My 1977 Bonnie only fires on one cylinder, the right. I have switched (left side) the plug wires, condensers, coil, plug wires, plugs, new points left side, and still have no life to the cylinder. Any suggestions as to where there may be a short in the fabulous, World Class, Lucas electrical system.
i know this sounds daft but you have checked the fuel is getting through to the left pot?? if you take the plug out from the bad cylinder and reconnect the ht lead, hold the plug in well insulated pliers with the electrode against the cylinder head and get someone to kick it over,is there a good spark. try same with other side. better if it slightly dull outside tho, not so easy to see in sunlight
Sprintdave: Thank you for your reply............ I tried what you suggested and could not see a spark on either cylinder. I also noted that the battery is slowly draining each night possibly indicating a short somewhere in the wiring, isn't that a Lucas Moment. After running the bike for a short while on the right cylinder, I also noticed there was no liquid trace in the left card. I will trace all the wiring again today and also clean the main jet. Nothing rides like an old Triumph, but now I am beginning to understand why all my friends purchased Japanese Bikes.......
simple i know but have you tried a replacement battery,not an old one off another knackered bike but a known to be good one that isnt too old. the battery could be totally shot. you obviously need a good spark first then look at the fuel side, do one at a time or you will never know the reason is the fuel known to be new or could it have gone off??have you checked that fuel is getting through to left cylinder now. not sure but wont it be the float or pilot jet that is more likely to be the problem, check fuel pipe and/or inline filter if fitted, maye the tank filters are blocked not allowing the fuel through. check float height is correct. do the simple stuff first, dont get carried away with too tech stuff, Bonnies and all old brit bikes are relatively simple to play about with
Thank you once again for your reply and patience...... A mechanic once told me "My best customers do their own mechanical work." Hallelujah........ After chasing wires, swapping everything over at least three times, tearing apart the carb (It's clean now) I finally decided to check the points once again for the 1000 time. Yellow and black left set of points, right cylinder "A" OK, white and black wire, left cylinder, something looks funny. White and black are connected on top of the plastic insulator and not beneath it like yellow and black. Switch over, ignition on, tickle carbs, kick start.... vroom vroom vroom, all is well in River City. The 38 year old Bonnie came to life like the day I drove it home in 1977....
Another Lucas Moment to Cherish..........OK next electrical problem: Turn signals. Put on the right and the left front twinks with the rear right. I have found something of a short in the arm sticking out of the headlight going to the turn signal housing.... Wiggle the arm around or unscrew the nut and then tighten back and it works for a day or two.... In the past I have run a ground wire from the light inside of the housing to the post and it cured the problem. Any other suggestions would be appreciated.
