MC-54B 250CC Power Loss By sskains (Read 2,597 times)

[sskains]

I'm having issues with the power on my scooter. This is a new bike from 2008, it only has 30 miles on it but has no power. I've already changed the following on it:

New Carburetor - I have adjusted the air/gas ratio already.
New Magneto Stator
New CDI Ignition Box
New Spark Plug

When it is on the service stands with the tire off the ground, it accelerates to nearly 8000 rpms without any issues. As soon as I put it on the ground and drive it, I can't go faster than 30 on a flat surface. It kind of hangs sometimes if I am throttling, then release, then try to throttle again, which leads to me think it is the CVT or clutch. I'm not sure what steps to take from here. Any help is welcome.

Thanks!

[Cruiser]

Welcome to Scooter Doc, sskains. From the brief description of your problems, I have to assume your scoot is not red. (Just jokin').

This scoot according to some experts is the most popular scoot there is, so we should be able to get you up to speed.

When you are cruising at 30 mph, what does the tach read? It takes a lot less power to spin a wheel while on the centerstand than driving down the road. If the tach reads low like maybe 4000 or less, then it sounds like the engine is maybe starving for fuel or there maybe is a bad air leak in the air box or inlet to the carb.

Let's see what the other Scooter Docs come up with.

[sskains]

The RPMs sit around 3,000-4,000 on the street. Going up hill, I can only get it to about 20 MPH. Steep hills it can't even make it up. I am currently running premium, 89 octane I assume, with some octane booster and fuel treatment. I haven't checked too deeply into the air flow yet. I will check that out.

Another thing is the fan light comes on frequently, which would be a sign of what you mentioned.

[mcalli]

First, the 54-B requires gas octane of 91 or greater. (obviously the gas isn't causing the problem, but you really should use 91 or 93 octane).

I don't think the RPM's have much to do with it because my rpm's are at 4,000 when I am traveling at speeds of 45 to 55. My tach reads about 2 for 20 miles, 3 for 30 miles, and 4 for 40 to 50 miles. It goes up from there. about 6 for 60 miles. I am a novice, but this makes sense for me.

I don't know much about mechanics, but I do know that JR is usually right on the money, so I would try his suggestion. (He's right about most stuff- the red being fastest being the exception. Any one with any smarts at all knows it is the blue that is the fastest) lol

[Jeff]

Adjust the valves, clean out the cvt, check/replace the vacuum/fuel lines and fuel filter(s). You've already done everything else except paint it red.

[speedracer]

Has nothing to do with the subject so please excuse me. I don't think ethanol in the gas hinders power or MPG. Nascar now runs 15% ethanol and Indy cars doing 240 mph run 100% ethanol gas. Nascar actually announced higher HP by using ethanol. My gas stations all have at least 10% ethanol in the gas.

It just doesn't help Red Scooters at all. They are beyond help.

[mcalli]

You mean I can put regular 87 octane in my tank? My bike (54B) was manufactured (assembled) in the USA. and it has tags on it telling me to use 91 or greater octane. I don't have to?

[mauiboy]

My understanding is that the octane rating refers to the fuels ability to avoid detonation (knocking). I believe it works on the basis of the higher the compression ratio the higher the octane needed. So if you have a moderate to high compression engine you could need a higher octane rating and lose power and mpg and potentially damage your engine if you went too low or too high, a low compression engine should in theory lose power and mpg with a high rated fuel and in theory you could blow your legs off using 87 fuel in an 18:1 compression racing engine.
The compression ratio is basically a measure of the difference in volume within the cylinder with the piston at the limits of its travel. Higher compression = less energy required for detonation so a fuel more resistant to detonation is required.
I believe this is right, please anyone chime in if I have misunderstood!
The issue is a little complicated by various factors
1- in some markets lower octane rated fuels are sold without some of the detergents etc that are added to higher octane fuels to make them a premium product. This creates an impression that a higher octane fuel = a 'better product'. In some respects this can be true, in others it is not so.
2- different markets use different methods of measurement such as RON, AKI (anti knocking index?), MON etc. So you can walk up to a pump in one country that has 93 written on it and the same pump in a different country and the fuels would not be equal.
3- different markets are tolerant of different qualities of fuel. Sometimes the economy and general engine development is a factor in this. Put basically, in the middle of the jungle where everyone uses 40 year old honda engines with wide tolerance everything from guiness up comes out of the pump (and wider specifications on the fuel keep it cheaper) but in a more modern environment where engines with tight tolerances and where an extra cent or two per liter won't starve anyone the fuel will likely have tighter specifications.

Personally I run 3 or 4 tanks of plus and 3 or 4 of premium then switch back, I'm going to see after a few thousand miles if theres much of a difference.

Sino scoot engines are fairly rugged and tolerant. Precision isn't a word that comes to mind. 'Good enough' seems to be the philosophy, along with not overcomplicating things. You possibly could run 87 in the scoot. The first few times I would carry a bottle of octane additive incase I head knocking.

Again, if any of this sounds like bubbles to anyone chime in, I could be wrong and I don't mind being told This is also all for octane rating / gas engines, although some similar thinking can be applied to cetane / diesel.

In the UK higher octane fuels are marketed on giving you more MPG per tank which in some ways is counter intuitive to traditional thinking but I believe this is due to the extra detergents and additives added which help a cleaner ignition in more modern engines. It doesn't help trying to understand the situation however

[Alleyoop]

Mcalli,
Where in the world did you get the idea that the tank was manufactured and assembled in the U.S.A? If so please put up the link of the manufacture.
Alleyoop

[mauiboy]

For a given definition of assembled it may be true in a certain light Perhaps if you define assembled as putting some decals on and screwing a few bits together. You know, marketing speak (thinly veiled lies somehow justified by a vague association to something akin to a truth).

The scoots are physically made in China (assuming they dont outsource some of the process or purchase parts from cheaper markets) but there is some final physical assembly in the USA after it is decrated. I haven't seen them marketed as such but it is possible somebody is saying that. Just saying depending on how you look at it it is correct (especially if you work in marketing or for a hedge fund).

[Alleyoop]

Man you realy went all around the maul-berry bush with a lot of B.S tell it like it is it is made in china and assembled and crated there period. Distributors put there decals on and call them whatever sounds racey.
Alleyoop

[mauiboy]

I thought from my tone you may have figured I didn't agree. I'll get back in my box.

[Alleyoop]

HAHAHA!! no I figured you agreed i was just funning you on the other B.S you wrote
Alleyoop

[mauiboy]

No worries, not much longer before China it outsourcing to the USA anyway

[mike6736]

Heeeeyyyyyyyy Ally......That tickled so hard I think I found your oil leak!!! I just laughed so hard I fell...

Your killing me

Mike