Noob needs some advice

Larry Baltz /
sagscout
Aug 24, 2019 11:55PM

Hi All,

I have an early 70's Peugeot 103, All stock, 6V, No Brake lights, No kill switch.

Moped starts very easy with just a little choke with one or two kicks. Runs smooth and tops out at 25 MPH. When engine is hot if I shut it down for more than 1 minute (less than a minute or so, no issue) it will not start again for at least 1/2 hour. While in the no start condition spark appears to be strong and blue & float bowl is full. Maintenance since I got this thing a few weeks ago, includes Gas Tank flush (no rust or crap in fuel line) complete carburetor clean and soak (disassembled), New spark plug, and other non-engine related tasks.

This problem was my main reason for carb removal/cleaning.

Any suggestions as what to chase next?

Thanks.

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Re: Noob needs some advice

live ɘvil /
themotorhead
Aug 24, 2019 11:57PM

Make sure carb is not flooding. Flooding would come from a leaking float needle which is part of the float valve.

An engine needs more fuel when its cold.

Its getting too much after warmed up.

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Re: Noob needs some advice

Rebel Moby /
rebelmoby
Aug 25, 2019 10:15AM

Could be carb float valve has a spec of dust and is weeping into the throat. Gurtner carbs have brass on brass seat arrangement so it is very sensitive to dirt. Check that the point is facing UP on the float valve (often it is assembled pointing down, almost everyone has done that - OOPS)

Also make sure the blade is fully retracted for the choke when it is released, partial covering the bore wil give a richer mixture.

Verify your timing in case you are creating too much parasitic heat in the engine by too much advance timing.

The condenser can be troubled by heat (sworn enemy of all condensers) and the spark you see might not be strong enough to fire across the gap when it is in the compressed environment of the combustion chamber. It would not hurt anything if you did the external condenser modification anyhow.

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Re: Noob needs some advice

Larry Baltz /
sagscout
Aug 25, 2019 11:14AM

Truly appreciate the advice. I will start checking all of this.

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Re: Noob needs some advice

Larry Baltz /
sagscout
Sep 12, 2019 09:36PM

I think you nailed it. I wasn't able to correct the overflow, so swapped to a Dellorto SHA 15.15 and without the leaky float bowl, no more flooding and starts every time (even when hot).

Now I just have to dial into the correct jet. I think 70 is too big.

Thanks for the good advice!

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Re: Noob needs some advice

Don Ohio /
don45640
Sep 12, 2019 11:18PM

70 should be way too big. If it's stock,try a 52.

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Re: Noob needs some advice

Larry Baltz /
sagscout
Sep 12, 2019 11:59PM

> Don Ohio Wrote:

> -------------------------------------------------------

> 70 should be way too big. If it's stock,try a 52.

Will do. Thank you.

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Re: Noob needs some advice

Larry Baltz /
sagscout
Sep 16, 2019 03:40PM

> Don Ohio Wrote:

> -------------------------------------------------------

> 70 should be way too big. If it's stock,try a 52.

Hi Don,

While waiting for the smaller (50's) jets, I disassembled, checked, and decarbed the piston, head, and cylinder and replaced the gaskets. It looked like new inside so reassembled and saw no great improvement. Sluggish start and top speed is 25 mph on a slight decline. I figure I'd check timing and it was advanced 50% farther than factory spec (opening the points very late about .75 mm btdc). Fixed that, gapped to .4 mm and wow what a difference! Fast start off the line and top speed is now 28-29 mph on the flat.

The jets arrived and I swapped down from a 68 to a 58 (largest I ordered in the 50's) and it would barely run, and then only on full choke. I'm guessing I need to stick with the bigger jets. FWIW, the Delloto has the plastic "12" slide...

Is it worth replacing the reeds on this and should I take the plunge and replace the bottom seals/gasket? It's not 4 stroking, the stock exhaust baffle is cut to 3.5" so how fast should I expect this to go?

Lots of questions and thanks to everyone for the help so far and in the future

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