I know it seems a little late to be posting my first real build update of the season, but I guess it's better late than never, as they say. I actually started work on the project back in March with installation of the braking system, but that soon developed into something I hadn't originally intended, and in no time at all things just got so out of hand that I had to abandon that thread temporarily in order to post something earlier than next August...
I then turned to installation of the carbs, and that went pretty well until I dropped the carbs on the cam cover and put a nice long three inch gash through the paint on the left upper side, which meant I had to pull the cover, strip and repaint, then re-install.
Of course, once I got the cover off, I couldn't help noticing that the valve adjustment covers were looking a bit cloudy (and a bunch of other polished parts were looking grim, too), so that was when I made the "mistake" of purchasing a bench grinder and polishing wheels; whereupon the entire build went into retrograde as I pulled all of the engine covers and other items (like the rear brake plate) for much needed re polishing. I haven't decided yet, but I've been eyeing the front forks as well...
So, after getting everything all polished up and back on the bike, I continued work on this post and, well, you know me by now if you've read this far... I (as usual) got so completely carried away with the subject that the post was beginning to look almost as daunting as the brake project has become (shudder!), so what I've decided to do is to split the post into two parts; the first to cover carb and airbox installation, the second (to come later) will get into a discussion of the airbox function and installation of the throttle cables and grip. I hope it will have been both worth the effort and the wait.
On to business. This pic shows the carb rack with its mounting paraphernalia; at top is the rack of carbs and on the right is the manifold for carbs 1&2 with everything assembled and ready to install. At left, we have the installation components spread out for clarity: the # 3&4 intake manifold (with O-rings) and carb insulator boots, along with the attachment clamps. At bottom are the overflow drain tubes, and the vent tubes draped over the rack should be noted as well
The carburetors have been thoroughly cleaned and rebuilt, then bench-synced, leak tested and had their float heights checked via the clear hose method. The rubber insulators are new from BikeBandit, and all the other hardware came from "Box-'O-Bolts" auctions on ebay.
To begin installation, I mounted the intake manifolds to the carbs. These have the vacuum ports for carb sync testing built into them; they're plugged with a screw and copper crush washer. Later manifolds don't have this feature as the port is on the carb, IIRC, so it's best to make sure you have the correct manifold for the right carbs. They come as a right or left set; the little port screws and the "bridge" connecting each manifold pair should be oriented downward when mounting the manifold to the carbs.
I installed the manifold o-rings (these are the same o-rings used in the valve adjustment covers, BTW) and smeared a little grease on them to help them seal...
...then inserted the whole assembly onto the head. I had to spread the manifolds apart slightly to get them to fit down over the studs, but the whole thing slid on easily enough
I then attached the manifold/carb assembly to the head using eight flange nuts (no washers of any type used with these)
Once the carbs were in place, I connected the overflow hoses to the outlets on the carb bowls and routed them down the back of the engine, along with the carb vent hoses, which are attached to vent outlets between carbs 2&3 (upper left). All of these hoses are gathered together using a little hard plastic band (lower right)...
...then route down between the engine and swingarm. The vent hoses terminate at the swingarm, while the overflow hoses are gathered by this little bale on the frame
Now that the carbs are in place, it's time to install the air induction unit (or airbox, if you prefer). Here is the infamous stock airbox assembly spread out for your perusal (and, if I may, a note to those who are thinking of putting pods on their bikes: you might want to keep a copy of this picture around for... you know... later
)
Moving boustrophedonically (... now, there's a $5 word for you! You can pronounce it by repeating this rather grisly little phrase very fast: "
Boo Stro fed
on Nick Lee", with the accent on
Boo and
on. It means "as the ox plows [or turns]" - in other words, moving from one side to the other and back again in a zigzag pattern, like oxen plowing a field. It's a Greek concoction and is interesting in that its definition is actually shorter than the word itself. I like it, though; it has great rhythm).
Anyway, major digression here. As I was saying, moving boustrophedonically, starting at the upper right we have the plenum drain hose, the filter/element case drain and the element box/breather cover coupling hose; all with attachment clips. Next comes the element cover, the foam element, a rubber element cover seal, the separator plate (AKA seal plate, punching metal, etc) and the filter/element case.
Continuing "as the ox plows", we find three tiny little metal bits (and we'll get a closer look at them later): two small tubular spacers and an old friend, a case washer identical to the one we used on the chain case. Next comes an oval case "nut" that fits down into the filter case, followed by two airbox support brackets with mounting bolts, the air filter clamp and the front air filter cover.
In the bottom row are the tool tray, the air filter element, the airbox plenum and, finally at the very bottom, the plenum to carb clamps.
Now, if you'll pardon me, I'd like to do a minor rant here for just a second. That's a whole passel of parts, no matter how you look at it; it's also a prefect example of why you shouldn't rely on just the Clymer book. Take a look at their section on the air filter and compare it with this picture, for one example among many.
I'm not saying don't get the Clymer book, just don't try to rely on it alone. Get the Honda manual as well - in fact, I'd get it first. You can download a version of it from this site, but don't get cheap on me; go out and actually buy a copy you can hold in your hands. The hard copies are different than the digital versions here on the site and, at least in the section I compared together, more comprehensive. Besides, it's difficult to study a digital version when you're asses-to-elbows in grease trying to set some critical gap .
And they come in a nifty spiral setup so they lay flat and help you keep your place, too!
'Nuff said. I thank you for your indulgence (but
do get the Honda book, OK?)
I started out by installing the plenum to the carbs. Now, with nothing else on the bike, it's a little easier to do than it would be with all of those pesky electrical geegaws and cables and bothersome what-not that can
just get in the way, but there's still a bit of a trick to it.
First, I made sure all of the intake boots (available new from David Silver Spares @ $36 a set) were secure and correctly oriented in the plenum. This doesn't matter as much with the center boots, as they are symmetrical, but the outer two boots for 1 & 4 carbs are angled and must be oriented correctly. Fortunately, Honda helps with this by molding small dimples into the plenum face with corresponding extrusions on the boot. Just line them up and you're good to go (note that Honda originally glued these to the plenum, but it was merely to accommodate assembly at the factory and glue is not necessary here. You can use it if it helps keep the intake boots in position)
Next, I removed the upper rear engine hanger bracket to make some room, then inserted the plenum from the left side of the frame kind of catawampus in through the electrical panel "bay", extending the "shoulder" of the plenum down and out through the space vacated by the engine bracket. A couple of things to note are that I've pre-installed the boot clamps onto the plenum, and though the intake boot kissing the carb bowl may look a bit distressed, it can handle it; after all, if done correctly this entire process takes approximately (as Spock would say) 7.33517 seconds to accomplish...
...bringing the rest of the plenum down 'til all boots are level with the carb bowls...
...then gently pushing the left "shoulder" past the down tube 'til the whole thing just "snaps" in to place (Note: The plastic on the plenum shoulder is pretty soft, but you might consider putting a sheet of paper [or whatever] in between the shoulder and downtube if you're concerned about your paint. I didn't use anything, and it didn't even smudge the powder coat)
With the plenum in position, it's a simple matter to slip the intake boots over the carb throats and tighten down the clamps
This interesting and vaguely pornographic shot reveals the installed plenum from the rear, with the two filter case connection points top and bottom, and a
vagin oval shaped air corridor surrounded by a rubber grommet
There's a matching opening in the filter case, with a protruding lip surrounding its perimeter that slides into this grommet (this is a NOS plenum and, while the rubber itself is still nice and pliable, the 30+ year old glue on the grommet has dried a bit, as you can see)
Now, there is an air tight fit between the grommet and case lip, and you have to wiggle the filter case around and use a fair amount of force to get it to slide into that oval-shaped opening in the plenum. My NOS grommet, being a virgin, was just too tight, and no matter how I pushed or wiggled it, I just couldn't get the case lip to penetrate the opening. I finally used a little P-80 lubrication, after which it gently and easily slid right in... all the way... and it was sooo... and... I...
OK, that's enough of that...
Now that I've, er, mated the filter case to the plenum it's time to consummate the deed. This is the airbox (and I'm using "airbox" to designate the combination of both the plenum and filter/element case) mounting hardware
At left are two little tubular spacers that fit into corresponding holes in both the plenum and filter case, while the oval-shaped "nut" secures the lower case mounting bolt. Next is the rear mounting bracket with bolts and washers, while at the bottom is a case washer similar to the one we installed in the chain guard. Last (but not least) is the front mount aith its associated bolts and washers.
I began by installing the spacers. These fit between the plenum and filter case, connecting them together; one on top (below left), the other on the bottom (right)
They're necessary because, without them, tightening the connecting bolts and nuts would compress the ABS plastic, causing it to flex and eventually tear.
Spacers in place, I installed the plenum/filter box connecting bolts and washers. The lower sections of the plenum and filter box are secured together by a 10mm 6x25 bolt, an 18 mm washer, split washer and this special oval "nutplate", which fits down inside the filter box (right)
The top 6x25 bolt not only completes pairing of the plenum and filter case together, it affixes the front airbox mounting bracket to the assembly. The bolt, with a split washer and 18mm washer, is inserted from the inside of the case through the case body and into a nut that's welded to the back of the mount
Next, the rear mounting bracket is attached to the rear "nose" of the filter/element case utilizing the case washer, another 10mm 6x25 bolt and split washer...
..the bolt screws into a nut on the back of the bracket, just like the front bracket had. Note the orientation of the bracket, with the longer "leg" extending away from the airbox
Here's an overall view of the airbox as it sits in the bike. The front bracket mounts to a plate welded across the frame with a 10mm 6x12 bolt (and the plate is slightly angled, so the bracket is "bent" to match it), while a 10mm 6x40 bolt attaches the rear bracket to the bike at one of the frame cross members. The inset gives a more detailed look at the orientation of the brackets...
The two final parts that finish up the installation are the drain hoses for the filter/element case and the plenum. They come in two sizes, and while they may look similar, they're actually quite different
The longer hose is the plenum drain hose. It is has an internal foam filter
Foam filter. Remove this when using hose for drain on the filter/element caseIts primary purpose is to drain any gas that might somehow escape the carbs and splash into the plenum. The foam acts as a kind of barrier that lets gas out but doesn't let in a lot of air or debris, so that the correct pressures are maintained inside the plenum during engine operation. It connects to the plenum via this outlet formed into the plenum body where it's secured by an omega clip
It then routes down and through this bale on the frame, which it will eventually share with the battery vent
The shorter hose attaches at the base of the filter case and is actually no longer available; however, the plenum hose can still be had and, with a couple of mods, will work fine. Just cut it to length and remove the internal foam filter mentioned previously. The hose differs from the plenum drain in that it uses no internal filter; it's (obviously) shorter (@11"), and it terminates in a special tip that looks and operates like this :
This hose and tip are necessary because one of the functions of the air filter element stack is to condense liquid vapors from the blow-by gasses as they're being cycled through the PCV system (more on this in Part 2). The condensate (mainly water) dribbles down here and collects at the little tip; just squeezing the bulb opens a slit in the side that lets it all drip out. Nifty, eh? Now, because this is part of the air intake system it needs to be air-tight, and that's another thing the little tip does; it closes off the drain tube and helps maintain a negative atmosphere within the filter/element box, a condition that is necessary for proper functioning of the air filtration and crankcase ventilation systems.
So, the obvious idea is that the hose needs to be kept plugged until it needs to be drained. The biggest problem with this is that the fancy schmancy little hose tip demonstrated above is made of unobtainium, and is dang nigh impossible to find. I managed to snag one through the kind auspices of a fellow forum member (Thanks, G-man!!), but what I originally had to resort to was a small plastic plug that fit tightly into the end of the drain tube and could be removed for draining when necessary...
It's actually a weatherstrip grommet from an early Corvair and is still available - here's a link:
http://www.corvair.com/user-cgi/search.cgi?part=C8500. They're around three bucks for a pack of 10 (so you've got a couple left over. Who knows what use you might find for them).
Whatever works to keep the hose plugged. Meanwhile, the hose routes down through the same wire bail as the carb overflow tubes, as shown in the above pic.
Now that the airbox is mounted in the bike, the next step is to install all of the anti-pollution goodies, and that's what I'll cover in part 2 of the post. The official Honda designation for this accumulation of parts is the "Blow-by Gas Scavenging Device", and this is a drawing of it purloined directly from the Honda shop manual (find this in your Chilton's)
I'll be looking at this a little closer to try to understand just what it is, why we should use it and how it works.
"til next time
