In the motorcycle world you tend to get bikes which sail through their service and repair, some that may have one or two additional faults and some which have a multitude of hidden faults. We call this the motorcycles ‘dark side’.

In the past couple of months we have welcomed a few ‘dark side’ motorcycles to the mono motorcycles workshop. These are motorcycles which have been booked in for what should be straightforward service, repair or wiring work, only to end up remaining with us much longer than anticipated due to unforeseen faults.

Below are some insights into some of our ‘dark side’ motorcycles and their stories.

Honda CX500 turbo. motogadget rewire.

The Honda CX500 joined us on the 15th January as an unfinished and not running motorcycle. We had been tasked with installing a motogadget wiring system including an m.unit and associated alternative dash, indicators and lighting options.

The CX500 was built by a father and son team. Sadly, the father passed away recently, and the son is finishing the project in honour of his father.

However, the bike’s journey with us has not been without its challenges.

Having received the bike as a non-runner, we had no baseline to work from. The ignition switch was not present so we could not check for a spark.

Therefore, Daniel spent 25 hours installing the motogadget wiring and with all of the electrical side working and the pump priming, he fitted the tank, added fuel and no spark. Then we had to investigate why.

Daniel first removed the plugs and found no spark at leads. He then removed the ignitor box and replaced and cleaned the plugs/wiring to the crank sensor. Still no spark.

Daniel noted when cranking that the m.unit was flashing a fault on the power line to ignitor box. He then had to unwrap all of the wiring to the ignition system to check it, but he could not find issue.

Daniel tried running a power supply to another pin on the m.unit but still no spark. At this point everything was pointing to the ignitor box which was an original component on the bike.

We spoke to our customer, let him know what was happening and he then sent two replacement ignitor boxes and a spare set of coils.

Daniel unwrapped the wiring loom, fitted the supplied ignitor box and the bike had a spark.

Daniel refitted the fuel tank and the bike fired up and ran but ran very rough.

To test a theory, Daniel swapped over the coils supplied by the customer and changed the HT leads and then and only then did the bike run correctly and idle independently.

Honda Pan European. Interim service. Check brakes and coolant. Supply/fit rear tyre.

In late February we welcomed a Honda Pan-European  for an Interim service and to check the brakes. We had been asked to assess the rear brake as our customer felt it was stuck on. Under investigation where the caliper had seized, it had pushed the seal out and jammed the piston.

With the brake pads on the metal and the piston jammed against the disc, unfortunately the pads, rear disc, and pistons all needed replacing alongside a full caliper strip down and repair kit being fitted.

When the parts arrived and as we took the rear wheel off to prepare for the rear tyre, we were met with a shocking site.

The rear swing arm had rotted away! We then checked the previous MOT and it mentioned ‘some corrosion’ at the swing arm, but what we discovered today was way beyond ‘corrosion’ We also found out at this point that the MOT had run out last October.

At this point we unfortunately declared the bike unsafe and stopped work. We contacted our customer who advised us that he had access to another swing arm.

Once the SH swing arm arrived, we were able to start the process of the repairs. During the process when we removed the rear brake pads, and they fell apart.

However, now the rear end of the bike has a new disc, new brake pads, new pistons, a caliper repair kit and more importantly a swing arm which will hold the rear end of the bike together.

Triumph Night Storm. Repair wiring to fitted switchgear. Supply and fit correct brake lines.

Our customer had had momentary push switches, mo.blaze bar end indicators and Berringer clutch/brake levers installed elsewhere. Since these had been fitted the fuel gauge and dash had stopped working and the bike had intermittent cranking. Our customer advised that he had removed the clutch switch as he was advised it could have been this causing the fault.

Customer advised that he had also removed the throttle bodies and had pinned out the ECU to the clocks as he believed this might have been this causing the fault.

We were initially asked to make repairs to the wiring for the momentary push switches/indicators, repair the fuel gauge and re-bleed the brakes.

On arrival of the bike Daniel checked all the fuses, the clutch switch and the switchgear, etc. Daniel found an engine management light on for an ABS fault, No comms CAN network fault and Intermittent ignition.

Daniel then removed the fuel tank and handlebar switchgear. Under the tank he found that whoever had fitted the momentary push switches had used the incorrect gauge wire. The meant that there was a full load going through these switches and momentary push switches are designed for a control unit to switch them.

Daniel rewired both switches with the correct gauge wire and added an Axel Joost Multi-Flash relay to control the indicators and removed the four flasher relays which had been installed elsewhere.

Daniel then added in a control relay for the high/low beam, rewired the kill switch and connected the map sensor correct way round.

Daniel then removed all the connectors for the brake lines, measured the brake lines and had new lines made so the lines then ran neatly. He then turned around the line running from the lever to the ABS pump and made up new line from the ABS pump to the T-piece under the bottom yoke.

He then bled the brakes but once under pressure he found that the connectors the customer supplied leaked. He then had to measure up the lines and order replacement T-piece lines.

Daniel then connected up the repaired switchgear and tested. he then connected the dash but the fuel gauge was still not showing. He then examined the plug from the dash and found the pins inside it were bent.

He therefore cut off plugs, soldered new plugs on but the fault was still the same. He then removed the dash and stripped it down. Upon investigation he found the plug was breaking away from circuit board and he therefore had to repair the circuit board.

Once Daniel plugged the dash back in and tested it, it was then working correctly.

Daniel then re-fitted the fuel tank and ran the bike up on the bench. The engine ran, but was idling at 2000rpm but no longer hunting. He slowly rode bike around the farm and the speedo and fuel gauge were both working and the  rev counter and all the lights working.

However, even at this point there was still an engine management light on. A TEXA diagnostic test showed TPS sensor out of range and no power to the idle controller on the throttle bodies.

The engine was left to cool down and then Daniel removed the throttle bodies, loosened the TPS and reset it. He then refitted the throttle bodies and ran engine, but the revs were still high. It was at this point that he noted that the idle screw which is set and painted at factory had been moved.

Daniel adjusted the bike down, so the bike idled correctly, but there was still no output at the idle controller. He then replaced the short loom to the controller but the fault was still the same.

At this point we spoke with our customer again and he advised that he had pinned out the loom to try and find the fault. Daniel then inspected the plug at the ECU. He found that the locking pin was broken off and all the pins were opened up inside plug.

Daniel also found the pink SV feed wires bent badly and by moving the plug the throttle control could be heard moving and the management light went out.

What all of the above points to is that the Triumph will now need a new wiring loom as not only have so many of the plugs been damaged, but that the ECU plug had been damaged and cannot be repaired.

Events

Open Day, Sunday 23^rd March

Join us on Sunday 23rd March 2025 for our joint Open Day at mono motorcycles and DJK Motorcycles, New Barn, Funtington, Chichester, PO18 9DA.

Come and talk to us about your 2025 service, repair and MOT requirements and about what quality used bike options are available to you.

We are really excited to welcome back CCM Motorcycles to our Open Day. CCM will have a display of their stunning motorcycles and there will be test ride opportunities too.

We are really pleased to welcome Dunlop Tyres to our Open Day for 2025. Dunlop will bring examples of their vast motorcycle tyre range, be able to give advice and offer a tyre matching service. I’m sure there will be a freebie or two available too (they are very generous like that)

We will have hot food served all day by Hunger Busters and Barista Coffee and Cake supplied by Our Little Place.

This is a great opportunity to get out for the start of spring and think about your options for 2025. It’s also a fantastic opportunity to find out more about who we are and what we can offer, whilst also supporting local businesses in the process.

We look forward to welcoming you to our Spring Open Day. Tell your friends, share this event and let’s have a great day together.

For all your motorcycle service and repair needs, contact Daniel or Katy on 01243 576212 / 07899 654446 or email info@monotmotorcycles.co.uk