My Roketa MC54-250B Experiences at 13,200 miles

[scooterollie]

Agreed! Spare fuses should be included in our tool kit. I recently added spares to mine. Probably one of these improperly rated Chinese fuses! Wonder if it has any lead in it? Don't chew on it! (LOL)

[fufu2wheel]

I stopped putting spare fuses along with the tool kit after breaking all of the bus fuses inside the tool kit when I need them.. bus fuses are not very durable when you put them along side of metal tools and spare spark plug..

The fuse holder on my scooter has room for an extra spare fuse, that's where I keep the spare now, some other "fragile" spare items I put them in a ziploc bag with paper towls and latex gloves in the glovebox of my scoot.

[scooterollie]

The fuses on my linhai are not the glass type, no chance of breakage there. One spare for me won't do it as I have fuses of three different values in the fuse block. If you do have the glass type, keep some in the little tin they come in.

[12string]

That's me, I keep mine in the "tin they come in. Great storage container.

[earlwb]

yeah I keep the fuses in their little containers too. In my case the fuse element simply broke, it did not melt. it has a neat little micro sized fracture running all the way through one portion of the element. You have to look at it with a magnifier to see the crack. Anyway that was interesting.

The tripmeter finally quit working at about 5946 miles. I reset the tripmeter at the gas station and that was the end of it then.

At about 5914 miles the rear trunk latch fell off, forever lost somehere on the roads someplace, never to be found again. It is amazing how quiet the trunk box is with a bungie cord strung out over the top.

Well my scooter made it over 6000 miles yesterday. I am past that point now.

A odd thing happened at about 5993 miles. There was a fairly stiff headwind going home, and I was trying to maintain speed up this hill leading to the DFW airport freeway overpass on Airfield Drive, when at about 1/2 way up the hill the scooter just up and died at speed. I had given it a lot of throttle to try to maintain speed and not slow down. Anyway I coasted off to the side of the road onto the shoulder. I took a looksee to see if anything obvious was wrong but didn't find anything. So I goofed around a little pondering my next action. After a few minutes I tried the starter and the engine fired right up in a split second and idled like a champ. I rode it on home no problem and today no problem. So I was thinking it might have been the fuel pump was finally overcome by the lack of vacuum trying to get up that hill into a stiff headwind. But the original owner stated it tended to die on him when it was raining. That day when I rode to work we had a very light rain, more like a misty intermittent sprinkle, so little rain the roads were almost dry. Anyway it did sputter once when I pulled away from a stop light, but that was the only time. So what the heck, maybe the ignition coil is moisture sensitive. I'll have to swap that sucker out later and see what happens.

6000 miles on the odometer.


Yes the bungie cords are handy things to throw into something on the scooter. I'll have to look for a new trunk latch mechanism now or fabricate a new top latch part. I can't believe that they riveted the top part on but the used nuts and bolts on the bottom part. I think the rivets came loose. Go figure.

[earlwb]

At 6114 miles, today was oil change day, and I wanted to do a few other things as well.
So I changed the oil, replaced the ignition coil (which wasn't bad and still working, but the original owner had done some creative things with the spark plug cap and wire earlier), put in a new spark plug, and temporarily install a fuel pressure test gauge so I can test the engine fuel pressure.

Here is a short video clip of what the fuel pump does when the engine is running. Ypu can see the fuel pressure start to drop when I rev up the engine.


I am somewhat surprised that no one has tested the fuel pressure on the OEM setups to see what they really have. My fuel pressure tests show the vacuum fuel pump behaving exactly as I had surmised earlier. So there are no surprises there. On a four cycle engine you don't really have good pressure pulses that a fuel pump can use like you do with a two cycle engine. Anyway on my engine, I measure about 1.25psi at idle and about 1.5psi at 1800 to 2000 rpm. From then on fuel pressure gets inexorably less and less as the engine speed increases and the load goes up. Cruising at 40 mph results in about 0.5psi or so of fuel pressure. 50 mph plus is about 0.25 psi to 0.5psi. Go up a hill and try to maintain speed and not slow down, and fuel pressure goes toward zero. When you cut throttle at speed and slow down, when engine vacuum is highest, the fuel pressure goes up to around 1 psi sometimes a little more of course. There is a side vacuum diaphram on the carb that limits the fuel in the carb and that probably keeps the manifold vacuum from going too high in this case.

Of course at speed the engine is opening the carb's fuel inlet valve as it draws fuel out of the carb, but in this case the effect on fuel pressure should be negligible. This correlates with what I see with the engine intake manifold vacuum measurements too. Where at speed you have less engine vacuum, and the faster you go or the more load the engine is under, so that you have to give it more throttle decreases your intake vacuum towards zero. So it is somewhat fascinating and amazing that the vacuum fuel works as well as it does.

So if you use a small electric fuel pump, and a adjustable fuel pressure regulator, setting the fuel pressure to be about 1.25 to 1.5psi ought to be about right then. As the highest fuel pressure is a little over idle speed, there doesn't appear to be much reason to go for more fuel pressure as it runs the risk of the carb's float and fuel inlet valve being overloaded.

A final thought on using a fuel pressure gauge lets you check the one way valves inside the fuel pump too. When you turn off the engine the fuel pressure should not drop from 1.25 psi much at all. When I turn off the engine on my scooter, the fuel pressure, very very slowly, drops to about 1 psi and stays there for a really long time if not a hour or longer. So if the fuel pressure with the engine off drops to zero fairly fast, that means the one way valves in the fuel pump are not working correctly.

During my oil change process, I compared the Linhai clone engine drain plug to a Honda Clone engine drain plug. As you can see the Linhai engine uses a larger plug cap than the Honda clone engine uses.




The spark plug is looking quite nice color-wise, so no problems with the engine's air flow mixture settings.


The vacuum fuel pump as seen on the lower right side, mounted to the frame.


Here is more details about the vacuum fuel pump.


and of course my fuel pressure gauge testing setup mounted on the scooter, so I can check the fuel pressure.


Here is the engine vacuum pump fuel pressure at idle, about 1500 RPM. 1.25psi.


While I was in there, I took a pic of the CDI unit and its pinout wiring color coding here. The CDI unit is located on the right side just in fron of the top of the right rear shock. Also the voltage regulator is there as is the starter solenoid too. The ignition coil is just below the starter solenoid and in front of the voltage regulator.
The CDI unit uses a 4 block and a 3 block connector arracngement, but it is only using 5 of the 7 pins available.

[scooterollie]

Good work, Earl! Same drain plug as used on a Yamaha Vino - I scoped one out last night.

[tvfritz]

Earl,, reading your post is like going to college....mine is the same as your so it's escpecially informitive to me. Where to find a pressure regulator ?? and are you going to go with an electric pump ?

BTW, when I was flying ultralights I rebuild my vacuum pump every year. We have had pump failures from debris from within the pump itself (fuel tank usually double filtered) just thought I'd add that.. Hey Earl.... don't you ever let that scooter sit

[earlwb]

tvfritz,
The most common adjustable fuel pressure regulator is something like this one here:
www.jegs.com/p/Mr.+Gasket/747753/10002/-1/10323
It has a knob that you use to adjust the pressure level with.

The most common type of electric fuel pump is like the Mr gasket 42s which comes under a number of different brand labels. Napa Auto Parts Stores can get these items no problem too.
www.hallspeedshop.com/electric-fuel-pump-p-2100.html
the Purolator Facet electric fuel pumps work well too:
www.jcwhitney.com/webapp/wcs/stores/servlet/Product?storeId=10101&Pr=p_Product.CATENTRY_ID%3A2005660&productId=2005660&catalogId=10101

you can also find discounted OEM, no label pumps and regulators too.
Usually you can find them on Ebay a lot too.

Some riders have simply gone with the pump itself without a regulator and they had good success. So in some cases you may not need a pressure regulator.

Yes I have a regulator and fuel pump. So now I can install it myself as I know what to set the pressure to now. But I plan on trying a Mikuni vacuum fuel pump first and see if it works better or not. Several people installed those and reported good results. I like the simplicity of a vacuum fuel pump, so it is worth a try first. The pumps look like this one here, but you can get them for less from other sources as well.
www.sip-scootershop.com/pages/index.php?PORTAL=Froogle&COUNTRY=US&ID=21035&PORTALID=0&EXPLODIM=px&_requested_page=%2Fpages%2Fdetails.php

A interesting though crossed my mind. That is at cruising the fuel pressure drops, then I wonder if the float bowl level drops any, making the engine run a little bit more lean. Unfortunately, I don't have a ready solution on how to measure the float bowl level in the carb while the engine is running and I am riding off down the road. That would require modifying the carb so I could make the measurements. Also I would have to measure the exhaust temperature as well.

I thought if that as some people had problems with the engine running at WOT with a electric fuel pump. So in thinking about it, I wonder if the engine was really running on the rich side and not lean in that case. Hard to tell.

Oh yeah, I almost forgot. I have been running regular grade gasoline (89 octane rating) without any problems so far. I am on my 4th tank full so far. I haven't heard or felt any engine knocking at all.
I haven't seen any improvement or degradation in the gasoline miles per gallon either.

[earlwb]

scooterollie, thanks that is nice to know. Especially if one breaks the oil drain cap. A Yamaha Vino has the same plug. So one can go in and ask for a Yamaha Vino drain plug. Of course I bet they ask a pretty penny for it too.

[yarddogbbq]

nice instructional earlwb,

we are anxious to see what an electric pump on your machine will do.

cause i think these vacuum pumps and valves are a limiting factor for power and might cause stalling.

you approach wot and loose fuel pressure.........on vacuum valves and pumps both.

my tank is above the engine and i believe i have a valve instead of a pump. i never run better than right after a full tank fill then it runs like a striped 244cc, a tiger. (well maybe not a tiger) but impressive.

good pics and video.

i have a facet fuel pump on my suzuki, i think i will try it on the scoot soon easy to take off.

im curious how the bali would run.

take care

ydbbq

[pattiey]

Hi guys, I am new at this. Just ordered my new scooter. Would like to get your opinion though. Is it worth getting an extended warranty? Never had a bike before but am very willing to learn and a quick learner. Love all your lessons! Thanks. Always been my dad's "son" so to speak, and not afraid to get my hands dirty. But I don't know what kind of history this bike has, and if the extended waranty is worth it. Thanks.

[csgary]

I would very much doubt that an extended warranty makes sense in this case. You will have enough trouble getting parts based on your regular warranty. The extended warranty goes in the same category as undercoating, stainproofing, etc. In most cases it's strictly for suckers.

[earlwb]

So far warranty issues are a crap shoot. If you read the fine print, they typically only cover the engine itself, nothing else. Internet sellers are mostly drop shippers, so after sale support may or may not happen. So since I never tried using a warranty yet, I just order my own parts and fix it myself. I would have to say that unless you bought the scooter from one of the advertisers on this website, you are just wasting your money with a extended warranty, as they won't honor it.

[earlwb]

I decided to test some fuel pump configurations today.
First was the nice little Mikuni DF44 single cylinder vacuum pump. The small size had me concerned, and rightly so. I tried it anyway to see how it would perform. Although it works OK, it only outputs 0.5 psi fuel pressure which is too low. If you were to ride at speed fast or into a headwind with a hill, you are running out of fuel at the carb. There isn't enough fuel pressure to keep the engine running at speed.
So that ended its use on my 250cc engine right away.
Now on a 50cc or 150cc, this fuel pump may be perfectly adequate. So I consider using it on a 50cc to 150cc engine a good possibility.

That led me to go ahead and install the electric fuel pump with a pressure regulator, so i can set the fuel pressure. I adjusted it for 1.5 psi to match the highest fuel pressure I could get out of the OEM vacuum fuel pump. After testing and ensuring I didn't have any fuel leaks or seepage. I put everything back together.

I went for a 25 mile test ride, and the engine runs great with the electric fuel pump. Before it felt a little anemic and seemed to be a hair on the lean side as you rode along at certain speeds. Now it accelerates to 50mph like it used to accelerate to 40mph. I went up a hill where I could go 50mph into a mild headwind, and I gave it the throttle to hold 50mph up the hill too. It didn't start to stall or die, it just went right on up the hill. So the electric fuel pump is a success. it is like I gained more horsepower, but I didn't hop up the engine or add anything to it. That is so neat.

Now there is a darkside to the whole thing. The electric fuel pump draws enough power that with the radiator cooling fan on, you are just barely holding on, battery charge-wise. At idle or low speeds for a while the voltage starts to drop below 12.5 volts. Do you can wind up with a net deficit on battery charge, if you can't cruise 30 mph or faster. I'll be watching that over the next week to see how it is doing. With warmer weather, the radiator cooling fan is on pretty much the entire time. I think maybe I'll be installing a solar powered battery charger might be a good idea, and park the scooter in the sun when I am at work. I sorta hate to do that, as the red color will fade. But in thinking about it, what the heck, it is a Chinese Scooter, it isn't like it cost me $8,000 bucks and I need to take care of it carefully. I can glue the solar panel to the top of the trunk box. So not a bad idea at all.

One final note, my scooter has a positive ground, not negative like we normally see. So you need to test the electric fuel pump's wires to see if the negative one is grounded to the metal case or not. My pump fortunately, has it's motor isolated from the metal case. So when you rig up your power wiring, triple check with a voltmeter the polarity and wire it accordingly. The electric motor does not like reversed polarity on it.

Size comparison:


Mikuni Df44 under test:


Well then, that leads me to installing a electric Fuel Pump, as shown here I have the pressure regulator attached to the fuel pump so that it forms a unit. I used a 1/8"NPT coupler and two right angle 1/8" NPT to 1/4" nipple fbrass fittings.


I needed to move the fuel pump and regulator farther forward, so I fabricated a crude mounting plate out of 0.10" thick scrap aluminum plate.


Here is the electric fuel pump and regulator installed and under test, so I can check fuel pressure and make any adjustments. IMPORTANT! You need to run the engine for a while and check frequently for any fuel seepage out of the fitting joints. They need to to be tightened into the units quite tightly. Once it doesn't leak, then don't tighten them any further.


Here is a pic of the Fuel Pressure set for 1.5psi. Which matches the OEM vacuum pump's best pressure at about 1800 RPM.


Since I was in there messing around, I replaced the puny little running light bulbs with these SMD LED light units that have 9 LEDs in a SMD package.

[scooterollie]

Earl,
Nice work! I still wonder how the Linhai 300 electric pump would do on the 250 engines. I have inquired a couple of times about price and never got an answer. Didn't follow up as it was not a priority.

["Big Guy"]

Earl,

Keep replacing your lights with LEDs and you might alleviate the voltage problem with the fuel pump.


-Rich

[earlwb]

Thanks,
Today, I replaced the last of the light bulbs with LEDs. Only the headlights and the instrument cluster lights are incandescent now. I haven't found mini 12vdc twist socket lights that will fit into the mini sockets on the instrument lights.
There is the possibility that Roketa's engines were spec'd with a lower wattage alternator rotor. But I don't know how to confirm that at this time. I was surprised as to how much current the fuel pump requires. But if the fan is not running, no problem. So winter will be a piece of cake, but summer is a problem.

The Mr Gasket 12s Micro Fuel pump draws about 1 ampere at 12vdc. Since my earlier tests showed my scooter to be marginal when the radiator fan turned on, then that extra 1 ampere draw is enough to put it over the edge slightly at low speed, like idleing the engine.
The Mr Gasket 42s also draws about 1 ampere at max delivery too.
The Purolator Facet pumps look the same as the Mr gasket models, so they draw about the same current as well.

Guess what, I was at Wal-Mart today, and there it was in the battery section a Coleman CL-300 Solar Trickle Charger. It outputs 300 ma at about a 1.5amphours rate. I can bolt it down to the top of the trunk box, and hook it up, more or less permanently. It has a diode built in to prevent reverse current flow. So it might turn the current draw imbalance back into a balance again. I'll hook it up tomorrow morning. I think if the CL-600 charger isn't much bigger, it may be the way to go. But this CL-300 is pretty big, so it'll use up most of the trunk top lid.
It has a charger jack to match the charger jack I already have on the scooter battery too.

[earlwb]

funderp47 had a good explanation for the diode that is shown on the circuit diagram.
I can't explain it as good as he did.

It appears from the schematic you posted above that the headlights on that 250 scoot are DC powered, unlike the small scoots. The diode seems to be there to prevent the headlights from coming on until the engine is running and the rectifier/regulator is producing dc.

With the engine not running, it would seem the diode is reverse biased (open) and would block battery voltage to the headlight. The connection to the headlights and tail lights seems to be coming from the rectifier at the connection above the diode. (Anode + side). The diode would also prevent reverse current from the battery into the rectifier in the event of an internal short.

When the regulator dc voltage becomes higher than the battery voltage, the diode would become forward biased (closed) and pass the higher voltage and charging current to the battery.

You seem to have it figured. If that diode shorted, battery voltage would be available to the headlights without the engine running. I don't know what effect that would have on the regulator with it connected straight to the battery through that shorted diode.

With that diode open, it would seem no charging voltage could get to the battery. Diodes usually become shorts when they fail.

The fuse looking symbol in the top of the starter solenoid relay is rather odd. It looks like there is a fuse there to protect the wire from the battery through it to the key switch. That wire is connected to the bottom of the diode (cathode side). Then there is another fuse in the downstream side of the key switch to the dc accessories. If the fuse (if it is) shown on the solenoid blew, it would seem you would have no gauges or accessories when you turned the key switch on.

If it works like the diagram shows and the way I THINK it does, then the rectifier/regulator would have to be sized to provide headlight dc power, unlike the small scooters that use AC for the headlights. The diagram also seems to show a 3 phase regulator with six wires.

The small scoots typically only have four wires (single phase).

Thanks for the diagram.

[scooterollie]

Earl, I like the solar panel on the trunk top idea. Wonder if a charge controller would be needed if it was hard wired into the system? I have one that I put on the garage door window for the prolonged snowy, icy times in Winter. Plug it into the 12V power port.

I did see somewhere that early CFMoto engines had a lower coil number in the stator. Mine had the 18 coil stator, the larger variety. An occasional dip into the red zone at idle may not be a problem as long as you balance it out with enough cruising.

[earlwb]

Well maybe it isn't so bad as I was thinking yesterday. I'll have to watch it. But this morning, when I checked the battery voltage, I got a 12.85 volt reading, which is pretty good, and within range. So maybe the load on the system makes the onboard voltmeter tend to read a little low.

I don't think it needs a charge controller. It only puts out 300ma peak current. It has a diode built in to prevent reverse current flow as well. So I can leave it plugged in all the time.

Anyway the Solar panel was larger than I envisioned on my huge trunk box. I needed to fabricate a adapter plate out of a clear acrylic panel. I sort of simultaneously bolted the panel to the trunkbox and the solar panel to the adapter plate. So a ten minute job wound up taking over a hour to perform. But it is looking good so far. At least I have a plan for keeping the battery charged up, just in case. I can plug it in or unplug it as needed.

[jimk]

hey.. Here is one at Harbor Freight(I love that place) www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=44768
Roughly the same thing, but smaller panel, ugly orange though, but that may be fixable..
Also here is a larger one, www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=41144
It is also more powerful... Might not be bad, but would be huge on the trunk, might have to come up with a different mounting option for it...

JimK

[earlwb]

The small solar charge looks quite useable, but I don't know if they have a diode in there, so you can leave it connected all the time or not. But that would be easier to affix to the top of the trunk box. The big one is nice, but it doesn't have any easy way to attach it to something. I think they assume you'll just leave it sitting on the deck of a boat or something as needed. Of course you could move it around to keep it pointed at the sun better.

I got to thinking about my voltage measurements. It is possible the readings are on the low side because of the wiring. I might have the wire overloaded some and I'm seeing a voltage drop because of the wire I tapped off of, is too small. I'll have to think about that for a while.

What I did was tap into a convenient wire for the voltmeter. Then I used that same wire to tap into for the fuel pump. That extra ampere on the wire might be causing the voltmeter to read lower than normal. Although the wire I tapped into looks large and OK, the copper strands inside might be fewer. Anything to save a buck at the factory.

[fufu2wheel]

Maybe these flexible solar panels would be good application?

www.ecogeekliving.com/100maflexiblepanel.html

[earlwb]

Oh yeah, I like them.
That may be the way to go, as they flex, making it easier to conform to the curved trunk box lids.

[caudell999]

Hello everybody, I recently purchased an MC54-250B from All New Sports. I have about 75 miles on the scooter and a couple days ago I started out of my drive and the scooter died. I couldn't get it started again. It was almost as if it wasn't getting fuel as it would not kick. At the same time I could smell fuel as if I had flooded the carb. Anyway, I took it back into the garage and had to use the SUV to get to work. Later that evening I took off the cover inside the seat storage comp to see what was going on. I started the scooter and let it run for about 30 seconds and it started running rough again, then died. Just before it died and for a few seconds after it died, fuel came pouring out of a little black tube coming from the left side of the carb. I called All New Sport and Carl told me to take the carb off and send it back in for a replacement. I don't think I need to send it in because it is most likely something simple. Before it started to die, I put 75 miles on it without any problems. Anybody out there have any idea what could be causing my scooter to run rough and die?

[JiuJitsu]

Well there should definitely not be fuel pouring out a little black tube anywhere!

Sounds like that hose needs to be clamped back on... is there anything near it that looks like it should be attached there?

You can compare what you see to this picture of Earl's carb...

[caudell999]

Earl, I have a picture of my carb but don't know how to post it to this web site. Do you have an email address I can send it to?

[earlwb]

It is probably a float that is stuck in the carb. I have had that happen several times over my many years of using motor vehicles (not just scooters). Sometimes the float gets a little off to one side, pubs up against the pivot pin support post and gets stuck there. Most of the time, you get the carb out and upside down, remove the float bowl, check the float and fuel cut off valve, don't see anything wrong, put it back together and it works fine for ages. But you still have to do the ritual of take the float out and look at it to fix the problem.

[scooterollie]

Caudell99,
Welcome to the dawg Pound!

For maximum viewing and response and to not add confusion to another thread, it is best to start a new thread when you have a different issue.