New Engine Misfires Every Stroke

dan428 · Aug 22, 2012

I just finished building my bike.. tons of frustrations due to mismatched and defective parts in the kit.. and also the chain.. but I won't get into that.

I started up the engine for the first time, and it seems to be constantly misfiring about every other stroke. I thought maybe I mixed in too much oil into the gas, so I tried to add more gas to the mixture.. ran it for a while hoping to burn off the gas in the tube. Ran it for 10 minutes or so and didn't seem to have any effect.. assuming it did get through the old gas mixture (I think it did).

It simply makes the popping sound constantly and I can see white smoke shooting out the exhaust with force when it happens. Even when I rev it up, the misfiring continues. Power is pretty low and there's a jerking, uneven power as it happens. Starts up fine. It stalls if I apply the choke (runs better with open). It has stalled while idling as well since I put the new gas mixture in..

Any idea of what's happening? I don't want to ruin the motor by running it like this too much..

dan428 · Aug 23, 2012

I have realized after looking at the bottle of oil I used to mix the gas that I did put too much oil in.. so hopefully that's the only reason the engine is having some issues.

I accidentally put 12oz of oil to a gallon rather than 8.. so it was something like a 10:1 ratio rather than the 16:1 recommended breakin period. Could this be the reason for the hard smoky running?

MotorBicycleRacing · Aug 23, 2012

dan428 said:
I have realized after looking at the bottle of oil I used to mix the gas that I did put too much oil in.. so hopefully that's the only reason the engine is having some issues.

I accidentally put 12oz of oil to a gallon rather than 8.. so it was something like a 10:1 ratio rather than the 16:1 recommended breakin period. Could this be the reason for the hard smoky running?

16 to 1 is bad info from China that never gets corrected.
8 oz of oil is way too much!

start out with 6 oz oil to a gallon
then go down to 4 oz oil which is 32 : 1 ratio.

dan428 · Aug 23, 2012

MotorBicycleRacing said:
16 to 1 is bad info from China that never gets corrected.
8 oz of oil is way too much!

start out with 6 oz oil to a gallon
then go down to 4 oz oil which is 32 : 1 ratio.

hm, I added more gas to the tank, and it seemed to run worse after that.. very rough and it stalls out now after running for a minute.

not sure what to do.. I changed the needle position of the throttle.. first to the top notch -- seemed to run ok but wouldn't throttle up properly.. now i have it at the 2nd to bottom notch.

tightened the carb.. some gas was leaking out one of the screws. it's obviously a simple engine but I'm not sure what's causing my issue. I had my bets on the too much oil idea, but not sure it's panning out.

any more ideas? maybe the spark plug is 'fouled up' from the oil? should I take it out and try to clean it? :s

BigBlue · Aug 23, 2012

dan428 said:
any more ideas? maybe the spark plug is 'fouled up' from the oil? should I take it out and try to clean it? :s

That might be a good start.

Chris
AKA: BigBlue

Bikeguy Joe · Aug 23, 2012

If you are already four stroking, adding more gas to the gas/oil mix will make the problem worse.

Mix a fresh batch of fuel at 36:1 and get rid of the old stuff, from the tank too.

THEN, after you have a correct baseline, start with the clip second from the top. Use a new plug as well.

If after that, it's still four stroking, go to the top notch with the clip.

If after that, it's still four stroking, you may need to adjust your float so it sits SLIGHTLY lower.

If after that, it STILL four strokes, you'll have to go to a smaller jet, or solder the one you have closed, and re-drill.

There are a few threads on that, so do a search when/if you get to that point.

2door · Aug 23, 2012

Like Joe said, but DO NOT try mixing your fuel in the tank. Mix the fuel/oil in a seperate container then shake the container before filling the fuel tank.
Empty that stuff you have in the tank now and get rid of it. I can only guess what ratio you might have by trying to "add gasoline" to the mix you already had.

Tom

dan428 · Aug 24, 2012

I'm not sure what to do with the old gas/oil mixture.. I don't have anywhere I can dispose of it. The tank doesn't have much gas in it because I purposely left it low, but the gas container is a full gallon.

I took out the spark plug, and it was drenched in oil.. i cleaned it and ran it a bit today after moving needle notch to 2nd position.. seemed to run a bit better in that it didn't stall as much and had some power.

I said "4-stroke", because it seemed that word was being used as synonymous to 'misfire'.. but I've since found it's not quite the same thing. the engine is not quite 4-stroking.. but it is still misfiring. it runs smoothly only when spinning down after throttling and letting up to slow down while riding.

there seems to be oil around the spark plug after my most recent run after I reinstalled it.. maybe leaking or I didn't tighten it enough? i'll take apart the carb tomorrow..

i've also read that these engines are expected to run rough at first.. so should I just run it like this and hope it fixes itself after a few tanks?

Bikeguy Joe · Aug 24, 2012

"Running smoothly when spinning down" indicates that under load it's missing badly.

I am still betting it's four stroking, especially with the fuel mix/tuning techniques you've described.

P.S., you can pour the old gas mix in a mower, tractor or other. Most (all that I've ever seen) will run fine on two stroke mix, especially if you pour it into a tank that already has gas in it.

dodge dude94 · Aug 24, 2012

I would yank the air cleaner and see how it runs. If it is rich it will run better since there is obviously more air being introduced via the carb..

2door · Aug 24, 2012

Pour the unused fuel in your car's fuel tank. The car won't mind it at all because it will be so diluted.

To answer your question. Yes, just run it a little. The Chinese 2 stroke is notorious for slow break-in. They continue to run better the more miles they accrue. You still might be a little oil rich. I'd put a new plug in it and check the plug color after a couple of tanks of fuel have been burned.

Don't run it long without some kind of air filter. Unless the filter is extremely oil soaked and dirty, removing it will not increase performance.

Tom

dan428 · Aug 24, 2012

dodge dude94 said:
I would yank the air cleaner and see how it runs. If it is rich it will run better since there is obviously more air being introduced via the carb..

i actually did run it without the filter on earlier.. that's when I realized it doesn't run well with choke enabled. other than that.. I don't think it affected it much. I was thinking about taking off the muffler though in case that's causing problems.

the only extra plugs I have are the used ones (still perfect condition) from my car.. they aren't compatible are they?

dan428 · Aug 24, 2012

alright I rode it for the first 'extended' period today (~5mi) after some minor adjustments.. it didn't really have any major issues, but you're right 'bikeguy joe', it definitely is 4-stroking at times as I listened for it while riding.

The biggest issue was that I stalled out at one point and was unable to start.. then realized the fuel wasn't going through the line. I think my tank isn't venting properly.. i opened the cap and fuel started flowing again.

the misfiring almost makes it sound like a mini harley.. the power is actually quite good now.. much better than earlier.

I have a 50-tooth sprocket on it because it was the only one I found which was designed to fit over the coaster brake on my bike. I was able to easily reach about 25mph on it according to GPS.. which is about what I expected so I suppose it isn't running all that bad right? it might go quicker since the tires are very low and I didn't run it full throttle for long because its still in break in period.

anyway.. still considering disassembling the carb but I also feel like it's running well enough that I should just run it like this and hope it smooths out over time.

maniac57 · Aug 27, 2012

dan428 said:
alright I rode it for the first 'extended' period today (~5mi) after some minor adjustments.. it didn't really have any major issues, but you're right 'bikeguy joe', it definitely is 4-stroking at times as I listened for it while riding.

The biggest issue was that I stalled out at one point and was unable to start.. then realized the fuel wasn't going through the line. I think my tank isn't venting properly.. i opened the cap and fuel started flowing again.

the misfiring almost makes it sound like a mini harley.. the power is actually quite good now.. much better than earlier.

I have a 50-tooth sprocket on it because it was the only one I found which was designed to fit over the coaster brake on my bike. I was able to easily reach about 25mph on it according to GPS.. which is about what I expected so I suppose it isn't running all that bad right? it might go quicker since the tires are very low and I didn't run it full throttle for long because its still in break in period.

anyway.. still considering disassembling the carb but I also feel like it's running well enough that I should just run it like this and hope it smooths out over time.

I took a small nail and poked a hole in the center of the gas cap from this same problem. No issues since and the gas only leaks when overfull.

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New Engine Misfires Every Stroke

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