Hi I'm having trouble with the ignition on my TR7T 750 and currently have no sparks on either side. Before it failed entirely it was popping and backfiring a good 'un. It's recently been brought out the garage after the winter and so I wasn't expecting it to be spot on straight away. At first I thought the issue would be fuel having been laid up for about 6 months so I cleaned out the carb, replaced the fuel and gave it a general once over - it all seemed ok but continued to pop and bang when kicked over. I left it a few days and tried again and this time it didn't even start so I checked the spark and found nothing on either plug. I followed the troubleshooting guide in the service manual and both the coils check out ok with all the voltages in the right places - I also freshly charged the battery overnight to make sure that was good, both the primary and secondary coils checked with an ohm meter - about 2.5ohms and 4.5Kohms? on secondary. The pulse sensor?? (not sure if that's the correct name) measures 1100ohms as per the manual and the measurements back to the GB11 amplifier also seems to fit with the service manual. I've checked and cleaned as many earth connections I can find and also checked the connections in the headlight bowl - have I missed anything?? If left the spark can (on occasions) return on both sides and then it fires up for about 10 secs before dying and then the sparks have gone again when I check them. It does seem like a bad connection but I can't find it and am running out of troubleshooting thoughts. I think people have mentioned about testing a spark generated by connecting to wires on the pulse sensor? - but I might be wrong One other thing (not sure if it's relevant) but I can almost guarantee a nice load backfire when I switch off the ignition - as if doing that generates a spark and ignites what's hanging around in the cylinder. So I was wondering if I ought to cut my losses go with a boyer (or similar). I do like the idea of keeping things as original as possible but not if that means I can't enjoy the ride. If anyone has any thoughts on how I can narrow things down more then that would be great, or if the general consensus is to replace the ignition system with an afternmarket option then what is best? Boyer are about £100 (I think!) but I like the sound of Tri-spark which looks more discreet but over twice the price. kind regards Jon
The std Rita system was pretty reliable if its sparking when the ignition is switched on and off the the main unit is OK check for broken or disconnected wires, but it sounds like the hall sensor has failed, you can get the units repaired and spares from http://www.aoservices.co.uk/index.htm
ah - ok thanks What and where is the hall sensor - is it something I can test to see if it has indeed failed? Is it part of the Rita unit? I also saw there is a Moira unit now - is that perhaps an option worth looking at?
A Hall sensor is your pulse sensor. It is a proximity device actuated by the crank rotation. The brief sparking you describe is a classic symptom of an electrical winding failing as it warms up. It may well show the correct resistance until it fails and cools again. If you test when it fails you may get an open circuit.
Many thanks both - I've left a message for Al Osborn, so hopefully he'll get back to me soon. Am I right in thinking that the spare part for this is T1290131? I saw it mentioned here https://www.triumphrat.net/air-cool...l-crank-position-sensor-nerdy-and-boring.html but I wasn't sure if that part number was suitable for Triumphs that were getting on for 40 years old. thanks Jon
No. That part is for air cooled Hinckley Bonnevilles of the 790/865cc type but it does perform essentially the same function. I think this is the straight replacement choice...... https://www.feked.com/electronic-ig...nder-side-points-boyer-bransden-mkiv-12v.html
Brilliant - thanks so it looks like it may well be time for a Boyer as per my initial title That's no problem, I just wanted to cover off other options. Your input has been a great help and I appreciate the time you've spent helping me.
