I took a long ride yesterday with no trouble. it was raining very heavily for part of my ride. my ride was almost 40 miles round trip with no trouble. when I got home, I found a port matched intake gasket and swapped it out. I also tightened all my screws, nuts and bolts. it seemed to be running much better after swapping the intake gasket. but today on the way home from kmart, the engine cut out and wont start again. I put the other intake gasket back on, changed my spark plug, checked my wiring, still, no start. I took the head off to have a look inside. no score marks on the cylinder, but I do hear a pfft sound when rotating the piston. also, the head and the piston are completely back. I am running 5oz/gal and have been since after break-in. the throttle needle is leaned out as far as it can be.
66cc engine trouble
- Thread starter motor_bike_fanatic
- Start date
I am using lucas semi-synthetic 2 cycle oil for air cooled engines and I have a pocketbike expansion chamber
There are many, many no start threads on this site.
Plenty to research the possibilities of your engine's troubles.
I will share the basic requirements of an internal combustion engine with you in hopes that you can find one of them at fault.
1. Fuel.
2. Air mixed with fuel at the correct ratio.
3. Compression.
4. Ignition timed to occur at the precise moment when it is required.
The air part should be no problem, but can the carburetor deliver the correct amount of fuel to the intake charge?
Is your fuel valve clogged?
Is the fuel filter clogged?
Is there debris in the float valve that could be blocking the flow of fuel into the carburetor?
Is there debris that could be blocking the tiny hole in the fuel jet inside the carburetor?
Has the fuel jet come loose inside the carburetor?
We will assume that you have compression. If your engine spins over very easily that might be suspect though.
Does your engine have spark?
Did any water get inside the magneto housing?
Black inside the combustion chamber is normal. It is called carbon buildup. A thin, even coating is acceptable. A thick, chunky looking coating is not.
Messing with the slide needle clip position will only affect the fuel to air ratio from 1/4 throttle to 3/4 throttle slide position.
What position is the slide in during the majority of your riding?
Plenty to research the possibilities of your engine's troubles.
I will share the basic requirements of an internal combustion engine with you in hopes that you can find one of them at fault.
1. Fuel.
2. Air mixed with fuel at the correct ratio.
3. Compression.
4. Ignition timed to occur at the precise moment when it is required.
The air part should be no problem, but can the carburetor deliver the correct amount of fuel to the intake charge?
Is your fuel valve clogged?
Is the fuel filter clogged?
Is there debris in the float valve that could be blocking the flow of fuel into the carburetor?
Is there debris that could be blocking the tiny hole in the fuel jet inside the carburetor?
Has the fuel jet come loose inside the carburetor?
We will assume that you have compression. If your engine spins over very easily that might be suspect though.
Does your engine have spark?
Did any water get inside the magneto housing?
Black inside the combustion chamber is normal. It is called carbon buildup. A thin, even coating is acceptable. A thick, chunky looking coating is not.
Messing with the slide needle clip position will only affect the fuel to air ratio from 1/4 throttle to 3/4 throttle slide position.
What position is the slide in during the majority of your riding?
the engine started and ran fine all the way to the store and about halfway home before cutting out. if riding in the rain had caused a problem, I suspect it would have shown itself either on the way home yesterday or when I left to go to the store today. I also understand the basic requirements of internal combustion engines, which you have taken great care to over simplify. I don't often ride at full throttle. I was going uphill at full throttle when the engine cut out. after thinking about it a bit, I suspect gum in my carb. I filled up after my ride and it was still a bit rainy. I didn't think I would get any water in my tank, but perhaps I did. I will check tomorrow. I could be wrong, so any suggestions are appreciated.
Well cool then!
I have learned to not assume beforehand that folks know much about engines.
I was not trying to be condescending towards you.
I wish you the best of fortune in diagnosing the problem.
By order of difficulty;
1: Figuring out what's wrong with a motor
2: Figuring out what's wrong with someone else's motor
3: Figuring out what's wrong with someone else's motor remotely, with only their description to go by
Repairing an engine is simplicity itself, remove busticated bit & replace - it's diagnostics, figuring out what the problem is in the first place that is the challenge, a bit tricky sometimes even with an engine you know well, so you start with the basics to see where the failure is.
Trying to diagnose what's wrong with someone else's engine, one you don't know and haven't heard run can be seriously problematic, particularly if it's not running at all as there's little to go on, you simply start with the basics and hope you stumble onto the problem.
Trying to figure out why someone else's engine isn't running with only their description to go by is virtually impossible as you're completely dependent on their understanding and aptitude, their attempts to diagnose and describe, which only one thing can be truly gleaned from - that being if they fully understood the problem, they'd not need assistance.
So what to do? Start with the bone basics and using them to eliminate possibilities, both engine and user related, running down the list of the known to try and find the unknown and working from there. It isn't condescending - there's simply no other option, all engine diagnostics start with the basic questions regardless of experience;
Fuel?
Air?
Fire?
...and you work from there.
1: Figuring out what's wrong with a motor
2: Figuring out what's wrong with someone else's motor
3: Figuring out what's wrong with someone else's motor remotely, with only their description to go by
Repairing an engine is simplicity itself, remove busticated bit & replace - it's diagnostics, figuring out what the problem is in the first place that is the challenge, a bit tricky sometimes even with an engine you know well, so you start with the basics to see where the failure is.
Trying to diagnose what's wrong with someone else's engine, one you don't know and haven't heard run can be seriously problematic, particularly if it's not running at all as there's little to go on, you simply start with the basics and hope you stumble onto the problem.
Trying to figure out why someone else's engine isn't running with only their description to go by is virtually impossible as you're completely dependent on their understanding and aptitude, their attempts to diagnose and describe, which only one thing can be truly gleaned from - that being if they fully understood the problem, they'd not need assistance.
So what to do? Start with the bone basics and using them to eliminate possibilities, both engine and user related, running down the list of the known to try and find the unknown and working from there. It isn't condescending - there's simply no other option, all engine diagnostics start with the basic questions regardless of experience;
Fuel?
Air?
Fire?
...and you work from there.
the problem is electrical. my cdi might be fried, but it could just be water absorption from riding so hard in the rain. i guess i will know in a day or two.
