Project Kawasaki KLX110 Pitbike: Oil Cooler

Cooler mounts where stock airbox used to be located

Aug. 21, 2008 By Eric Tabb

Project Kawasaki KLX 110

While building up the Project KLX110 pitbike, one of our first concerns was how reliable the engine was going to be. Luckily the Moto HP 150 kit has been well tested so our worries about the reliability of the kit itself were eased. However, with the high cost of parts and labor to put this motor together, we still wanted to make sure we did as much as possible to make the engine last as long as possible. With that in mind our search was on for ideas and products to maximize engine life on our project bike.

Increasing the KLX’s engine size from 110cc’s to 150cc’s brought about a huge increase in power. Unfortunately along with more power comes more heat. Knowing that heat is one of the worst enemies of an engine we wanted to identify ways to keep our engine cool. The stock KLX relies partly on air passing over fins attached to the cylinder and cylinder head and partly on the oil inside the engine to keep it cool. Air-cooled bikes are notorious for loosing power as they get hot so it was in our best interest to find a way to keep things as cool as possible, especially with adults being the primary riders

Oil Cooling

Since the KLX lacks liquid cooling, adding bigger radiators or changing the type of coolant like we might do on a liquid cooled bike was out of the question. That left us to focus on keeping the oil temps down. One common and very effective way many of the professional motocross teams do this is by adding an oil cooler.

Oil coolers work by using a series of tubes in which the engine oil flows through. These tubes are mated together and separated by fins which allow air to pass by as the motorcycle moves. As the air flows through the fins and past the tubes full of oil the heat from the circulating engine oil is dissipated into the air. The cooler oil then flows back into the engine where it can then do its job of lubricating and keeping things cool.

When searching for oil coolers for our Kawasaki KLX 110 we found that there were many options that ranged in price, size and how they attached to the bike. We really liked the Moto HP oil cooler kit not only because the oil cooler itself is large but because the kit is specifically designed for the KLX/DRZ110. The kit comes complete with the aluminum oil cooler, braided stainless steel oil lines, K&N oil filter, a billet adapter that replaces the stock oil filter cover and all the mounting hardware required for installation. The cooler mounts where our stock airbox used to be located, behind the left fairing so it is out of the way and somewhat protected like a standard radiator would be.


Installation is fairly straight forward and the instructions provided in the kit are easy to follow. The basic steps are to first drain the engine oil, remove the stock skid plate, oil filter cover and oil filter. Next install the adapter which holds the new oil filter and has the new oil cooler line connections built into it. After the adapter is mounted the oil lines are attached and routed according to the instructions so that the other ends will eventually hook up to the cooler on the left side of the bike. The kit even includes a bracket that holds the oil lines away from other parts on the bike that get hot, like the exhaust.

Once the oil filter adapter and oil lines are installed and routed the oil cooler can be hooked up and mounted. The left shroud needs to be removed since the oil cooler actually bolts into the stock airbox location using a bracket. Before mounting the cooler however the oil lines should be hooked up to the cooler and tightened down and the routing double checked. Finally the bracket and cooler are mounted to the bike and the left shroud re-attached. The bike should be refilled with oil, started and checked for leaks. If there are no leaks the skid plate should be bolted back in place, keeping in mind the skid plate is now critical in protecting the adapter and oil lines under the bike.

In our case everything went together very smoothly and we had no oil leaks. With the oil cooler tucked in behind the left shroud the KLX now looks like it has a factory supplied radiator, very trick! In fact it looks so trick that it often attracts lots of looks by other riders and people at the track. We feel confident we now can ride the 110 hard for long periods without worrying as much about engine temps getting too high.

In fact another added benefit to using the large Moto HP oil cooler is that we gained approximately 150cc of oil volume which will also help in keeping the bike cool.

At $385 retail the Moto HP oil cooler kit may not be the cheapest kit on the market but it is a quality product that has been specifically designed for our bike. We feel the potential increase in the life of the engine and the gained points in the coolness factor are worth the investment.

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