Modern Vespa

I find my (carbureted) LX 150 takes a few minutes to warm up before it is willing to move. If I give too much throttle too early, it will stall out (always starts right back up). The behaviour is more pronounced in the cooler season (5C), but happens in the summer too (30C).

I am familiar with the autuchoke, and always figured this warm up was just how it is with autuchoke and carbs. But I thought I'd put it out there and ask for others' experience with this.

The thing is, I could swear when I first got the bike a couple of seasons ago, I would just start it up and ride away. But now I am second guessing my memory.

Back then I had problems with stalling out, which was solved by valve adjustment an AF mixture + idle adjust. Overall the bike runs much better now, but can't help wondering about the start up process.

Last thing... I currently have a 35 idle jet, with a 38 in my box that I never got around to installing yet. If I went ahead with it, would it make the startup worse?

Have you tested the auto choke to ensure the needle is moving?

What's the condition of the rubber diaphragm? Is it stiff? Cracks developing in it?

I've been taking with scootchilla to solve his problem which siunds a lot like yours. He's in NY with cold temps.

bigger pilot jet with the fuel mixture screw turned appropriately should make starts easier with all other components in proper working order.

Yes. Got 3.5mm of travel over a 5 minute bench test. 20 Ohm resistance. Assuming you meant the main slide diaphragm in the carb, I think it's in good shape. No cracks. Maybe a little stiff, but I am not sure because I don't have a new one to compare against. I can see the slide moves freely and the rubber feels flexible to touch. Let me know when you solve it! Good to know. Since it doesn't seem to run well until the autochoke closes (and shuts off the extra fuel), I thought adding more fuel through a bigger jet might make it worse. But I know the new jet needs mixture adjustment, so I guess it offsets?

Your symptoms are classic for mal-adjusted valve clearances on a Leader engine. Adjust those first - otherwise you can try everything else but just go round in circles, possibly causing more problems by trying to mask it.

I adjusted the valves about 3000 miles ago. Could they go out of adjustment that fast (I think service interval is 15000 miles)? Or perhaps more likely, I did not adjust properly and I am still a little out of spec?

For what it's worth, the adjustment really helped. Before adjustment, the bike would stall at stoplights whenever the engine was hot. After adjustment, that problem went away and the bike generally ran better.

If it's starting in the winter in Canada, your auto choke is working.
Lean running four strokes are notoriously cold blooded.

Ah whoops! Didn't read close enough to see that your problems clear up. Nevermind

I am a little confused... if the auto choke is working, doesn't that make the bike run rich during start up (when it is being cold-blooded)?

If they've been adjusted once already, it's quite likely they might have gone out-of-spec again. Nipping up the oily locking nuts tightly enough on the rocker arms can be a bit hit and miss, especially with the engine still in the scoot. Added to that, once the parts have started to wear, that wear may accelerate.

I know it's a bit of a PITA to get to them, but checking the valve clearances will help. If they're OK, you're not left with the nagging feeling that they might be the root cause of your problems, and if they're out then you've probably found the solution.

What Jim says...!

I've never had to adjust my valves and i have 48,400 miles on him. We have the same bike. Wonder what's causing them to keep going out?

Who knows - I've had five scoots with Leader engines, and three have had to have the valves adjusted at least once. Two had over 30,000 miles each and the valves never needed adjusting.

If the auto choke isn't working, the bike isn't going to start if it's outside in Canada in the winter.

My LX 150 would do that at the beginning of the season until Seafoam worked its way through the system. Snapping the throttle open repeatedly until it bogs down when under load would clear it up in a few minutes.

what does kerosene & linseed oil do that normal detergent gasoline cant? (besides lighten your wallet)

^^always!!

I had a bit of hard staring and mine's a '07. At 46,000 miles i swapped out the carb. Symptoms are gone now. Now if i was handy i could of rebuilt it but i sent to MJ Rally and he rebuilt it. Maybe PM and see if he still has it and would send it to you to try. Only cost me $170.00

So if you look back at cars in the 70s,when most of them had carburetors, and now, what's one of the biggest things that has changed in terms of how people drive them, especially in the Winter?

If the only carbureted vehicle you've ever owned is your Vespa LX150, it does seem like it takes a lot to warm it up in the Northern Winter. If you've ever had a VW Beetle, it seems about right.

Yup, I was actually surprised to hear so many suggestions that it is not right and might need valve clearance adjustment, etc. This is actually good, because it means maybe it can be improved. I had expected the consensus to be "that's just how it is". But having only owned the one Vespa, I don't really have a reference, which is why I asked.

I ended up swapping in the 38 idle jet today, and am curious to see what difference (if any) that makes. I'll redo the valve check on some rainy weekend.

I've had a carb rebuild in mind for awhile, just because the machine is more than 10 years old and it seems like a good idea. But it runs well enough that I keep putting it off - I tend to prefer the approach of "if it ain't broke..." But maybe now's the time. I think I'll buy the parts and just keep them on hand.

If you can DIY i'd go for it. If i remember correctly MJ replaced the rubber bits. Your bikes is as old like mine so it wouldn't hurt. 06/07 is considered the same. Good luck

Meh. Idle jet change had no real impact on warm up time.

Canada has nothing to do with this slow warm up issue. I have the same issue in sunny warm Florida on a 2006 GT200L. At least 5 minutes before I can ride off. Starts right up too.

Adjust your valve clearances! Classic symptom on the Leader engine...

Block heater?

In Florida? The engine just needs some TLC.

Yes in Florida. Here's a quick update....

I was advised to add some seafoam to the gas. Remember this thing has sat for just over a year. Two fairly long rides yesterday after a long initial warm up time. Put the Vespa away for the night.

This morning, well close to noon.... the time it took for a warm up allowing me to ride off?..... 50 something seconds. BOOM! Issue resolved.

Thanks for the input.

Warm it up first and it will ride better and probably will last a lot longer
Much like having coffee in a morning before starting work
Fire it up let it come off choke then ride
A slow wake up is best.🥱🛵

Absolutely!
Ahhhhhh the joy of riding these Vespas! Unlike anything else in the two wheeled world. Enjoyed them as a kid in Italy in the 70's. Now at mid 60's, those young years are all over my face as I ride. Beautiful.

Absolutely not! The engine wears the most when it's cool - so "warm it up" by riding it! A GT200 should be able to be started and ridden straight away - if it needs to warm up before it falters or stalls then the valves need adjusting. This has been recommended in the Piaggio tech memos since the Leader engine first came out...

LOL. YA .Splittin' hairs are we?

Valves adjust. Naaaaaah. Seafoam did the trick here.
Warm up it is. Takes 1 minute. And Vroom Vroom.

Love it.

Enjoy the weekend remaining.

ElAzule is Seafoam, point set match. Woosh

Never use the stuff personally

It's all good. We have our prefs. I do appreciate other points of view and experiences. Manufacturers have the right answers to their productions' malfunction remedies, no doubt about that. So no arguments there. But every now and then a little twist can throw the whole concept off. Like a "red herring" situation. In this case, Sea Foam stepped up, cutting my ride anticipation wait time down from approximately 5 minutes to just shy of 1 minute.
Tomorrow, I'll see if I can start and run right from the git-go. And I will report accordingly. It's all good. Main thing for this old guy is memories. Beautiful memories relived. Yoooooooooow!😍

I went into this thread thinking it was new, not a necro, and I ran into a Judy post.

That lady in Hawaii riding her plum LX150 was a very kind soul. She offered me her phone #, although I never bothered her in that manner. I kind of wish I had. I would have told her how wonderful she was, and how her kindness helped me.

Judy was a class act, always looking to help out.

THIS! A warm up by gentle riding warms the engine quicky and safely. Much less time spent idling a cold engine.

Update on extended "warm up" wait time……
Today I cranked up and within 30 seconds I rolled on for a nice ride. So all is good in Vespa Land. Shweeeeeet!

Yebbut - can you ride off happily at 0 seconds?

Not until he burns the old gas and snake oil out.