Bosch WR-1 Hard Start Relay Fitting

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Bosch WR-1 Hard Start Relay Fitting

Post by Admin on Sat Sep 07, 2013 6:42 am

Quite a few owners (including myself) have suffered from random no start situations which by popular opinion is caused by a worn ignition switch which in turn causes a voltage drop reaching the starter solenoid which in turn causes it to not operate.  Anyway, to overcome this a relay is fitted and the circuit supplying the solenoid is shortened so that the power in the ignition switch is used to power the relay rather tghan the solenoid which is now in effect wired in a shorter circuit which is completed by the relay.

Content of kit which cost me approx £40 delivered from in the US but you could make one yourself fairly easily.


Pull off the small black wire from the back of the starter solenoid and clean both the socket and tab with switch cleaner/wet and dry.

Undo the nut securing the other wire and clean both connections.

Plug the blue kit wire into the now free thin black wire and the kit black wire into the tab on the back of the solenoid.  I added a piece of shrinkwrap onto mine so it wasn't exposed

Put the red wire with the loop on the stud next to the thicker black wire - its supposed to go underneath but as my personal prefernce I put it on top before replacing the nut.

Job done!  I tried it out with it loose at first just to make sure it all worked which it did to my relief!!!

Once I was sure it was working it was time to make it look tidier.  I decided to use some double sided velco tape to stick it on the ledge near the airbox with the earth wire going to the cross bar just in front.  I also taped the fuse to the relay to make them one item then taped as much as the wires as I could to "hide" them.  Sure theres a better way to do this!

Whilst I had easy access I took the opportunity to split apart and clean the battery connector.

Finally, reconnect your battery! :-)


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