No vaccumn 83 Aero 80

[sculpt]

I purchased an 83 Aero 80 basket case a couple of years ago and have very slowly been working on it. It is cleaned up (not panels) and ready to run. I have spark and a new air filter but it wouldn't start. No fuel was reaching the carb. I discovered there is no vacuum from the brass vacuum tube beneath the carburetor to the line going to the petcock. Where do I go from here?

[Wheelman-111]

Greetings:

Pull vacuum on the petcock vac line with the fuel line disconnected to see if the petcock is the problem. If fuel flows, reconnect and "prime the carb with another 10-second pull, then check the carb bowl to see if the fuel got by the float needle valve. If it still won't start, check engine compression with carb held wide open. It should run if compression is around 90 or more

[sculpt]

Thank you for your input. As I feel no vacuum at all from the line I guess I should probably check the compression? Is there a particular type of compression gauge that fits in there relatively easy?

[tazland001]

Have you tried to spray carb cleaner in the intake of the carb to see if it will start? If it rolls over that will rule out a few problems that could exist. One thing you can do to prime the carb is to put your hand over the intake of the carb and hit the starter button and if you feel gas hit your hand. If you feel the gas then the vacuum is working. Have you checked the petcock to see if the vacuum is working on it? You can just suck on the bottom hose(the smaller of the 2) and see if it releases gas. If everything checks out and you still can't get the carb to prime check for cracks in the vacuum line and look for any leaks at the base on the intake mani. You can crimp the vacuum line from the petcock and give the carb straight flow. I have seen some carbs leak when you do this but for the most part it works. If you do crimp the vacuum line and get the carb to fill and you try to start it and gas spits back out the carb then the intake valve is not seating correctly. If it still won't start or you still can't get vacuum I will shoot you some more tips.

Taz

[Wheelman-111]

Greetings:

By "Intake Valve" Taz means the reed block, and he's right. A broken reed can cause a lot of problems. Easy to check, harder to reassemble unless you pre-order the gaskets which you will destroy taking off the reed block. Look around for other possible csources of vacuum loss = checking crank ends and even lifting the head to look for a peek-a-boo piston won't require gaskets to re-assemble. You don't even have to lift the head if you get a Harbor Freight Bore Scope...

[tazland001]

My bad I thought the 80 was a four stroke. lol I never worked on the 80cc.