1992 Nighthawk – Petcock Assembly

I took the Nighthawk’s fuel petcock apart to clean it, and¬† —after I was done— realized that I didn’t know how it goes back together. I checked the repair manual, Honda’s general service manual, and Google for assembly instructions, to no avail.

After some head-scratching, a fresh pot of coffee and some try-and-error assembly attempts, I finally figured it out. It’s not rocket science, of course, but I decided I should do my part to close this tiny little internet knowledge gap. So, here it goes:

This is a Keihin petcock from a 1992 Honda CB750 Nighthawk – all disassembled. By the way, this pile of scrap metal is worth a whopping $215 (check it out on BikeBandit).

Feel free to comment on how clean the parts are. Took me 3 hours of soaking, scrubbing and wire-brushing.

Step 1 – The fuel strainer screen (the orange thingy): According to Honda’s maintenance schedule, it should be checked and cleaned on a regular basis.


Screen goes in first, then the rubber gasket and the “crap collector” (yes, that’s the technical term … I think ūüôā ).


In the photo below, the parts are lined up in the order they go together: left to right, top to bottom.


Step 2 – Membrane #1: First up, the metal ring and the smaller membrane. Make sure that the rubber membrane’s nipple (yes, I said nipple) is fully seated in the metal ring¬† – you might have to push and wiggle it to get it where it needs to be.


Step 3 – Membrane #2: Next up is the piece that separates the two membranes. Make sure that the vacuum tube connector faces down (not up, like in this picture).



Then attach the larger membrane.


To attach the larger membrane to the other side of the metal ring, it might be easier to take it off the petcock (see image below). Again, make sure the membrane’s nipple is fully seated in the ring.


Note that the larger membrane has nipples on both sides. The bigger nipple faces down (attached to the metal ring), the smaller will face up.

Step 4 – The black disc: Put the black metal disc over membrane #2. Each side of the disc is different, but you’ll know which one is the right one when the hole in the disk lines up with the smaller nipple.


Step 5 –¬† The spring: The spring goes next. It’ll seat perfectly in the black disc and the lid.


Step 6 – The lid: Make sure the lid and the spring line up.


Step 7 – Bolts: Screw in the bolts – done.


Knowledge gap: closed. World: saved.

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1992 Nighthawk – Take 3

Argh, this bike is going to my downfall. Every time I pick up a wrench to do one small thing, I end up¬†wrist-deep in¬†motorcycle¬†guts. ¬†Meanwhile, laundry and dishes are¬†piling up everywhere, the backyard¬†looks like a jungle, and the only thing left in my fridge is a stick of butter. And I haven’t blogged in two weeks.

So, here’s a recap of my latest grease monkey adventures.

First up: The oil change — or:¬†Things that stink, for 500.

Oil for the bike's belly, beer for mine.
Oil for the bike’s belly, beer for mine.

I am not sure what I expected from 20¬†year old oil, but I didn’t think it would smell as bad as it did. It was black, felt like what you find at the bottom of a french press coffee maker, and had a nasty¬†smell to it. After draining the old oil, I “rinsed” the engine with a liter of fresh¬†oil until the oil came out looking like it did going in.

You’ll notice the funny bend in the brake pedal. Not sure how that happened since the bike shows no other signs of a drop. (Thoughts and theories welcome!)

I read somewhere that I am supposed to check¬†the crankcase breather tube on a regular basis. Here I am, fancying myself a decent amateur mechanic, and I didn’t even know such¬†tube existed. Oops.

I'm no expert but I don't think this tube has been doing any "breathing" ...
I’m no expert but I don’t think this tube has been doing any “breathing” …

I did some research on the “internet box” (Chris’ term, not mine) and came across¬†a great forum post about the purpose of the breather tube – check it out if you made it your life’s goal¬†to fill your brain with nerdy¬†motorcycle trivia: Crankcase Breather ¬†(scroll down to post #3)

As you may remember, the old battery had started leaking and in an effort to prevent more acid from spilling all over the bike, I had to cut the negative battery cable*. I had ordered a new battery cable¬†(used, from a 1997 Nighthawk) and¬†as I was finishing¬†up the oil change, the mail¬†girl¬†(what’s the pc term for a mailman that’s actually a really cool young¬†woman?) showed up in my driveway with my new battery cable.¬†Lovely timing!


Next, off with the tank. The tank comes off so easily, I am not sure why I hadn’t done it sooner. It’s not like I was going to try to run the engine with whatever (if anything) was left in that tank.


The frame is actually black, just really really dusty.

And before I knew it, curiosity had taken the better of me – I loosened the cylinder head cover bolts and peeked under the cover.


I could tell from the stickiness of¬†the gasket and the trouble I had pulling the cover up that it had never been lifted before. I felt like an archaeologist accessing¬†an ancient tomb for the first time in millennia. And from what I could see, the guts of the engine are in pristine condition.¬†I don’t think I’ll have to mess with the guts of the engine at all. So, moving on to the carbs.

I argued¬†with the carbs for a good 20 minutes before they realized that resistance was futile and gave up. (And when I say “argue”, I mean: apply brute force; and when I say “I”, I mean: Chris)


The carbs looked surprisingly clean.¬†The inside of the carb insulators … not so much.



The one you see in the photo is particularly corroded, the¬†others were contaminated with¬†carbon deposits. Nothing a good carb cleaner can’t handle – but I can’t risk having that stuff get into the engine, so off they come!

Why is she replacing the plugs, oil, and battery +cable, but pulling off the tank and carbs, you might ask.

Rest assured, there is a method to my¬†motorcycle assembly/disassembly madness: Following¬†my initial success, I want to see if I can actually get the engine started, but I don’t want to try until the fuel/air system is¬†healthy enough for that. That means I’ll have to clean the air filter, flush out the tank, check the fuel lines, and clean the carbs.

But that’s a story for another day.

*The post-mortem on that: the acid had actually evaporated and the spilled liquid was completely harmless. Oh well, can’t be careful enough with that stuff.

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1992 Nighthawk – Take 2

Today is spark plug day!

After sitting in a parking lot for 14 years, the Nighthawk’s spark plugs had developed a bit of a vintage look, to say the least. I soaked¬† them in Liquid Wrench penetrating oil for a few days, and now they look good and ready to meet my favorite¬†tool:¬†a two¬†foot wrench and a 18 mm spark plug socket.


The oil bath was definitely a good idea, the plugs are coming out surprisingly easy. I am a little worried about the crusty ports, the penetrating oil knocked a lot of the rust loose and I am not sure how to prevent it from dripping into the engine.


The tip of the first plug doesn’t look so bad (somehow I expected worse) but I wonder if the owner ever changed them or if these are the original plugs. After all, the bike has less than 12,000 miles on the odometer.


The other three plugs are pretty foul. Judging from their black carbon coating, I suspect that the bike was¬†quite unhappy before the previous owner decided to “abandon” it.


So far, we have a (fairly) clean air filter and four unhappy spark plugs.

I bought a new battery but before I try to start the engine, I think I’ll do an oil change and pull the tank off for a carb inspection. Stay tuned.

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1992 Nighthawk – Take 1

I really shouldn’t ever go on Craigslist. I mean, I almost never do but I did last weekend and found an old, neglected 1992 Honda CB750 Nighthawk with less than 12,000 miles under its belt. And for whatever reason, I immediately wanted it.

The tags expired in 2002, it’s been sitting in a parking lot somewhere in Maryland ever since. For some reason, the owner decided to get rid of it now, brought it to friends who run a Honda dealership in Virginia and they sold it to me for $600.

1992 Nighthawk

This bike has literally not been moved or touched in 14 years. It’s crazy to think that the last time this bike was out on the road, I was a second-year in college.

This is where my journey with this bike begins – and I invite you to come along. Advice, suggestions and smartass comments are, as always, welcomed and encouraged.

Our first evening together

Everything “perishable” on the bike is rotten to hell, but the body is in great shape – the bike has never been dropped, not a single dent or scratch on the tank.

The seat does not look very inviting … it needs new foam in addition to a new cover.

Rotten Seat

The turn signals hanging on for dear life only by their wires.

Turn signals

The exhaust pipes are beyond rescue.

Rusted pipes

The paint has seen better days.

Sun-faded paint

And the list goes on …

I am not entirely sure yet if I want to restore the bike back to its old glory, or if I want to turn it into something entirely different, a caf√© racer for example. For starters, I need to figure out if the engine is still okay. I suspect that it is but to find out, I’ll have to put in a new battery, replace the spark plugs, and give the air filter and the carbs a quick cleaning (a complete carb rebuild will follow after that).

Before I start wrenching, the bike is getting an air bath with the leaf blower, to get rid of all the dead spiders, leaves and debris that have collected in every crevice and hollow space of the bike.

Leaf blower

I’ve said it before and I’ll say it again: a leaf blower is an essential tool for every motorcycle mechanic (who is too lazy to pull out the air compressor).

The spark plugs look pretty rotten, I am worried that rust has seized the threads, so I’ll just give them a bath with liquid wrench and let them sit for a day or two.

Spark Plugs

A quick peak at the air box and filter reveals a surprisingly clean airway. I mean, it’s obviously not clean but considering that the bike hasn’t been moved in 14 years, I was fully expecting to find a family of mice residing in the filter.

Air filter

While messing with the air box, I suddenly realize that there is a greenish-clear liquid spreading under the bike, slowing creeping towards me. I had noticed a few cracks in the battery earlier and made a mental note to use extra caution during removal, but apparently pushing the bike out of and back into the garage had “awakened” the cracks and acid started pouring out and dripping down onto the floor. $H!T


Hustling to get the bracket off I run into the next problem: the bolts on the leads are rusted so badly that I can’t get them off — I have no choice but to cut the wires instead in order to remove the battery.

Cleaning up an acid spill is quite the ordeal so I am calling it a night for the little red devil. Stay tuned for Take 2.

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Rebuilding Carburetors – 1999 Nighthawk 750

Part 2: Carburetor Separation

The carburetors are off the bike – what next? In this post, I will explain how to separate the four carbs from each other and disassemble them so they can be cleaned. FYI, I took the photos while I put them back together – that explains why the carbs are so clean and shiny. They were much (much!) dirtier when I took them apart.

Before you get started, make sure you have the following items:

Carburetor kit

Four carburetor rebuild kits – I bought them online for $16/kit.

Carburetor kit

Cleaning supplies: Simple Green, a can of WD40, at least two cans of carb cleaner, an old tooth brush, a small brass wire brush, and fine steel wool;

Continue reading Rebuilding Carburetors – 1999 Nighthawk 750

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Rebuilding Carburetors – 1999 Nighthawk 750

Part 1: Carburetor Removal

Most modern bikes are fuel injected – our Triumph Speed Triples are. But the 1999 Honda Nighthawk and the 2004 Honda Hornet are carbureted. Both bikes feature four carburetors (one for each cylinder) … delicate little devils that don’t require any of your attention – until they do.
Carbs like to be synchronized, and eventually, they will demand to be rebuilt.

This three-post series explains how to remove, separate and rebuild the Nighthawk carburetors. Note that no matter how ambitious you are, this usually turns into a multi-day project … though it could be done in a day, I suppose. Make sure to order a rebuild kit (which is basically just a set of replacement gaskets) before you get started. And when I say “a rebuild kit”, I mean: one for each carburetor.
So, in the Nighthawk’s case, I needed four.

In case you’re not sure – the carburetors are tucked in between the air cleaner and the cylinders:


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How to built a paint booth for less than $50

Headlight mask, front fender, and tail section sanded and primed

Last summer, I decided to repaint my Honda CB600F Hornet – I love the matte black but it needed a touch up on the tank (because the factory put the clear coat OVER the decals – so when I pulled them off, you could see where they once were ūüôĀ ), and the aftermarket front end’s color was off from the rest of the bike.

I had everything I needed for this project: a spray paint starter kit, a bucket of matte black paint, and no clue what the hell I was getting myself into.

Continue reading How to built a paint booth for less than $50

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Light of the wicked – snuffed out

I think this is a bible reference – hope God doesn’t mind. ūüôā

This post explains how to troubleshoot a broken brake light.

Today, as I was getting the 2007 Triumph Speed Triple ready for a potential buyer (yes, we’re selling her), I noticed that the front brake wasn’t engaging the brake light. Not sure how long that’s been an issue but I didn’t want to sell the bike with a major safety feature not working properly, so I went into troubleshooting mode.

Triple wiring diagram
Triple wiring diagram

The light itself was definitely working, because it lit right up when I engaged the rear brake. I pulled the tank and the air box to get a closer look at the wires. Multimeter in hand, I incrementally went backwards, from the rear brake light switch towards the front of the bike.

Continue reading Light of the wicked – snuffed out

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