Motorcycle Repair: CB 650 Nighthawk, nighthawk 650, pet cock

Question
QUESTION: Hello,

Have a 82 Nighthawk 650 which has been a pain in my a** for a long time.  Got the bike not running.  Stripped and rebuilt the motor.  Had her finally but together a couple of days ago.  The first time I fired her up, it did not want to start.  Engine turned over but, would not go.  Put a couple of drops of fresh gas down the carbs and she would kick over and die as she should.  Hooked up the tank and tried to kick her over and nothing.  Huge back fires and motor just kept turning over.  Took the tank off, removed the plugs and wire brushed them as well as cleaned them with brake cleaner, put them back in and kicked her over with the tank on again.  Walla, she fired on the first try and ran/sounded great.  The next day, heard a slight tick in the cct.  Installed a new cct and started again, she started fine with the new manual cct.  Adjusted the cct to clear the slight tick and shut her off.  Tried to start her again and nothing.  Motor turns over with back fires.  Loosened the cct and still, nothing.  What the heck is wrong with her?  I think the plugs are fouled again but don't understand as to why she keeps causing the plugs to fail.  The plugs are new and the only reason why I cleaned them and reinstalled.  I know she is getting fuel because she is back firing.  The timing seems right or she would not start.  Battery is new.  Plugs once recleaned and installed, the bike fires up like a champ.

Thanks

Taz

ANSWER: Hey Taz,

I didn't see anything in your description about a carb clean/rebuild?
If you didn't clean the carbs yet, then I highly recommend doing it.
I can give a quick run down on how to clean the carbs if you'd like? Because you don't have to completely disassemble them to clean them and you don't necessarily need to purchase a rebuild kit.

I would also clean the fuel pet-cock and make sure the tank is clean.

Basically what I'm driving at, is if the plugs are fowling, then they are getting too much fuel for whatever reason.

P.S. What is "CCT"?

---------- FOLLOW-UP ----------

QUESTION: Heloo Jeff,

Thank you for the reply.  I have not cleaned the carbs for at least several years.  I will attempt to do this on the weekend.  If you could tell me as to what I may need to do to clean them that would be great.  The fuel pet-cock seems to be always open, I did notice this last night.  When I shut her off, it was still running gas.  How do you clean the pet-cock.  I did expect the tank and it is clean with no rust or other issues.  I was also told that I would need to balance the carbs, never done this and there is not a lot out there about doing this, can you tell me what might be involved in this?  

CCT = cam chain tensioner

Answer
First, if you don't have a shop manual for your bike, get one. It is a must to preform any work on your bike. It will show you how to remove the pet-cock, some info on carb syncing and how to remove/disassemble the carbs.

For the carb sync you will need a carb sync tool (manometer). I use the Morgan CarbTune II, which can be found here:
http://www.carbtune.com/
Its a tad on the expensive side, but I've used it for 3 different motorcycles that I've owned and I plan on keeping it forever. It also comes with everything you need to hook it up to your bike. Also, it uses rods for display instead of (deadly) mercury.
Here is an article I found that tells how to preform a carb sync, and they just so happen to be using the Morgan CarbTune:
http://www.motorcyclistonline.com/howto/motorcycle_carb_sync/index.html

The pet-cock will need to be removed from the tank to clean. There is a small bowl on the bottom that can be removed and it has a small screen/filter that comes out. I generaly use compressed air to blow everything out of the bowl and the screen. If you feel like taking it a step further, you can dismantle the pet-cock by removing the 4 screws that holds the body together. Once everything is apart, you can blow it all out too. If any of the rubber is bad, you can purchase rebuild kits off ebay or from your dealer.

How I clean carbs...
A couple of things first..you don't need to completely disassemble the carbs to clean them and you don't need to purchase a carb rebuild kit, unless you have a bad seal or bad rubber on the carb. In most cases, the rubber is fine.
- Remove the carbs from the bike (following instructions in your manual). You do not need to separate each carb from each other; leave them joined to each other.
- Remove the float bowl. Then remove the floats and the float valve.
- Remove the main jet and the Needle Jet holder (what the main jet screws into).
- Remove the slow speed jet and the pilot jet/air mixture screw (be careful with this one, as there is a small spring and washer and rubber seal on each screw).
- Now on top of the carb remove the top cover off each carb (four screws). Be careful removing the final screw as there is a spring underneath the cover and it could shoot out when you take the cover off. Remove the spring.
- Peal back the rubber on the slide slowly and be careful not to rip it. Pull the slide out.
- Now soak the carbs, jets, floats, slides, gas lines and whatever else that was on the carb, in some carb cleaner. I know Gunk makes a carb cleaner sold in a big jug at WalMart.  There are many kinds though...some are environmentally friendly and smell like citrus. Its up to you. I've even used Diesel fuel, but that can be really bad for you. Let it soak overnight. Turning the parts over every once in a while helps too.
- After soaking, arm yourself with some rubber gloves, a toothbrush, compressed air, needle nose pliers and lay out some clean rags.
- Pull each piece out one at a time with the pliers. Give it a scrub with the toothbrush, rinse it and blast it with compressed air. If it is a jet, be sure to blast all of the holes in it. Then wipe it off with a rag and place it on top of another clean rag.
- I would do the carbs last. Be sure to scrub all the dirt off on the outside of them. Then blast any and every hole on or in them. Be careful that your face isn't on the receiving end of one of the holes, or you will get a blast of air/carb cleaner on you.
-Once everything is clean and dry you can reassemble everything and put the carbs back on the bike.

Some tips:
- Don't go nuts removing or tightening the jets. They are made of brass which is soft, and can strip or get damaged very easily.
- If you turn your pilot jets/air mixture screws in first and seat them lightly, make a mental note of how many turns for each one. That way when you put them back you can set them at the same spot. Otherwise you will have to refer to your manual for the setting for them.
- The rubber boots on the back of the carbs come off pretty easily. But getting the carbs out of the rubber boots on the engine side can be a challenge. I've used a hockey stick to pry against the engine and the carbs to pop them out (and to pop them back in). This can save you allot of struggling. If you are worried about scratches you can wrap the stick with a rag.
- The hair dryer is your friend. I use a hair dryer to heat up the rubber on the slides just before putting the caps back on. The rubber generally shrinks a tad and it doesn't always seal perfectly. Heating it with a hair dryer expands it enough to make it seal again.
I also use the hair dryer for heating the rubber boots on the back side of the carb (air box side) for when the carbs are being installed again. I get the carbs popped back into the rubber intakes on the engine first, then I work the boots at the back on to the carbs. Heat them with a hair dryer and make sure they are pushed on all the way. You don't want any air leaks.

I hope this helps?