trouble shoot a Peugeot that won't start

Earl Laboissonniere /

1978 Peugeot 103 LVS U2 hasn't run in 25 years so I did the following which is all a novice such as myself knows to do:

- New spark plug

- New fuel mixture

- New carburetor

Then it started no problem. I replaced the throttle cable. It ran for about 90 seconds then stalled out and will not start. So I pulled the carburetor off and check the main jet to see if it may of been plugged (when I blew thru it I couldn't really tell), I opened the float bowl it was clean except for a few very small specks of something. Other than those two things is there something else I can do to make sure I didn't plug something in the carburetor? I assume there is an idle jet, but I don't know where it is.

With the carburetor back on and the fuel valve open I removed the main jet and fuel did come out. I double checked and there is spark.

Any suggestions would be greatly appreciated by myself and my grandson.

Re: trouble shoot a Peugeot that won't start

What carb you using?

Re: trouble shoot a Peugeot that won't start

Earl Laboissonniere /

OEM Gurtne 12mm.

Re: trouble shoot a Peugeot that won't start

Earl Laboissonniere /

Also when I pulled the spark plug to check for spark it looked clean. Meaning no carbon build up from trying to start. So the carburetor is getting fuel, but I am not sure it is going to the right place to (chamber) to ignite.

Re: trouble shoot a Peugeot that won't start

You may have soft seized it. No replacement carb comes jetted specifically for your bike. On a two stroke, the oil for lubrication is carried with the fuel, and metered by the jet. Too small jet=too little lube=kaboom

What carb did you buy? A dellorto Sha 15/15 with a 1mm shim is the recommended replacement if you don't replace with a bigger intake manifold, and runs around a 70 jet. The stock gurtners are notoriously unreliable and the clone replacements come jetted wayyyy to lean.

I'm not trying to be mean, just letting you know that unlike a four stroke, no carb you can buy will work plug and play.

Re: trouble shoot a Peugeot that won't start

Earl Laboissonniere /

So I should check my compression to see if it is soft seized?

Re: trouble shoot a Peugeot that won't start

Can't really trust the compression as the rings haven't gotten hot for years, but is is a good idea to check

You can check the cylinder visually by unbolting the cylinder head and looking into the bore. If the sides are smooth and without scoring or smearing your probably fine. But with a bike that old, you may be looking at a tear down to replace the bottom end seals

It's important that you say what carb you installed and what jet is in it....that way we can tell you what jet to run, you want to handle that first so you don't seize it when it does run.

The best option would be to clean the original carb and reinstall it. Or if you did buy a factory replacement style gurtner, put in the jet from the original carb.

These are single jet carbs. (edited)

Re: trouble shoot a Peugeot that won't start

Earl Laboissonniere /

Thank you Aaron. Yes I did purchase a new carburetor, a OEM Gurtner 12mm. The jet from the original Gurtner is 245. The new Gurtner is (well the stamp is cut off by the screwdriver notch), but I do see a 64.

If I unbolt the cylinder heads what kind of trouble can I get myself into?

Re: trouble shoot a Peugeot that won't start

Sorry, missed that it's an OEM gurtner. Try cleaning the original carbs jet and putting that in. At least then you'll know it's not gonna seize when it does run, as it's the same carb.

The gurtners can be very finicky. If you hadn't just bought an OEM one is advise you to get a dellorto...but I digress, at least get an in line fuel filter from an auto parts store. They hate any particulates.

You could have fouled the plug too, when it ran. Was it idling? Or with throttle?

Re: trouble shoot a Peugeot that won't start

Earl Laboissonniere /

Again thank you.

New spark plug. When I pulled the plug to check for spark it was clean of any fuel or carbon even after several days of trying to start it.

I will clean the old jet and install it in the new carburetor.

Re: trouble shoot a Peugeot that won't start

Basically none. There are no valves, cams pushrods or anything in the head. Four bolts and it will slide off, it's just a chunk of metal with fins... then you can look. And hopefully just put it back on. Use some kind of penetrating lube, even wd40 so you don't strip the bolts, go gently. But otherwise not a big deal.

There may be a decomp valve, which could be causing a problem as well. But it'll just be connected to the head with a cable. Don't need to remove the cable it'll stay attached just fine.

If your cylinder looks good, but you have low compression. The decomp valve can be at fault. But really don't worry about that now. I'm more concerned about the cylinder bore.

I'm here all the time by the way and although I'm no genius I'll do my best to help. (edited)

Re: trouble shoot a Peugeot that won't start

Earl Laboissonniere /

Thank you.

I will pull the cylinder head off this evening and check the bore for and indication of a soft seized. And yes there is a decompression valve. Which brings me to another question. I replaced the RH grip when I replaced the throttle cable. The old grip has the lever for the decompression valve. Any idea how that small lever comes off? It looks like it just slides into the groves and should just slide out. I don't want to pry with too much force for fear of breaking it.

Re: trouble shoot a Peugeot that won't start

Do you mean you replaced the whole throttle assembly? Removing just the grip shouldn't affect the decomp cable at all.

You can remove the the head without taking off the cable.

Re: trouble shoot a Peugeot that won't start

Earl Laboissonniere /

I misspoke in that when I replaced the grip and throttle cable I also replaced the brake lever unit which is a casting that has the "stop engine" i.e. decompression lever attached to it. The new brake lever unit didn't come with the stop engine lever and I would like to reuse my old one. But I can not remove it from the original unit. It looks like it just snaps in place, but I don't want to apply too much presser for fear of braking it.

I attempted to attach a pic, but it is over the maxim size allowed.

Re: trouble shoot a Peugeot that won't start

Do your controls look like this? If so, once the cables are removed and the control housing is off the bar, the lever should just sort of slip out. There may be a screw-in retaining pin that goes in behind the front of the brake lever and into the bar itself to keep the control from rotating.

IMG_2806.jpg

Re: trouble shoot a Peugeot that won't start

Earl Laboissonniere /

Hello Joey P,

Very similar. I was thinking that it should just slip out as well, but it isn't. I will keep working it. And no there is no retention screw of any kind.

Thank you

Re: trouble shoot a Peugeot that won't start

Earl Laboissonniere /

I took the cylinder head off, the bore looks fine. And the piston moves freely when I turn the fly wheel. I am getting spark, fuel into the carburetor and air. Still won't start. The spark plug is dry. Fuel isn't getting to it. Any thoughts? Suggestions?

Re: trouble shoot a Peugeot that won't start

Check the needle valve under the float. It could be clogged from fine particles in the tank. Def get an inline fuel filter too to avoid that. Never seen your carb but it very well could have a screen type filter like the banjo of a SHA has. It could be clogged. Also did you mount the carb level to horizontal? Carbs are gravity fed; they don't work well at much of an angle.

Keep trying. I got my ped running with help from MA.

Re: trouble shoot a Peugeot that won't start

Have you examined your reeds yet? Will the bike reliably run by spraying some starter fluid in the spark plug hole?

Other than that, perhaps broken piston rings.

Re: trouble shoot a Peugeot that won't start

if you know it is fuel related u can verify by squirting in some premix in the spark plug hole and start. If it runs right off the bat then dies, then try again... but this time keep feeding the carb with premix and messing with the throttle to keep it running. HAHA take that non running pugot

This will let u know a few things, if its fuel related or not, if it will possibly run on choke or not (tiny choke lever), and how off it is meaning how big the air leak is or if it idle circuit or main thats clogged, say if works at WOT and will not idle then suspect main and visa vera.

I think the gurtner has tiny idle passages(take a look on myrons page for a cutaway) good luck and post any findings.

Re: trouble shoot a Peugeot that won't start

Earl Laboissonniere /

Thank you Pat Splat, Joey P, Jai Dot, Aaron Blair,

Thank you for your comments and suggestions.

So last night I pulled the new carburetor off and replaced it with the old one after disassembling it and giving it a deep cleaning (less the air filter). Spaying starting fluid directly into the carburetor and into the cylinder via spark plug opening. It ran for 10 seconds (the time it took to burn the starting fluid). I repeated process but only got choking and coughing, but not starting. It was getting really close to starting, but not. Pretty much the same results not using starting fluid just applying the choke and peddling like heck. But the fact that it did start for a short time can I assume that wiring and grounding is good.

Almost like my timing got off center?? But I don't see how that could be because it ran somewhat okay just the other day. Maybe something with in the ignition? Compression? How can I trouble shoot compression / ignitions issues? Better question is should I trouble shoot those areas? Once again I feel obligated to mention am a novice at this and my comments and questions may not be on target.

All comments are useful, because I don't know what I don't know.

Thank you to Moped Army folks and everyone have a productive day.

Earl

Re: trouble shoot a Peugeot that won't start

I'd bet money it's a fuel issues. Those carbs really cause problems. I cleaned my stock gurtner over ten times before I got it running. And still ended up replacing it with a dellorto Sha 15:15.

If it ran at all, it's not timing stopping you. Is the choke on? Are you running the stock airbox/airfilter?

Try filling the float bowl manually maybe?

It just seems like you aren't getting enough fuel. Have you tried shooting some premix down the carb?

Re: trouble shoot a Peugeot that won't start

Yeah, based on your issues, I completely agree. At some point, fuel isn't getting into the cylinder. You said that fuel comes out when you pull out the main jet. Let the carb drain completely dry, put the main jet in, attach the fuel line / turn on the fuel, and then remove the main jet. You should have fuel flow out of there fairly quickly.

If not, one of your passages is still clogged.

> Aaron Blair Wrote:

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

> I'd bet money it's a fuel issues. Those carbs really cause problems. I

> cleaned my stock gurtner over ten times before I got it running. And

> still ended up replacing it with a dellorto Sha 15:15.

>

> If it ran at all, it's not timing stopping you. Is the choke on? Are you

> running the stock airbox/airfilter?

>

> Try filling the float bowl manually maybe?

>

> It just seems like you aren't getting enough fuel. Have you tried

> shooting some premix down the carb?

Re: trouble shoot a Peugeot that won't start

its premix in a bottle toss the starting fluid.

Re: trouble shoot a Peugeot that won't start

If the bike has done some caughing or poping when trying to start yes it could be that the flywheel timing has slipped. Maybe the PO had the flywheel off and it was not cranked down tight enough.

You can check a rough estimate of the timing by just removing the spark plug and then use a small screwdriver to feel for the top of the piston. When the piston is at the very top of the stroke then glance at the rubber grommet that holds the spark plug cable and you will see the arrow line will be about 3/4 if an inch to the right of the center of the rubber grommet.

If its like roughly in that area give or take a 1/4" it will start. If it's 2-3" on either side your timing has slipped

(edited)

Re: trouble shoot a Peugeot that won't start

Earl Laboissonniere /

Hello, cheetahchrome, Aaron Blair, Joey P, pat splat, Jai Dot. Thank you all for taking the time to comment.

Update. I re-gap the spark plug down to .021, recleaned the carburetor, and poured premix into the cylinder via spark plug opening. Peddle like heck and it started YEA!!! Runs poorly, low power. I did take it out for a quick ride to show my grandson, he lives 5 minutes away (he was very excited, needles to say). So thank you for the advice an encouragement. Tomorrow my grandson and I will replace cables.

PS. I am looking for engine covers. Ideally green, but origional engine covers if anyone knows where I can buy them.

Thank you

Earl

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