Runnin' rough:

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Allen_Wrench

Allen_Wrench

Resident Mad Scientist
Feb 6, 2010
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Not much time to type. No internet at home right now, doin' it from work. Got a question tho':
Was cruisin along, keepin' her at around 15 mph cause I'm still breakin' in, and (like a dolt) I ran out of gas. Seems I fouled the plug as well. Nice coat of varnish.
Filled her up with pre-mix at 32 to 1, cleaned plug as best I could. Runs rough, doesn't idle well, no power. Will be putting in a new NGK plug. Engine is a DAX 66cc. Plug was stock.
How does one avoid fouling plugs? Better yet, what all causes plugs to foul on two-strokes?
 
Norman

Norman

LORD VADER Moderator
Jan 16, 2008
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32 to 1 mix is fine.
things that can cause the spark plug to fowl.
plug gap too wide.
idling engine to much or not getting engine up to operating temp.
weak ignition.
clogged air breather or partly clogged.
ignition leak not good and tight on spark plug or cdi box.
leaded gas.
plug heat range not hot enough.
buying an expensive spark plug with trick electrodes, 2 strokes like these tend to eat plugs so a cheap spark plug with the right heat range and proper gap will be your best bet and keep a spare plug handy.
try a different brand of regular gas and maybe a different brand of 2 stroke oil.
run a paper fuel filter it will keep the nastys out of the carb.
run the bike a little harder to get the spark plug hot so it will burn off the carbon on the electrode.
the list can go on and on.
 
W

wildemere

New Member
Feb 12, 2008
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Cheap oil or motor oil will foul plugs.

I haven't fouled a plug since I ran motor oil in my Victa 20 years ago.

Modern 2 stroke oil is anti fouling.

Get a NGK BP6HS and some good name brand motocycle oil.
 
Allen_Wrench

Allen_Wrench

Resident Mad Scientist
Feb 6, 2010
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Thanks again Norm. I just went ahead and swapped out the original Chinese plug for an NGK 3212. It seems to amke a noticeable difference. Runs much better.
But now she's doing something else strange: once she's all warmed up, if I back the throttle all the way back down she dies. Not a big issue, mind you, but it creeps up on me. Then I have to re-start and keep an eye on my revs. I wonder if it's my idle setting? The new plug is gapped at approximately .30 and the engine is a Dax 66 cc, 38t rear sprocket, 32 to 1 mix with 92 octane. I also wonder if my throttle cable is still stretching, I'll have to check that.
 
ruppster

ruppster

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Mar 3, 2010
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Make sure your throttle cable isn't backing off the adjuster nuts. All I can say from my limited experience with these kits is loc-tite is your friend. Try moving the needle clip up one notch if you still fouls plugs. It sounds like your running rich.
 
Norman

Norman

LORD VADER Moderator
Jan 16, 2008
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you can play with the idle speed it won't hurt a thing. On my bike when its cold it doesn't want to idle once its warmed up it idles fine. I adjust it to suit the day or night when I'm out ridding.
I think your gap on the spark plug is 0.030 you wrote its .30 if you can try a smaller gap see it it helps. I run any where from 0.017 to 0.020.
things are probably wearing in so stuff will get slack, like the throttle cable, clutch cable ,and the chain.
You can also go to regular gas the cheapest low grade it burns faster and will work better than the higher grades of gas. If you run the higher grade of gas in these low compression engines the stuff is still burning as it goes out the exhaust port so your wasting energy.
 
Allen_Wrench

Allen_Wrench

Resident Mad Scientist
Feb 6, 2010
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Thanks folks. It's been a while since I tinkered with these two-strokes, so I'm re-learning a few things. First of all: Norm, your assumtion was correct. I meant to write that the plug was gapped at .030, not .30. I lost my zero somewhere back there.
But my loss of power after warm-up turned out to be a combination of things. I did find a bit of slack in my throttle cable again. I think switching to a lower octane will also help. But I also noticed at the end of a run that my choke had gone part-way closed. The screw that holds it is not as tight as it was in the beginning. What I believe to be happening is, as I bump and vibrate along, the internal baffle :confused: being a hair heavier than the external lever, is beginning to slowly close off the carburator. That's how I found it. I'll have to tighten that little lever. Yet another thing to check when the bike starts acting up.
 
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