2018 Starter Relay Corrosion - Clean and Grease
 

I recommend you check, clean and lube your main battery connections at the starter relay.

I love my 2018 EC300 and I can always get it started, but sometimes it is a chore. It started 100% at the dealership before I bought it, but has been getting progressively harder to start. Now with 8 hours run time only seems to start about 20% of starter button pushes or kicks from cold.

It has a charged uprated lithium battery, updated CDI and standard wiring. Starter generally spins the engine fine, but often no start (suspect no spark). The kick start is not 100% either, but more like 20% (again suspect no spark). Once I get it running it runs fine. Jetting is good and will idle nicely for many minutes.

In an effort to improve starting, last night I added a ground wire from the battery to the ignition coil and then another ground wire from the ignition coil to the starter housing bolt. Paint on the frame mounting tabs under the coil mounts had been masked off properly before painting at the factory so they were clear of paint, but had just a little surface rust. I cleaned up all connection surfaces with sandpaper and then added a coating of No-Ox electrical contact grease (a grease that keeps out water and corrosion).

Testing the starter after this seemed a bit better, but still only about 50% chance of starting.

Took off the right side panel to have a look at the starter relay and 30 amp fuse block. Noticed WHITE POWDER CORROSION on the main +12 VDC power lead from the battery and also output lead of the relay. There is a star washer under both of these 2 electrical connectors that bites into the connectors and bolts to keep them secure and provide electrical contact.

The problem is that the air gaps caused by the star washers will allow water and corrosion. Also white powdery corrosion covered the ring connector feeding the 30 amp fuse block on the +12V battery lead bolt. Cleaned it all up and applied enough No-Ox compound to keep out the water and then reassembled.

Seems to work better now.

While I had the tank off to run the ground wires I also disconnected every accessible electrical connection on the wiring loom and applied a dab of silicone dielectric grease (Dow Corning DC-4) on the face of the connector and re-mated them so as to keep out water and corrosion. They all still looked clean, dry and shiny after 8 hours run time in relatively dry San Antonio Texas.

A Related Tip:
On all my vehicles lead acid battery posts and leads I always apply a mixture of suspension grease and a little baking soda. It keeps the posts and battery leads from corroding. Got that tip in my 1978 Honda Accord Factory Tech Manual and have been using it ever sense.

I hope this helps. Cheers, Steve

That Didn?t Fix the Electric Start Issue
 

Today the bike kick started 3 times in a row just fine.

However the starter continues to spin over the engine just fine but the engine doesn?t start.

I did not ride it and get up to temperature but did run it long enough so it would idle nicely while I was running the fuel out of the carburetor.

So cleaning the battery cables at the starter relay and adding a ground cable from the battery to the coil might have improved the kick starting but didn?t fix the electric starting issue of good cranking but no starting.