Honda CB450 Starter Overhaul


How To

As reliable as vintage Japanese electrical hardware may be, everything has a service life, and that includes the starter motor on our subject 1970 Honda CB450K4, which had been displaying a tendency to drag and otherwise turn slowly making the CB450 somewhat hard to start.

BikeMasterNew starters for the CB450 haven’t been available for some time, and while used starters are — typically for around $50- $90 — it’s possible you’ll end up buying the same problems you already own. That makes rebuilding your starter a good option, and fortunately, kits like the one we got from Honda specialists Common Motor Collective are readily available. The $65 kit we purchased is very comprehensive, with all new wear and service parts including a new drive-end bearing and seal, a new brush plate assembly with brushes, starter housing O-rings and gaskets, planetary gear bushings, the armature support plate bushing, the rear cover bushing, and new fiber gaskets and replacement nuts for the starter battery cable post.

Save for the hassle of having to remove the left side cover, which also houses the alternator, removing the starter on the CB450 is relatively easy. The side cover must be removed, as it’s otherwise not possible to re-engage the starter drive chain once the starter has been removed, as the photos will make clear. First, however, you have to remove the shift lever, followed by the drive chain sprocket cover. Make sure to have a new side cover gasket on hand, typically around $12-$15. Once the starter has been removed, make sure the armature and field coils are good before going any further. You can research how to confirm all of this for yourself using a simple multimeter, but we took both pieces to our local automotive electrical shop, where a quick test confirmed that 1) the armature was running true and the windings weren’t broken or damaged; 2) the commutator end was in good condition with even resistance, needing only a light sanding to clean up the contact face; and 3) the starter field coils were good. If it hadn’t passed these tests, we would have had to look for a used starter and start over.

How To

Getting all parts clean before reassembly is paramount. Brake and electric parts cleaner works best here; just remember it’s nasty stuff, so wear gloves and work in a well-ventilated area. Although not technically complicated, this can be a challenging project as it involves a fair amount of detail. Although the photos don’t show it very well, note that the brush plate keys to the starter body for proper alignment.

2/10/2021 6:09:10 PM

Hi Nile, thank you. Quick question please. Mine is a’68 CB450 and my starter does not have a thrust washer? Any thoughts? Only 5190 miles. My Best -David

12/18/2017 3:56:08 PM

Thanks Nile, we did clean up the commutator, but didn't mention it in the article. These things almost always get cut down to fit the space available. One end of the starter was notched fit the end cap, and the other had a cast in line to match up with the body. We appreciate your comment.

Nile B. McCoy
12/15/2017 4:55:04 AM

A good article on starter overhaul. HONDA recommended a small scribe mark where each end cap joins the body to insure bind free reassembly. Remember to clean & polish the commutator, removing any carbon and debris from the grooves therein whilst your starter is disassembled. Nile B. McCoy Registered Honda Technician, emeritus.

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