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Scooter quits after several miles. Starts when cools down.

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A common problem but I've tried a lot of stuff and I'm still struggling.  I've read other posts and I think I've done everything.  Any advice will be appreciated.  A nice member has already helped but he is tied up today and I'm working on this...

 

 

A completely Stock SX200 - Scooter just rebuilt with new seals and bearings by a reputable experienced mechanic.  Runs well for about 4 miles until hot and then dies.  Will restart when it cools and go for another 4-6 miles, then it cuts out again.  This happened about 5 times now.

 

WHAT I'VE DONE SO FAR:

1)  Pulled the carb several times and cleaned and blew out.  Changed the float 3 times:  once with a new Scootopia one, and I also tried a couple original floats.  I run only non ethanol gas.  I sanded the back of one of the original floats a bit to make sure it wasn't getting hung up.  But, the same thing happens every time no matter what float, and when it cools I it starts on the first or second kick, and I make it 4-6 miles, and then it cuts out again and won't restart until cool.

2)  I pulled the fuel tap and put a high flow rear exit OMG/Italy tap.  Changed fuel line.  drained the gas.  put new gas in.  checked flow and it is flowing.  Rode it and same thing happened 4 miles later.

3)  I pulled the coil.  Put in another coil I had in a bin.  Same thing happened - it started easily when cool and ran it for a bit and then it died.  (Note:  I don't know if the coil I just swapped out is good, but the scooter did run until hot and then died just like with other coil.)

 

OTHER INFO - Things I notice...

 

When it dies I pull the plug after trying to restart at full throttle to see if the plug is wet.  I kick it over about 10 times with throttle full and then pull the plug but it's not wet?  maybe very very slightly moist but not wet?  looks dryer than I would expect.

 

When it dies I check for spark and there is spark.  I check with an inline spark tester and the spark looks good.

 

I checked the compression when hot and I got it pumped up to 115 - seems OK?

 

I pulled the gas cap off after it died several times,  and it did not make a suction noise, and it will not start when hot with the gas cap off.

 

I tried shooting some carb cleaner into the carb with the air boot off when it is hot, and it didn't start.  It did not fire.  Maybe I should try this again?  It is possible I didn't shoot enough in...

_________________________________________________________________________________________________________

 

I'm running out of things to try.  I don't think it can be the condenser if I'm getting good spark even just after it quits?  It doesn't make sense it is the coil if I'm still getting good spark after it dies?

 

What else can I do?

 

Thanks for reviewing and any input will be appreciated.

 

 

 

 

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Make up another ground cable separate from the original, ground the motor to the chassis in a different spot

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Thanks Panel63.  I'll give that a shot tomorrow when it stops raining.  Anything else I can try - anybody?

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Did you measure the end gap of the piston rings to chec for wear, and it the cylinder freshly honed?

Try a different consensor and HT coil one at a time to see if these things change the symptoms.

It may be some electrical components that are

Acting up and in their way out to pasture.

Is the cylinder head torqued?

Have you done a simple leak down test?

There is a good short video on how to do this on the new SLUK site with a bicycle inner tube and a blood pressure gauge and pump.

Best of luck with this.

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Did this problem just start or has it been happening since the rebuild?

Did it run ok for some time after the rebuild and then start acting up?

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It was a rough barn find scoot. Got it a year ago and it is the first it has ran in 40 years.

I'll check out that video on the leak down test.

I would think the excellent Lambretta mechanic that did my seals and bearings that removed the top end did torque down the head, but I don't believe he honed the cylinder or check the end gap of the piston rings. Not sure on those.

And thanks! I'll look into these suggestions.

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Sounds like an electrical issue or fuel starvation like vapor lock of the fuel line. Do you have clear line on it so you can see if there is gas in it or not? and it is not run over the tins where it can get hot? or kinked?

 

I would try seeing if it will fire on carb cleaner a couple more times like you mentioned. Then you can be more certain in going after fuel issues or spark issues.

 

Sometimes spark indicators will flash but the spark isn't good enough to fire...Condensor and coils will both give those symptoms...

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TR - thanks. I've been thinking fuel or electrical... Like I noted above, when it dies, I have pulled throttle wide open and kicked it over 10 times. Then I pull plug and it looks pretty dry? Strange. Then it cools down and it's a first or second kick scoot. Frustrating.

I want to try all the simple stuff before I start pulling the top end apart. Not really my specialty measuring ring gaps... I'm experienced only with the basics.

Tomorrow when not raining I will start it, run it for a few miles, then let it idle in my driveway until it cuts out. Then I will try shooting carb cleaner in again, but more this time, to see if I can get it to fire.

Thanks to all. Much appreciated.

Note: As mentioned above compression after it dies when warmed up holds at 115.

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I'll check compression when cold in the morning.  good question.  should have done this already.

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If it only happens with under a half tank it's a vapor lock due to gas cap vent clogged. If issue goes away with a full tank that'll be a clue to drilling our and blowing out has cap cent holes.

Do a flow test with tank full on Res and On

Then another with tank almost empty on Res

Should be at least a half pint per minute... more is better

If it flows different rates then rebuild gas cap or tap or replace

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now that's a good question.  (above).  I was just trying to solve this on my own without bothering the excellent mechanic too much:)  and, my excellent mechanic lives a solid couple hour drive away, but...probably time to go back!

 

I'll post my Sunday morning progress anyway since I've put a few more hours into it this morning:

1)  Lambrettayeroc - I just drove it a couple miles after the rebuild and then took it home.  So, no, the scooter had not been run for more than a couple miles after the rebuild until yesterday when I took it out for 8 miles and had to push it home the last couple.  Before that the scoot was a barn fresh mess.

2)  I checked compression again today cold and hot:  Cold today 120, and Hot 110.  Yesterday I had Hot at 115 but I don't think the scoot was as hot as today.

3)  I put in a third coil this morning out of my bin.  And it did the same thing.  Like clockwork the scoot died after a few mile drive as I let it idle in my driveway after the ride.  I've learned to take it on a 3 mile ride, and then let it idle in my driveway until it cuts out.

4)  Yes, it has a clear fuel hose and I can see fuel in there.  Tank is half full.  I did check the fuel flow yesterday after swapping the tap but forgot to mention - 1-12 oz per minute.  I also did blow air through the tank cap yesterday but forgot to mention.  I even swapped it to another cap yesterday.  And I did add another ground wire between the motor and the frame as Panel 63 suggested.

5)  After it died this morning when hot, I sprayed carb cleaner in and I got it to fire once right after it died, but tried to do it a few more times and no go.  sprayed and sprayed and kicked...   pulled the plug after I gave up and it was wet.

Note:  the carb cleaner crackled when I sprayed it in.  I've only put carb cleaner in the past to start a cold engine.  Not sure if the scooter is running too hot to cause the carb cleaner to pop and crackle or that is normal?

 

After it dies I also put the inline spark tester back on and it shows spark.  How good the spark is, I'm not sure.

 

Thanks to all for your input.  I guess I can still try and solder another condenser in, but I gave it a solid bunch of hours and it is probably time to take it back to an excellent mechanic.

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if you have an extra condenser, you can simply hold it to the cases as the bike is running or grow a third arm and do it while you kick the bike over, it will essentially run better when the condenser is on the engine, and immediately start to bog and die when its removed, save you some trouble of undoing fan shroud and removing flywheel, etc

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There are 2 typical possible sources for this:

 

1) Bad coil.

2) Fuel starvation

 

 You already changed the coil. Get another one and try again. More likely is it, however, that you have vapor lock. Install a clear fuel filter close to the carburetor. Drive the scooter without the side panel and once it's acting up, check out the fuel in there. Is there fuel? Is it bubbling? Next, sacrifice an old gas cap and drill a big hole in it, then install a vent tube, or just drive it half full without a gas cap at all. I'm pretty sure that will narrow it down to the most likely culprit.

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I think you have narrowed it down to the condensor... Try what Nick says, add the condensor lead to the wire running to the coil and tape a grounded to engine wire firmly to the can of the condensor. Add a connector so you can unplug it. Go for your usual ride and see what it does... If it continues to run well after the bad time, unplug and see if it quits...

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Hi Bernard.  -  I did already put 3 coils in as the story above goes - not one, and the scoot dies after the same amount of time with each.   And I always had a clear fuel line in, and I replaced this once with another new line, and another in line clear fuel filter, replaced the tank cap, blew air through both tank caps, replaced the fuel tap, changed the gas, checked the tank, filled it to more than 1/2, rebuilt the carb twice and tried 3 different floats, checked the flow to 12oz/minute...  

 

 


I just went to the garage and the scooter kicked over and started on the first kick because it has cooled.  But I know it will die again in few miles.  like clockwork.

 

So, Yes,  I hope it is narrowed to the condenser.  A few of you have said this now, Mike, TRs and Nick.  I guess I did all the easier stuff first, multiple times, and now I'm going to try that with the condenser (Nick and TR).  I appreciate the thoughts on this.

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If plug is too wet then fouling could cause it to cut out...

My old DL 150 years ago would run great while cold but while sitting at lights would cutout once hot. It turned out to a miss adjusted mixture screw... a bit too lean for engine when hot but fine when cold.

You said above it cuts out while your parked after a few mile ride. Does the idle speed climb up higher right before it cuts out...?

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Well, yep you did the simple stuff.  Condensor quality can vary alot and be flaky, but will bet next your stator is the problem.  I experienced the very same symptoms you have, after checking all that simple stuff first. 

 

Your excellent mechanic also knows everything about when that happened to me.

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To hopefully completely eliminate carb and fuel delivery (after Spiderwebb mentioned his problem above), I just swapped out to another SH1/20 carb.  I rejetted the one going in to match the one I had in there.  Took it for a ride, and exactly as before, the scooter cut out after a few miles use.  Ugh.

 

Time to pull the stator and try soldering in a new condenser.  Not too much heat...  I may try and find a replacement stator if this doesn't work, but for now, I'm going to try a replacement EFFE (Italian) condenser.

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It was the condenser.  It wasn't anybody's first thought, including mine.  

 

Turned out to be a simple condenser swap.  This morning I had it running for an hour, alternating riding it, and then letting it sit and idle, over and over.  Didn't stall or cut out.  Turned it off, and it started right back up.  Seems to be fixed.

 

Thanks to all that offered some insight.

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