Topic: 1977/1978 Airbox

[flybox1]

what size jets are in there now? and what exhaust configuration do you have?

[fendersrule]

I've yet to drop the jets out to check them. Been busy with housework and oil changes.

I plan on checking the jets today and relaying my findings.

The exhaust is the stock 4 into 4.

The carbs have been syncronized.

There is a "gulp" sound if you open the trottle too quickly at idle (like, trying to rev it to show off). That's the only time where you'll hear or notice that sound. Not sure if that has anything to do with anything.

[hiljak]

Hi Sean,

I would be interested in selling the pods. I'm not sure what brand they are, but if they aren't K&N, then they look/work just as nice (check out my build thread).

Right before my 200 mile trip, I did soak them in engine cleaner, and used some K&N oil on them. Basically, all you need to do is install them on your bike when you get them; no cleaning or oiling is necessary.

Personally, I like the looks of pods more than a clunky airbox. But what I feel that I am giving up for looks just isn't worth it for me.

Let me finish putting the box on (should be this weekend) and giving the bike a spin to see how it is.

If the jets are not stock, then you can certainly have them.

Ok, cool. I'd like the pods and jets if you're not going to use them. Just let me know how it works out for you.

[flybox1]

housework?!?!     pssshhhhhh    you got bike work to do 

that 'gulp' is the mixture being off at idle - fuel screw setting and pilot jet are incorrect for the pods AND/OR an accel pump circuit clogged.  dont let your carbs go back on until you are positive the pump circuit works as intended.

gotta know whats in there before you order. 
likely that the PO half-a$$ed it and only swapped the mains. 

[fendersrule]

Good info.

I'm planning (hoping) to leave the carbs on while I check the pilots. There seems to be enough room to get the bowls off and go about my business with the carbs on. Wrong expectation?

The "gulp" sound I can handle in the future after getting the airbox (and the correct jets back on).

On know on my CB450, dropping the bowls is cake.

[flybox1]

I'm planning (hoping) to leave the carbs on while I check the pilots. There seems to be enough room to get the bowls off and go about my business with the carbs on. Wrong expectation?  unless you have small hands, its easier to pull the carbs and work on them off the bike.

The "gulp" sound I can handle in the future after getting the airbox (and the correct jets back on).  i hope you dont handle it.  it should go away when the correct carb parts are installed and if it doesnt, find out why  

[Heisenberg]

Hey guys... Quick verification on air filter for different bike... figured I wouldn't start a new thread.

I'm going through the same process for my 78' cb550k.   Finally found myself a stock air box online w/ boots  .  Should arrive Wednesday. I need an air filter too, but I'm confused about which air filter to order.

I'm running a 4-1 exhaust.

 btw LOVE this site.  I find myself on here all the time

Thanks!

[TwoTired]

Hey guys... Quick verification on air filter for different bike... figured I wouldn't start a new thread.

I'm going through the same process for my 78' cb550k.   Finally found myself a stock air box online w/ boots  .  Should arrive Wednesday. I need an air filter too, but I'm confused about which air filter to order.

I'm running a 4-1 exhaust.

For economy I use the Uni NU-4055.  Reusable with the cleaning and oiling kit.
The Mac exhaust requires the 78's PD carbs to be re-jeted and adjusted.  The small step change that the foam filter makes can be included in that reconfiguration now rather than later.  If you just want to use the stock carb settings from the book, you'll need the stock exhaust components, too.

Probably should have made a new thread rather than hijack this one, as the 550 is only a sibling to the 750 of those years.  Repair details are rather different.

[fendersrule]

I dropped the bowl out of #4.

The main jet is a 110.

The slow jet, which I have no idea how to remove.....is this stock?

Uploaded with ImageShack.us

If it isn't stock, link me to what I need.

[fendersrule]

Also, the screw on the very right (right next to the slow jet) I took out and put back in. What is the setting for that screw since I shouldn't have messed with it?

[fendersrule]

Guys, the jets are stock on #4. I'm assuming the rest are all stock.

Bike seemed to have run great....

Ill start putting airbox on.

Please let me know what to do to the screw to the very right in the photo

[flybox1]

It's the fuel mixture screw.
If you are going all stock, turn it IN until it gently seats, and then turn it OUT 1.5 turns.
You shouldn't need to adjust it, or won't need to, until later...

[fendersrule]

Got the screw adjusted just right.

Bike runs great with the airbox. I haven't taken it to higher speeds or really have driven it around too much yet, but all well so far.
 

[fendersrule]

Does the top of the airbox need a hose to be ran? And where exactly to? So far, nothing but the carbs are connected to the airbox. I tried to do some research, but turned up with nothing.

[flybox1]

Great looking bike. I love the green.
There is one hose, to the top of the airbox, and it comes up from under/behind the battery tray.  It connects to unit that separates condensate from toxic fumes that come from the valve cover.  Yes ther should be a tube from the valve cover, running over the carbs and down to this unit. Inside the unit there is a sponge which prevents moisture back up into the airbox.  The moisture should drain down into a single, capped tube, which should be drained during schedulex maintenance.  It's the K8's emissions unit 

[toytuff]

Very nice! Yeah, it get's the 

Great color also!

tt

[fendersrule]

Thanks flyboy. Sounds like those vacuum hoses are optional.

[fendersrule]

And thanks Toytuff!

I went on a 200 mile ride last week with a couple nice Harley's with some rake.

During our pitstops, no one approached the Harley's. It was always the Honda.

[TwoTired]

I wish it were optional breathing toxic fumes.

It IS good for the engine you know.  Using air box vacuum to apply negative pressure to the crankcase, this not only helps "boil off" crankcase condensate and draws out blow by gasses, it is a ring sealing aid as well.

Further, if you leave the top air box fitting open, it is a handy bypass for unfiltered air to bring grit inside to be blasted on to the cylinder walls.

While true that some emission control units in other vehicles were a pain, this isn't one of them, and well worth the effort to ensure it's function.

[fendersrule]

Cool. I'll plan on putting a hose. Do you know the size/length I should ask for?

[TwoTired]

It's # 48, I think.

http://www.westernhillshondayamaha.com/fiche_section_detail.asp?section=2451914&category=Motorcycles&make=Honda&year=1977&fveh=131105

12mm hose from a bulk reel.  I don't recall it more than a couple feet long (on my F bikes), if that.  I don't have access to them right now.

[fendersrule]

Cool, thanks! I'll go pick up a couple feet of 12mm vacuum hose.

Thinking I may have to pull the tank now to install it.

[fendersrule]

Looks like I'll have to order this, or wait to go to the honda shop on Monday. Part stores don't have metric vacuum hoses.

Felt like I got 10 more horsepower with the airbox.

[fendersrule]

Ok, got the hose in from UPS today. I'm going to post some pictures of some questionable things. These are the last "what to do with this?" things. Then this bike will be 100%.

This is where I "thought" the vaccum hose from the airbox went to. Turns out, this thing probably pukes stuff by the rear wheel:


This is the only "open" port. I assume this is where it goes?


While looking around, I also found this hose on the carb. I believe this always has been disconnected. Any ideas?

[flybox1]

Second pic...that's your cam chain tensioner, and no hose attaches to it.
Might want to look into what it does and how to adjust it.  Its kinda important 

Last pic is the atmospheric vent for your carbs.  Leave it as is, and uncapped.