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Ok, so I know first I need to check the fuel line going to the right carb, but the fuel line for the right carb comes from left carb. So the order is: gas tank --> petcock --> left carb --> right carb. But the problem is, I don't know how to connect the fuel line that goes between the left and right carbs. Does anyone know how to do this on an '82 nighthawk 450?

Park the bike somewhere it will be safe from fire. If it is dripping, a catch can, and get yourself a manual on your bike - I found one at Bike Bandit, but you can find it out there elsewhere.



Check it out here.

No one will be able to help you as much as you can help yourself once you bridge the gap, roll up your sleeves, and own your bike.

Everyone here is willing to help, but these sound like a good job for a manual and self learning. Good luck. It is a cool bike.

I already checked the fuel line arrangement on my CX500 and its different than yours.

Mine is a couple of years older and has a gravity feed petcock and the fuel line has a tee shortly after the valve

camthepyro wrote:Ok, so I know first I need to check the fuel line going to the right carb, but the fuel line for the right carb comes from left carb. So the order is: gas tank --> petcock --> left carb --> right carb. But the problem is, I don't know how to connect the fuel line that goes between the left and right carbs. Does anyone know how to do this on an '82 nighthawk 450?

Trying to remember, had a 81CB400 and a 81CM400 in the past, same engine. There's a hard tube between the carbs to carry the fuel from the single accelerator pump to the other carb, think the main fuel flow from one to the other is a hard tube too, items 10 and 13 in schematic below. One nearest the needle valve should be the main flow.

http://www.bikebandit.com/partsbandit/s ... 175214.asp

I still have a Clymers manual at home for 78-82 Hawk Twins, I'll see what it shows tonight if I remember. We're doing our 8-10 hours of monster sitting today so I'll be wiped out by evening.

By the way, thanks for your help everyone. Yeah, I actually already ordered that clymers manual from bike bandit on saturday or sunday, so I'm hoping it will get here soon so I can get working on it (I hate when something is broken and I can't fix it...).

Ok, so I pulled out the carb assembly and took off the float bowl for the right carb. It was completely dry, so I don't think gas has been in there for a while. Anyway, it seemed like the pin was sticking, so I took it out, soaked it in gas, and put it back, after that it seemed like it was functioning a little better, so I put it all back together.

Before it seemed like the engine was only running on the left cylinder (like the right carb was getting any fuel to the right cylinder, which would make sense if the pin was stuck closed), and I confirmed this by pulling out the spark plug wire while the engine was running, and when I did this before, nothing happened, the engine didn't sound any different, and it didn't stall or anything. Now when I take out the spark plug wire, the engine kind of sputters, and after about 30 seconds it stalls, which is good, because that's what it should do. But I'm pretty sure it's still not running right, because the right exhaust header doesn't get nearly as hot as the left, and if I pull the right spark plug wire out, it takes about 30 seconds to stall, but if I pull the left wire out, it stalls immediately. So I was thinking maybe the right carb is clogged up with sludge or something, so only a little bit of gas gets through (which would explain why the right cylinder doesn't get as hot, and why the spark plug not firing doesn't affect the engine's performance as much as it should), so I went and bought some fuel system carb cleaner stuff (the kind you put in the gas tank) and mixed that with the gas, and I'm hoping that will clean out the sludge or whatever's in the carb.

Does this sound like an accurate diagnosis? Did I make the correct choice in treating it?

I had this happen when I first bought the bike.
The screw on the carb that connected to the vent hose was loose so I just had to screw it back in.

camthepyro wrote:Does this sound like an accurate diagnosis? Did I make the correct choice in treating it?

If the right carb float needle valve was gunked up, it wouldn't be out of line to suspect that the carb may have clogs elswhere that are affecting the idle performance. Gas additives like Seafoam are effective in removing light varnishing, so it's worth a try, but don't get your hopes up. If small passages are already clogged up, the additive usually doesn't help. Sometimes there's no substitute for pulling the carbs and thoroughly cleaning out the jets and passages. To do a good job, it's best to run something flexible like fishing line through the smaller openings. Just soaking in carb cleaner doesn't always do the trick.

Actually the float needle wasn't really junked up, it just seemed a little stuck from lack of any kind of lubrication, which is why I soaked it in gas. But yeah, if it doesn't improve I'll take out the carb and take it apart completely and make sure everything is clean.