XR100 oil cooler install with pics
Posted 13 October 2007 - 10:06 PM
I guess this is called the OLD Skool method. but basicly its the only way to install a cooler with a stock cylinder and clutch cover on a XR80/100. The Aftermarket cylinders have fittings and a few companies make aftermarket Clutch covers with fittings as well (for the APE100 in Japan). But if you dont have those they you are stuck..
Yes its true most XR100's dont need a cooler, but if your like us and you run it very hard and have it heavily modified then its a must.
We have a PRC built 110cc xr100 with basicly every mod I can do to it at thise point. We use the motor in a road race (RS125) chassis for roadracing so the load the high RPM usage is very high. The motor was damaged last race due to overheating and so this install was much needed.
So to start remove the clutch side cover and clean it well.
Put the motor in a vise or something strong to hold it as you will need to drill into the engine cases.
First this is to find the location of the oil passages in the engine cases.
the white Arrow shows the oil passage area. You will see this on both the engine and the cover.
and on the cover
This passage is the output of the oil pump. It flows oil upwards in this channel to the small pinhole at the top (engine side) where it flows to the cylinder head. This is where you need to pickup the oil flow and send it to the cooler.
First this is to drill out the plug in the block used to seal up the hole from the pump passage. Also you can see the location from the pics above.
You will want to use a 1/8"NPT fitting. Use a 1/8"-27 NPT tap and "Q" drill bit. Make sure to start with a very small drill and work your way up. Also put grease on the end of each bit to capture metal shavings so that they dont fall into the oil passage, and blow it out after each drill from the inside of the motor to the outside. This is very important as shavings can damage the motor.
Dont drill all the way into the internal passage, only about 1/3" from the outside edge of the cases is fine.
Later you will install an 1/8" to -4 AN fitting with thread sealer here but do not do this yet.
The next step is to drill the Clutch cover..
The location of where you drill is sort of up to you and the room you have. For our particular installation I choose to drill into the top most area of the oil passage in the cover..
Again using the same 1/8" NPT to -4 adapter and a 90deg -4 AN fitting.
As you see in this photo the oil passage is not only on the cases but on the cover as well. Though this is a narrow passage and to tap this correctly I had to use 2 1/8"NPT taps. One was a standard tap right out of the package the second I cut off the lower 1/3 of it to allow myself to reach the thicker upper part of the tap. As you can only tap down about 1/4" due to the other side of the passage wall.
After this is done again install the NPT fitting and thread sealer.
The next step is to block off the oil passage to force the oil to head out of the first fitting we installed.
As you notice in this photo the arrow points to a machined hole that leads from the pump passage to the oil passage way up to the head. We need to fill this hole so that the oil travels out the fitting.
Here is where my best friend JB weld came in..
Take a small metal rod approx the same diameter as the hole at the base of the shaft where you drilled and tapped for the fitting. This is about 1/16" or so.. Put grease on the rod and slide it down in the hole(this keeps the JB weld from sticking to it), this will keep the JB weld from filling the oil passage up and thus blocking oil flow completely.
Next mix and apply JB weld into the bottom of the passage completely covering the hole, make sure its fairly thick as we dont want it to fail and let oil through. You can see in this pic where I applied the JB weld
Every 10 minutes turn the rod a few turns to make sure the JB weld does not stick to it and seal it all up..
Lastly install the fitting as described above and you are now good to go.
Put on your clutch cover install your engine and start it up.
Make sure to test oil flow by removing the inspection plug next to the spark plug and also remove each of the hoses to your cooler to test flow and pressure just to be safe..
Posted 14 October 2007 - 08:14 AM
This is one of the best "How to" I've ever seen. Great photos and excellent desciptions. What oil cooler did you buy and how did you mount it on the bike. Any photos of the end product? I would recommend a Kitaco Hi-Flow oil pump to go with this since you'll be pushing the oil through an oil cooler and extra plumbing. An oil temperature dip stick from XR's only website would tell you how effective it is.
P.S. I bumped your gas gauge for this post. Awesome job!
Posted 14 October 2007 - 09:29 AM
I will post a pic of the bike later today..
As for the Oil Cooler. We used a custom EARLS bike cooler and custom braided plumbing from EARLS as well.
As for the Oil Pump, our Oil Pump was heavily customized by PRC (www.xtrememinis.com) when the motor work was done. So its up to the task.
You can read about us and our bikes on that site as well, Austin my son is listed as his featured rider..
Posted 14 October 2007 - 09:34 AM
I'll also expand it a bit in that this applies to the Honda 100s and 125s going all the way back to the first of them of the early 70s. I'm overhauling my own '72 SL125, and it's exactly the same, as is a '75 CL100 motor I have. They all have the same oil pump/oil passage up to the head.
Again, good work.
Posted 14 October 2007 - 10:11 AM
this is the bike itself..
It works ok..
Posted 13 November 2008 - 10:28 AM
Rob the sparky
Posted 13 November 2008 - 05:55 PM
Posted 13 November 2008 - 10:58 PM
All RS125 frames will require modification of some kind.
The pre95 frames like ours required a significant amount of work.
We removed the shock mount on both the frame and swing arm, then fabricated it back 7" from its original postion, this required both work to the frame and swingarm and renforcing many areas. We also had to clearance the right motor mount spar to allow for spark plug removal.
All told it was many days of work.
I would be happy to speak to you offline if you are looking into doing a conversion yourself you can email me at email@example.com
Also if interested this bike is for sale currently, also email for more info.
Posted 14 November 2008 - 05:22 AM
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