Honda Tact (Aero 50) Help - What's This Rubber Thing?

[nexentt]

Hi everyone, new to the board here.

I recently bought this old Honda Tact from a neighbor as a fixer-upper. Here she is:


As I understand it, this is a Japanese version of the Aero 50. It's almost identical in many of its components, but there are some differences.

One, is this:





As you can see, I haven't got an Autobystarter like most Aero 50's. Instead, i've got this rubber thing. Currently, the only major issue with my scooter is that it can't start cold. It takes about 15 minutes of patient kick-starting to slowly warm up the engine. Once it's warm, it runs beautifully.

Now since this doesn't have an autobystarter, is this rubber thing supposed to help cold starts? I've tried playing around with it, and noticed that if I block the air vents (seen in the 2nd closeup photo), it seems to start a bit easier when cold.

Anyways, have any of you seen this before? If so, any idea how exactly it's intended to work?

Any comments are appreciated, thanks!

[sanjuro]

I've never even seen a Honda tact/aero in that color. Sweet bike.

To me, that looks like some type of vacuum or emissions type assembly.

[nexentt]

Yeah, I've tried experimenting with it a bit.

I've tried removing the cap and covering the entire face of it with my hand while kickstarting it. It does start up a bit more easily, and you can feel suction against your hand coming from the tubes - meaning that if it's left uncovered, air freely flows through.

I've got a theory that it's intended to be covered during a cold start, allowing less air into the carb, meaning a higher fuel/air ratio to help it start up.

But yeah, that's just a theory. It'd be great if someone has experience with one of these and knows exactly how it works.

[Wheelman-111]

Greetings:

That's an attractive scooter rat thar! What year is it? Man--o, there are more differences than similarities to the US '87 Aero. Air box, cooling shroud, even the belt cover all different.

I can't tell from the pics where those two fat hoses go from the Mystery Rubber - but it appears to be a breather for the carb vent. If my theory is correct, it would put carb fumes back into circulation with some sort of rubber flapper one-way valve. The EPA wasn't the only entity trying to clean up emissions... Open vents are a big source of HC. Those tidy Japanese!

Wheelman-111
Founder
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Oh, almost forgot!
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Welcome to the Forum.

[noiseguy]

Wow. That's a lot of tubes. It looks like there's a bunch of other tubes terminating where the second tube goes.

My guess is that it's a vent cover of some sort. I don't think it was meant to be plugged, but if it starts easier that way I don't see a reason not to continue. But without a service manual page it's hard to say.

Speaking of which, if you come up with a PDF version of the service manal for the Tact, I'd love to host it here.

[Kenny_McCormic]

I would just add a primer to it and call it good.

[nexentt]

Greetings:

That's an attractive scooter rat thar! What year is it? Man--o, there are more differences than similarities to the US '87 Aero. Air box, cooling shroud, even the belt cover all different.

I'm not exactly sure what year it is, but according to the seller it's a 1991. And yeah, there are quite a few little differences, but I've been referring to this manual , and it seems to be similar in a lot of its major mechanical components.

I can't tell from the pics where those two fat hoses go from the Mystery Rubber - but it appears to be a breather for the carb vent. If my theory is correct, it would put carb fumes back into circulation with some sort of rubber flapper one-way valve. The EPA wasn't the only entity trying to clean up emissions... Open vents are a big source of HC. Those tidy Japanese!

I took some more pictures of the mystery rubber piece. I unplugged one of the tubes so there's a better view of where the tubes lead to.

As for the rubber piece itself, it don't believe it's a 1-way valve; it's completely open, allowing air to freely flow between the two tubes and the outside air. And like I mentioned, if I remove the cap and cover it with my hand while the engine runs, you can feel a vacuum sucking against your hand.

I would just add a primer to it and call it good.

A primer, eh? Is that a viable alternative to a bystarter? At the end of the day, I'm just looking for a solution to its trouble with cold starts. What sort of primers would fit/work with this engine/carb?

[Kenny_McCormic]

Custom job, would have to drill the airbox, and pump a squirt of gas in there.

[noiseguy]

Odd. It's a fresh air vent of some sort. Odd in that there's vacuum applied as well on one end of the manifold.

It also appears that there are some spots for lines in at the front of the airbox... three of them to be precise.

My concern is that you're missing some bit to the setup; a good microfiche of the scooter used to order parts would go a long way here. In the US, you can use www.partsfish.com to look up exploded diagrams, but only on US models, and I've never seen a setup like that on a US scoot. It would be good to find a similar web source in the UK for your bike. You need to get the exact model and year off the registration plate on the bike to do this.

All this reminds me of 80's automotive carbs in the emissions era, until the OEMs wrote it off as a bad job and went to fuel injection across the board.

[noiseguy]

This looks promising. I found the Vision Met In models on here for UK. They look very similar to the US Elite (SE50) models:

http://www.bike-parts.fr/

If that's a 1991 I'll eat my hat. That looks more like a mid-80's scooter to me in terms of styling. The later Vision's don't have that funky tubing.

[nexentt]

So I've done some research and found a few Japanese websites, and found some pics for reference:

It might be tough to see from the small pictures, but it doesn't look like I'm missing any parts. And the 3 holes in the airbox you were referring to don't look like they're intended to connect to anything.

As well as a few tidbits of information relating to the mystery part from this translated site.
" Auto choke and adjust the concentration of the mixture according to temperature changes automatically, auto cook automatically open and close the fuel valve by rotation of the engine." Any ideas?

Unfortunately I haven't been able to find any specific info on the operation and function of the little mystery rubber piece - but from some of this new information, any guesses?

[noiseguy]

OK, here's my take.

That little vent thing is just meant to hang out in the engine compartment, open to the air. There should be a retainer clip somewhere, I'm guessing it's either attached to the engine somewhere or in the same place as the white carb cover that should be over the entire carb / air cleaner assembly.

The "autostart" is part of the manifold that all those hoses are plugging into. My guess is that there's a sliding mechanism that should be either opening or closing some of those pipes based on engine temp. It may or may not be working.

As I thought, this is an older (early 80's) bike. The closest US analog is the Honda Express, which is a US moped of the same era. Looking at the '82/83 model, the carb looks very similar. Take a look at this (and other Express manuals), I think they'll cover it. Page 3-4, for instance, shows a replaceable "bystarter element," which may mean a foam filter wad is meant for that little box on your scooter as in the Express:

http://www.mopedriders.org/html/manuals ... resssm.htm
http://www.mopedriders.org/article_cat.php?fldAuto=2

[Wheelman-111]

Greetings:

The chrome details, the kicker cover with that backward lever as well as the leading-link fork suggest this is a derivative of the US-market '83-84 Aeros. Perhaps that service manual can afford some clues. It's possible that the model surfaced in Japan as early as 1981.

[noiseguy]

Greetings:

The chrome details, the kicker cover with that backward lever as well as the leading-link fork suggest this is a derivative of the US-market '83-84 Aeros. Perhaps that service manual can afford some clues. It's possible that the model surfaced in Japan as early as 1981.

The '83-84 Aero uses a screw-in bystarter in otherwise the same design as the later models. He needs to refer to the US Express manuals if not the exact UK microfiche/manual for his model.

[motomaster99]

did you consider just getting say an 84 aero carb. and replacing your mess of hoses and then you'd have an electric "choke" or bystarter?