getting gas,spark,compression, wont start

ok i got a 78 puch free spirit that iv just finished rebuilding. after some adjustments we finally got it sparking. iv also got my carb filling with gas so i know its got gas. and its obvious that its got compression. now a few nights ago it started up and was running but only when i gave it gas, if i cut the gas off it would die immediatly. but now it wont even start. we checked and were still getting spark, i took off the petcock and it was clogged so i cleaned it and put a filter in. now thats working fine and im getting plenty of gas into my carb but for some reason the moped wont start. any suggestions?

Re: getting gas,spark,compression, wont start

Mike Scouty McScoutington /

how does the pipe look? cloggy cloggy? and how do you know that you have compression? is your timing set right. i would check those 3 things and see if you can get it worked out with those.

Re: getting gas,spark,compression, wont start

uhh im not to sure about the pipe although i do have some black liquid dripping out of it every once in a while. i know i got compression because when i stick my finger where the spark plug goes in i feel it pushing the wind out when i turn flywheel. i can also hear the air getting compresed in there. im not to sure about my timing, maybe ill try that in a few spots. well im gonna go try that now

Re: getting gas,spark,compression, wont start

See Ya Moped Army /

Yes, but how much compression? The finger test doesn't tell the whole story. You need to check it with a gauge.

Re: getting gas,spark,compression, wont start

i dont have one of the gauges. its a brand new piston so its not all scratched up or nothing and my cylinder is very clean. ok i just sprayed starting fluid on the spark plug and it started right up but it will only stay alive if i give it gas, once i get off the gas it dies. i tryed changing the timing and that didnt work so i put it back where it was, iv tryed changing the idle screw a few times, wasent helping. i guess im just not getting enough gas to the piston.the bowl on the carb is filling up so its gotta be something between the bowl and the intake. my jet it cleaned so i really dont know what could be wrong.

Re: getting gas,spark,compression, wont start

how sure are you that you set your timing correctly? it's not something that you just guess at, and if you adjusted it once, how do you know that you set it back where it had been?

I would say that you are not getting gas, unless your spark plug is soaked, then your gas is not really there, either that or you choked it to much, flooded it, and then you would not be getting spark.

you put a new filter on an old line, that is never a good idea, old lines shrink inside over time and the smallest air bubble will then give you a sort of vapor lock, and putting that new filter on that old line makes it that much easier to trap air in there, so unless you know you are getting gas by taking the bottom off the carb and having gas run all over the place, it's not really there.

you don't have one of those little banjo bolts on your carb with the hiden filter screen in it that could get cloged with a spec of dust, do you?

Re: getting gas,spark,compression, wont start

Completely clean the inner workings of the carb with a fine wire and carb cleaner.


Live to ride, Ride to work

Re: getting gas,spark,compression, wont start

no it was the original filter in the tank, but it fell out and i didnt know so now its in. i do have one of those little screens on my carb at when the gas enters, but my bowl is filling up so i know its getting past that. i guess ill just take the carb apart again for the 3rd time and make sure everythings fine

Re: getting gas,spark,compression, wont start


Re: getting gas,spark,compression, wont start

it's really easy to miss some crud in the jets, I like to use a wire twist tie wire, peal the paper/plastic off and run it thru a few times untill you see a clean round hole in each jet.

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