Rough Riding at lower speeds

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Mopedamauter79

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Mar 31, 2008
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For some reason now in the last couple days only it's riding rough from 15 kph - 30 kph. Once It goes past 30kph it's smooths out and rides normally.. I checked everything and the engine does not appear to be loose and everything looks normal.
 

Pablo

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Dec 28, 2007
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It could be a number of things, but since it's running fine at high RPM's I think it must be fuel. I think you are past the break in stage, right?

If so, it could just be running rich. I would say run it hard for awhile, until it's good and hot. Then run full throttle for a minute of so on the way home, shut it off and glide in. Allow the engine to cool and look at the plug. Report back. Black dry/wet plug? Light tan? Glazed?
 

Mopedamauter79

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Mar 31, 2008
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I took the spark plug cap off and looked at the spark plug and it looks normal to me. I don't have the tool to remove it and look at the end going into to the engine. What socket would do this ?
 

Pablo

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Dec 28, 2007
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I took the spark plug cap off and looked at the spark plug and it looks normal to me. I don't have the tool to remove it and look at the end going into to the engine. What socket would do this ?
Not sure what to say. You'll need to look at the business end.

A spark plug socket (13/16"). One lousy one comes with the engine kit.
 

Bikeguy Joe

Godfather of Motorized Bicycles
Jan 8, 2008
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Yep, the tool that comes with the kit will do it. Once you get it out, it should be from a chocolate brown to a (lightly) oily black.

If you've run the stock plug for awhile, you may just need a new one.
SPARK PLUG CROSS REFERENCE

About 3/4 of the way down, you'll see the NGK B5HS, or any of it's equivalent plugs....buy one from a mower shop, motorcycle store, or even SBP has them.
 

Mopedamauter79

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Mar 31, 2008
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Yep, the tool that comes with the kit will do it. Once you get it out, it should be from a chocolate brown to a (lightly) oily black.

If you've run the stock plug for awhile, you may just need a new one.
SPARK PLUG CROSS REFERENCE

About 3/4 of the way down, you'll see the NGK B5HS, or any of it's equivalent plugs....buy one from a mower shop, motorcycle store, or even SBP has them.
Well lucky for me I ordered one from Pablo. I have the b6 version of spark plug. I will go to Canadian Tire and see if I can find that deep socket. I will take to carb cover off and clean out the air filter again and see if that helps. The spark is only a few months old so I don't think it would be time to replace one already but then again I have started it up alot under pretty cold temp. Who knows. I'm still learning about these engines. I have learned quite abit from when I first got one.
 

Mopedamauter79

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Mar 31, 2008
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UPDATE: I found the exact kinda of spark plug I needed at Canadian tire today. I also got a device made for removing spark plug's. It's called a spark plug tool and it's 13/16.

Waiting for the engine to cool down and then I will check the plug and post my findings.
 

Mopedamauter79

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Mar 31, 2008
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I got the spark plug out and I put in a new one just for the sake of it. Anyway this is what the spark plug looks like that I pulled from the engine.

 

Mopedamauter79

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Mar 31, 2008
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It seems to be runing better with the new spark plug. I think the mix could be to rich to as it seems it's not burning everything up compelty.

Now that the warmer weather is coming I want to put a smaller back sprocket on the wheel. I have a 48 tooth on it and I want to put a 44tooth on. How much of a speed gain would I get.

Also could my sprocket not be 100% aligned ? when I look @ the back wheel when I'm moving it has a slight back and forth wobble to it. Nothing extreme of course.
 

MB-Monkey

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Nov 19, 2008
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i slight side to side is ok its the up and down that stresses the chain and pops it off the sprocket. Your mix is important as is the E-clip setting after break in crappy running at low rpm would seem to be a rich mix issue but you would need to do like the guys said again now and run it hard for a while run WOT for a couple min close to somewhere you can let the motor cool off and check the new plug. if it is oily and rich move the e-clip up one (the e-clip is attached to the needle accessible thru the top of the carb where the cable comes out. My 66cc huffy was doing the same thing until i leaned out the motor i went thru 3 plugs in about 500km before i got it right.
 

Mopedamauter79

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Mar 31, 2008
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Yeah but I always run it hard. I'm usually pushing it very close to it's max. I can't figure out how to move that clip piece up the needle or down without breaking the clip..pliers?
 

MB-Monkey

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i would recommend taking the assembly apart by sliding the spring out of the slide and removing the sliver slotted disk then you can have the needle in your hand a small needle nose pliers will remove it from the pin move it up one notch and reassemble make sure you hold onto the spring as it may go flying
 

Mopedamauter79

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Mar 31, 2008
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I had the entire thing apart and I could not get the clip up but then again I didn't try with pliers. Is there a chance I would not have to shorten the chain for a 44 tooth sprocket ?
 

Mopedamauter79

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Mar 31, 2008
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It's close to the top and I think I might be able to make up for the extra slack by pushing the pully closer to the back wheel. I need a new one anyway it's jiggles back and forth and that could be making the chain go from side to side alittle on the sprocket.

The throttle cable going into the carb. Moving the cable up more does what exactly ?
 
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Bikeguy Joe

Godfather of Motorized Bicycles
Jan 8, 2008
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The clip slides off the needle with a sideways push, I don't even use pliers, just set it on the workbench (open side down) and push the needle down sideways.
 

Mopedamauter79

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Mar 31, 2008
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Ottawa
Could the type of Oil be affecting the bike and making it run rough. I have this synthetic 2 stroke oil I'm using and I'm wondering if I should use actual oil made for 2 strokes engines.