ok all you guys. i am in the final stages here. this grande is so close to going somewhere. all parts have been clean reworked and whatnot. it will start and turn over for about ten seconds then die.....can crank back up and the same happens....i have tried the little screw in the carb in all kinds of positions but still nothing different......what do you guys think??? thanks!!!!!!!
this is just a couple shots in the dark.. but a lot of grandes i have seen (well, 2) and heard about tend to get a huge build up up of oil and whatnot on the cylinder head around the decompression assembly. mine was running a little weird so i took the cylinder head off and soaked in engine de-greaser and then rinsed it off and used a soft detailing brush to clean all the crap off.
also, is your spark strong? what color is it? if its yellow/orange, thats no good... weak spark. you should have a big blue spark...
also, when you cleaned your carb did you use a fine piece of wire to make sure the jet is completely clear? as well as the float needle (rocket ship liiking thing under the float..) that should be completely free of varnish and everything. im sure you saw zippys photo essay on cleaning a vespa carb, right?
how about your airbox? did you clean the filter element (little screen thing) with brake cleaner or something? and make sure there is no debris in the airbox itself..
i know other people have already mentioned a lot of this.. but it pains me to know someone has a grande that isnt running.. hopefully someone else will mention something else to try also...
-casey
Couple of things
Are you using fresh gas from a clean container. Sounds like it could be water in the gas.
Did you flush the tank when you had the fuel petcock out?
Adjust the cable length where the cable goes into the elbow pipe on top of the carb. screw it out a bit to increase the engine rpms.
Check the tail light/brake light bulb dual filament.
Check the ground wire on the tail light, clean and trighten all ground contacts.
Do your rember to clean the Idle jet shown in the pictures?
make sure the Gas cap hole is not clogged and also the rubber insert.
Are you depressing the choke each time you try to start it?
Are you releasing the decompression lever after it starts?
Is the decompression valve closing? You may have to remove the cylnder head to check to see if the decompression valve is leaking. This is not hard just three hex head nuts. while you're at it, you can decarb the dome of the cylinder head. Then lay it on the bench and pour a little gas on the inside of the decompression valve and let it set for a little bit to see if th gas leaks out. If it does, you have a defective decompression valve and the valve or cylinder head will need to be replaced.
The head nuts should be torqued at 7 1/2 lbs.
Good luck
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