My MC 54 250B, 2008 model just does not run much at all. By bobf (Read 3,856 times)

[Alleyoop]

FANTASTIC BOB!! So now it is a FACT that the PUMP is bad and allowing fuel to flow through the VAC LINE.

Now if you want a good FUEL PUMP you should get a MIKUNI: You can get rebuilding kits for them as well.
Alleyoop

www.powersportsplace.com/parts/mku-df52-176?seid=pspse1&gclid=Cj0KEQiAl5u2BRC6yszC1_75v5wBEiQAD-hdz4SecBl0UTKlb684k9WY-6ZP6sFpGXRW0kAQOz1JIM8aAvSd8P8HAQ

[bobf]

Thanks for this info. If my new fuel pump is another failure, I will give this consideration.

If I look at Rocketa I find my fuel pump at something around $120 but on sale for about $65. That makes your suggestion seem real low cost.

[Alleyoop]

Parts from Roketa are very expensive and not because they are special, everything for the scoots are made in china.
You can buy and spend whatever you want that is your choice, all I can do is give you some suggestions and you can decide.
Alleyoop

www.roketapartsdept.com/products/ROKETA_MC_54B_250_FUEL_LOW_TENSION_SWITCH-18264-609.html

[bobf]

This might even be the Rocketa part I was referring too.

My scoot is MC 54 250B. The one you posted is for the MC 54B 250. The 54B signifies the horizontal engine machine and the 250B is more of a variation of some sort. It is on my paperwork and in their catalog stuff.

I won't go into my scooter parts list to check as it does not matter. I won't go near Rocketa to buy anything any more.

Thanks for your inputs.

[Alleyoop]

Roketa shows the same FUEL PUMP for either one the MC 54B 250(VERTICAL 244cc HELIX MOTOR) or the MC 54 250B(Horiszontial 257cc LINAHI MOTOR).
Alleyoop

[bobf]

Sorry Alleyoop. But I have to challenge your numbering. The MC 54B 250 is for the horizontal engine and I have the vertical engine. The 250B has nothing to do with the engine size or vertical or horizontal.

The MC 54B 250 with the horizontal engine has not been available for some time now and my MC 54 250 with the vertical engine is now in closeout status.

www.roketapartsdept.com/catalog/MC_54_250_ENGINE_AND_EXHAUST_PARTS-606-1.html

Shows the vertical engine and top view of cylinder is pointing straight up.

www.roketapartsdept.com/catalog/MC_54B_250_ENGINE_AND_REAR_WHEEL_ASSEMBLY_PARTS-612-1.html

Shows the horizontal engine with cylinder is pointing to the left.

[Alleyoop]

Yep, all i wanted to show you is one has the linahi and the other the helix and MY POINT IS THE FUEL PUMP is the same for both available or not.

[bobf]

That fuel pump thing is OK with me, I am never buying from them anymore anyway.

I was not trying to put you down at all as I see that confusion often in the various forums. So I offered proof of which machine is what. Nothing more and nothing less. I have no idea why some also put the B after the scooter name as it has nothing to do with the engine for sure.

Your help has been appreciated. Will let you know after I get my new fuel pump as to how well it will be working.

[Alleyoop]

Hope the new pump solves your problem and you can get riding again.
Alleyoop

[bobf]

I have put much back on the scoot and have tried to get the valves properly adjusted. Been running reasonably well recently but I do have some questions about the start routine.

First I will comment on the cold start.

From a cold start the engine fires right away and the RPM's go straight up to as high as 4,000 rpm. This will last for a short bit and then start to slow down and then it sometimes goes all the way down to near 1,000 rpm. Sometimes it stalls and I have to restart. Then as it warms up it slowly rises up to between 1,500 or 2,000 rpm where it will hang around and just keep running.

What seems to be wrong with that way of starting and warming up? Is there something wrong with the fuel system, air or fuel control mechanism, that I need to adjust or replace?

OK, now I will comment on the valves and adjustments.

I have taken the time to mark the top of the adjusters with black Sharpie marker. Then as listening I take one valve at a time and tweak this way or that and listen for tapping and steady firing. When done I clean and then remark the valve lifter thing. Always want to have a marker to get back to what I thought was a good point if things get worse.

Now, which valve would likely cause the backfire that happens on occasion. I have things pretty good but still getting numbers of backfires during idle time. If I know which valve is likely the one causing the backfires I could spend some time going to that valve and fine tweaking till it is quieter.

I won't be putting on the plastics till I am really convinced it is running correctly. As I hate taking it off in the first place.

Finally feeling like I am making headway toward a rideable machine.

[Alleyoop]

The high rpms at cold start and then going down and dieing and the backfiring at IDLE sounds like you have a PRETTY GOOD AIR LEAK somewhere. That is why the rpms are so high when cold running really LEAN then as it warms up whatever is leaking seals a little and the idle drops.

So get a spray bottle of water and start it up and spray around the intake manifold and hoses looking for the air leak. When the water hits the area with the AIR LEAK the RPMS(IDLE WILL CHANGE). Also check around all hoses and AIR BOX for any open connectors and or hoses that are not connected to anything.

If you could get some pictures of the top of the motor and hoses It could make this much easier cause I know what I would be looking for.
Alleyoop

[jct842]

Just looking at the out side finish on the two pumps it doesn't take an expert to see the mikuni is better. I bought one a few years ago and got a rebuild kit for it too.

[bobf]

OK Alleyoop, you win again. I went back to the scoot thinking not more air leaking as I had gone over that all recently. But again you were right. It was my air housing from the rear around to the front of the carb. I had put it in very carefully and had use my rubber mallet to ensure it was well seated on the carb. I had the bands tight on the carb and the air intake box. I had put a large washer on the screw holding down the molded air housing. But apparently I did not tighten that screw down very well. The air housing was found to be half off the front of the carb.

It is now back on, all clamps and screws are very tight. I have run it a couple times and let it cool between and it seems to be working well now and the first idle is a bit fast, up to around 2500 for a minute or less, and then it starts slowing down to about 1800 rpm. Getting to think I am near the end of messing with the starting and running things.

Now I also have found where my coolant is coming from. It is dripping from the weep hole under the pump area. So I will order those two seals and new gasket tonight. So maybe next weekend I will have it all back together and running well again.

Then the covers go back on. Then I get to ride again. Then if the wife wins the discussion I will have a for sale sign for it. Been a confusing but learning few months for me.

You help has been good too. So thanks a bunch for all the help.

[Alleyoop]

Good news it was an easy fix glad I was able to help with your scoots problems, but at least before you sell it ride it around a little

The idle sounds good, the 250s usually idle good anywhere from 1800-2000 rpms, you can adjust it to where it idles the smoothest.
Alleyoop

[bobf]

Allyoop, a question about my carb and starting idle speeds. As I wait for parts I have ordered I sometimes start the engine. Question about the starting speeds. After first starting it tends to run pretty fast, over 3,000 rpm and sometimes reaching for 4,000 rpm, prior to starting to slow down and finally ending up just below 2,000 rpm and idling.

Those high rpm's are for about the first minute or two and then a slow slow down to regular idle or less. It will sometimes drop well down to the 1,000 rpm or less and if not accelerated it will stop. Then in a bit of time and warm up it will start rising up to the near 2,000 rpm level. Then it will settle in and just run well.

To me the start up to near 4,000 rpm seems a bit much and the wheel is really spinning. Not sure I would like that to happen should I start on the wheels or side stand, instead of the main stand which would keep the wheels off the ground.

Should I consider those start up routines to be a problem? Something about the enricher that might be the problem? If needing a new one, where to look for a quality one not costing bundles?