Hi, @simonmarsden66 this was my first time trying to do timing on this bike with a strobe light, It would be way easier with a second person given the advance / retard adjustment is on the right side of the bike and the timing inspection hole is on the left hand side of the bike. That said, doing it the way I did worked, but took a lot longer than this short video showed :) Really appreciate the comment and if you haven't already, please subscribe! Really appreciate the comment and the feedback!
I picked up a 78 T140v in a partial trade a few months ago. I've got it running really nice and barely leaking any oil, but it has one flaw, the carbs tend to overheat after a ride, no matter which phenolic spacer or o-ring i use. The bike will run great on the ride but if it sits for 10 minute the heat transfers into the carbs and all of the sudden it won't want to hold an idle. Not until it's cooled off. Besides the different spacer options I've tried leaning and richening the carbs, which didn't fix the problem. Before I realized it was the carbs over-heating I replaced a bunch of parts that didn't need to be replaced, like coils, spark plug wires, electronic ignition, etc. I didn't realize timing needed to be done after cylinder one. I've been doing it on the left side. I have a Pazon ignition, so maybe it doesn't mater as much but I'll try it on the left and see if there's any difference. I do a similar solo timing set up, but I include a mirror so I can stand on the right side and rev the bike while look at the timing rotor.
Hi @daveco1270, as mentioned in my videos, I am just a tinkerer and not at all an expert on these bikes, so please take what I am not going to say with a grain of salt and confirm with others more knowledgeable. With that disclaimer out of the way, I am guessing that your issue isn't so much that the carbs are overheating, but that the Amal carbs may be worn. Assuming you have original Amal's on the bike it could be that the slides inside the carb are sticking either when cold or as they rise to running temperature and this would definitely cause major fluctuations and issues with the idle. My suggestion is to check the carbs when the bike is cold to ensure the slides fall up and down with zero hang ups and fall to the bottom of the chamber with an audible 'bang' or 'click'. Then do this same test when the bike is hot (turning it off first of course). You can do this by taking the air cleaners off and actuating the throttle or physically lifting and dropping the sleeve (again, while the bike is off).
You're saying the red mark on your rotor is the top dead center mark. The two marks on these rotors are 180 opposite each other, so that wouldn't make sense. Unless I'm misunderstanding you (which could be the case). I've always thought those rotors have 2 timing marks (at 180 degrees opposite from each other) because they're used on earlier models that have the timing pointer down at the bottom (at 5 o'clock) and later bikes with the smaller window and the timing mark at 11 o'clock. This way the same rotor can be used and timed on either model. If you use the timing tool that screws into the back of the engine and clicks into the crank at TDC and 38 BTDC, you'l see that TDC doesn't line up with any mark on the rotor (unless you put your own mark on there.)
Hi @daveco1270, I bet you're right and really appreciate this comment! My assumption when finding two timing marks was that the 'other' one was for Top Dead Centre as couldn't think of any other logical reason to have the second mark listed on the rotor. I am going to take your good advice and use the timing tool to check but I am already confident you are correct. Really appreciate the input and will do my best to update / correct that video. Thanks again for your comment and if you haven't already, please subscribe. I would really appreciate it :)
@@MadTinkerman @MadTinkerman I'm fairly new to these old bikes myself, but it's a lot of fun learning to work on them. I picked up my first vintage bike (a 1975 Honda CB750) about 5 years ago thinking I'd learn basic maintenance. Then two years after that I bought a 1964 Triumph TR6. Now I'm a bit obsessed with old bikes. I love the Triumph 650s, and having a single carb motorcycle is so nice. I like them better than the bonnevilles. My T140 Bonneville can be a bit moody, as I mentioned in another comment. It's got 2 year old new Amal Premier carbs on it, so they should be in good shape. I'm tempted to try these 60 dollar Russian Pekar carbs a guy sells on ebay. They'll fit right on the Triumphs and he swears they're better all around carbs than the amals. I hate to put Russian carbs (that are probably Mikuni copies) on a Brti bike, but I might do it as an experiment.
@@daveco1270 with your cabs only being two years old that rules out my theory. If you do try out the Russian Pekar carbs let me know as I would be very interested in whether they work better for you or not.
Good vid man.
Thanks! Appreciate the comment.
I'll be doing mine soon
Hi, @simonmarsden66 this was my first time trying to do timing on this bike with a strobe light, It would be way easier with a second person given the advance / retard adjustment is on the right side of the bike and the timing inspection hole is on the left hand side of the bike. That said, doing it the way I did worked, but took a lot longer than this short video showed :) Really appreciate the comment and if you haven't already, please subscribe! Really appreciate the comment and the feedback!
I picked up a 78 T140v in a partial trade a few months ago. I've got it running really nice and barely leaking any oil, but it has one flaw, the carbs tend to overheat after a ride, no matter which phenolic spacer or o-ring i use. The bike will run great on the ride but if it sits for 10 minute the heat transfers into the carbs and all of the sudden it won't want to hold an idle. Not until it's cooled off. Besides the different spacer options I've tried leaning and richening the carbs, which didn't fix the problem. Before I realized it was the carbs over-heating I replaced a bunch of parts that didn't need to be replaced, like coils, spark plug wires, electronic ignition, etc.
I didn't realize timing needed to be done after cylinder one. I've been doing it on the left side. I have a Pazon ignition, so maybe it doesn't mater as much but I'll try it on the left and see if there's any difference. I do a similar solo timing set up, but I include a mirror so I can stand on the right side and rev the bike while look at the timing rotor.
Hi @daveco1270, as mentioned in my videos, I am just a tinkerer and not at all an expert on these bikes, so please take what I am not going to say with a grain of salt and confirm with others more knowledgeable. With that disclaimer out of the way, I am guessing that your issue isn't so much that the carbs are overheating, but that the Amal carbs may be worn. Assuming you have original Amal's on the bike it could be that the slides inside the carb are sticking either when cold or as they rise to running temperature and this would definitely cause major fluctuations and issues with the idle. My suggestion is to check the carbs when the bike is cold to ensure the slides fall up and down with zero hang ups and fall to the bottom of the chamber with an audible 'bang' or 'click'. Then do this same test when the bike is hot (turning it off first of course). You can do this by taking the air cleaners off and actuating the throttle or physically lifting and dropping the sleeve (again, while the bike is off).
You're saying the red mark on your rotor is the top dead center mark. The two marks on these rotors are 180 opposite each other, so that wouldn't make sense. Unless I'm misunderstanding you (which could be the case). I've always thought those rotors have 2 timing marks (at 180 degrees opposite from each other) because they're used on earlier models that have the timing pointer down at the bottom (at 5 o'clock) and later bikes with the smaller window and the timing mark at 11 o'clock. This way the same rotor can be used and timed on either model. If you use the timing tool that screws into the back of the engine and clicks into the crank at TDC and 38 BTDC, you'l see that TDC doesn't line up with any mark on the rotor (unless you put your own mark on there.)
Hi @daveco1270, I bet you're right and really appreciate this comment! My assumption when finding two timing marks was that the 'other' one was for Top Dead Centre as couldn't think of any other logical reason to have the second mark listed on the rotor. I am going to take your good advice and use the timing tool to check but I am already confident you are correct. Really appreciate the input and will do my best to update / correct that video. Thanks again for your comment and if you haven't already, please subscribe. I would really appreciate it :)
@@MadTinkerman @MadTinkerman I'm fairly new to these old bikes myself, but it's a lot of fun learning to work on them. I picked up my first vintage bike (a 1975 Honda CB750) about 5 years ago thinking I'd learn basic maintenance. Then two years after that I bought a 1964 Triumph TR6. Now I'm a bit obsessed with old bikes. I love the Triumph 650s, and having a single carb motorcycle is so nice. I like them better than the bonnevilles. My T140 Bonneville can be a bit moody, as I mentioned in another comment. It's got 2 year old new Amal Premier carbs on it, so they should be in good shape. I'm tempted to try these 60 dollar Russian Pekar carbs a guy sells on ebay. They'll fit right on the Triumphs and he swears they're better all around carbs than the amals. I hate to put Russian carbs (that are probably Mikuni copies) on a Brti bike, but I might do it as an experiment.
@@daveco1270 with your cabs only being two years old that rules out my theory. If you do try out the Russian Pekar carbs let me know as I would be very interested in whether they work better for you or not.