bikerbill2021
New Member
Hey all
So Im not much of a poster here, but love this site, lots of bad ass bikes and props to all the riders on here.
Anywho, I'll get right into it. 1976 CB360T. Got it as more or less a basket case, been tinkering with it on the side in my shop (VW tech by day). Got it from a younger guy who got bored with it, he did a good job, but somethings were left undone/half done. Trying to get it running right, but it is driving me up the wall.
So I'll break it down, bear with me, as this is long, but I'm at a loss here, the bike is in "time out" at the moment while I figure this out/focus on my other projects.
Bike has stock air boxes, with what looks like some form of harley short pipes on it. I have no idea what the brand is, they have baffles in them, and they are quite loud. The kid had half the carbs apart, it looks like he either chemical dunked or media blasted one of them and left the other one dirty, Im leaning towards media blasting, as I've been finding small sand particles in the the clean carb.
So I tore them down, gave them a good cleaning, checked the jetting, which according to the Honda manual I have all is stock, except for the mains, which are 110s at the moment (Located in PHX AZ). Replaced the diaphragm of the dirty carb, as it was torn, diaphragm on clean carb was good. Fuel mixture screw at 1.5 turns out on each.
Hooked up a temporary gas tank with clean gas (tank is at the body shop), and fired the bike up. Thing was all over the place, idle was hanging/bike was revving out of control up to about 5k, only firing out one side, smoking bad etc. So I pulled the carbs back off the bike, in the process I found the intake boots were not tight to the head, inspected them for cracks and tightened them down, all is good. Back to the carbs, cleaned up the butterfly mechanism, as they appeared to be sticking open/not snapping back into place, bench synced them, and gave them a good cleaning once again.
Bike ran pretty decent after that, was firing on both cylinders, throttle was responsive, exhaust was a little smokey but not bad. Took it for a ride, pulled hard until about 6-7k, then started missing. Brought it back to my shop, damn thing started idling out of control again, couldn't get it to calm down unless running the choke at 3/4-max, and it seemed to be chugging gas. At this point I noticed some light smoke emitting from the breather tube, nothing crazy, just some light puffs of white, but enough to have me concerned.
So tore back into the bike, checked for compression on the hot/warm motor, was at 142 on the right and 137 on the left, was told around 170 is what a fresh motor will put out, so assuming thats good. Pulled the points assy and mechanical timing advance out, inspected them both, cleaned them up etc, everything seemed good, new battery in it as well, as I've heard these machines are not happy with a poor power supply. Pulled the carbs once more to check everything, and cleaned them again. (kept finding sand grains, which kept my prior assumption of media blasting strong).
Put it all back together, grabbed my shops emission tester to see exactly wtf was going on, and fired it up. The right bank, with the "clean" carb, was running way lean, almost 18% fuel trim, and hydro carbons were way high too, you could hear it missing/not firing properly as well. Hooked up the left bank with the "dirty" carb, and that one was pretty happy, around 13.5% on the fuel trim and much lower hydrocarbs, seemed that cylinder was basically carrying the whole engine.
So after these findings, I tried swapping coils to see if it was possibly ignition related, bike started idling super high again, and couldn't get it to calm down unless I ran it with 3/4 choke on again, and kept doing so once I switched the coils back to their original spot. And thats where I stopped for now.
So I'm at a loss now, this thing has a mind of its own. My thinking is the "clean" carb was possibly chemical dunked, and ate away some seals I'm missing on the inside, causing a leak? Is it possible I'm missing something on these carbs? It seems to be something internal causing a massive air leak on that "clean" carb, anything you guys can think of to help me would be great. Ive talked to a fellow tech at Honda whose worked on these things since new, he said these are some of the worst carbs Honda ever put on a bike, and I'd be better off just adapting some newer carbs to it, would rather not, but will if I have too.
heres a shot of the bike, maybe some one can identify the pipes
So Im not much of a poster here, but love this site, lots of bad ass bikes and props to all the riders on here.
Anywho, I'll get right into it. 1976 CB360T. Got it as more or less a basket case, been tinkering with it on the side in my shop (VW tech by day). Got it from a younger guy who got bored with it, he did a good job, but somethings were left undone/half done. Trying to get it running right, but it is driving me up the wall.
So I'll break it down, bear with me, as this is long, but I'm at a loss here, the bike is in "time out" at the moment while I figure this out/focus on my other projects.
Bike has stock air boxes, with what looks like some form of harley short pipes on it. I have no idea what the brand is, they have baffles in them, and they are quite loud. The kid had half the carbs apart, it looks like he either chemical dunked or media blasted one of them and left the other one dirty, Im leaning towards media blasting, as I've been finding small sand particles in the the clean carb.
So I tore them down, gave them a good cleaning, checked the jetting, which according to the Honda manual I have all is stock, except for the mains, which are 110s at the moment (Located in PHX AZ). Replaced the diaphragm of the dirty carb, as it was torn, diaphragm on clean carb was good. Fuel mixture screw at 1.5 turns out on each.
Hooked up a temporary gas tank with clean gas (tank is at the body shop), and fired the bike up. Thing was all over the place, idle was hanging/bike was revving out of control up to about 5k, only firing out one side, smoking bad etc. So I pulled the carbs back off the bike, in the process I found the intake boots were not tight to the head, inspected them for cracks and tightened them down, all is good. Back to the carbs, cleaned up the butterfly mechanism, as they appeared to be sticking open/not snapping back into place, bench synced them, and gave them a good cleaning once again.
Bike ran pretty decent after that, was firing on both cylinders, throttle was responsive, exhaust was a little smokey but not bad. Took it for a ride, pulled hard until about 6-7k, then started missing. Brought it back to my shop, damn thing started idling out of control again, couldn't get it to calm down unless running the choke at 3/4-max, and it seemed to be chugging gas. At this point I noticed some light smoke emitting from the breather tube, nothing crazy, just some light puffs of white, but enough to have me concerned.
So tore back into the bike, checked for compression on the hot/warm motor, was at 142 on the right and 137 on the left, was told around 170 is what a fresh motor will put out, so assuming thats good. Pulled the points assy and mechanical timing advance out, inspected them both, cleaned them up etc, everything seemed good, new battery in it as well, as I've heard these machines are not happy with a poor power supply. Pulled the carbs once more to check everything, and cleaned them again. (kept finding sand grains, which kept my prior assumption of media blasting strong).
Put it all back together, grabbed my shops emission tester to see exactly wtf was going on, and fired it up. The right bank, with the "clean" carb, was running way lean, almost 18% fuel trim, and hydro carbons were way high too, you could hear it missing/not firing properly as well. Hooked up the left bank with the "dirty" carb, and that one was pretty happy, around 13.5% on the fuel trim and much lower hydrocarbs, seemed that cylinder was basically carrying the whole engine.
So after these findings, I tried swapping coils to see if it was possibly ignition related, bike started idling super high again, and couldn't get it to calm down unless I ran it with 3/4 choke on again, and kept doing so once I switched the coils back to their original spot. And thats where I stopped for now.
So I'm at a loss now, this thing has a mind of its own. My thinking is the "clean" carb was possibly chemical dunked, and ate away some seals I'm missing on the inside, causing a leak? Is it possible I'm missing something on these carbs? It seems to be something internal causing a massive air leak on that "clean" carb, anything you guys can think of to help me would be great. Ive talked to a fellow tech at Honda whose worked on these things since new, he said these are some of the worst carbs Honda ever put on a bike, and I'd be better off just adapting some newer carbs to it, would rather not, but will if I have too.
heres a shot of the bike, maybe some one can identify the pipes
