Honda Spree and Elite 50 Forums

Hello guys - new guy here. Been a car guy all of my life, but never have messed with these little scooters. I have an 84 Aero 50 that I bought a year or so ago at a yard sale for $50. It's mostly all there (except the air filter housing and a few other small things). Anyway I wanted to start off by asking about the compression. I'm showing 100 psi (cold). Is that acceptable? It has 1,350 miles on it too by the way.

Also, I'm waiting on a aftermarket air filter too. I've read on this board where these things wont run right without on so hopefully it will be here today. The bystarter on the old carb was bad so I did purchase an aftermarket on on Amazon and it's on now. It will crank and run for a few seconds and then die.

I've also cleaned the gas tank out really well and installed and new manual petcock and filter - it didn't have the vacuum type on it when I bought it.

Thanks in advance for the help here.

viewtopic.php?f=11&t=680

^^HERE is a LINK to the service manual for your bike.
This manual is found on this site along with many others.
The compression service limit can be found in it.
The symptom you describe points toward the carburetor still needing some cleaning.
Possibly the bystarter reservoir in the float bowl is not filling fast enough to maintain idle when cold.
There is a tiny hole in that reservoir(lets fuel fill reservoir from the bowl) that must be clean and open for proper operation.
Also, I would change the fuel lines to new to eliminate the possibility of those old lines being narrowed by age, and
reducing the flow of fuel to the bowl. Make sure to plug the vacuum port that was used for the original petcock.

Thanks Motor for the info. I have the service manual for the scooter so I'm good there. New fuel lines as well. I have a new carb on it right now so I know the carb is definitely clean. I'm guessing that I need to try it with the new air filter (aftermarket too) and rule that out first. It should be here today.

One other thing that I'll mention is that it would fire right up with the original OEM carb (pa 05A) and run fine for a minute until it started leaking gas - I cleaned the carb in my ultrasonic cleaner real well - checked the float/needle seat too and that was ok. I assume the leaking is just from the bowl gasket being 35 years old. It was pretty flat. If the new carb doesn't work, I'll just rebuild the pa 05 carb that I currently have.

Will the bystarter from the new carb work on the OEM carb?

shanes72 wrote: ↑Wed Jan 19, 2022 10:18 am
Will the bystarter from the new carb work on the OEM carb?

Those clone carbs sold to replace the OEM are troublesome and often give problems.
Sometimes they work fine. It's a gamble.
I would guess that the bystarter WILL interchange.
You will need to compare closely and determine if the fit is proper or not.

I'll see how the new carb works with the new air filter installed first and go from there.

As far as the compression goes, the service manual just says 170 - I don't see a minimum required or anything like that.

What do you think about 100 psi compression?

With only 1,350 miles on the engine - what would cause the low compression? I have no idea if the engine may have been run with now/low oil or how it was treated in the past. I did check the reed valves too and they looked ok - not broken and pretty clean and flexible too.

Do you think new rings, etc are in order or could it be something else? I could always take the head/cylinder/jug off and take some measurements too. Just trying to think of anything else that would cause the low compression on a low mileage engine.

Appreciate your help here Motor -

I did use an automobile tester so that could be an issue too. LOL - I'm no ace mechanic either on these little engines. I've built plenty of 350's and 327's over the years but nothing this small. I'll see if I can find out anything on the correct compression tester to use.

Thanks again Mike -