Bike running RICH!

[jetjock79]

Hey everyone! Just found this forum a couple of days ago, and have been reading through everything. Just bought an '85 NightHawk 650 and she is pretty cherry. Got it from the original owner who was an older gentleman who didn't ride much. The bike had 4,300 miles on it (I know....it would have been better with more miles, but I know she wasn't abused). The bike had been in the shed for the last year, but the guy always maintained it at the dealer.

I have already changed out the oil, oil filter, gear oil, replaced air filter, and have run a two tanks of sea foam through it. I cleaned out the needle, diaphragm and slide, and the passage ways in the carb, along with the jets. I checked all of the ignition system for all of the resistance parameters (as per Clymer), but have not checked timing yet. I have one issue (and maybe it's just me), but she seems to be running rich to me, especially on a cold start. After sitting overnight, she starts fine with half choke (one quick touch of the start button and she is running....everytime!), but she seems to stumble through throttle inputs from idle-4k. Once warmed up,....she clears herself out and revs just fine and sounds healthy. It does seem to me that the exhaust smells as if she is running a little rich, even with the air filter cap off....and every so cycles....you can hear a slight pop from the left exhaust, like rrrrrrrrrrrrrrpoprrrrrrrrrrrrpoppoprrrrrrrrrrrrrrr (either #1 or #2 cylinder is the culprit). Once on the bike and running it....she accelerates fine, but then past 4k....she gets an extra push as if a turbo has just kicked in. I know it sounds like a clogged pilot jet,...but I cleaned them thoroughly and checked to make sure they were ok. Even a buddy of mine that heard her run while she was warm says it smelled rich. I did check the plugs and they looked fine.

Any thoughts about this....I'm pretty handy mechanically, but this is stumping me. What would cause it to run rich when cold (with or without the choke), and run rich at idle-4k when warm? Thanks guys and gals! Hope to ride with any NightHawk owners out here soon!

P.S. I'd like to sync the carbs....any advise on what signs to look for on the bike to tell me she needs it? Thanks!

[Tryvelcro]

Did you pull the carbs all the way off the bike?  When you were done cleaning them, did you do a bench sync?

Mr. Bee is the 650 carb guru (well, he really just knows his bike inside & out).  He's out nomading still, I think, but he's got an awesome bench sync write-up here:  http://nighthawk-forums.com/index.php/topic,2961.0.html

[sackman]

My 84 HN runs a little rich also. Once in a great while it will stumble in first or second gear but then cleans herself out. And just like yours when ya get the revs up in 4-5 gear it excellerates like it's got a turbo. Not sure that is normal as I have never owned a NH before but I like it!

[cjbear11]

The '83-'85 Nighthawks are basically maintance free bikes. Which means most things are non-adjustable, the carbs being one of those, as well as the timing. You can however change the mixture on the carbs just slightly for when you're in high altitude locations, by turning the pilot screws until the limiter stops them. I'd check all four of those to see if they're on the leanest setting or not. Does the bike have the stock air filter, or does it have a K&N, UNI, etc? 

[jetjock79]

My bike is all stock and I just replaced the air filter with a new OEM filter. All the air mixture screws are set to factory settings (2 5/8 turns out). I know this because there is a tab preventing them from going any richer. You can only adjust them 7/8 turn leaner.....but right now they are set at factory setting.

I just want to solve this issue for teo reasons: #1 I love my machines running perfect and just humming along. Must be a guy thing, but when your machine is purring due to your knowledge of how to tune it....it's a great sense of satisfaction. #2 this is the most important reason.....I don't want to do any damage to the engine. I know this bike will run forever as long as you take care of it!

I'm trying to find a buddy that might have a manometer (carb sync tool), because paying over $100 for about a five minute use is a little too extreme for me. The book only advises syncing the carbs every 4k miles.....so I won't get that much use out of it.

[jetjock79]

I did pull the entire assembly off the bike when I cleaned the jets. I didn't bench sync them, but the bike was running tjust like this BEFORE I cleaned out the carbs. Timing? Carb Sync?

[jetjock79]

Also,....I'm Using the NGK 8EA-9 with an "R" under the numbers. Is that resistance type, or Iridium.....I can't recall what that letter stood for. Should I use a hotter or colder plug?

[Munkey]

Are you sure it's running rich? It's hard to make a stock bike run rich without changing jets to a larger size. Clogged or dirty jets will make a bike run lean because they can't pick up enough fuel. That's why bikes with dirty/clogged jets need to have the choke on to run. A bike that's just started on a cold engine will need a slightly richer mixture until the engine warms, that's where the choke comes in. The choke either cuts the air flow into the carbs or increases the amount of fuel flowing through the carbs depending on the carb design. What you are describing sounds like normal cold engine behavior to me. Your engine will need a certain amount of choke to richen the mixture until the engine warms up. It will not have full power until the engine gets to running temp and the choke is off. Some bikes are "cold natured" and need more of this than others.     

[gammer]

I just read this thread now and I agree that it from what you are describing, your bike is not running rich; it's something else.
When you cleaned your carbs, did you actually take them off the bike, take all the jets out and soak them? If not, then I'd recommend using the Pine Sol method:
http://nighthawk-forums.com/index.php/topic,4472.msg54844.html#msg54844

[jetjock79]

She starts cold with half choke....and if I were to immediately take the choke off....she will stay running for a while at a ow RPM and possibly die. I know all about that though....she runs SOLID I think. It's after she is warm....the exhaust still smells like she is running rich. I also get the occasional pop (not loud...hardly noticeable unless you are trying to hear it), out of the left side exhaust. She will run and be a little hesitant from idle to 4k, but then be smooth after that. She still runs excellent though....the smell and the slight pops are what are leading me to believe she is rich......eventhough the plugs look good.

I took out all the jets and thoroughly cleaned them with carb cleaner (not my first time cleaning carbs or jets). I made sure everything was clear. I understand it's almost impossible to make the bike run rich. As I was writing this....a thought came to mind.......could the choke channel be clogged somehow eventhough all the choke stems move up and down freely with the assembly?

Could a carb or four that are out of sync cause these symptoms? I'm going to check timing, but she runs like a clock (not as perfect as I want....but still very healthy)....so I'm more tempted to say it's a finer problem. I could be over OCD with this.....but I'm trying to get this engine to humm.....like it was new.

[jetjock79]

would the accelerator pump also cause this problem at lower rpms if it were bad?

[gammer]

Could a carb or four that are out of sync cause these symptoms? I'm going to check timing, but she runs like a clock (not as perfect as I want....but still very healthy)....so I'm more tempted to say it's a finer problem. I could be over OCD with this.....but I'm trying to get this engine to humm.....like it was new.

The exhaust from the 'pop' will smell rich, because it is unburnt gas. But the reason its unburnt is what we need to find. Not necessarily that its running rich.
Unsync'd carbs causes the bike to run ruff and 'uneven'. It generally wouldn't cause the odd pop.

Electrical timing is very hard to go out of whack on these bikes. The rotor that bolts onto the crank, is held in place by a 'key', that makes it impossible to change the rotors position. Its more likely that you might have an electrical issue with the wires or coils, then the electrical timing being off.

[Munkey]

My '82 650 will pop like that when on the choke. You say you start the bike then immediately turn off the choke. I've owned a lot of bikes over the years and when the engine is cold, they've all needed the choke on to run until the engine is warmed up at least a little bit.   

[jetjock79]

I use the choke to start the bike initially.....and keep it on until it's warm. I was just saying that I can start the bike with no issues, and she keep running with or without choke.

I checked all the resistances for the pulse generator, the coils themselves, and checked for sprk with another spark plug touching the engine. All was good and I got a spark.....I couldn't check the spark unit because there is no test for it, and I don't know how well the spark plug wires are....they seem in gret condition, and like I said before....I was getting a spark.

Is there another way of checking the coils and spark plug wires to check for good operation other than what I've been doing? I know that ther are always garage mechanic tricks that work much better than what the book describes sometimes.

[jetjock79]

I'm just worried it's going to be the spark unit because checking on-line for a replacement of the OEM is like $300!

[Munkey]

Sometimes the wires on old bikes like these start to go bad with age. Since the power to the coils usually goes through the fuse box, control switch and who knows what else before getting to the coils, this can lead to not getting full power to your coils. There is a article in the link below explaining how to do a simple inexpensive mod that fires your coils directly off the battery using a readily available relay. I have not done this on mine yet but know a couple of people that have and they swear by it. Might give it a shot.

http://www.wgcarbs.com//index.php?option=com_content&task=view&id=12&Itemid=26

[jetjock79]

Checked the wires going to the coil and they both have 12V going to them. Checked the spark on all four plugs again, and it might just be me, and I was checking during sunlight outside on this beautiful clear day....but the spark looked almost orange (I tried closing my hand over it and it was blue), you think Iridium plugs might do a better job? I have NGK's DPR8EA-9 which are resistor type plugs. They are for Standard heat range.....should I use a hotter plug?

Funny thing I did notice today though......she was running nice after a run on the highway (opened her up a bit and let her breath the fresh air), and then after checking the connections to the coils....I replaced the hoses that go to the PCV hose off the carbs. Sprayed carb. cleaner through all the hoses and leads from the carbs. Started her up and took her out to get dinner. I noticed that she was now running smoother than she has before! Almost a consistant rpm with only a "pop" every once in a while. Could the PCV system really affect the way the bike runs? I'm going to be checking timing soon,...but after today....I almost feel as if she is just fine with that, and I should be working on carb. sync'ing instead.

When she is at low idle,...I twist the throttle a little and she gets the hesitation (like a smoker taking a deep breath), and then I snap the throttle closed and she revs up higher just a little just before returning to the low idle. I think this shows how she might be running rich......no? Thanks again for all the advise!

[jetjock79]

Just thought I'd update this for anyone in the future searching through, and experiencing the same problem:

     I went through all the electrics (everything checked out great), went through the plugs (spark and color checked out great also), checked the timing (also spot on). Before getting to syncing the carbs, I wanted to make sure they were as clean as possible just to make sure I was covering all aspects. I took them apart completely again....but this time....I LIBERALLY sprayed two cans of carbs cleaner through all ports, and soaked and cleaned the jets with a guitar string to make sure I got everything...........RESULT; NO MORE POPPING and a much smoother acceleration with more power, and quicker warm-up. Looks as if I didn't get the slow jets as clean as I thought....and possibly the choke channel either. I tried "bench syncing" as best as I could, but I think I'm just going to buy the tool and do it dynamically, as opposed to statically. She runs awesome now, and about 98%.......should get 100% after the sync! Thanks everyone for the help, and I'm so glad to have found this NightHawk community!