2003 Honda CHF50 Metropolitan Scooter woes...

[Shuriken]

Yeah, in-laws dumped their scooter off on me.

Will start and you can hold the throttle just a bit off idle to keep it running for a sec but then it dies.

Carb is spotless... went through it with air and cleaner - wasn't dirty anyway. Fuel pump works.

Tried running with and without the airbox and it ran no differently. Thought it was lean so I gave it a shot of starter when running - no difference.

Try to open the throttle mid to full to rev it up and it sounds like it is choking/flooding and then it dies.

Engine won't turn at all unless you firmly clamp the break, then you have to keep your finger on the starter.

Sounds like an electrical issue to me. Anybody have experience with these?

[prometheus578]

"Gawd, I hate scooters!"

Well, I know that you're a competent mechanic... and your eyes are as good as mine... so what I'd do is sit there and stare at it for a while... while your mind runs over every possabilty.
Is it a two-stroke or a four stroke?

And, as people always do... I can imagine that before it was pushed off on you... someone had their pudgy little hands in there to "fix it".
You've already been into the carbs... I was gonna say that the idle screw could be truned OUT too far... or the mixture screw was dicked with.
Fuel pump, huh?
As long as the bowl has juice, but I can imagine you've checked that already.
Are you saying that it'll start but immediately dies?
I doubt there's a ballast resister on that machine.
Somethimes, like with Vespas, if it gets layed over, or someone overfills the gas tank, fuel gets down into the charcoal canister and plugs that up, but that usually only affects higher RPM power.
HHmmm...
Did I mention that I hate scooters?
Uhmmm....
Does it have a "choke throttle plate" or an electric enrichener plunger?

Does that brake lever you need to hold to start... operate the front or rear brake?

What's the compression like? Pull the plug and put your finger over the hole. Even a 50cc engine's compression should "fart" past your finger.

[Shuriken]

Nice post, Prom, and thanks.

1. It is a 4-stroke engine.
2. It has already been dicked with by some 4-wheeler repair shop, who gave up on it.
3. It does have a fuel pump because the gas tank is located under the floor boards and the carb is up under the seat. The pump clicks and I've observed that it's working - disconnected the hose and turned on the key.....
4. Bowl definitely is filling with Boy Scout Juice.
5. Starting and running: a, I grab either hand brake. (Both front hand brakes are linked. Not sure about rear brake, will have to take a look) Turn key to ON. Fuel pump starts clicking. Press and hold start button. Starter engages and the engine fires. Engine will not stay running when starter is disengaged or when throttle is opened. Engine will not idle by itself, either.

(This is what makes me think it is some kind of flooding issue or weak electrical component of some kind...)

To test the flooding theory, I simply removed the air filter/airbox to lean up the intake mixture. This did not produce any effect.

I have not tested compression - I don't have a guage that I can cram into such a small space, but I can test it with my finger and will post back.

6. I hate scooters too.
7. I still hate scooters.
8. Did I mention that I hate scooters?

9. Not sure about ballast resistor... I will look for that. Should be in the area of the ign. coil, I would guess.
10. I will also check idle mix screw setting.
11. Choke seems to be handled electronically. There is what appears to be a throttle position sensor on the end of the butterfly shaft. Additionally, there is another electrical device that, according to parts schematics, is called an Auto-Bistarter. Upon inspection, this device appears to move a little needle plunger type thing in and out of an orifice on the carb body. I would bet that varying voltage will electromagnetically withdraw the needle in varying degrees from the carb body. I suppose I could replace this but I don't know that it is faulty or if the electrical signals going to it are correct.

Thanks for the help.

[prometheus578]

Well, that auto "bi-starter" thingie.... is an odd gizmo.
Sort of similar to our enrichener plunger.
When cold, it is in the OPEN position.
now, what happens is... when you turn the ignition on, juice goes through the wires to the gizmo. Inside that cylinder is wax of some sort. The wire heats up, the wax expands and pushes the plunger down to the CLOSED position.

Now then... the reason I asked about the ballast resister...
You state that the bike fires when cranking, but when cranking stops, it dies.
Same as our bikes... when cranking, the coils get juice through a different circuit(The bike starts). Once the cranking is done, the juice goes through the ballast resister(The bike stays running)
So.. If this machine has a ballast resister... and if it's faulty, the bike could fire when cranking, but then die when the cranking's done.

Now then...
If there's a valve timing issue.. or there's really low compression... the bike will not run on it's own. Oh, it'll fire alright... just isn't producing the power to sustain itself. The only reason the engine is spinning over and running is because the starter is turning it! Once the starter stops doing that... the engine can't keep it's rotation going.
Now then....
(My ex-father in law would always preface his profound technical statements with "Now then". Usually meant he didn't know what he was talking about... sort of like me, now)
Anyway.... I think the fuel is OK.. as the bike starts. And whatever amount of fuel is needed to get it to start should be enough to keep it running... at least at idle.
You state that it dies when you try to give it throttle.
HHmmm....
Of course.. it's also dying at the same time because you're releasing the starter, so that's a confusing issue, but not the problem.
Don't really think it's fuel related... though... the idle setting could be too low... way low.... Bike is only running(firing) because the starter is helping it. Once the starter stops, the idle's too low to sustain the engine RPM. Opening the throttle from too low a RPM will kill the engine. Also, engine is cold, which doesn't help.
Of course... all electrical is done through that damned brain box.
Without a manual to tell you ohms readings and such, I doubt that you can check if it's good.
I'd finish checking out every last thing, fuel, valves, etc before replacing the brain box... as it may actually be OK.
And another thing....
Here's a game you can play. But like everything else... depending on what it turns up, it might not actually be correct. (Sort of like researching monkey behavior. The observable behavior changes due to the presence of the researchers)
Anyway...
Get out your timing light. Hook the induction clip to the plug wire.
Now then.... (see what I mean..)
Now then... When your crank the engine and the bike runs.. your timing light should flash as there's obviously sprk involved.
When you release the starter button and the engine still stumbles for a few more seconds... if the light is still flashing, that means the spark is ok. If the light stops flashing as soon as you release the starter button... that means you've got no spark in the run mode.
Again.. this isn't fool proof as sometimes it's hard to tell just when the spark quits.
No.. if you find yourself getting frustrated... here's what I'd do.
Turn off the lights in the garage. Take a rubber band and bind down the trigger on the timing light.
Lay the light on the scooter's seat facing toward you.
Now then... Press the starter button... and start dancing around in the "disco" strobe light.

You'll look really cool!!

[Shuriken]

I reset the ECU according to this web site but still got the same thing:
http://www.urbanscootin.com/forum/vi...hp?f=2&t=10660

However, I was paying more attention to the problem and there is a little relay in the fuse panel that seems to be opening and closing. I think the relay is supposed to stay on when the engine is running. It does not. It tries to close, then it opens, then it closes.... maybe 5 times per second.... I think I'm getting close...

[Shuriken]

This schematic shows at least 3 relays:
http://www.bikebandit.com/houseofmot...m2111sch315574

I'm guessing that if the problem is not the ECU ($300), it has to be a relay problem. If I had a wiring diagram, I could test the relays, I suppose. For $60 or so, I could replace them all, but I'd hate to do that only to find out the problem is the ECU.

[prometheus578]

Yeah, now you know why I hated electronic crap.
Stepper motors, Manifold absolute pressure switches, injectors, throttle position sensors, oil temp sensors, rejetting with a computer....
And if ya don't have the proper diagnostic equipment, you just have to take a bloody guess. And even with the right tools, too often you still have to take a bloody guess.

Sure, I enjoyed what I did... but I'm much happier being unemployed.

[prometheus578]

"Oh crap!"

Interesting site that was.
Hhmm....
Man, I remember some Triumphs.... You'd have to reset the thing if you removed the tank and turned the key on with it off.

Hey, I'll play your game....
Make sure you have the right key for the bike!
Vespas.. my "favorite" machines... had coded keys.
The key has an electronic transmitter thingie in it.
I'd always had to "Key" the new keys to the scooters, if you know what I mean.

Now, let's suppose... when they bought that scooter...only one key was "registered" with the brain box. (Should get two keys when buying bike)
If they have been using an "unregistered" spare key... yup... it'll crank, but not run. Some would run, but wouldn't go over 20 MPH.
Just a thought. I don't know what Hondas systems are like.

(Sadly, the longer I sit idle here at home.. the more I forget)

[Shuriken]

Re: "Oh crap!"

Originally posted by prometheus578
Hey, I'll play your game....

And indeed, it is an expensive game to play. You had it right when you said you hate all the electrical crap.

The relays are going to be held closed by a specified voltage on a specified wire. My worry is that if/when I replace the relays, I'll see the same problem, which means the ECU is cutting the voltage before it ever gets to the relay, which means ECU is crap, which means $300+

Scooter is only worth $1200 in good running order according to KBB.....

[prometheus578]

"I view scooters as disposable."

Hence, my love affair with Vespa.

No manuals... everything on disk.
No sections, such as carb, tranny, etc.
You'd have to scroll throw 87 pages to find something remotely pertinent to what you were looking for.
Step by step instructions for major components?
Nope...
Manual only talks of... from start to finish, how to completely tear apart and put back together.
"Hey, I only want to work on the tranny and want to know just only which parts I need to remove first."
Nope... have to remove the body.. then the engine from frame, then the carbs, then the....
Turn signals don't work... replace the ICU. Flashers work offa the brain box!(yeah, there's $300 for ya)

Wiring diagram?
Lists relay #1, relay#2, relay#3....
No explaination of what they are, nor what they do, nor what symptoms happens when they fail...

Best advice.. throw it away... and not buy another one.
Unless, you can find a scooter shop, where the mechanic has seen them all before... has experienced all the failures and knows exactly what the fix is. That's not taught... can only be gained by time.
Sort of counter-intuitive...
Almost impossable nowadays to figger out why something doesn't work without the proper tools or a good diagnostic manual.
Much easier if they would just say.... "If the bike exhibits this symptom, replace part "A". (and then a small explaination would be nice, too)

Sorry for the rant... I've been holding it inside for too long.

[Shuriken]

Ordered 2 relays. I am inclined to think it's the voltage going to the relay that is low, but we'll see.

[Shuriken]

Well, I am going to send back the relays.

I was able to start and run the scooter tonight and it ran just fine.

I spent about 4 hours going over every page of posts on urbanscootin.com and found out that these scooters are real flakey. Many people have the same problems. Stuff like the battery has to be 12.9 or it won't even turn the engine over, fuel pump issues, ECM issues, etc.

There is a trick to how you have to feather and manipulate the throttle and brake (which is also serves to decrease engine speed) to even get the thing started.

The only thing I did differently tonight was that I reset the ECM while the bike was connected to a properly charged, spare battery. I have no idea if that was it or not.

I think they just start sluggishly and trying to start the engine electronically drains the battery lower than 12.9 very quickly. Then there isn't enough voltage to hold the starter relay closed, hence the clicking.

Even when you have 12.9 and the engine turns over, it seems a trick to start it.

I think they are just junk. Great idea, flakey product. Honda hasn't impressed me with the Metropolitan.

[prometheus578]

"Man, that's messed up!"

I figured that Honda would be more mechanically user friendly.. guess not.

I cried when the General Manager at the shop I worked at said that we were getting Vespas.

It's too late at night for me to get worked up into a lather....
SCOOTERS..... Bah!

[Shuriken]

And today as I was about to return it to the inlaws, it wouldn't start again.....

Peice of utter garbage.

The only thing I can think of is to wire up a "real" battery under the seat in the storage compartment. They lose the storage compartment but get more than 5 seconds of "starting attempts" before the battery goes under 12.9?

What a joke.

[Shuriken]

This is what I just posted on the scooter forum:
http://www.urbanscootin.com/forum/vi...hp?f=2&t=10783


"Hello,

I've browsed all of the threads (yes, I spent like 5 hours doing it) in search of an answer to my problem. I imagine it's pretty simple, but first, some background:

I own and have repaired a bunch of bikes. Most recently an 85 VMX12, 79 XS1100, 71 CL350, 74 XL350, and an 82 XL500r. I am no stranger to old bikes and how to fix them. I said "old" bikes. Manual choke, predictable carbs, etc.

Well, the in-laws dumped their 03 CHF-50P Metropolitan off in my garage because it would no longer start. They ran the battery down each time they tried. The scooter was purchased used and ran fine for a season. Then they complained that is started getting harder and harder to start and finally, it would not start at all. That's the only clue I have.

Knowing nothing about it, I tried to start it and found that the starter and/or swing relays would rapidly click but the engine would not turn over. I initially purchased relays thinking that they were failing to stay closed (which they were) but later sent them back unused after discovering that this thing won't turn over if the battery is under 12.5. So I charged the batt and tried again, but the engine just turns over and won't fire. The battery will turn the ACG as long as it can and as long as you are holding the brake and pressing the start button. The minute the battery voltage goes too low, the relays won't stay closed. So then I try the kicker and still nothing.

I've gotten it started twice after jumping it and trying 10 minutes worth of various methods of cranking and feathering the throttle. After I got it started and ran it around for 10 minutes, it seemed ok, but let it sit overnight and it won't start again.

1. I'm eliminating battery as a problem because we installed a new one with full charge. It happily cranks the engine until voltage goes low and that's all.

2. I have reset the computer by providing 12v to the jumper wire on the harness. This reset the computer but did not make the bike start like it should.

3. I have removed and inspected the carb. It is spotless. I cleaned it nonetheless.

4. I have checked and cleaned the auto-bistarter (automatic choke). That did not work. So I replaced it with a brand new one. This did not solve any problems.

5. I have checked the fuel pump and it appears to work normally. (normal clicking, I have observed that it is pumping fuel from the tank to the carb)

6. I replaced the air filter because it was dirty, but this did nothing.

7. I have verified the ignition system in terms of grounding the spark plug and observing a healthy spark when cranking, so I believe the ignition coil, spark plug, lead wire, etc. to be fine.

Finally after getting the bike running one time, I let it warm up and then just let it idle for a few minutes. I killed the engine and checked spark plug color and the spark plug is soot black. Knowing that this is a rich condition on that carb circuit, I removed the airbox and air filter completely and ran the bike again but the condition was the same - sooty black plug. Elevation is 5700ft and I think it's got stock jetting.

So my theory is that the bike will not start because it is flooding on the idle/mid carb circuits. Since the jet needle is not adjustable, the only thing that would cause such a rich condition at idle would be choke problems or air intake obstructions. Since the problem did not clear up when I removed the airbox, it has to be a fuel problem.

The floats are not sticking because I do not have fuel running out of the carb. Therefore, it has to be an automatic choke problem (auto-bistarter). This is why I replaced it, AND YET THE PROBLEM REMAINS! (yes I reset the computer after replacing the choke)

So now I am left with one option as I understand it: replace the computer.

I would rather sell this flakey peice of junk than spend $300 on a computer, especially if I replace a computer and don't know 100 percent that it will fix the problem. But nobody wants an already flakey by nature scooter if it won't start.

So, out of desperation, I post here in hopes that another mechanic or scooter rider can point me in the right direction. I'm sure there must be other things I don't know about, as all of my testing has been done without access to a manual.

Anybody have any advice? What is the troubleshooting flowchart for when the engine will not start?

Something controls the choke. There has to be a thermostat somewhere that the computer reads. When the thermostat indicates that the engine is cold, the computer must send voltage to the auto bistarter that would cause it to withdraw the needle from the carb body, which lets more fuel mix with the intake charge. When the thermostat reaches a certain point the computer shuts voltage to the bistarter an it springs shut and the needle closes the choke passage. That's my thinking anyway.

There is a coolant temperature sensor. That's the only one I am aware of. Would that be the culprit?

These scooters are way too flakey. My Honda Civic has nearly 300k miles. I have honda bikes that are over 30 years old and still run fine. What gives? Certainly someone has some light to shed on this problem?"