I recently bought a mint condition 2008 model Triumph Sprint ST 1050 as where i was told by the previous owner that the bike is in great shape but with only a starting issue where the bike would not always start when the starter button is pressed, press it a few times then there will be a sound coming from the starter motor for a split second then nothing and the cluster as well as all the lights on the dashboard would reset press the starter button a few times with nothing happening and same story all over again i then proceeded to start with the basics by cleaning all electrical connections, relays, kickstand switch, clutch lever switch and the starter button with Spanjaard Lectro Kleen checked and cleaned all earths and replaced the battery, everything was perfect for about 2 days with the bike starting 1st time then exactly the same issue all over again and i saw that the lcd display on the cluster was dimming which meant the battery voltage was low... I then decided to charge the battery overnight, next morning bike started 1st time and i could hear by the sound of the engine turning over the battery was fully charged i then drove the bike for next 2 days and then same issue all over again... I then got the bike up and running again proceeded to check if the bike was charging by connecting a multimeter on the battery terminals and found that the voltage was sitting at around 13 volts on idle and once i rev the bike the voltage would drop to as low as 11.5 volts and when i leave the throttle the voltage would vary between 11.5 and 12.0 volts, checked the stator coil and the regulator/rectifier with the multimeter as where all readings was within spec which then made me think that it could only be an earth issue on the regulator/rectifier, i then decided to remove the unit and clean the mounting surface on the back with some course sandpaper and also cleaned the mounting bracket so that i have 2 clean metal surfaces to mate to each other and then also fitted a earth strap from the regulator/rectifier to the engine's main earth bolt... Started the bike put the multimeter on the battery and guess what the voltage is around 14+ volts, rev the bike voltage drops max to 13.7 volts leave the throttle and we're back to 14+ volts which means problem solved! It was an earth issue on the R&R all along, I'm now very happy with the bike as it starts everytime, runs great and has a lot of extra power due to not having any voltage issues anymore. I hope this thread will be of some help to anyone with the same issue... Greetings from South Africa
Hello! You and I will be friends FOR LIFE if you still answer questions on this thread. I have EXACTLY same story... I bought a 2008 Sprint 1050 in MINT condition and it has done the same thing and left me stranded twice. Dealership is clueless. They can't duplicate issue and have no answers. I have done a lot of reading and I am convinced it is the "low voltage" ECU software issue that happens on twins a lot. If the ECU isn't seeing 12.4 volts it won't start. Sometimes clik, but never more than 1st time and sometimes go "all dark" gauges and everything, I've been looking at the after-market "Starter Upgrade Kit" made by Motolectric. It upgrades all the wires and copper alloy, etc. to increace voltage. But I also think your fix is likely to fix as well. But can you post a pic or something to better understand what I need to do the ground (earth) the rectifier as you did? Quite frankly, I don't know where my rectifier is on the motor. Any help would be greatly appreciated.
