Engine Decisions...

I've considered using a Lifan or Piranha engine in the red SL90, but I needed to know if a Lifan or other clone would fit into the SL90 frame without significant modification to the frame.  I don't want to destroy the originality of the frame, so I needed to know how a Lifan would work as they are advertised as fitting into the SL90.  I've seen many Lifan transplants into other vintage Hondas, but not the SL90. Fortunately, after searching and contacting vintage Honda forum members, I was able to obtain photos of a Lifan transplant into an SL90 to help with the decision process. 

The Lifan fits, but you must drill new holes to mount the engine base to the skid plate.  Also, one of the rear engine mounts will need to be cut (see below) 

Finally, the upper engine hanger brackets don't line up (below)

Given the extent of the necessary modifications, I decided to stay with OEM stock Honda SL90 engine cases.  I have two SL90 engines - the original, with the correct VIN for the frame and a donor engine for parts (see below).  It will require a complete rebuild and I can bore out the cylinder and make some other improvements without having to modify the Sl90 frame.

The pitiful donor engine & sad original engine cases

Start of the Red Bike Rebuild

So here we go - the start of the red SL90.  The tank has quite a few small dings and dents that showed up when the paint was stripped.  The fenders are in fair condition.

I'm in the process of gathering up the key parts for the red SL90 - Fortunately, I have some spares, like the chain guard, tail light bracket and headlight stays (below), all freshly chromed.

I also have two SL90 seats, one with the original upholstery (in need of replacement) and one that was reupholstered with good materials, but does not look original.  I will reupholster the with the original vinyl (below) using the same type of kit I used for my blue SL90.

Original Tool Kit

Here's the original tool kit that came with my blue SL90. This is one of the accessories that help keep the bike "1969 orignal". 

Note that the tool pouch is a black vinyl pouch with the Honda logo and tappet information on it.  It looks nothing like the so-called "OEM" blue tool pouches you find on Ebay.  I'm guessing the black bags are somewhat rare as I have not seen one for sale.  Here's a close-up of the logo and info on the bag.