XZ550

June 17, 2021

I had been having some issues getting my XZ550 to start and fortuitously stumbled upon a write-up about the YICS system through an archived version of XZ550.com. One of the tell-tale signs of a leaky YICS is a difficulty in starting the motorcycle. Another symptom is engine hunting at idle. I decided to write up this post to explain my process for repairing the YICS, there doesn't seem to be much information about the repair left on the internet.

The first step is diagnosing whether your YICS has an internal or external leak. Begin by removing only the screw holding down the chrome cover. To check for an internal leak, attach a length of hose to each port and blow. You should feel resistance. If you feel air coming out of the other hose, then you have an internal leak. To check for an external leak, plug one of the hoses, submerge the YICS in water, and blow through the open hose, making sure to test each port. If you see any bubbles, then there is an external leak in the YICS.

May 03, 2020

As is frequently pointed out on various XZ550 forums, the stock starter seal is inadequate. I opted to purchase a 20mm x 35mm x 6mm double lip spring seal on Amazon. I also picked up a starter rebuild kit from ebay that came with new o-rings, a brush holder assembly, and a bearing. I've been using the wayback machine to view xz550.com before it was taken over by some Chinese company, giving me access to a wealth of knowledge.

According to xz550.com, you should: "Remove the spring clip and working from the "sealed" side of the bearing, gently tap the bearing out of the casing with a long thin drift or punch and a hammer. Be sure to tap on the OUTSIDE of the bearing." This was an incredibly helpful start, but I was unable to find any pictures or diagrams showing a breakdown of the process. Hopefully the following pictures will be useful to other inexperienced XZ-550 owners.