Engine rpm/4 stroke/low power issues

First time builder with very little motor knowledge here.

Just got my first bike mostly finished. 48cc BGF motor, 41 tooth rear sprocket, cheap walmart bike under it, 260ish lb rider.

The problem I am having is mostly low power issue. I have almost the same power/rpm's at 3/4 throttle that I do at WOT. I think it is 4 stroking, but as I said I'm not very familiar with motors. I checked my slide needle and it came stock at the 3/5 mark. I read that raising the c-clip makes it run leaner and can get rid of the 4 stroking issue. I raised it to 2/5 and it did get rid of some of the 4 stroking. I was 4 stroking in the 4-8/10 range, but with the leaner mix it went to the 5-7/10 range. I raised it again (leaner still) and am still 4 stroking, but now in the 7/10 range.

Before I raised the clip, my idle screw had to be all the way in to keep it idling, now at the 1/5 mark it idles way high even with the screw almost falling out. I swapped the stock plug with a ngk b6hs today to try remedying it. I noticed the old plug is darker than the tan pics I see of a good running plug. Almost to the point of being black. I still have it if a picture is needed to verify.

I am currently running a 16:1 oil mix for break in. I have only put through just over 3 liters of fuel through it. I'm going to lower the oil mixture to 32:1 on the next gallon.

As far as power goes, any incline in the road at all and it just kills my power. Even the normal up and down of the road I lose 40-50% power which doesn't sound right. I talked with a local MB'r here and he can go up the canyon road towing someone else without peddling. I know the engine still needs to break in but the power is way lower than I expected. And I know not to expect miracles. The first day I rode it, I was hitting about 28 MPH on a flat road, now it seems my top speed is about 23. Something I did robbed me of power and I don't know how to fix it.

I am willing to do anything recommended. I don't have alot of money to drop into parts, so the free fixes first would be appreciated.

I recently had the baffle removed to test power differences, I just put it back on yesterday as a matter of fact. There was a power increase but it was so loud I couldn't hear myself speak. Unfortunatly my cap is "pinched" to the baffle somewhat so I either remove the whole thing or none at all.

The baffle was covered in black oil/ exhaust but it wasn't plugged up.

Elevation here is 3745 ft. I put in the 32:1 fuel this morning and replaced the spark plug wire and boot and there is a marked power difference.

I just need to figure out why i'm not getting a lot of power from 3/4 to wot. I think I'm gonna measure the float tomorrow and make sure the jet isn't plugged up.

How do you measure the jet size anyway?

I do have the nt. Maybe I'll look into modifying the air intake before I go for replacing the jet. I don't even know what size I would need to make it just lean enough.

So I did some tweaking today and got my speedo running. I checked the float height, moved the slide c-clip to 2/5, and tightened the spark plug to try getting rid of that leak. Checked that air filter/foam was clean and that main jet was not clogged. Fuel feeds just fine, so no plugs there.

My top speed on flat ground is 19.5 give or take .5 mph, 41 tooth sprocket. Throttle is feeling good from open to 3/4, but from there to wot I get no extra power/rpm's. For me that range doesn't exist, and actually slows me down about 1 mph. No more 4 stroking so I think my slide needle is in the right place.

What do I need to do to get that extra power from 3/4 to wot? Bigger jet, smaller one?

I also noticed that I seem to be drinking fuel. I topped off and reset the odometer just before I left. Did 9.1 miles and I'm already down to 3/4 -2/3 of a tank. that means I'm getting about 54 -72 mpg.

Lol, anyone live close enough to Twin Falls, Idaho want to come help me?

I measured my float today like how it was suggested to on another thread. It was set way low, about 14mm if I remember right. I moved it up to 21mm from bottom of the gasket (with gasket off of course) to top of float. That was part of my tweaking this morning so that was done before I did my speed test.

So do you mean I need a bigger sprocket for more torque to climb hills, or a smaller one for more top speed?

So I found out that a local motorcycle shop has main jets available. I pulled my jet and it is unmarked. It's from a BGF 48cc motor, does anyone know the probably jet size? I was told they had a nice assortment of jets and some in the 5mm thread size I need. Does brand really matter or are all jets "marked" the same size the same?

Someone mentioned that a 66-68 would be good, it that for my altitude or just in general? This jet is so small, I'm amazed the motor runs at all.

Hey cannonball2, how did you get a 16:1 ratio? Are you using a shift kit?

Also, I have been doing more reading and I'm not positive if I'm running rich or lean. I know that I don't need alot of choke to get it running. From a cold start, I choke it all the way, but within 2-3 blocks travel, literally, I need to have taken the choke completely off. That's a sign of too rich right? The weather is in the 40's -50's currently, does that make a difference?

If you have an engine gear of 4 tooth and a rear sprocket of 44 tooth, wouldn't that be 11:1? Not sure how your math makes it a 17.6:1.

Not trying to argue with you at all, just trying to understand it. Not to mention I have yet to see or hear of a 4 tooth engine gear.

I understand that and I actually counted mine and got a count of 10. I'm just trying to figure out how cannonball2 has such a high ratio with a 44 rear and a 4 front. Does it make sense to you?

Maybe I need a pic of cannonballs2's bike to figure it out.

I have never heard of a "primary/secondary ratio". I honestly have no idea what you are talking about with your ratios. Your 20t/80t thing is just confusing as I have no idea how you have 4 gears on a fixie bike, let alone a 80t one.

Unless you are using a shift kit, my understanding is you have 2 relevant gears. The motor gear and the rear sprocket. You divide the rear tooth count by the front tooth count and you have your ratio.

I am running a BGF 48cc motor, 10t front gear 41t rear.