One of the most common items to find not working on old CT90's is the rectifier. While a CT90 may start with a poor rectifier the rectifiers primary purpose is to take the alternating current from the genorator in the engine and convert that to direct current or voltage to charge the battery.
If you are looking for information on how to test your existing CT90 rectifier,
I made a post at this link that includes a step by step process for performing the test.
While you could always purchase a new rectifier from any one of the outfits that carry replacement CT90 parts, one of the cheapest ways to go is to get a rectifier from Radio Shack that will only cost about four dollars, but does require some minor modifications to the wiring on your CT90. If your looking to do a complete restoration by all means go out and spend the $15.00 to $30.00 for a replacement rectifier, but if you looking for a cheap but very robust solution, go down to your local Radio Shack and pick up the following rectifier if there is still a store near you or you can purchase one online
at Radio Shack here at this link.
Here are some links to related posts:
How to Test Your CT90 Rectifier
Basic CT90 Ignition Coil Check
Basic Test os a CT90 Condenser
The Radio Shack part number is 276-1185 and the rectifier is actually a Full-Wave Bridge Rectifier that is rated 25 amps at 50 volts, so it will more than handle anything the CT90 can throw at it and more.
Out of the package this is what the rectifier looks like and it is a simple device with four spade type of connectors that you will need to connect the four wires that were going to you previous stock rectifier too. The package the new rectifier came in has a basic diagram for the posts and two of the posts are labeled so it is easy to hook up.
From the diagram you can see that two of the posts are labeled AC so the yellow and pink wire from your wire bundle (which are the two wires from your generator) would go to these two posts and it doesn't make a difference which wire goes to which AC post. The red wire with the white stripe (this is from the battery) would go to the post marked with the "+" sign and the remaining green wire would go to the post that is kiddie corner from the "+" post. The following photo shows the makings on the two posts that are marked on the rectifier.
The following photo shows all the wire attached to the rectifier. I have this wire harness off of the bike and on my bench as I am doing some other repairs to the wire harness.
And the next photo shows the rectifier connected into the complete harness. I was able to salvage the four wires in the correct colors from some other old harness I have which made this a little cleaner.
The rectifier has a hole going through its center to help mount it into the bike and the far side of the rectifier has a metal surface for heat conduction to help keep the rectifier cool in high power applications. I've never found this rectifiers to get hot with the low power they see on a CT90, but it doesn't hurt to try and get that surface butted up against a metal surface on the bike to conduct heat away and its good practice to use a thermal grease/heat sink compound on these interface surfaces to further help insure heat is conducted away from the rectifier.
Here are two assemblies I made up using a radio shack rectifier and the mount from old CT90 rectifier assemblies that will allow these to bolt right back into the same location where the original rectifier was located.
I used the old rectifier assembly base to mount the rectifier as the rectifier will generate heat and that heat needs to be sinked to the frame or some other heat sink otherwise the reliability of the rectifier may be impacted.
It's also a good idea to have your battery disconnected when installing a solid state rectifier to prevent it from being damaged.
Thank you for posting this. Bike runs good now.
ReplyDeleteThanks again. Found two nos 176-1185 on ebay
ReplyDelete