My MC 54 250B, 2008 model just does not run much at all. By bobf (Read 3,860 times)

[Alleyoop]

You only loosen the screws you do not take them out just a little loose just enough that you can move the plates. To help put a little bit of oil behind the screws so the plates slide back and forth easy.

You can also try this: Mark the plates where they are currently THEN JUST LOOSEN the two screws and try starting the motor and see if it starts easier and runs better.
Alleyoop

[bobf]

I wish they did as you say. What happens on my engine is they do not slip until really loose. Then as the engine is running they will be spinning while running and I have to hold them from spinning off or mark their location, shut down, lock them in the marked location and then restart.

I will try a drop of oil if I do it again to see if that helps while still some tension on the head to end the spinning. If running the exhaust one will spin freely and the intake will wiggle around but it does not spin as if to come off.

Later today I will do the fixed, not running, set up again.

[bobf]

OK, I am set up to do the none running setup. As before I have everything set up for adjusting, I think. My concern this time is about the setup as they say to line the mark, dimple in rotating part, with a triangle mark on the cover. I don't see a triangle mark on the cover, did not before either, so I just set it up as centered as I could in the hole itself.

So now I am rotating the engine to see if there is another center punch tool mark that I can find.

None found and I am back to the punch tool mark again. No triangle mark found but will try to set valves with the punch centered as best I can in the hole. Sure hope this works. If not I guess back to the setting while running. Which to me is just a lot of guesswork at best.

Will post a follow up after I do the valve settings.

[Alleyoop]

Yea the markings are very light and not really clear that stand out.
Good luck Bob hope it helps.
Alleyoop

[bobf]

OK Alleyoop, here is what I did. I tried several times to align the center punch mark with something I was only guessing at. Mostly just centered in the hole. Never found a mark in the hole or on the outside anywhere worth making a bet on.

Problem when aligned as I described. The right one was locked by cam pressure I assumed. I could not move it at all. So instead I considered moving to where I could adjust both and then try to start. Absolutely no guarantee of correct setting but if running maybe I could do the Honda set up. So again I am just unable to adjust as it will not maintain a running speed without me holding the throttle open a bit.

It is still blowing lots of black smoke out the stack. You suggested my changing the mixture screw. Can do I guess. Always thought better of messing with a controlled and locked setting. But right now I am out of control. Later this week, when holidays are over, I will go talk to the only shop that may be willing to help. Right now I will be willing to hear your ideas and suggestions. Valve job is possible for me in my garage. Any thing deeper and I have to go to a skilled and equipped shop.

Well, I did spend a bunch of time hand cranking the engine trying to get the center punch aligned to something so I could adjust the valves. Could the valves be off somehow from the correct timing positions? Just guessing out loud.

Thanks for your encouragement so far.

[Alleyoop]

If it is black smoke it is gas it probably is kind of sooty, if it was burning oil it would be blueish and if it was burning antifreeze it would be clouds of white smoke.

So It looks like it is drowning in fuel, Is the ENRICHER PLUGGED IN and does it get HOT after it is running a bit? Also do this CHECK the VACUUM HOSES AT THE INTAKE MANIFOLD it could be it is sucking in fuel through the VACUUM HOSE.

Can you get at the FUEL RATIO SCREW and turn it clockwise until it stops then turn it counter clockwise say about 2 turns. You can loosen the clamps and turn it sideways to do this then straighten it back up and tighten the clamps again. It is getting to much fuel from someplace and the only place is the ENRICHER the VACUUM LINE or the FUEL RATIO SCREW or the CARB IS FLOODING .

COUNT THE NUMBER OF TURNS CLOCKWISE UNTIL IT STOPS want to know if the mixture is set really rich.
Alleyoop

[bobf]

Is the item you are speaking of called the Starting Enrichment Thermal Valve? If so I can check the resistance as the Honda manual says approx 10 ohms. I have two here, one on the machine and one in the garage on the second carburetor. If they both check out then maybe a physical check out may see something wrong. They are both near 10 ohms, actually about 8 or 9.

I am running without the air pipe installed. Could this cause a problem?

Interesting ideas but where would the vacuum lines get gas to suck up? I will look around for that possibility. I just took off the vac hose that connects to the back of he carb by the round looking thing. Could not restart as the battery was struggling to do so. So now on charger for a while. I could also go back to the original fuel pump to eliminate the fuel pump from the question block.

I also had the other carb running a couple days back and it also was belching black smoke. A real confusing mess. Maybe I should just spend some time, likely tomorrow or Tuesday, just thinking through the changes I have made and swapping them back if I still have the older parts around.

Yes I will go in and reset the fuel ratio screw.

Will include resetting the fuel ratio screw later. First I will change the fuel pump.

You do give me many things to think about and thank you.

[Alleyoop]

The Vacuum Line from the Fuel Pump if it is wet from gas at the INTAKE MANIFOLD that means gas is flowing out through the vacuum line and that means the fuel pump is bad. That round looking thing is your ACV valve(AIR CUTOFF VALVE) what that does is when you are giving it throttle and you let go to slow down it allows some fuel to flow so the motor does not run LEAN and starting backfiring as it comes down to IDLE. So Check that vacuum line at the SAUCER and see if it is wet it should be dry, Also check the vacuum hose coming from the fuel pump that also should be dry.

WHY change the fuel pump we know it is working? If you have an ELECTRIC FUEL PUMP that may abe pumping to much and flodding the carb.
Alleyoop

BUT ALSO CHECK THE FUEL RATIO MIXTURE SCREW and REMEMBER COUNT THE NUMBER OF TURNS CLOCKWISE IT TOOK TO STOP.
Alleyoop

[bobf]

Reason for changing the fuel pump is the possible correlation of black smoke with the installation of the new fuel pump. Just a guess so I change back. Next time I run I will notice if the exhaust is black or not.

Vac line at the ACV was having coolant in the past. I did commented on that I think but maybe not. Today the hose was wet when I took it off. Did not check but tried to smell and did not smell gas. Will know better when I get back to working on the scoot again. Likely tomorrow afternoon as first possible time.

Battery is still on full charge so it will be a while till it is ready for more workout and I am needing a break for now.

[bobf]

Alleyoop, I thought I had sent you a note earlier but it is not here now. I must have left without saving. So I will do it again.

After I got done with driving the wife to shopping I was able to look at and run the scoot. So now I tell about the recent events and hope they help you when thinking of my machine.

I was having a problem with the starting so I took the vac hose off the AVC to see if anything was in the hose. Something wet but could not tell if gas, no odors I expected but maybe it was coolant then. Definitely something at the brass ACV tube.

So I tried to start the engine with the tube off and it did start and ran well. It was running fast enough that I could control the idle down a bit with the idle adjust screw on the carb.

It did blow lots of smoke from the exhaust manifold area and out the tail pipe too. Plenty of smoke but after a few minutes it started to clear and ended up running clean as it should. Fuel pump change the reason for that, or just running without the vac system connected at the ACV?

The black part of the enricher did get warm, not hot, as the engine was running.

I did not change the fuel ratio mixture yet as it is running well at the moment. The Honda manuals say not to change as it is a factory setup. I will not till other ideas fail, then anything goes.

Wondering now if this vac hose disconnected from the carb means anything special. As long as I leave the vac hose disconnected the engine seems to run well. If I put my finger over the vac hose end, the engine quits immediately. If I loosen another vac tube connection the engine keeps on running if I block this first vac tube. Not sure what I prove with that exercise.

Hoping your experience may learn something from my happenings.

[Alleyoop]

GREAT!! at least the scoot is running now. So it appears that it was sucking in gas from the ACV Valve and causing overly rich condition which we suspected it was getting extra fuel from someplace.

The hose you took off and it dies when you cover it up with your finger-- IS THAT the hose on the SAUCER piece on top or the SHORTER hose that connects to under the SAUCER and then back to a connector on the CARB?
Look at this picture and tell me which hose you disconnected and dies when you cover it up HOSE #1 or HOSE #2?

[bobf]

It is hose #2 at the back of the carb.

I can block that brass port - no effect. If I block the vac tube - the engine stops.

I hope this is a clue to end my six months of no scooting.

[Alleyoop]

Ok Can you tell me or draw me from that VAC hose to where it goes and where it ends. Boy Pictures would be nice but you do not have a camera so Maybe Draw it on a piece of paper or the computer and then post the drawing. Covering that hose SHOULD NOT CAUSE the motor to die so I am thinking it is connected wrong.
Alleyoop

[Alleyoop]

Here I drew what it should look like: The connections of that hose and where it may go:
Click on it to expand it to see better.

[bobf]

I will see what I can do. It sort of looks like a spaghetti pile. I have thought that myself. Just not sure where to change things so help is appreciated.

Once I get the sketch how to send it to you would be my question. I suppose I can run it from my printer into a file and then send the file to you. Another thing to learn for me but learning is possible even for us old folks.

How fast does not matter. I will work on the sketch till it makes sense and then send it to you. No guarantee of today at all. But as soon as it make sense I will send it.