Recently I acquired my first motorcycle - a 1976 xs650c. As a bricklayer by trade, I am completely new to 'mechanics', and have decided that I want to figure out the bike for myself, and it be 'built' not 'bought'. I didn't buy the bike so that someone else can get to know it and fix it for me. I bought it to learn about for myself.
I originally had hoped that my first post on this forum would be the backstory of the bike, as it's quite fascinating (I bought it off of the original owner, and it hadn't ran since 1982), but my desire to get it running at this moment outweighs story time. However, I feel it necessary to at least bring you all up to speed in order to rectify the current state of the bike:
First thing I did when I got the bike was rebuild both carbs (bs38). I then rebuilt the petcocks, and cleaned the gas tank. Before trying to start the bike, I made sure to set cam tension, valves, timing, and bench sync the carbs, all in that order. I also installed new spark plugs, and pod filters, as the 40+ year old filters that were on the bike turned to dust on contact. Through just a small amount of research, I assumed that the bike was going to be running too lean after installing the pod filters, and would need to rejet the carbs. Oh yeah - and the bike has spark. After a bit of kicking, the bike started up for the first time in 40 years. The exhaust was quiet, but seemed to backfire quite a bit. I wasn't too worried about it, as i figured i would just need to do some more fine tuning, and so moved onto installing a new (to me) chain. In the process of aligning my rear wheel, I found out that my bike has an aftermarket rear shock mount on the swingarm, which obscured the alignment markings above the axle that are needed for aligning my rear wheel. In order to remove the shock mounts, I also had to remove the mufflers. Here's why I'm mentioning this - the mufflers had some bad rust holes, and removing this solved 'some' of the backfiring. However, not all. Upon starting the bike again, I noticed that the right carb seemed to 'pop' a lot. Upon further investigation, I noticed that the right exhaust pipe was not near as warm as the left, and when I placed the backside of my hand at the end of the left exhaust pipe, it didn't feel as though it was firing consistently. At this point I also thought I could hear some sort of 'clanging' sound coming from the right side of the engine. I shut the bike off as quickly as possible.
A couple of days passed, as I tinkered with other little stuff on the bike - such as throttle cables, clutch cables, shock mounts, etc. Last night I picked up a compression tester, as I figured this would be a logical next step. 145+ on both cylinders. That's pretty good isn't it? So I started the bike up again, tried to listen more intently, and took advantage of the low light (it was getting dark out) to see if I could observe anything such as sparks or flames. It seems to be backfiring out of the right exhaust pipe, and right carb, and the consistent clanging sound seems to be (as far as I can tell) coming from the upper, right side of the engine. I've never disassembled an engine before, and don't really know what to do next. I've gotten this far by 80% service manuals, 10% youtube videos, and 10% on these forums. I figured that this would be a good time to get involved with the forum and ask for help. The only thing I can think of that I haven't tried yet is switching the spark plug wires to the opposite cylinders to see if its a wiring issue associated with the coil/spark plug wires.
I originally had hoped that my first post on this forum would be the backstory of the bike, as it's quite fascinating (I bought it off of the original owner, and it hadn't ran since 1982), but my desire to get it running at this moment outweighs story time. However, I feel it necessary to at least bring you all up to speed in order to rectify the current state of the bike:
First thing I did when I got the bike was rebuild both carbs (bs38). I then rebuilt the petcocks, and cleaned the gas tank. Before trying to start the bike, I made sure to set cam tension, valves, timing, and bench sync the carbs, all in that order. I also installed new spark plugs, and pod filters, as the 40+ year old filters that were on the bike turned to dust on contact. Through just a small amount of research, I assumed that the bike was going to be running too lean after installing the pod filters, and would need to rejet the carbs. Oh yeah - and the bike has spark. After a bit of kicking, the bike started up for the first time in 40 years. The exhaust was quiet, but seemed to backfire quite a bit. I wasn't too worried about it, as i figured i would just need to do some more fine tuning, and so moved onto installing a new (to me) chain. In the process of aligning my rear wheel, I found out that my bike has an aftermarket rear shock mount on the swingarm, which obscured the alignment markings above the axle that are needed for aligning my rear wheel. In order to remove the shock mounts, I also had to remove the mufflers. Here's why I'm mentioning this - the mufflers had some bad rust holes, and removing this solved 'some' of the backfiring. However, not all. Upon starting the bike again, I noticed that the right carb seemed to 'pop' a lot. Upon further investigation, I noticed that the right exhaust pipe was not near as warm as the left, and when I placed the backside of my hand at the end of the left exhaust pipe, it didn't feel as though it was firing consistently. At this point I also thought I could hear some sort of 'clanging' sound coming from the right side of the engine. I shut the bike off as quickly as possible.
A couple of days passed, as I tinkered with other little stuff on the bike - such as throttle cables, clutch cables, shock mounts, etc. Last night I picked up a compression tester, as I figured this would be a logical next step. 145+ on both cylinders. That's pretty good isn't it? So I started the bike up again, tried to listen more intently, and took advantage of the low light (it was getting dark out) to see if I could observe anything such as sparks or flames. It seems to be backfiring out of the right exhaust pipe, and right carb, and the consistent clanging sound seems to be (as far as I can tell) coming from the upper, right side of the engine. I've never disassembled an engine before, and don't really know what to do next. I've gotten this far by 80% service manuals, 10% youtube videos, and 10% on these forums. I figured that this would be a good time to get involved with the forum and ask for help. The only thing I can think of that I haven't tried yet is switching the spark plug wires to the opposite cylinders to see if its a wiring issue associated with the coil/spark plug wires.