2/stroke is 4/stroking?

[geebt48cc]

Hey there,

See, motor (Skyhawk 48cc 2/stroke) is doing everything right, but after about 1/2 throttle it starts 4 stroking. I'm doing every possible to watch for any air leak locations?..............but still???? (Maybe I need to take carb apart?) 25/1 mix,autolite plug 4093,Gap 020,new plug wire on CDI, and I've had C-Cip in all positions-leaving it in second from top)) Total miles is only about 200.

Thanks, ideas are appreciated. (See, when running normal, it would run over 30+ )

 

[GearNut]

A 2-stroke engine will 4 stroke when the air/ fuel ratio is too rich.
Try raising the needle clip one groove (away from the pointy end) and see if it helps.

 

[AussieSteve]

geeb, I would have suggested that you might need a smaller main jet, especially since the problem occurs only above half-throttle, but since it was running OK previously, it might turn out to be another problem besides the mixture.
As Gearnut said, raise the clip to the top and see if it improves the situation, for starters.

What colour is the plug?
Not familiar with an Autolite 4093. Is it equivalent to an NGK B6HS?
If not, I'd get a B6HS if I were you.

 

[geebt48cc]

4/stroking

Thanks Steve.......

One thing that could be a problem is that I took off the new plastic cover (Red) on carb. I'm just using the filter w/small black round holder for carb. Wow, does it ever get the air, but it didn't 4/stroke till I did this? It still does same 4 stroking with original plug anyway.

So, do you think taking that cover off has anything to do with it? (Still has filter.......just took the RED COVER off of filter.

This Autolite 4093 plug, was the cross from the NGK B6HS that I tried to get.

 

[a/c man]

It's still running too rich.
Move the clip up to the top position, dropping the needle all the way down.
If it's 4 stroking at full throttle your main jet is too big.
Most stock main jets run rich, mine did. Even with a performance filter and expansion chamber.

 

[geebt48cc]

2/stroke to 4/stroking

Also, I just wanted to say I've never seen this motor smoke at all, but the plug is half & half/some lighter (25:1 mix). So, I'm really not sure about it being to lean?

I've tried all positions on needle, and second from top works the best, but only to about 1/2 to 3/4 throttle. Also, it really takes very weak ,slow RPM's but idles well, and runs ok till I get to about 15mph.............then 4/stroke time without power.

?? (It has new style muffler thats solid state) Motor acts like it's restricted or something......(Low RPM's leading to the 4/stroking?)

Hey, TY

 

[GearNut]

That sounds like a clogged muffler.

 

[AussieSteve]

Also, I just wanted to say I've never seen this motor smoke at all, but the plug is half & half/some lighter (25:1 mix). So, I'm really not sure about it being to lean?

What colour is half & half/some lighter ?
ie White, grey, tan, chocolate, black? (Mine hardly smokes too, running 20:1.)

I've tried all positions on needle, and second from top works the best, but only to about 1/2 to 3/4 throttle. Also, it really takes very weak ,slow RPM's but idles well, and runs ok till I get to about 15mph.............then 4/stroke time without power.

The needle only has an effect up to ½ to ¾ throttle. After that the main jet takes over. This symptom is a sign that the main jet is possibly too large.

?? (It has new style muffler thats solid state) Motor acts like it's restricted or something......(Low RPM's leading to the 4/stroking?)

Maybe the muffler is clogged as well. (Solid State Muffler?) Is there a screw in the end?


What I would do is a WOT plug chop, with a new plug. At this point, anything else verges on guesswork.
Take a look at the plug pic in 'NT Carb Tuning Basics', then let us know if your's is lighter or darker.

Not sure about the red plastic cover. My carb doesn't have one. Post a pic.

 

[geebt48cc]

Yes Steve, the muffler has one screw in the bottom.....................What happens when I take screw out? Will then muffler come apart? See, all the seams on muffler look in everyway to be sealed. ???? I bought this past Dec 09..

TY I'll get a picture on here..............

 

[geebt48cc]

http://www.motoredbikes.com/attachment.php?attachmentid=26887&stc=1&d=1277612885

Steve, not the best, but you can see all stock.