Replacement relay (solenoid) for Mk3

Is there a generally recognized replacement for the starter relay (I don't think it's really a solenoid-it's not moving anything except electrons) for an 850 Mk3. It seems like there are a lot of posts about the unreliability of the original unit. Since I'm going in for the kill on mine, I don't want to reassemble it with a bad part.

$10 at O'Reilley's...

Re: Replacement relay (solenoid) for Mk3 associated questio

Thanks, will search it out today! Associated question: Some posts about grounds seem to infer that the frame is not a good ground strip. Is the connection to the head steady a good-enough ground or should a separate ground wire be run from the + or the frame itself?

IMPOTANT!!!

On e-start bikes, you want to make darn sure your thick ground wire from the battery is bolted as close to the starter as possible! Remember, on engine start-up cranking, there's a lot of amps running through the most direct metal-to-metal path to the starter housing.

I like a nice, thick ground wire from that same point (just behind and below the cylinders) to my electrical harness common grounds.

grandpaul said:

$10 at O'Reilley's...

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Read the reviews of it on the Advance Auto web page... it's a POS

powerdoc said:

Is there a generally recognized replacement for the starter relay (I don't think it's really a solenoid-it's not moving anything except electrons) for an 850 Mk3. It seems like there are a lot of posts about the unreliability of the original unit. Since I'm going in for the kill on mine, I don't want to reassemble it with a bad part.

Click to expand...

Most/many of these high current automotive relay are of the subvariant called solenoids, due to the technicality of the moveable core being and moving "inside" the coil.
Absolutely the original prestolite is a solenoid. I have disassembled and examined them. :mrgreen:

grandpaul said:

IMPOTANT!!!

On e-start bikes, you want to make darn sure your thick ground wire from the battery is bolted as close to the starter as possible! Remember, on engine start-up cranking, there's a lot of amps running through the most direct metal-to-metal path to the starter housing.

I like a nice, thick ground wire from that same point (just behind and below the cylinders) to my electrical harness common grounds.

Click to expand...

The ONLY place the ground should go is from the rear engine stud (as original) and the battery..... period .......any further creativity is a definite down grade.....
If you fail to connect this high current ground... you will burn the main harness red wire
The starter draws from 300 surge, down to 120 amps depending on what the battery supplies... my measurements are with a stock size yasusa

[.[/quote]


The ONLY place the ground should go is from the rear engine stud (as original) and the battery..... period .......any further creativity is a definite down grade.....
If you fail to connect this high current ground... you will burn the main harness red wire
The starter draws from 300 surge, down to 120 amps depending on what the battery supplies... my measurements are with a stock size yasusa[/quote]

So Dave,
You are saying the best ground path is from the engine case-to the engine cradle- then through the chaincase to cradle mounting stud and into the chaincase and to the starter. The starter is bolted to the chaincase not the engine.
Often there is poor conductivity from the engine case to the chaincase since the studs are hopefully mounted to the engine case with an insulating layer of locktite and there is a gasket between the chaincase and the engine case.
I discovered that when I left the chaincase to cradle stud loose and found the starter would not work. Since then I have connected the ground cable to the chaincase stud. Jim

Jim
The starter is bolted to the primary.
The primary is bolted to the engine cases...I can't imagine normal assembly, even with a bit of loctite, adversly affecting the electrical connection.
Have you actually done real measurements and found this to be a problem? I have not.
The battery wire is on the 3/8 rear engine case thru bolt/stud.
The engine cradle stud never needs to enter the picture, though it "might" have some connection through the paint (or powder coat). As you state, if connected direcly to the stud/nut it would also work, but is quite inconvienient for access.

Otherwise I can not imagine trying to start the engine through a unassembled engine/primary without a test connection somehow making up the short coming.

It wouldn't take much to remove one of the big slotted field screws and replace it with a stud on the OE Prestolite unit.
That would be a fairly short return path.
All the best.

dynodave said:

Jim
The battery wire is on the 3/8 rear engine case thru bolt/stud.
The engine cradle stud never needs to enter the picture, though it "might" have some connection through the paint (or powder coat). As you state, if connected direcly to the stud/nut it would also work, but is quite inconvienient for access.

Otherwise I can not imagine trying to start the engine through a unassembled engine/primary without a test connection somehow making up the short coming.

Click to expand...

Dave, The first time I ran into this was on my wife's mk3. It is all stock and low milage. I pulled the chaincase to replace the sprocket on the gearbox. While I was there I also did a main seal and removed and locktited the chaincase to engine mounting studs. After I put it together the starter didn't work. I jumped from the battery to the starter terminal to confirm something was wrong with the starter and then pulled it to find nothing wrong.
After re-installing it I found the whole starter and chaincase would light a test-light when I pushed the starter button. After finding the finger tight nut on the stud in the chaincase and tightening it everything went back to normal.
Since then I have made a habit of connecting the ground cable to the cradle- usually behind the nut on the chaincase mounting stud. I just figured if the chaincase did not have a good connection to the engine case on my wifes bike then it was not likely to be the only one. Jim

Wow Jim, I'll take your word for it, but I would have never suspected or predicted that set of circumstances actually occurring. All 4 alternator mount studs in helicoils...completely electrically insulated ...wow

dynodave said:

Wow Jim, I'll take your word for it, but I would have never suspected or predicted that set of circumstances actually occurring. All 4 alternator mount studs in helicoils...completely electrically insulated ...wow

Click to expand...

I wouldn't say completly insulated. I did get an initial hit from the starter and then just some noise. The one thing I did that probably made it worse was installing the studs with locktite and then went home for the night without assembling the chaincase. I would bet had I torqued the nuts before the locktite set it would have worked [at least until the nut got in the primary chain].
Any way I would not call it a solid connection. Jim

So maybe it is not so uncommon. One stud, wire brushed and installed last night with blue locktite. As tight as I could get it with my hand. Measued it this morning. Couldn't get any change by pushing the stud around. Jim

If you go onto Loctite's site, there is a Q&A which inquires about an electrically conductive loctite and they say there is not one. They do have a silver particle epoxy for attaching parts to a circuit board but they say it's too viscous for thread locking.