4 stroking help please?

[benger83]

i have a skyhawk gt5 66cc with cns carb . i have the oversized billet intake with after market air filter. bike runs great up to about 25 mph then starts to "4 stroke" on and off . my spark plug looks text book coco color and everything is tightened down nicely. it never did this till recently when i put a new carb on (last one broke) . acceleration is good but no top speed without serious vibrations. also should i be greasing up anything with some serious grease like the drive sprocket?


for you guys who are on here helping all the time thank you for the help its appreciated !

 

[stickerbush]

Can someone please explain what 4-stroking is? I've seen this mentioned several times in the forums but am not able to find a definition for what it is, why it happens, and how you know it is happening.

 

[Venice Motor Bikes]

4-stroking is kind of a 'sputtering' feeling in the engine at full throttle... It's because the air/ fuel mixture is a little rich.
It's usually fixable by simply installing a smaller jet in the carb.

 

[GearNut]

About every 100 miles or so, put a pea sized blob of good quality grease in the transmission gears, right where they mesh together. Don't worry about spreading it around on the gear teeth, it will do that all by itself.
Grease the bucking bar and the bearing behind it. (shaft and ball that are inside the engine sprocket shaft) You sometimes need a small diameter magnet to get the ball out.
Grease the release cam that fits down into the sprocket cover. Turn it backwards while gently pulling it out of the hole and when the flat on it lines up with the retaining pin it will slip out. Do the reverse to re-install it.
Clean, inspect and grease your wheel bearings on both wheels about every 500 miles.
Use chain lube to lubricate the drive chain every 100 miles or sooner if it looks like it needs it.

4-stroking on a 2-stroke engine:
‪What is "four stroking" ?‬‏ - YouTube

 

[stickerbush]

4-stroking is kind of a 'sputtering' feeling in the engine at full throttle... It's because the air/ fuel mixture is a little rich.
It's usually fixable by simply installing a smaller jet in the carb.

Thanks for the enlightenment on 4 stroking. My engine is also 4 stroking, identical situation as benger83 described in the original post for this thread. Running great at mid throttle but above that, it moves in and out of 4 stroking behavior. I've set the needle at the next to richest level (it came totally leaned out and would hardly run). I will try the next leaner notch next and see what happens.

 

[benger83]

hey thanks gearnut and VMB! (stickerbush) i heard that 4 stroking is when the piston fires twice instead of one correct fire. but i dont know i just know the motor will sound real good then it will literally sound like it is firing twice as fast on and off.


so should i move the c clip on the carb needle? will that help?

 

[GearNut]

Adjusting the needle clip affects 1/8 (just off idle) to 3/4 throttle.
The main fuel jet affects 3/4 throttle to full throttle.
At what throttle position does your engine act up?

 

[pedla]

I am still trying to figure out the 4 stroke thing. But yes youi should grease the main drive sprocket,often. It will make bike less noisy and let it carry on for longer.

 

[pedla]

AttnAleman. My Chinese wife is going to Ninja you and she will take pleasure in breaking your heart. Treat your((Chinagirl}with respect It will last. Hope your next fortune cookie
says; That was not Chicken.

 

[Greg58]

The best way to tell what four stroking sounds like is this. your bike sounds like a small dirt bike engine when riding then the engine starts sounding kinda like a lawn mower.