New member from France with a 1986 Aero 50

[GSX1400]

Ok, I'll do it again. The carb must be an italian FIAT one...Fix It Again Tony!

PITA though...I'll do that tomorrow, it's 9PM here.

Thank you very much for all the advice. I'll keep in touch.

[harleyracer59]

take a piece of bicycle brake cable fray the end. you'll notice the metal wires are different thicknesses. start with the thinnest and work up till its clear. only need 7-10 cm of cable.

[motormike]

https://www.google.com/shopping/product ... R0Q8wIIyQI

[cancunia]

If the engine dies at full throttle when you take your finger away, is that still the idle jet causing the problem?
It does sound like a fuel / air problem though. Are all of the joints tight between the carb & the engine, reed cage etc? Does the carb float move freely, and the float valve / fuel pipe unblocked?

Last year I very briefly had a Peugeot Ludix. I bought it as a non runner from a teenager who'd bought it from a friend. His friend had fitted an after market carb and it wouldn't start, they thought it was the reeds. After a lot of messing around, I found it was the float that didn't move. I bought a new float from a local shop and it started straight away. By that time, I'd also bought some new reeds and a few other bits but it was for sure the float at the root of the problem. I sold the Ludix as soon as possible due to the terrible build quality, the engine was solid enough but everything else was shoddy right down to the bathroom style halogen spotlights that were fitted (as standard) in place of headlights.

[noiseguy]

If the engine dies at full throttle when you take your finger away, is that still the idle jet causing the problem?
It does sound like a fuel / air problem though. Are all of the joints tight between the carb & the engine, reed cage etc? Does the carb float move freely, and the float valve / fuel pipe unblocked?

If the bike starts cold and then dies after 2 minutes, it's a blocked idle jet. The rest of the information is superfluous, but note you can get the bike running on the stand by restricting airflow, which makes bike pull gas from bowl through main jet. The engines will do all sorts of other odd running behavior on stand that they won't do with wheels on ground, so not a good diagnostic.

You're correct that slow fuel flow could mimic above but that's not the problem ever, in my experience they either flow or don't. Easily checked by waiting an hour and seeing if you can get another cold start, ruling this out as an issue.

[GSX1400]

Hi, feedback time!

So I took the carb apart AGAIN (sigh).
I checked every port/hole/circuit (how do you call the "pipes" molded in the carb that the gas flows in???).
Everything looked clear.
I could see the holes in the idle jet tube by taking off the idle screw. They're big enough to put a 1 mm drill bit. Anyways, big holes and I could see nothing seemed gunked up. When I blew carb cleaner from the intake of the carb into the idle circuit it would flow, etc...

BTW, I didn't dare take the idle jet out. I put a drill bit (1.5 mm, but I think a 1.75 mm would be better, 2 mm is too big) inside, a bit of leather in order not to make any marks on the tube and a good set of pliers. I tried to wiggle it a little, but...naaaah, I didn't feel like it.
Left the thing alone. I felt that it was to big a risk to take.

Making a long story short, I ended taking a wire (bike cable that I took apart to use only one slim wire) and sticking it up ...the idle tube until it came out the other side.
I did check if I could see any light out of there (with a powerfull tactical light) and it didn't seem so good. I didn't have any comparison picture though.
Pushing the wire through didn't make any gunk come out. The wire was clean.
I made it go back and forth a couple of times anyways, blew air as I could (mouth...).
I then sent some more carb cleaner in every opening that led to this idle system. I did see it come out and making a geyser under the throttle slide.
All the other carb circuits were clean and carb cleaner came out of them (bypass starter, main circuit and idle circuit).

Guessed the job was done, even if I still didn't see anything come out (dirt, gunk, whatever...).

Put the carb back on and...it f***ing works!!!

I let it idle, pushed the revs...only on the stand as the side belt casing is off at the moment.
Made it turn fast on stand and stopped it at once with the rear brake to see if idle was held and still level. Ok!
Superbe!!!

As I've been taking this carb apart many times, I wouldn't want to stay stranded at my next rally (end of october). I was thinking of changing the gasket kit.
What do you think of this one :
https://www.cmsnl.com/honda-nb50m-1985- ... 6-ZsmgzbIU

The reeds gaskets are new, the 2 inlet o-rings at the carb mounting too.

The fuel lines are shot. We have ethanol in our gas here (5 to 8% on regular unleaded gas and 10% in the other unleaded pump gas available). I've noticed that it harms the rubbers.
Hopefully I had a leftover of the fuel lines I had already changed when I got TT at first. It lasted around 6 years or so.
Not so much.

MANY thanks to all the contributors here.
Oh, and I now have 3 choke starters (one used that works ok). I can live some years of tranquility!

[GSX1400]

Oh, should there be an o-ring on the idle screw? I don't have any, and it works ok, just wondering.
On the carbs of my 4 cylinder Suzuki 1100 (Bandit-GSF), I do have 'orings on the idle screws + a spacer to protect it from the spring.

[GSX1400]

https://www.google.com/shopping/product ... R0Q8wIIyQI

Link doesn't work for me.

[GSX1400]

Last year I very briefly had a Peugeot Ludix.../..I sold the Ludix as soon as possible due to the terrible build quality, the engine was solid enough but everything else was shoddy right down to the bathroom style halogen spotlights that were fitted (as standard) in place of headlights.

When I was shopping around for a scoot, my Suzuki dealer, who is also a Peugeot one and who I know from the beginning of the 90's, told me to stay away from these Ludix and Clip Peugeot : they are crappy. And I think he also told me they were chinese made. Nothing to see with the Honda/Peugeot ones from the 80's.

[GSX1400]

Ok, so fun was short lived.
The bike works ok on the stand, it will idle for 20 mins without a problem. It revs ok.
Riding it brings issues.
It still dies when driving.
When you ride the bike, it'll pull strong from a start lifting up the front wheel! Full speed is easily 55 km/h and if I get time : 60.
So I did not do a compression test as the engine seems to be healthy enough.

I am convinced this is a carb issue.
Why? Follow below :
I swapped the spark plug to be sure upon stalling. It's ok, nothing changed (BPR 6 HS).
When it dies, I stop on the road and look at the plug : it's sort of greyish, dry. Clean. I tried putting the plug to the ground and checked the presence of a spark when turning the engine over. It sparks ok.

I checked if there was gas in the bowl at that moment just when the engine stalled. Ok, gas in there (I opened the drain plug).

Back home.
Tested the gas flow from the tap. Ok when turning engine over.
No gas in the vacuum tube.
No leaking gas when engine stopped.

Tested the floater. Ok. It closes the gas feeding.
Measured the floater level : between 12.5 and 12.9 mm (Honda says 12.2 mm so sounds ok). No ajustement possible anyways.
The rubber tip of the valve float looks ok, not deformed. Sleek sides.

The bowl is clean, no dirt, no deposits.

Swapped the by-starter with the old one and problem remains.
The by-starter circuit in the bowl are clean, light show through.

I checked all the carb circuits and I can see light when pointing through the holes. Nothing looks clogged/dirty.
I did another carb cleaner test (spray stuff) and the carb cleaner gushes from all the holes.

Reminder : reed gaskets new, by-starter gasket ok (new on the new by-starter of course and ok on the old one), O-rings new on the carb inlet pipe.
No leaking gas on the carb so gaskets all ok.

Went for a ride testing a trick. I took off the cover of the air box and the filter.
When the bike is going to die, I keep driving it and cover about 2/3 of the air entry. It stops dying (gotta be quick to do this while keeping on driving!).
If I take my fingers off, the engines starts dying again. Do the trick and it'll come back to life again.
Other test : drive the bike at, say, 50% throttle. Can ride about 1 km like that and it starts dying. Open the throttle a bit more and it'll come back and keep on running for a couple seconds and start dying again.
Open full throttle and it'll almost stall and suddenly go back in revs ony to stall a couple of seconds later.
Getting it to start again is very hard. I have to kick start it at least 20 times before it starts running rather badly first then better by blipping the throttle.
Get back on the bike and you can ride it around 200 meters! That's nothing...
Then do the 20 kick starter stuff again etc...
Took me more than an hour to get back home and it was getting worse and worse.

First trip this afternoon I did a 10 km trip without a problem. Only died 1 km from home.

I need help on this one before I burn the "*kin' thing. This is driving me up the wall.
I don't understand what's wrong and can't see anything clogging up the carb or whatever.

Tonight I left the carb in my ultrasonic cleaner with a special carb cleaning fluid. I did multiple cleaning sequences at around 60°C (about 133° F).
I haven't reassembled it yet. Need some sleep and let the pressure down.

[cancunia]

Is the main jet needle secure, what position is the needle clip on?

[GSX1400]

I'll check that needle. Never touched it or took it apart.
A friend of mine told me to check the petcock : maybe gas coming through but not enough?
Also told me to check the 2 crank rubber gaskets. When I took the variator off the other day, the gasket was at its place and everything clean.
Told me to do a pressure test to be sure.

[bonesv]

I'll check that needle. Never touched it or took it apart.
A friend of mine told me to check the petcock : maybe gas coming through but not enough?
Also told me to check the 2 crank rubber gaskets. When I took the variator off the other day, the gasket was at its place and everything clean.
Told me to do a pressure test to be sure.

Be careful using pressure tester because it only needs to be 6-7 pounds per square inch (whatever that is in metric terms) to see if it leaks out. A very slow leak-down is not necessarily indication of bad seals but a quick leak-down could be seals or other source; i.e. gasket or oil pump o-ring.

[GSX1400]

Still working on the bike.
There was a little hole in the vacuum pipe. Cut that bit off.
Still no progress.

Had a look at the petcock filter. Super dirty. About 20% clogged with dirt, no rust. Took a picture of the inside of the tank (I have an endoscopic camera) : clean, no rust issues.
Cleaned the petcock, pushed air backwards. Clean. Ok. Flushed tank to clean it too.
Still no progress.

Put a fuel line without my added filter on it. I have a little Mann filter WK21. You can't see inside easily, not sure if it's clogged or not. Took it off to be sure.
A little progress, I can drive at 20 km/h on a very light throttle without stalling. If I open throttle too much : ends up dying again. If it starts dying and I cut off, it idles at stop and I can get back riding IF I open slightly the throttle.

Put a fuel reserve directly on the carb and clog the vacuum line to test if it were the petcock that would be restricting flow of gas.
Same as above without filter.

The fuel inlet on the carb is clean and not clogged. The chamber of the valve float is clean. If I put the valve float inside it and turn the carb the otherway, the valve will fall. Not stuck inside.
Floater moves freely BY HAND.
Could it stick when gas tries to move it???

When I partly block carb inlet it will drive ok.
So looks like not enough gas is coming in the bowl because when I compensate by blocking air inlet it revs ok.

The valve float cuts gas ok. I tested it stationnary, carb on the table putting it upside down and blowing air in by mouth.
The floater is not leaking so it floats ok : we can imagine that fuel level is ok then?

I tried a leak test with a Mityvac pump with a dial.
I can't manage to have the carb inlet pipe sealed correctly. Don't have what I should need : a good sized plug.

A friend of mine, 2 stroke enthusiast, told me that the only thing that could be wrong at this stage would be the seals at the crankshaft. If leaking the vacuum could be unsufficient and not allow the engine to rev under load (it does rev when on the stand).
I don't see any leaks, but he says it could be leaking only from outside/in (hence the vacuum problem).
I don't see what else could be wrong, I ordered the crankshaft seals. They're inexpensive and my friend told me they were 32 years old so...no harm to change them.
Is it as easy to access on the alternator side as on the belt side?

Any other ideas on this mystery? Oh and my rallye coming in on 28th oct...

[GSX1400]

The gaskets should be : 91201GK8003
Superseeded by 91201KBN922

Anyone confirm?