Honda CT90 Engine Reassembly

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I have one 1971 CT90 where I was going to rebuild the clutch because the kickstarter just wasn't turning over the engine like it used too,  and I also had a Big Bore kit from DrATV that I wanted to install. My intent was to just do the top end and rebuild the clutch with new disks, but when I opened up the cases to rebuild the clutch pack I found a slick black slime in the bottom of the case.  I didn't like the idea that there could be black slime in the rest of the engine, so I decided to disassemble the entire engine to make sure I cleaned everything out.  Since I was tearing everything apart I thought I would document step by step how everything goes back together in this post in case others were interested in knowing what the inner workings of a CT90 engine look like. Links to Related Posts: My Honda CT90 Clutch and Headset Nut Tool Cut Away of a CT90 Engine - CT90 Engine Exposed! Repairing Damaged CT90 Spark Plug Threads Using a Time-Sert Thread Insert CT90 Clutch P
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A 3D Printed Points Cover for Use On a Honda CT90

 I have a long list of items that I want to create designs for that can be 3D printed and one of those that I decided to do recently was to back engineer the aluminum points cover from a CT90 and create a model so that I could 3D print the cover.

The points cover on a Honda CT90 is really just a vented dust cover to keep the points clean, so it seemed to be a natural to turn into a 3D printed part.

Here is a picture of the final 3D part installed on one of my CT90's


I printed this part using ASA filament due to the potential of the part seeing high heat from the cylinder head.  It is still winter right now and I have only taken this on short rides and haven't had any issues just yet, but when the as the temperatures increase and I take the bike out on longer rides it will be interesting to see how the part holds up.  I think it will be fine in the long run as the cover is isolated by two paper gaskets from the head itself, but I'll provide an update if I do run into any issue.

Here is a picture of the 3D printed cover next to a stock aluminum cover.


Besides potential high temperature issues, the countersunk screws used to mount the cover can potentially crack the plastic cover if the screws are over tightened.  To give the cover the greatest chance of working I would recommend printing with the infill set at 100%

I tried printing the cover is several different orientations as it can impact the surface finish because supports are required to deal with the over hanging features.  I found printing the cover in the vertical position as shown below gave me the best results.



If you would like to try and print this CT90 Points Cover for your bike the .stl files are available to down load at Prusa Printable here at this link.

I hope you found this post useful and I would like to hear how the design works out for you if you print one up for your bike.


Helpful Links (Shop Manuals, Wire Diagram, Model Information, etc.)






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