Starter solenoid has a mind of its own...

So I just finished an '86 Radian project of mine. Runs like a dream, cranks first try, good to go. BUT I have an issue. When riding my starter will randomly kick on, and I have to reach down and whack the solenoid with my hand to make it stop. Someting during startup it stays on as well, responding to some tough love.

Now before you say "your solenoid is obviously bad, get a new one" you should know that this IS a new solenoid, and the last one had this issue as well. What's the liklihood of both being bad, seeing the new one is brand new?

Also, before you say "you've got a short in the harness, find it" you should know that I have replaced the entire harness, and the issue was present both before and after.

I'm going to take my starter button apart and give it a good cleaning, but I just wanted to put it out there and see if anyone has any especially bright ideas. I've been wrenching on bikes for about a decade and this behavior is just a bit odd.

 

Randomly kicking on is a sign that something is triggering it, cleaning/inspecting your starter button is a good start. I'm not familiar with that bike but common sense says you should not be able to press start in gear without the clutch etc. etc. There may be other systems in play for that bike.

As for the solenoid sticking upon startup, you say it's new but where did you get the solenoid? I have a Vulcan 88 in my garage now, guy dropped it off along with 3 solenoids because they were sticking. The two he got from Amazon were burnt up on the inside and I ended up reinstalling the factory one as it looks good inside. If it is a good part, then you should check/clean your connections at the battery, solenoid, and starter along with battery to engine ground. Something is causing that circuit to heat up and burn the contacts in the solenoid. Might need to pull the starter as well and inspect brushes etc.

 

Its an 86 Yamaha Radian YX600, the electrics are just like the xj, nothing terribly fancy.

I did get the solenoid off ebay, so maybe I have inadvertently purchased an inferior part. After I give the button a good cleaning I'll see about getting a better solenoid.

Oh, and it has this sticking behavior even with the key off, so I'm assuming its all solenoid.

 

+1 inspect, don't assume. Even new parts can be faulty (though that the problem is present with two solenoids and two harnesses does make that less likely).

I'd also suggest checking the pigtail from the controls to the main harness, including the solder joints in the controls.

 

The starter switch sounds like the most likely culprit to me. I would take a screwdriver, reversed, and used as a hammer to lightly tap around the starter switch with the bike on a stand in neutral, key on, and see if the solenoid triggers. You can try tapping the solenoid that way, too.

 

I have ran into this problem with my 550 similar engine. It turned out to be the starter clutch. It is rare to have this issue with this engine. One test you can do is when you hear the starter kick in touch a test light to post on the starter, if it lights brighter than normal it is the starter clutch. Now when the starter engages it is now a generator making the test light bright. I hope this helps.