help!!! engine flooding

I'm in the process of getting an old bike to run. I've had it going a few times and after about 2 or 3 minutes it stalls. Then it stopped starting. I'm getting lots of spark and I think compression is strong. So I thought it must be the carb. I bought a new dellorto sha14 attached it and noticed the engine got completely flooded when I tried to start it. I put the old carb back on and the same thing happened. Where do I go from here?

Re: help!!! engine flooding

You bought a new carb because the engine appeared to be flooding? That wouldn't have been my first impulse, but.. whatever.

What other changes did you make.. What model / year bike is this? A few details and some history about the bike's troubles would be helpful.

Re: help!!! engine flooding

It's an old Malaguti, with a morini engine. I got the new carb because the engine was stalling after a few minutes of running. Also there were a few peices missing from the original carb. Little spring that makes the choke lock andthe cover and filter

Re: help!!! engine flooding

Don Pflueger /

since you get the same result with either carb, i'd look at a few things.

i would do a compression test first. you need to have 120 lbs or higher to run correctly.

i would also clean the exhaust out. a plugged exhaust will cause a flooding like situation.

i would also make sure you have the correct spark plug with the correct heat range for your engine. too cold of a heat range will acvt as if the engine is flooding too.

if all these things are in order, and the engine still acts funny, then i would check fuel flow, and make sure you dont have an air leak. you can drop the exhaust and look up thru the exhaust port. while looking in the port, roll the engine over slowly and look at the piston side wall. any scrapes or smear marks are a good indicator of a lean situation caused by an air leak or lack of fuel in the mix or lack of oil. these scrapes will lower compression and make the engine seem to act as if its flooding.

once you get the engine to run and stay running, then do a plug chop to determine if the carb you are using has the correct main jet.

Re: help!!! engine flooding

How do I do a compression test? Is it possible something is wrong with the wireing? I'm getting great spark from the same type of plug I use in my other Malaguti, and it runs like a top. What causes flooding?

Re: help!!! engine flooding

Don Pflueger /

i doubt you have a wiring problem. and having good spark means nothing if the insulator is burned and the plug cannot attain proper heat range. try a new spark plug first. to test compression, you need a compression tester. sears sells a decent one for about $25. well worth the investment. flooding is usually caused by;

a worn inlet needle and seat in the carb

dirt lodged between the needle and seat

a bad float

rusty or sticking float hinge pin

too large of a main jet

a crack in the carbs body

plugged air filter

plugged exhaust

fouled plug (doesnt cause flooding but presents the same symptoms, black and wet)

low compression (again, does not cause flooding but if the fuel cannot be compressed to become volatile, it will present symptoms of a flooded cylinder)

Re: help!!! engine flooding

would a leaking decompressor valve cause flooding and backfiring?

Re: help!!! engine flooding

The muffler has been cleanded. Compression is high. Plug is new. I dont understand what you mean about the insulatoer being burned. It has a brand new spark plug cable if that is what you are talking about. I have no idea what the next step is. Seeing how far I can throw it maybe.

Re: help!!! engine flooding

I forgot to mention I also tried Quickstart. Not peep from the engine.

Re: help!!! engine flooding

Don Pflueger /

the insulator is the white ceramic just below the tip where the spark is created. the insulator must reach a specified temperature for the fuel to be burned properly. every plug is different, and new doesnt always mean it works. what compression numbers do you have? is the exhaust port clean as well?

Re: help!!! engine flooding

Don Pflueger /

it wont cause flooding, but it will cause a loss of compression which means that all the fuel will not burn properly. and yes it could cause backfiring cuz the cylinder is running too lean since its sucking air thru the valve and since the temps are so high, it may be causing fuel to burn before it should or at the wrong time. most backfire is caused by dirty or misadjusted points, or the stator is out of time.

Re: help!!! engine flooding

Don Pflueger /

spray carb cleaner in the carb throat. try to start it. if it fires you have a fuel problem. if it does nothing, you have either an electrical or compression problem. pull the plug and check for spark. if you have spark, then you have a compression problem.

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