Aero 80 Heat Controlled Carb/Choke (bystarter)

[Bear45-70]

My Aero 80 is acting up. Starts and runs fine when cold as soon as it warms up the motor dies from being to rich (wet plug). I've been thru the shop manual from cover to cover and all they talk is cleaning the air filter for it and removing and replacing it. Nothing about how it works and not even a good picture of hose routing. So where do I get info on it?

[Bear45-70]

This thing is not electrical and has half a dozen hoses running all over the place on the carb. Sort of like an old heat driven choke on old carbs but this thing does it with vacuum off the manifold, run thru a heat controlled valve bolted to the head and then back to the carb on a couple of hoses. See the gang of hoses behind the carb, those are only four of the six hoses this thing has.

[martynkim]

Parts Bike! http://seattle.craigslist.org/kit/mcy/1903875957.html

[Bear45-70]

I already have a parts bike to rob parts off as necessary. I even have a spare heat contoller and filter and 2 carbs, but I like to understand why it is doing what it is doing and not just replace parts.

[Wheelman-111]

Greetings:

Another Forumista had an issue with an '83 or '84 Aero recently. That one was 50cc, though. He too had pics of an oddball carb festooned with a Medusa's head o'hoses.

I wonder if the Aero's Electric bystarter was Honda-san's '85 answer to issues encountered with the heat-controlled choke system? Did any earlier scooters than the '84 Spree have them?

Anyway Bear, won't your issue be resolved with the CT mani and a manual-choke carb?

[Bear45-70]

Greetings:

Another Forumista had an issue with an '83 or '84 Aero recently. That one was 50cc, though. He too had pics of an oddball carb festooned with a Medusa's head o'hoses.

I wonder if the Aero's Electric bystarter was Honda-san's '85 answer to issues encountered with the heat-controlled choke system? Did any earlier scooters than the '84 Spree have them?

Anyway Bear, won't your issue be resolved with the CT mani and a manual-choke carb?

True, the CT would solve this issue, BUT I don't have a carb for the CT as yet. But as luck would have it the spare Aero 125 carb I bought arived today. Same bolt flange as the 80 carb and has an electric bystarter. I can't find the specs but the two carbs are identical, including the venturi and they use the same carb kit, which probably explains why the 125 lacks the major go you would expect from a 125 on the big end.

[Bear45-70]

To my great dismay, the 125 carb has a longer throttle stroke than the stock 80 carb, so it will not work. However since I figured out how this insane vacuum and heat operated choke works, that is suppose to work, I just made it into a manual choke by running a line from the carb bystarter fitting to a valve and from the valve to the intake manifold. Mounted the valve in the left side of the center cover under the seat and I'm golden. Works great and I put 20 miles on the scooter testing everything out.

Did the GPS run with the 80 while out and about. Got 43 mph indicated and 40.5 mph on the GPS. This is with a 90 main jet instead of the stock 88 which causes a bad stumble at WOT. The stumble is gone, why on earth did Honda install one step too lean a main jet? Makes no sense unless it was EPA required for emissions by the environmental *. I also bypassed the idle mixture limiter, but the screw is right where the manual says it should be, 1 1/2 turns out.

Now starts the search for more mph, would like to see 50+ mph, the wife has stated she will not ride it faster than that. Have a CT manifold and am looking at a 19 mm carb. Also have a Ruckus variator on the bench.

[Bear45-70]

Here is what I did to fix this issue.

Read all the instructions first and then start working.

Get a good valve that seals well (I got a small ball valve) with 1/4" hose barbs and about 3 feet of 1/4" fuel resistant tubing and 8" of 3/16" tubing.

The vertical nipple on the front of the carb goes to the plastic inlet filter with the 3/16" tubing. You must plug the second nipple.

Then from the 1/4" nipple at the rear of the carb run to the valve, it faces toward the back of the carb (the front of the scooter).

I mounted my valve in the left side of the center cover down near the carb level. Drilled a hole for the handle portion of the valve to stick thru to the outside and then secured the valve in place.

Run the other side of the valve to the 1/4" nipple on the manifold. I used tie straps on all connections.

Valve open is like the bystarter when cold. Once engine warms up, close the valve and ride. My wife has no problems with operating this system. Oh yeah, make sure you do NOT kink the hoses, otherwise the system will NOT work (experiences speaking here).






If you look carefully at the top hose off the valve in the bottom picture you will see it has a bit of a kink in it, but it is better than the first piece I had there which kinked completely closed. Made me a bit crazy as to why it didn't work at first.

[az_slynch]

Wheelman asked,

I wonder if the Aero's Electric bystarter was Honda-san's '85 answer to issues encountered with the heat-controlled choke system? Did any earlier scooters than the '84 Spree have them?

The '81-'82 Express SR has that goofy vaccum rig. It's controlled by a vaccum switch with a bimetal spring inside that bolts to and is warmed by the head. I bet the Urban Express had the same rig.

Glad you got a workable solution, Bear. I spent some time on my old SR's bystarter rig because the stock airbox had disentigrated before I got the bike and I had to fab up a replacement system to make it work.

[Bear45-70]

This afternoon I ran down to my local Honda dealer and I picked up NOS (New Old Stock or NLA, No Longer Available) throttle cable for mounting my spare 125 carb to go on to the Aero 80. The slide is longer in the 125 carb and since the twist grip is the same, the cable has a longer travel in it.

They also had the NOS righthand headlight cover/reflector for the Aero 80. So it now has all it's plastics in place.

[Bear45-70]

It has been a month since I converted my Aero 80 from the amazingly complicated and weird bystarter system to a manual valve controlled system fuel enrichment system. Engine starts and runs every time, even for the wife without me present. Engine starts quickly and starts to load up withing 20 seconds or so. Shut the valve off, engine clears out with in 5 seconds and settles down to proper idling. Scooter runs great and I now declare this mod a success.

[Wheelman-111]

Greetings:

Clever work-around, B. Pics of completed scooter?

You still have some work to do to complete the Honda 2-stroke collection: An '83!

[Bear45-70]

But I have two '83 Aero 80's, one 1985 Aero 50 and one Aero 125 (1984 was the only year it was available in the US) (I also have the kick starter set up off and '84 Aero 50 to put on the '85) and I am considering a second 125. Then there of course is my 1985 Spree. All red by the way.





Since these pictures I have added the front basket to the 80.

I still have to finish making the clamp to hold the crate on for now.

But my sister just finished moving last Friday and my daughter is still moving for the next week at least and I'm the guy with 2 trucks and trailers, so my time has been utilized, shall we say.

Sometime this winter I will come up with a lockable trunk for at least 2 of the scooters.

[Bear45-70]

Simplified drawing of what I did.

[konaking]

In hawaii it never gets cold enough to need a bystarter. Most people just put the bystarter needle back to its normal position and disconnect the power wire when their bystarter gets old and jammed