MOPED ARMY

What color is the plug while its running good ?

Sure sound like fuel to me.

Pulling the gas line from the tank... you get good flow continuously ??

You have an inline gas filter ??

Take the carb back off and blow it out with compressed air (especially the float needle and seat)

Are you capable of checking the timing ?

Do it if you can.

It wouldn't usually be a 'timing issue' if it just ups and dies... (unless its getting REALLY hot... which incorrect timing can cause).

Do you know compression is good ?

If its not fuel or overheating... then it can sometimes be an electrical component that quits working when it gets hot.

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As far as the piston being black and charred.

its when the piston starts to go gray that indicates detonation (bad bad bad) and overheating.

If its black around the edges and going gray under the spark plug you are heading to disaster (holed piston)

(same as a pllug going white)

as far as compression, i haven't checked it. what are symptoms of bad compression?

geeez doood... I wish someone would write a nice guide that contained advice and how-to about checking compression and setting timing.

We'll have to find somebody to do that.

Do these ------>

1... Why does the petcock just 'trickle' ?... no good.. take the petcock off and clean it till it flows good... check the filter on the new carb for crud buildup.

2... Do a crude check of compression (finger over the spark plug hole while somebody else pedals)... do it properly - read the guide.

3... This ped has points ?... then set timing per my 'guide'.. (I hope your ped has T and F marks on the flywheel.. use the cig paper method)

4... If the plug is white... Then you better put a richer main jet in now... you can go back down later.

5... The plug is white ?... Then DO NOT put a hotter plug in it !

Do all of those and then answer if it doesn't get better.

Chris,

I am in favor of you taking it to Ike before you have a disaster.

Everything Fred says looks good to me except for the fuel flow. One man's trickle is another man's satisfying piss. Imagine the rate at which your ped can use fuel, like how long would it take to consume a pint, then let the fuel flow into a pint jar and see how long it takes to fill, it should fill at about 10 times as fast as you can use fuel. This gives you a better idea of adequate fuel flow and will also show a clogged tank vent.

If you can easily drain the float bowl, Turn off the gas, drain the bowl and see what comes out. Then ride til it quits and turn off the gas and try again. If you get a lot less fuel, you have a fuel flow problem, which could be causing lean running and you need to fix it before you can jet correctly.

You also must have the timing correct before you can jet correctly.

Ron

ChrisR

The oil on the rear hub is not related to your engine problem.

There is a seal or fiber washer that should go on the access screw or hex head bolt , whichever you have on your Grande. There is also an oil seal (Black rubber "O" ring) that goes on the shaft that the rear clutch rides on. Either of these could be causing the excess oil.

As far as the engine issue, i agree with the other guys, to take the fuel petcock off and clean it. take the fuel line off at the petcock end or you'll have heck a of a time getting the petcock out.

The petcock has a plastic tube covered by a wire or nylon mesh filter that sticks up into the frame. Pull the petcock out carefully and slowing so the mesh filter comes out with the petcock. Once out, put it on the bench and carefully unscrew the mesh filter. Then you should see a plastic tube. You can remove this to, it just pulls out. Use some WD40 to loosen the gunk around the tube before you pull it out. Note which hole or side you took the tube from. This is the Full ON hole, the other hole is the reserve hole. You don't have to take the ON/OFF stem out and I would not recommend it.

With the tube out, take the petcock and squirt some strong detergent into the holes on top and gas line fitting end on the bottom Then run very hot water into the holes to try to melt and dislodge some of the old varnish. You can also use acetone but flush it with water immediately. Squirt WD40 in the holes and then use compressed air to blow through the fuel intake stem. Turn the valve to the UP position and blow air into the fuel intake stem and the repeat for the DOWN position. You should be able to get both holes free this way.

Before you put the petcock back on the bike get you a skinny funnel to stick up under the fuel stub on the frame and then flush the tank with about a cup of acetone, swish it around and follow with a couple of cups of gas until it runs free.

Then put the petcock back on the bike. Stick a fuel line on the petcock end with the other end free and put some gas/oil mix in the tank and test the petcock in all three positions to make sure you have free fuel flow and that it will shut off.

Remember you have to have enough fuel in the tank to go above the plastic tube for the DOWN position to work properly.

You can also run hot water and soap through the old fuel line if it is the heavy plastic Vespa original. This will make it a little more pliable and easier to reinstall. If you use this fuel line, use in in your fuel flow test to make sure it works OK.

Got it running perfect! I decarbed the cylinder and piston, and put on a new base and head gasket. Now my chops are golden brown!