Moby stalling after pedaling.

Kyle Osborne /

So Got spark, and went to fire it up today, but as soon as I'd stop pedaling,or even before that it'd stall out....any reason why?

I know i'm getting ignition, becasue when I release the decomp as I"m pedaling, it gets really easy to pedal until I slow down the pedaling, thenit gets harder until I engage the decomp again. I can also hear it. I've tried using choke and not using choke and even giving it a bit of throttle....

and I have a 6/12v Moby 50v, According to Rebelmoby

anyhelp/advice is appreciated.

Thanks.

Re: Moby stalling after pedaling.

If it stalls when you stop then you could have a bent clutch drum not allowing it to spin at idle because the clutch is catching on the bent part and causing a stall.

Just an idea though. Can you ride it if you crank it and take off before the stall ?

Re: Moby stalling after pedaling.

Is the plug wet with fuel or just sort of dry-ish.

Check that your are actually getting fuel to the engine.

Give it a leakdown test to check for vacuum leaks.

Re: Moby stalling after pedaling.

Kyle Osborne /

yes, the sparkplug is wet when I pull it out.

I also switched the switch on the side of the headlight, and I got some backfire afterwards while pedaling...but still no luck in firing up.

my brake light also works.

Re: Moby stalling after pedaling.

Kyle Osborne /

Rebel Moby Wrote:

-------------------------------------------------------

> Is the plug wet with fuel or just sort of dry-ish.

>

> Check that your are actually getting fuel to the

> engine.

> Give it a leakdown test to check for vacuum leaks.

I don't have the tools to do a leakdown test...is there a redneck/ghetto way of doing one?

but I asm getting gas, the spark plug is wet

Re: Moby stalling after pedaling.

Take off carb and exhause pipe, remove spark plug, insert car fuel line in the plug hole, put engine at bottom dead center, block intake and exhause with your hands, use lung power to see if there is a vacuum leak. The engine should hold vacuum.

If it can then while the exhause is off clean it really well and check if the exhause port is carboned over, clean the port with some popsicle sticks by carefully poking at the carbon.

Timing might be off - you need the cam/clutch puller tool for that... (edited)

Re: Moby stalling after pedaling.

I had a hell of a time getting mine to run recently. I kept checking for spark and setting timing but it still wouldn't start even though it was all looking good. What finally worked for me was grounding the condenser to the frame and I found a small piece of metal that was stuck in one of the rotor grooves. Just the smallest problem can stop a moby from running well. The electrical is very finicky and I'd double check everything connected in the ignition and the flywheel.

Re: Moby stalling after pedaling.

Cleats Onionpockets /

You're certain you're getting consistent spark? New plug? Solid wire from HT coil to plug, right? When in doubt, swap out ht coil and replace condenser first on a moby.

Re: Moby stalling after pedaling.

Kyle Osborne /

Cleats Onionpockets Wrote:

-------------------------------------------------------

> You're certain you're getting consistent spark?

> New plug? Solid wire from HT coil to plug, right?

> When in doubt, swap out ht coil and replace

> condenser first on a moby.

Yep, already replaced condenser, and I've got a strong constant spark.

Re: Moby stalling after pedaling.

Kyle Osborne /

Jordan Guest Wrote:

-------------------------------------------------------

> I had a hell of a time getting mine to run

> recently. I kept checking for spark and setting

> timing but it still wouldn't start even though it

> was all looking good. What finally worked for me

> was grounding the condenser to the frame and I

> found a small piece of metal that was stuck in one

> of the rotor grooves. Just the smallest problem

> can stop a moby from running well. The electrical

> is very finicky and I'd double check everything

> connected in the ignition and the flywheel.

Yep, it's grounded to the frame..I got it mounted beside the HTcoil with the metal bracket it came with.

Re: Moby stalling after pedaling.

Kyle Osborne /

Well, I think I found the source of my problem, leaking carburetor. I had a makeshift cardboard gasket on the carb, but the gas soaked through it and now leaks....

It's beeen a PITA finding some gasket material as well...I can get a roll of it 36''x18'' for $8-$12 depending on thickness...but I only need a little3-4'' piece...and I don't wanna spend that much on it...when I only need a small piece..

it's a Gurtner Carb.

it's Gurtner part number #18880 I need....

and no way I'm gonna use that gasket in a tube stuff....I heard of clogged jets and stuff...and most don't get along very well with gasoline present...

Re: Moby stalling after pedaling.

If it is leaking on the figure 8 gasket when just idling or shut down then the float is too high, upside down or there is dirt in the needle seat. Fuel level is actually supposed to be about 2mm below the top of the bowl like any other carb. If it is weeping out of that union then there is too much fuel in the bowl which would also mean it is weeping into the carb throat.

Go to the plumbing shop anyhow and get some gasket material there if $8-12 is too much $ for you, they will sell you a small square of gasket material for you for a buck or two. Can also get a 25mm oring at the plumber shop so you can replace that on the Gurtner as well.

Re: Moby stalling after pedaling.

Kyle Osborne /

Hm, plumbing shop? Never would've thought of a place like that. I'm gonna see if the nearby NAPA or Car Quest has anything....

So close, yet so far

Re: Moby stalling after pedaling.

Kyle Osborne /

alright,so I lowered the float a bit by a couple mm...but I think I may have to lower it some more, as it's still seeping gas at the figure 8 gasket...but it turns out I"m not getting any ignition, but I am getting spark....

and I think when I re-installed my carb the first time, I didn't seat the throttle cable right...so I think that's why it's also wasn't working....it was letting all the fuel into the cylinder and not igniting...and I figured that out because I was getting fuel drips out of the tailpipe/muffler.

am I on the right track?

Re: Moby stalling after pedaling.

Off track.

You need to go on wiki and read Fred's Guide.

You need to make sure you clean the carb as well as the needle seat and tip of the needle so when the fuel rises in the fuel bowl it will be shut off before it becomes too full. Clean all of the carb -

http://mabecanemobylette.freeforums.org/cleaning-the-gurtner-carb-t662.html

Then check and set the float level -

http://mabecanemobylette.freeforums.org/gurtner-float-levels-t667.html

Then give it the leak down test to see if you are busting your ass on a bike that has leaning crank seals in the carter.

Re: Moby stalling after pedaling.

Kyle Osborne /

alright, so I got the carb cleaned out and such, lowered the float to what it said in the pic in that link....13mm on pointy side.

Tried starting it again, didn't go. but once I cut off the fuel supply to test if it was something else, it did start. It only used the fuel that was in the carb, but it did start...and idled for about 3 seconds, I gave it some gas and the RPMs went up, engaged the decomp to turn the engine off and then tried starting again, and it did....then it went till it ran out of gas in the carb.

It will not start though if I have the petcock on....I also took the muffler to clan it out.....and discovered about a 1/4 cup of black fuel sloshing around inside it(that was from teh 1st time I tried starting it with fuel,so it's not old fuel...)....I emptied it out and cleaned the muffler up, took the tail bit off and cleaned inside it....gonna try again tomorrow.

Seems I"m getting closer....

Re: Moby stalling after pedaling.

Gurtners are a pain in the butt to clean. If she is still no start with the fuel turned on then it has to be either the float valve not sealing, or the float not floating.

The float valve is enough of a pain to mess with that I made a test stand because I got tired over time removing and reinstalling many Gurtners on many bikes... test stand is actually only like 5 minutes to make if you look see on this thread at the 6 or 7 post...

http://mabecanemobylette.freeforums.org/viewtopic.php?f=29&t=667

Re: Moby stalling after pedaling.

Kyle Osborne /

the float floats, and I'm pretty sure it's sealing, as I tested,by putting the pointy end inside the top piece of the carb, and it seemed to seal..I felt no play or anything and it felt firm when I tried moving it while it was seated in the top bit, it felt bottomed out, and it bottomed out hard,and I turned it and couldn't feel or hear any grittyness.

as for that stand, is there anything I could substitute for kerosene?

and how will I be able to tell if my adjustments are correct/float needle is seated?

thanks for the help.

Re: Moby stalling after pedaling.

I am pretty sure it was leaking or you would not have a non runner only when the petcock is turned on.

You can use diesel if you like or petroleum based paint thinner, make the rig set up the carb, load fuel and look for it over flowing... leave it be while you go get a coffee and then look again if is has leaked - no leak the float is sealing and good to go - if it did leak then give it a clean or adjust and try again...

...at least it is not going on the bike off the bike on the bike off the bike on the bike off the bike on the bike off the bike on the bike off the bike on the bike off the bike on the bike off the bike on the bike off the bike on the bike off the bike on the bike off the bike on the bike off the bike on the bike off the bike on the bike to figure out where the leak is...

Re: Moby stalling after pedaling.

Kyle Osborne /

haha, yea true. thanks. I"m pretty sure I have some petrol based thinner around...

Re: Moby stalling after pedaling.

This may sound dumb, but is the fuel tank vent clogged? Try running with gas cap off for a minute?

Re: Moby stalling after pedaling.

Kyle Osborne /

ok, making progress, adjusted the float and and started the idle screw with the spring under it all the way in and adjusted it out about a 1/4 turnout....itruns.but it idles too high...

and it kinda bogs down when I give it more gas....the choke is off.

Re: Moby stalling after pedaling.

If she is not flooding now then you might need to shift attention to the timing if she bogs when the throttle is twisted...

Re: Moby stalling after pedaling.

Kyle Osborne /

alright, and the points should open fully 2.5mm before the piston reaches TDC?

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