Aero 80 idle issue

[Ruckenstein]

I can't get this dern thing to idle properly. It will get up to 40 mph

It seems to like 1/4 throttle. Also the throttle needle doesn't seem to affect rpm a great deal.
The coil does however have some breakage. I will be replacing it tomorrow. Would the coil if not fully connected make it not want to idle through improper spark?? That's all I can think of. First 80 ice worked on.


New air filter
I've been through the carb
I'm 99% sure the carb plumbing is correct
Clean gas
Pretty much new petcock (works properly)
New filter
Gas tank is rust free

[Ruckenstein]

Missing an air filter cap. ISO!

[breaze]

Sounds like you figured it out but remember that those 80's have the elaborate bystarter/choke system which, if not working properly, can really have an effect at idle. You can replace the bystarter hoses with clear hoses to make sure nothing is flowing after the engine warms up, but I have had better luck just capping the system off once the engine is warmed up in order to set the idle.

The by-starter system has a temp-activated valve on the cylinder which pulls air from its own mini air filter and fuel from the carb to supply to the intake when the engine is cold. Once warm, the valve should close and not be a factor. If you cap off the feed from the choke to the intake and the feed from the carb to the choke valve, then it should have no effect on the idle.

If you feel that the bystarter/choke system is having a negative effect on idle (not functioning properly), servicing is fairly easy:
1) fill the temp-activated valve on the cylinder with carb cleaner overnight
2) replace the hoses (I use clear 1/4" for fuel lines and 3/16" for air lines)
3) replace the air cleaner element in the small air cleaner housing (can use any sponge filter material)
4) when functioning properly, you should see fuel flowing while engine is cold and see nothing flowing once engine is warm

Hopefully the airbox piece will do the trick for you.

[motormike]

Good advice from breaze...

[patthesoundguy]

Not good advice... AMAZING advice! Thanks Breaze!!

[Ruckenstein]

What a great reply. Unfortunately the Airbox cap didn't work. I did replace the vacuum with clear lines. My question is about the location of spraying the carb cleaner. Is it necessary to unscrew the 2 little Phillips screws that hold the valve system? If so that's a *. I took the remainer of the clear hose and connected long stems to the 2 and 3 ports on the "1,2,3" valve stem and am letting it sit over night. I did notice capping off the whole system made the bike run completely better. Really considering a carb swap if you have any ideas. I really want this bike running correctly while there is still good weather. Thanks for the help!

[bonesv]

Really considering a carb swap if you have any ideas. I really want this bike running correctly while there is still good weather. Thanks for the help!

http://www.jiangwayne.com/scooter/p_i.php?i=349
I think you could get this to work. Just have to figure out how to supply juice to the bystarter.
I am running this on a 72cc af16 elite with nice results.

[motormike]

There is a thread about the re-routing of these "choke" hoses as modified by
past member Bear 45-70...and eliminating some of that OEM hardware.
I will find that thread and post a link for you to consider.
Keep using the same carburetor with this modification.

LINK> viewtopic.php?f=3&t=16059&hilit=Aero+80 ... ar&start=0

[1man8scoots]

Bear never got it to work properly in the long run.
You have an air leak somewhere. Side seal or intake manifold. I just went through this on a customers nh80. Ended up being the vario side seal after doing a leak down. Cost more to diagnose and fix than they paid for the bike. Fwiw I've replaced 1 bystarter in my life and the shop has done 2 in 20 years.

[1man8scoots]

Move to denver paul.

[Ruckenstein]

A quick note. While messing around with the hoses I noticed that if disconnected the hose on the top intake was off the valve, the bike would Idle great and become much more responsive to air adjustment and throttle adjustment screws.
I tried to spray some carb cleaner down into the "number one" slot on the choke valve and the fluid just came right back out.

[kevinv710]

the old temp bystarter got 2 issues:
1- the surface of the head pin got worm spot, that causing not closed all the way.
2- the bystarter housing got dried oil build up for a long time, that malfunction the metal plate.

[Ruckenstein]

Bear never got it to work properly in the long run.
You have an air leak somewhere. Side seal or intake manifold. I just went through this on a customers nh80. Ended up being the vario side seal after doing a leak down. Cost more to diagnose and fix than they paid for the bike. Fwiw I've replaced 1 bystarter in my life and the shop has done 2 in 20 years.

So it was the crank seal directly behind the variator? I need to get me a leak down tester and get hip to using it.
I checked for leaks on the intake and carb.

[Ruckenstein]

Compression test read around 90. Put just a little 2 stroke oil down the plug hole and ran another test. Jumped up about 3 psi. Is that a significant amount to conclude bad rings?

[motormike]

Compression test read around 90. Put just a little 2 stroke oil down the plug hole and ran another test. Jumped up about 3 psi. Is that a significant amount to conclude bad rings?

No Paul,...3 psi is not significant.