The age old problem... Scooter wont stay running, hard start By jbrukardt (Read 6,564 times)

[jbrukardt]

So, im a new scooter owner, but an old mechanic.   I'm pretty good with small to medium engines (read lawnmower and tractor), but some of the intricacies of scooters (vacuum, etc) are new to me.

I bought a 2011 Puma Romeo 50 for a friend, a homeless gentleman i try to help out who is a damn hard working and honest man, but is stuck in a vicious cycle of not being able to keep a steady job, because he doesnt have transport to a steady job.   Picked it up for $350, not a steal, but not bad either, knowing it had some problems.

It has a tao tao 50cc swapped into it at some point (per the previous owners info), and has run fine in the past with that engine, but has always had a tough time starting and holding idle.    It seems to be temp related to a degree, previous owner could get it fired up regularly in a heated shed, but I can only get it to start 1 time in 15 out in the cold (35ish F).   I know these machines are not designed to be run in that weather too.

So, you guys seems super helpful, and I wanted to run my plan of attack by you for getting this scoot running smooth so i can give it to my buddy.  

Heres what it is:

2011 Puma Romeo 50cc in seemingly good shape, 700ish miles on it, with a 50cc taotao engine swapped into it (prev owner said engines were identical)

Heres what it does:

1) If it does start, idles mid (not super low, not high) for 2ish minutes, then conks out
2) tough to start, starts maybe 1 in 10 times
3) the minute you put any throttle into it, it dies
4) seems to "recover" after waiting about 1 minute if its not starting.  You let it sit for 1-2 mins, then attempt to fire it up, and it turns over instantly and idles.   That makes me think flooding, but i dont know these motors that well.

Plan of attack:

1) Check for vacuum problems, im actually heavily leaning towards this being it.  The previous owner said he "messed with the airbox" and it seemed to be better).   Any guides out there for testing vac? I saw something about spraying propellant down the vac line
2) Check for loose wires coming from the CDI
3) Clean the carb
4) Adjust the carb (including checking if the butterfly valve covers the pilot outlets)
5) Theres something about a gasket/spacer on the intake manifold that goes bad, any details on that ya'll can give me an idea on?
6) check out the enricher, make sure thats working right (watched a few videos)
7) and most importantly, most also most in depth, set the valves.  This procedure i can do in my sleep from my other small engine experience


Ya'll seem like a real friendly helpful community, and id be glad to take any advice you have, or guidance, in hopes that i might pass it along some day.   Im confident i can get this thing running, but i can get it running faster with experienced minds lending me just a tad of knowledge.  Thank you very much in advance.  

[Bashan]

You are a special individual for trying to help another person out without expectation of reward or judging them. That's all I'm going to say.

Check the valves first, you wouldn't believe how many problems they can cause on a GY6. 50cc? Usually .002" intake and .003" exhaust but maybe some of the 50 GY6's could weigh in.

Vacuum problems manifest as hitting the throttle and ....bluh...
Falls on it's butt. Yeah, you can use the bit of starter fluid sprayed here and there and see if it buzzes up a bit. Alley uses I think WD 40 and sees if it disappears. Or maybe he just told me that and is chuckling? I've also found going over the vac lines from start to finish usually shows you the problem if it's there.

Now...Vac is different than intake! Vac is the lines from the intake manifold and anything to do with the manifold and where it couples with the head. On the other side of the carb is the negative pressure created by the intake of the carb against the airbox. As a small engine expert I'm sure you're aware of this without the this bonehead telling you. However, leaks in the intake side cause maladies in the mixture by allowing fresh air in that is not "recognized" by the CV carb which is dependant on pressure differentials. Make sure there are no leaks on either side of the carb.

Hmmm, wires from the CDI? Probably not...those are usually cut out, come back quick symptoms...but check them. I use a multi set for continuity. If you need me to show you how let me know.

The spacer? That's that 1/8" plastic POS between the head and intake manifold. Yeah, it can leak. Check it. I hate that thing. It should have a gasket on each side of it. Hell, I don't know, there's a paper thing goes on one side. I just make sure there's a gasket material on each side. Could they not adapt their design to that bit of height discrepancy!!?? It's not that big of a problem maker. It's that black plastic spacer, just check it for leaks.

The enricher! That may be a problem. Pull the enricher off of the carb. Hook it up to a 12v battery, polarity does not matter. Within a few moments it should extend out about 3/16". Also check it's seals.

Hmmm..butterfly cover the pilots? That's never been a big concern for me. Alley is really the guy for setting the carb. He also knows a boatload about everything else I've touched on. Are you back up to speed yet Alley? If not I'll wait.

Y'all......JB?? You from my end of town there bud? Yes, these are very nice people hanging around this bit of cyberspace. I'm proud to be counted with them and we're proud to have you. Rich

[jbrukardt]

haha, im a transplant, grew up up north, moved south (barely: to maryland) a long time back for a job, and to get away from the snow. Ive picked up a few mannerisms without even knowing it over the years.

Thanks for the comment about checking the valves first, i was leaning more and more towards that already. Gonna do that this weekend if the weather clears up. For all that effort to excape the snow, this year, its here in force and it makes workin outside a tad tough.

i think ill understand the vac/intake/etc lines better once i get the side off. Im used to stuff that has fuel pumps, albeit limited (crankcase vac controlled) ones.

[Bashan]

Maybe these will help some:

Maryland.....the south? I'm sorry bud....try Toledo to Birmingham, that's a transplant. Wait, more like an entire brain into another body transplant. Do they say Y'all in Maryland? I guess we don't have a copyright on that. Except down here it's "Yeull" with as little movement of air and tongue as possible. Sometimes we only stir three or four atmospheric molecules producing speech. Any more than that is considered bad form. Yes, that's why the south lost the civil war, they couldn't hear each other. It happened, let's move on.