why so slow?

Thank you Dan. Ive been away a couple days but still riding. Still the same. No more pebble noises, that was from a loose chain. But, Ill get up to 20mph and it wont go any faster. Its pretty aggravating. I will get a smaller rear sprocket soon. I still feel like it should move faster than 20 the way it is tho.
 
20MPH is to little, IMVHO. Just a thunk but are the brakes fully disengaged?

Don't laugh, I've done it.

Also, very often a bunch of little things can contribute to a problem. But is a good idea to make any changes one at a time so ya really know the culprits.

But as said, the break-in will help. Would check the big 3, though. Fuel, air and spark. Lots of great information through the search feature above. Cool part of just slogging through threads and posts is stuff will come up that is yet unconsidered and comes in real handy at some point. That and is kind of fun to see the many approaches and work arounds.
 
Try making a lap around the block without the air filter, see if that's restricting airflow. If so, you need a free-er breathing air filter. I had that problem with a "High Performance" carb kit, came with a bad filter. Wouldn't rev up high, limited my top speed.
 
Just to rule out the obvious, have you taken the air filter off and looked at the barrel move up in the carb when you turn the throttle?

Does it go all the way up?

Slack in the cable won't let it.
 
so I took the carb off, took out the slack in the cable, took a link out of the chain to make the alignment and I still can only get up to 20. after 20mph it seems like the revs go away. ill give it gas but it doesn't take it. this is soooooo frustrating.
 
pedalurassoff said:
It goes all the way up but it doesn't fully close. Is that normal?
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It closes to where it hits the idle screw.
A good throttle setup is one that gives you full open throttle, and when you let of it snaps back closed against the idle screw with an auditable a click but that's not your problem.

Have you put an NGK Iridium plug in yet?
 
I figuerd that about the screw. No new plug yet. Ill order one. I think this is just as far as my motor goes without changing the sprocket. Oh well.
 
Perhaps I overlooked it, But do you have a 49cc by chance, If so 25 or 30mph is probably about right. My 66/80cc hits close to 40mph. BUT it took a while to get everything dialed in just right.
fatdaddy
And OH YEAH The ngk B6hs plug is a great all round plug.
 
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fatdaddy said:
My 66/80cc hits close to 40mph.
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Curious: your weight? Sprocket size? Wheel diameter? My rig (witj me and my backpack on it) weighs about 400-lbs. I have a 66 on a 29er with a 44T sprocket and JUST hit 30 at what I consider a safe maximum RPM.
 
I'd spend some time listening carefully to your engine as it reaches 20 mph. Is it actually running smoothly or is it 'four-stroking'? When two strokes hit walls in their power band it's usually from one of two things: improper carburetor mixture, or a blocked or improperly installed exhaust system.

You should make sure it's not four-stroking heavily at maximum speed, and start using way less oil. Most of these engines can get away with 30:1 or even less with quality oil. The 16:1 recommended will surely kill your engine given time, as it's like running an extremely lean main jet, except you won't get the benefit of getting a proper plug reading, because the excess oil will darken the plug.
 
Kioshk said:
Curious: your weight? Sprocket size? Wheel diameter? My rig (witj me and my backpack on it) weighs about 400-lbs. I have a 66 on a 29er with a 44T sprocket and JUST hit 30 at what I consider a safe maximum RPM.
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So who said anything about SAFE brother HAHA. If ya got it dialed in pretty good you can make a China girl SING. I dont recomend holding it WOT all day long, but I gotta know what my girl can do. There's a couple places in town where the speed limit is 45mph and I (almost) keep up with traffic. I've also had more than only one car clock me. Uphill and against the wind is a different story.
fatdaddy.usflg
 
Hi guys i'am new to all this put if you need a strong motor you to get a screaming roo from Australia bolt it in and ride like you stole it. All day you can sit on 7500 not a problem i can get up to 8900 pulls hard with next to no vibs. They scream for rev's.
 
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