you let the clutch out the bike pulls hard and fast, in fact you'd better be careful or you will loop it out and end up on the ground without even knowing what happened!

 First Ride

Our first real break-in ride was out in the So Cal desert where the conditions were quite dry and slippery. The openness of the terrain made this an excellent location to test the roll-on power and the fourth gear. Well, let's just say with this much power the 4th gear is almost overkill for all but fire-roads or really long straights, the bike is scary fast! Roll-on power was incredible with the bikes ability to rev almost instantly without hesitation. This is in part due to the removal of the auto-clutch as well as the opened up intake system. Even though the terrain was dry and slick our 150 proceeded to pull second and third gear wheelies without hesitation. With such slippery conditions you really had to pay attention in the corners to avoid either washing the front tire or sliding the rear end out exiting turns. This is where the clutch comes in, allowing you to just feed in the right amount of power and avoid doing a 180 out of a turn. I even had one guy take one ride that lasted maybe 30 seconds before he brought it back and stated "You could hurt yourself on this thing".

After break-in we were ready for some real action so we proceeded out Lake Elsinore's new adult Motocross track. This track is perhaps the best track at the park with a straight away long enough to get into 4th gear and jumps that were all easily doable with our 150, fun fun fun. The track is where this bike really shines; here the power becomes 100% useful and is very controllable with the use of the clutch. Power is so snappy that you can come up to a table top or small double a little slow and slip the clutch to make the bike launch off like a mini cool you can't help but get a big grin beneath your helmet. Out of the turns you have your choice of slipping the clutch if things are a little slick or just rolling on the throttle if you have the traction. Either choice results in a thrust of acceleration to carry you easily over the next jump.

Watch Video

 Last Corner

The word on the street is the high-compression piston yields even a bunch more power over our setup. No thanks, our bike is right where we want it. It has the power for the track, the power for wheelies, the top-speed for desert rides and the ability to control that power whenever needed. Now that the bike is fully broken-in our next step is to do a little jetting testing to make sure we are dialed the best we can be. After all the performance increase the bike handles even better than before. The works shock is really plush and has yet to bottom. The one gripe I do have is with the stock forks with the stiffer springs. The fork actually feels decent over jumps but in the corners just doesn't track and settle like it should. This is the next area of focus along with the addition of a couple more aftermarket parts for comfort and durability. Until then that won't stop us from enjoying ourselves on our Project bike.


Hiraoka Products
Chino, CA 91710 USA
909-762-0830 Newsletter
Join our Weekly Newsletter to get the latest off-road news, reviews, events, and alerts!