bickel777
CB750 New member
Hello everyone,
This is my first post here, but I'm hoping someone can share their advice/wisdom with me on this problem I'm having...
I got this 1993 CB750 Nighthawk 2 months ago...the previous owner had it for ~2 years, and before that it'd been sitting for ~8 yrs. The bike was running rough when I bought it and I figured it needed some carb cleaning/tuning up etc...
I had my (1st) mechanic rebuild the carbs, which he said were "all gunked up". He really is just a car mechanic but has bikes and works on his own. Anyway he got the carbs rebuilt/cleaned but couldn't get the thing to start right...He said it was having some fuel supply issue and ended up disengaging some spring inside the petcock so that it always flows. Then it started but wouldn't idle <4K rpm. He gave it up and I took it to an actual shop that went back into the carbs and fixed the idling issue.
However, neither of them addressed the original issue I had with the bike since I bought it. The bike dies mid-ride after ~15 miles or so and sustained highway speeds (>45 mph or so). It's fine, then suddenly the throttle doesn't respond, the bike sounds terrible (low rumble) and smells very rich, and I pull the clutch in and the bike dies...the bike starts back up if I let it sit for 5-10 minutes, but will die again a few miles later.
I took it back to the shop, and told them it was still dying. They rode it around some more and deemed that the issue is a bad gas cap, and may not be venting correctly causing a vacuum and therefore fuel starvation (which I've not heard of before). They claimed they rode it for ~50 miles straight (@65 mph or higher) with the cap popped open, and has no issues.
Since, I've gone on 3 rides myself with the cap closed, waiting for it to die so i can pop open the gas cap and see it that fixes it. However, the bike hasn't died on any of the 3 (~30-50 mi each) rides. Today, after I got home, I let the bike sit for awhile then decided to open the gas cap...When I opened it I heard a loud hissing then a pop.
I'm just not sure what to do with this bike, it used to die all the time, but now it isn't but I don't feel the true issue was ever solved.
Other useful facts about the bike:
- Brand new battery
- New gas tank added by previous owner (OEM), but gas cap is original
Hopefully someone has some suggestions or can make sense of all this (Sorry for kinda long story).
- Scott
This is my first post here, but I'm hoping someone can share their advice/wisdom with me on this problem I'm having...
I got this 1993 CB750 Nighthawk 2 months ago...the previous owner had it for ~2 years, and before that it'd been sitting for ~8 yrs. The bike was running rough when I bought it and I figured it needed some carb cleaning/tuning up etc...
I had my (1st) mechanic rebuild the carbs, which he said were "all gunked up". He really is just a car mechanic but has bikes and works on his own. Anyway he got the carbs rebuilt/cleaned but couldn't get the thing to start right...He said it was having some fuel supply issue and ended up disengaging some spring inside the petcock so that it always flows. Then it started but wouldn't idle <4K rpm. He gave it up and I took it to an actual shop that went back into the carbs and fixed the idling issue.
However, neither of them addressed the original issue I had with the bike since I bought it. The bike dies mid-ride after ~15 miles or so and sustained highway speeds (>45 mph or so). It's fine, then suddenly the throttle doesn't respond, the bike sounds terrible (low rumble) and smells very rich, and I pull the clutch in and the bike dies...the bike starts back up if I let it sit for 5-10 minutes, but will die again a few miles later.
I took it back to the shop, and told them it was still dying. They rode it around some more and deemed that the issue is a bad gas cap, and may not be venting correctly causing a vacuum and therefore fuel starvation (which I've not heard of before). They claimed they rode it for ~50 miles straight (@65 mph or higher) with the cap popped open, and has no issues.
Since, I've gone on 3 rides myself with the cap closed, waiting for it to die so i can pop open the gas cap and see it that fixes it. However, the bike hasn't died on any of the 3 (~30-50 mi each) rides. Today, after I got home, I let the bike sit for awhile then decided to open the gas cap...When I opened it I heard a loud hissing then a pop.
I'm just not sure what to do with this bike, it used to die all the time, but now it isn't but I don't feel the true issue was ever solved.
Other useful facts about the bike:
- Brand new battery
- New gas tank added by previous owner (OEM), but gas cap is original
Hopefully someone has some suggestions or can make sense of all this (Sorry for kinda long story).
- Scott