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Post by prodigit on Jun 9, 2013 2:33:04 GMT -5
So the idle jet reduces fuel flow with open throttle?
I thought that opening the AF screw (run richer), could affect the main JET too, though very little.
Anyone has any idea how much the fuel ratio is, from the AF screw and main jet? (like AF screw only allows 1/10th of main jet's fuel to flow?)
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Post by prodigit on Jun 9, 2013 2:28:26 GMT -5
Rain on chinese bikes mainly makes chrome parts rust.
For that reason try to avoid as much chrome on your chinese bike as possible.
And try getting a bike with treated bolts. Most bolts and screws are plain steel, and rust like crazy.
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Post by prodigit on Jun 9, 2013 2:26:48 GMT -5
Most scooters and motorcycles get best MPG when the engine is going between 2k and 3k RPM.
Usually that means ~30-40MPH on 150+cc bikes.
At that point, there's least wind drag, and the explosion from the fuel vapor is optimally used in the cylinder. That is for long stroke engines.
Short stroke engines do better ~3-4k RPM (like sports bikes).
50cc scooters ride best between 25-30MPH, where ever the variator maxes out.
Wind drag increases exponentially, once you go past 35MPH on a wind still day. Below 35MPH, even a 50cc engine has enough power to overcome most wind drag; but at higher speeds it becomes increasingly more difficult.
That being said, my TaoTao ATM50 gets ~112-120MPG at a constant 30MPH with the engine warm, and ~103-105MPG at a constant WOT.
With start-stop it gets ~98MPG.
My BMS TBX 260 EFI got ~83MPG going 40MPH (where the variator is maxed out), and averaged at ~80MPG on my standard rides (I usually rode long distance, few stops with it).
My Honda Shadow VT750 gets ~55MPG across the board, but I changed the rear sprocket, so it won't rev up so high on the highway, and I think right now it's around ~63MPG.
I've noticed if you want ~100MPG, you got to put such a tall final gearing that the engine is barely able to accelerate.
80+MPG I only got because of EFI, but on a carbed bike, should be fine for a person riding level ground, not too much wind, not too heavy. The gearing that will be able to accelerate, but not very fast on the highway.
60MPG usually gives you reasonable fast acceleration on the final gearing, on just about any engine type save for <250cc's, which if it's a 150cc basically it accelerates fine until 50-55MPH, after which the engine displacement becomes an issue, not the gearing or MPG.
On a car it's different.
40MPG gets you a car that can accelerate, but not very rapid. 60MPG gets you a final gear of a car engine that will barely be able to accelerate in final gear. That is a regular carb'd 4cylinder car. Not speaking of Hybrids or semi-electric here.
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Post by prodigit on Jun 9, 2013 0:36:16 GMT -5
The a/f screw is more for idle adjustment than off idle. Interesting! Could you expand on that please? I was wondering why the AF screw didn't do much @ WOT on my bike. Adjusting the AF mixture screw, does not affect WOT at all? |
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Post by prodigit on Jun 9, 2013 0:26:53 GMT -5
In short: NO! In long: It depends on 2 factors, IMHO: 1- If your engine is running too lean, premium fuel can prevent pre-detonation, due to overheating, and, 2- Premium fuel can have added premium ingredients (esp BP's fuel), that has more stored energy per cc than regular fuel, causing better performance with less fuel. There is a 14.7:1 air/fuel ratio that must be kept for best performance of the scooter. If you're running lean (eg: 16.7:1), the bike's performance goes down. However, if you fill your tank with more energetic fuel, the ratio may go upto eg: 16.7:1.1 using more energetic fuel, which basically is the same as 14.7:1; as the AFR is different for different type of fuels or flammable liquids. That being said, if a CDI pre-detonates, there's nothing that premium can or will be able to improve on this. If it pre-detonates too early causing the engine to overheat, premium fuel could help even earlier predetonation, caused by the overheating of the cylinder on the compression stroke, but at that point you're destroying your scooter by allowing the CDI to detonate too early in the combustion stroke. There is a sweet spot where the spark should spark, any earlier, and most of the energy released will be lost to heat (as it's energy is released too early to press the piston down, thus it goes sideways towards the cylinder walls). If it is too late, too much of the energy is wasted as hot exhaust, as at the moment of combustion, the cylinder is already on it's way down, and whatever energy is still remnant in the hot gasses will be exited through the exhaust valves. Just some remarkable inspiration of the moment guys  |
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Post by prodigit on Jun 8, 2013 23:41:16 GMT -5
Yeah, the shifts are too soon; but the engine really doesn't have that much power.
It's power curve is below ~3.5k RPM, above that, there's no real torque improvement, which makes the bike an excellent bike for upto 30MPH.
You want to shift to 5th gear in 30, but can't (doesn't have a 5th gear).
The bike definitely needs a larger front sprocket, however, with the shifting, it can barely keep up with the cars starting from a green light.
At top speed (60MPH on the speedo; for reference 40MPH on the speedo equals ~35MPH in real life), the engine is revving too high. It definitely can use a sprocket change. I'm gonna ask if Rebelgears can make a front sprocket with 'groove lines' on the axis, like the original sprocket.
If they do, the housing can host 1T up, from the stock 15T to 16T. That's all that would fit in the housing.
Also interesting to know, for the other guy who bought a MC-05-127, it seems that the chain is eating through the rubber. If you open the front sprocket housing (2 screws behind which the front sprocket is), after riding it a bit, you'll notice a lot of black debris. This is the protection rubber. Once that's gone, the chain will eat through the rear fork (which is really bad)!
So instead on getting lower on the rear sprocket, I'm going to up the front sprocket by 1T!
The fuel addition wasn't paint thinner, but Chemtool B12.
I fueled up with Shell Premium fuel, after the bike stalled when the tank had 20% gasoline in it.
Lucky it stalled right in front of a gas station!
Seemingly a fuel issue, the carb doesn't suck enough fuel. As soon as I filled her up, she fired up again (more fuel flow from the tank).
The jets are too lean. I still ride with the choke 25% open, as the bike seems to perform best at that point.
Perhaps I could drill out the main jet some, but then I'd need a bigger main jet needle, which I don't yet have.
I don't know the carburetor well enough to be drilling out, or replacing the jets.
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Post by prodigit on Jun 8, 2013 2:50:53 GMT -5
There's a lot you can do with the AF screw.
In most conditions you can optimize fuel flow, for the most part with the AF screw.
If it runs perfect at idle, but lean at WOT, you can make it run a bit richer at idle (less good idling), but running better over the rev range.
Just at WOT, if your main jet is too small, it will run a bit lean. You could compensate with a choke (if you have it)..
Any of the experts want to comment on compensating a lean running bike by opening the choke a bit (reducing the airflow a bit), until the bike reaches better performance?
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Post by prodigit on Jun 8, 2013 2:41:48 GMT -5
Did you adjusted the valve clearance?
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Post by prodigit on Jun 8, 2013 1:41:00 GMT -5
5w isn't thin. God only knows who wrote those specs and if they knew why they did it. I don't know that I have ever even seen 5w40 oil... Who knows what the engine number means as well could be anything... The manual says to put 10W30 oil in. Since it lubricates both engine and gears I think it's wiser to go with heavier oil. 10W40 is your stock Hot South Florida weather oil. I'm gonna start with my special mix of 10W30 and 15W40 in this baby, see how that goes. time for the first oil change. Did 58km, or 36 mi. Seems like I was right on the bat on this info, performs as I had estimated. |
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Post by prodigit on Jun 8, 2013 1:34:55 GMT -5
I think one of the best upgrades to do is replace the non electric fuel pump with a electric fuel pump that comes with a micro fuel filter. Only 40 bucks to do. It uses a Mikuni carburetor, which does not use a fuel pump. Seems to work fine though! |
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Post by prodigit on Jun 8, 2013 1:25:06 GMT -5
Downshifting 2 gears in the rain may cause the wheel to lock up.
I've had it happen, momentarily; lucky it was a small lockup, until the engine revved up high enough to have the wheel grip.
Another reason to only downshift at very low RPM's.
When RPM's go below ~1200 in second gear, the clutch disengages. You can start from a standstill in 2nd gear, but feel the clutch gripping. A good way to wear it out, so I recommend you not to do it.
When changing gears you can't make the clutch grip slowly by moving the pedal slower. It grips immediately, making the transmission somewhat jerky.
The engine does not rev up very fast, so down shifting in higher rpm is hard, and revving up the throttle as you downshift (eg: from 4 to 3, or 3 to 2nd gear) is not easy at all, and does not work very well.
To change gears on a motorcycle usually you need to push the pedal about 1in with the foot. On this motorcycle you need to push it 3in, which makes it additionally very hard to shift gears. (since the first 2 in is basically the clutch engaging)
It's easy to shift forwards, but I can't shift backwards easily.
I would have preferred to have a push/pull gear shift system, than a push/push (toe/heel) system. The heel system does not work very well at all. Engineers could make it work, by just making the lever more adjustable.
You can tune it a bit, but if you're tall, a person being only 5in shorter might not be able to ride the bike without re-adjusting the pedal.
The rider's foot pegs are very small, often my shoes are only touching the pegs by 1 or 2 in. The brake or shift pedals are in the way to comfortably rest the foot on the pedal.
And the license plate holder is not conform to the size of Florida motorcycle license TAGs.
I literally have to bend the plate a bit to fit.
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Post by prodigit on Jun 8, 2013 1:08:14 GMT -5
Concerning the piece you have, I don't know if it's meant to be on the side of the sprocket or the other side. I'm still looking into that, but I believe it supposed to be on the right side (opposite of the sprocket).
Though I gotta look into it again, to make sure.
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Post by prodigit on Jun 8, 2013 1:03:43 GMT -5
One of the big rollers goes on the side of the disc brake!
Lucky I caught it on time!
It could warp and damage the disc and braking system not to have it there.
It should fit in the rubber, and seal off the axis from dust entering, as well as keeping the right distance between disc and fork.
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Post by prodigit on Jun 7, 2013 23:48:16 GMT -5
What?
You have 2 rollers for the rear?
I only have 1 roller!
The other roller is for the front wheel.
If you have 2 rollers, use them both. I only have one roller and that piece you're holding.
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Post by prodigit on Jun 7, 2013 17:58:31 GMT -5
I don't know why you say to make it look correct. The piece fits perfectly in place. When you tighten the axle with the nut, the rear fork will come somewhat together, close the gap difference. Well, I just done my first 50km, initial impressions: 1- The first gear is pretty small; fast acceleration, jerky take off, and slow down 2- The first 4 gears are engaged within 20-25MPH. after that speed, you're basically running in 4th gear all the way until engine revs max. I'm missing a 5th gear, but not sure if the engine will pull it 3- Top speed so far is ~63MPH on the speedo, speedo is at least 5MPH off, so I guess 55MPH. It's still the breakin so I didn't go all out. 40MPH on speedo = ~35MPH roughly estimated on a few side speed meters. 4- It seems that the engine runs best ~30-35MPH, beyond that and RPM's go up beyond 3k RPM roughly estimated. For that reason I want another gear, but the engine barely is able to accelerate past 50MPH in 4th gear. Still, it has plenty of power from 25-50MPH, so I'm going to do the rear sprocket change. Since it's easier to do a rear sprocket change than a front one (don't find any place where they make them). Besides, the engine doesn't have enough power to be doing too big of a sprocket change anyway. Changing the front sprocket to 1t more would be awesome, but the rear sprocket can be changed from the stock 40T, all the way down to 35T. Stock sprocket:  Because the rear sprocket is even, I presume that the front sprocket will be odd (15T most likely), so I'd go no lower than 36T. 36T is a 10% difference (possibly in speed and MPG, but also slower acceleration in final gear). I'm gonna order a 36T rear sprocket, just to be able to ride more comfortably in the city at lower RPM's (getting an even better MPG). A front and rear sprocket change would be best, but I don't think the engine has got the power to be able to do that. A smaller rear sprocket results also in a less jerky takeoff. Other impressions: - The transmission really suffers when riding. It does not have a very good working clutch. Usually as soon as you shift gears (up), it will engage. However if you shift down, the engine has very little time to rev up to the higher RPMs. I believe it is therefor best to be lazy in downshifting (tardy downshifts); meaning downshift only when RPM's are very low, or shift as soon as you're almost standing still (speeds below 5MPH). - Keep the bike's idle very low (800-1000RPM). It will help the clutch from disengaging the bike, so you won't get into trouble at a stop (with the engine's high idle trying to keep you in gear). - ~900RPM (roughly estimated, one of my pet peeves is that the bike doesn't have a tach, even though it's a manual geared bike) the exhaust pipe/muffler oscillates with the exhaust thuds. So exactly on the perfect idle, I feel it oscillates, so I can either go below, or above that idle (I put the idle slightly higher ~1000-1100 RPM I believe). |
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