Motor sputtering

artmaker

Active Member
Joined
Jun 12, 2008
Messages
332
HI guys,

So... rather than keep adding to a long thread, I'm starting one over.
BRIEF recap, had motor issues with it dying when idoling or coasting.
Cleaned the carb twice, gave up. Bought a brand new carb. Also learned what a little black screw does... adjusts the throttle. OK, helpful.

(Had wheel issues so couldn't do much for awhile.)

Today. Wheel back on the bike, fired up the motor, got the throttle adjusted, it RUNS. It does not die, BUT...
what is with this sputtering and spitting? It sounds sick.
I left it idol for a good little while to heat up, and still no dying, so making progress I think....
Took it for a very short ride, and I also seem to have lost speed. I was getting 24mph out of the bike, now barely 18mph.

I took a video of the motor running, throttled up, idol, etc. Motor heads can usually diagnose based on sound. That's my hope anyway.
ALSO I noticed hot air escaping from where the exhaust attaches. (Another of many issues I have with the kit I bought from thatsdax. He forgot to include exhaust hardware. I used what I had that fit, really not looking forward to replacing the gasket since one screw has darn near a stripped head.)
But... does that really effect sputtering at all? I thought the exhaust pipe was just a muffler... that the motor would run without it. Unless that's causing compression problems???

Anyway here, have a listen.
 


darwin

Well-Known Member
Joined
May 26, 2008
Messages
4,052
You need to adjust the fuel mixture screw and or clean out the black plastic idle jet located under the black plastic idle rpm adjustment screw.
 

artmaker

Active Member
Joined
Jun 12, 2008
Messages
332
Ok, I can see adjusting the screws, (there are two actually, trial and error I guess with adjusting.)
That black screw pushes the throttle bar back as if I were turning the throttle on the handlebar. Adjusting that did in fact keep the motor running when idol or stopped. The other screw I'm not sure where to put it. AIr fuel mix? I'll keep playing with that. But….

Wouldn't either of those just cause the motor to run fast or slow? Not spit and sputter?

I seriously doubt any cleaning is needed here. Again BRAND NEW carb.

Only other issue I did not mention,
I changed the gas in spring when I first started having issues with the motor. (First thing I did was drain and replace last years fuel.)
And after my two failed attempts at cleaning and putting back the carb, I bought a can of START and put the recommended amount in the gas tank thinking anything I may have missed cleaning jets it would help with.

Well it's still in the gas. I could sure drain out the old gas and try fresh. Is that a possible cause of the sputter though?


(Meanwhile…. my brand new tire is late being delivered, hoped to ride to a local event this saturday and put my old tire and old tube on, rode around just fine, be it slower than normal… came back about 5 hours later to head for this fireworks show only to find a flat. Guessing my tube finally gave out. (Got a new one, just waiting on the tire now.) So until my new tire shows up, I'm down again. Hopefully it comes soon.)

Lastly… what about the spark plug? Could that be misfiring? maybe a wire??? Or is this just a fuel/air mix issue still?
I just need some direction what to try next.
 

darwin

Well-Known Member
Joined
May 26, 2008
Messages
4,052
The fuel mixture screw is brass and is usually on the side of the carb, assuming your using an original type carb that came with the motor. Screw it in all the way, don't use a lot of force it's brass ok. Then back it out 1-1/2 turns. Let the motor warm up for a few minutes then adjust the screw in small increments to where it will increase rpms without hesitation/sputter and sounds solid. Turning the screw out/in may be needed but at 1-1/2 your close to where it needs to be.
 

curtisfox

Active Member
Joined
May 13, 2010
Messages
618
Also just because its new don't mean that it can't have gunk in the tank or carb.........Curt
 

artmaker

Active Member
Joined
Jun 12, 2008
Messages
332
HI again,
sorry for the delay, dealing with rear wheel issues... again. Got that squared away (hopefully for good.)

So back to this sick sad motor. Yes it was idling that high, I had the little black screw in kinda far just to keep it running.... pulled that out a bit.

I did screw in the brass fuel mix screw all the way, back out one and a half turns and COULD NOT start this damn thing. Tried a little throttle, nothing.
Walked across the street to my mechanic (poor guy up to his elbows changing a motor but took time to help.)
Two pulls and he starts it. WTH??????? Said he gave it a little throttle. I swear so did I.
But I thanked him, we talked about the fuel mix screw and he said this is what will take care of the sputter.

So let it warm up a bit, rode around a few blocks, stopped and tried tweaking. NOTHING is making any difference. The only way I know the screw does anything is if I screw it all the way in, at idol the motor will quit. Back out the one and a half turns and I have tried quarter turns in either direction. It just sounds sick and sad and it has lost about 10mph of power too. Even while running at top speed I can hear it misfire.


So... Next part I'm going to throw at this thing is a new plug.
Can anyone recommend one better than the stock one it comes with? Maybe hotter? Or ???? (I know little about plugs. Materials, specs etc. Willing to learn though.)

I swear... I never ever had near the issues with my old 2 stroke as I have with this piece of flaming crap. I've already replaced most of the parts on it.

Know what? I already ordered a new bike. (With built in gas tank.) NEXT YEAR I plan on having a back up bike. With a simple 2 stroke motor. Events I want to get to, I'll get to and not sit here ordering still more parts.
Really beginning to think the motor itself might just be bad. What a waste of time and money.

BTW... this is the bike I ordered. Back ordered since it's out of stock. Be my project for next summer.
https://www.bicycle-engines.com/zeda-angel-roller-v2-engine-ready-motorized-bicycle-built-in-gas-tank/
 

darwin

Well-Known Member
Joined
May 26, 2008
Messages
4,052
2carbs same issue, weird. Have you tried checking/adjusting the valves at all? There's posts vids on how to do it. Search here or on you tube. Only other thing would be maybe no key in the crankshaft key slot and it's a bit off on timing. Is the gap on your plug at .028?...………………..………………………….
 

artmaker

Active Member
Joined
Jun 12, 2008
Messages
332
2carbs same issue, weird. Have you tried checking/adjusting the valves at all? There's posts vids on how to do it. Search here or on you tube. Only other thing would be maybe no key in the crankshaft key slot and it's a bit off on timing. Is the gap on your plug at .028?...………………..………………………….

Not sure on the plug. Hate to keep pestering my mechanic but I simply don't have a socket the right size to get it out. Ill pick one up at harbor freight next time I'm out that way.

I ordered a new plug, nothing fancy just a standard 4 stroke plug.

Now... what exactly are you talking about with key in the crankshaft????? And wouldn't my car mechanic think of that? (Maybe not, not really a car thing is this?)
 

mattrgray

Member
Joined
Aug 30, 2017
Messages
103
This could be an air leak. From the sounds of it you've taken the carb off a few times and that may have weakened the gasket. Also new gaskets can shrink slightly and cause air leaks. Take your carburetor off and inspect the intake gasket and if your unsure just take some pictures. Best of luck!
 
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