TGB r50x

[bashan]

Hi guys, Bashan again. I got a guy with a machine that revs up and down unfettered.  I don't know what to tell him. Here is his thread on Doc but I'm going to send him over here. He will need to sign up so it may be a bit till he gets online with y'all. Thanks, Rich

[tominbmore]

Thanks Rich! Very thoughtful idea.

tom

[bashan]

Sure Tom, these are good people and they will take care of you. Don't be a stranger. I bet there's some Doc's hiding over here....AREN'T THERE!? I see you guys, you can't hide from me....wait a minute..I'm over here too aren't I? Never mind.  Rich

[2TDave]

Welcome guys. It'd be easier for members to help if you started from the beginning. Type of scoot, mods done and issue.

[tominbmore]

Hi,

The issue is spelled out in the link above. But seeing as it is a lengthy thread, I will recite it for y'all.

I bought a 2007 TGB ("Taiwan Golden Bee") r50x scooter, 49cc. It had 1950 miles on it, was in impeccable exterior condition, and, on the 75-mile ride home to Baltimore, it rode like a beaut. The restricter had been removed, so I was hitting 43/44 on flats and 51 on down hill. I know nothing about engines (as you will quickly note from the thread on the scooter doc forum!), but I knew the scoot was in good condition because it made no odd noises, got full mph, as I just stated, and didn't have any weird smell issues, etc.

The next day, in the evening, I started noticing that it wasn't getting its max speed, and that twisting the throttle would sometimes give me a feel like there was something interrupting full juice to the engine. There were no weird noises, but I had the hunch (totally a guess because I am a 100% newbie) that the engine was a bit pinched and straining. Then, a handful of times it would just stop giving gas, the dash would turn off, the engine would cut out.

Ever since, on tests I have conducted after tinkering, the scoot will ride fine for 5 to 10 minutes (although noticeably not at the max speeds I enjoyed on that initial long ride home).  And then soon enough it will repeat the same starved for gas/curt off during mid-ride act.   ??

I uploaded pics and vids for the scooter doc guys (I'm gonna have to ask you to refer to the thread for that b/c it is a bitch to do the whole process). I learned what the various tubes are, and some very general concepts about how a carb works and how a two-stroke engine works etc.   I learned how to drain the tank, thinking that maybe the issue was that the night after I got home I put only 87 grade gas in the tank.  I replaced it with a 3/4 full tank of 93-grade. Test ride, and the same shutting down eventually happened.

Many folks on scooter doc told me they think I was having "lean" issues, based on symptoms of (1) cutting out at high speeds despite initially starting, (2) air filter looking fine, (3) rpms sometimes bouncing at idle, or sometimes slow to come back down to 2000 rpm after I laid off the throttle at a stop light.

Then I went through a long process feeling very dumb as I tried to find out which of the screws was the air/gas ratio screw (see thread link). I finally did, and tried to do the lean/rich test helpfully supplied to me by alleyoop. But (1) I couldnt tell whether the rpms went up when I twisted the screw 1/8 to the right -- it looked like it twisted *a little* -- and (2) after I tested the throttle, after I laid off it, the scoot just kept on revving, I mean seriously revving, somewhere around 7000+ rpm.

I was convinced a poltergeist had grabbed the throttle and possessed it. I cut the motor, waited, started up again, and sure enough the revving occurred this time without me even twisting the throttle! While it was in this process, I twisted the same screw slightly one way, then the other. Strangely, neither effort changed the symptom!

I did this all again today, wondering whether this would change or maybe tyhis time I could deduce the problem. But although it started normal, at a resting 2000 rpm, the revvving thing happened soon enough after I tried to tinker * very slightly* with the air/fuel ratio screw. Very noisy rev, this time more like 5000 rpm.

Keep in mind that I have full oil, the right kind, and there is a little smoke coming out of the exhaust when she idles... not heavy plumes of smoke, and not super thin either. seems normal there. I haven't looked at spark plug yet. i found it at the front of the engine area, facing forward, but didn't know what tool I need to unscrew it.

Also, you should know that alleyoop, at scopoter doc, just today suggested that in light opf these developments I now should take off the carb and spray it with carb cleaner in all the holes. I cant begin to imagine how to take off the carb. As someone with a 9 - 5 job and a girlfiend, I cant imagine how I could find the time to learn to take off all the tubes, etc, and somehow remove it.

Anyway, any insights are weklcomed. One of the issues for me, even after I learn basics about where things are and what they do or how they might cause issues, is BIG doubt about whather I have found the right part, and whether I am turning the screw the right way etc. Seems a bit like flying blind. I feel tempted now to just roll 'er down to the local shop, pay up the $80 - $120 or whatever it might cost, and learn the ins and outs on my own time.

Rich says dont use a mechanic, period... But it's hard to learn when folks are communicating across the internet.

I appreciate any input you all are willing to share. Ask away if you need more info from me, also.

Tx!

[190mech]

90GTVert(Brent) has tons of info in the tech section like this;

49ccscoot.proboards.com/thread/363/carburetor-cleaning

Go have a look at all this good stuff!!

PS, If its not a dirty carb(Im guessing idle/pilot jet),it could be a bad air leak ..

[tominbmore]

Will do, thanks!

[tominbmore]

Hi guys,

Got a question about CDI units.

Been a big gap in communication from my end... I decided in the end, bc I am such a noob at this, and time = sacrifice, to take 'er down to the local scooter shop. $65 diagnostic cost, but if you decide to go ahead and ask for repairs after that, the $65 gets folded into any hourly labor + parts.

the head mechanic called me to say that he tested everything, then in the end realized it was likely the CDI. He put a new one on, and it seemed to be OK. He is taking 'er out for a proper ride to see if the problem is totally gone (the problem was that she would not get enough mph, then would shut down, after just 5-10 minutes of riding).

Anyway, he quoted the CDI as $41.00, and I have already seen online that a CDI for a 50cc can run anywhere from $10 to $100 maybe.

I wanted to ask you all whether his quote is reasonable or whether he is engaging in ridiculous mark-up. I also recognize that not all parts are created equal, and furthermore that some might be pricier because they work only with certain models (mine, for example, is a TGB r50x, not the most common 50cc scooter out there).

Any thoughts? I saw on youtube that replacing a CDI box with a new one takes maybe 10 minutes tops, which means if they replace it I know that labor costs will be minimal. But I still wanted to see what input you experts had about CDIs, as well as
(1) what good ones cost, and
(2) how I can tell whether the one he is offering me for $41 is a good quality one or not.

I'm OK with some mark-up, especially for the convenience of not having to wheel 'er home myself and do it at home (don't have a truck). But I am NOT Ok with being hosed if that's what the shop is doing.

Tx!

[90GTVert]

I'd imagine a CDI for your scoot could be had cheaper, not sure, but either way $41 is not ridiculous.

The toughest part of replacing a CDI is usually locating and reaching it. Otherwise it's just plugging and unplugging connectors mostly. Even if it takes only 5 minutes, some shops have a miniumum labor charge of 0.5 to 1 hour. That's taken care of with the $65 diagnostic charge though from the sound of it.

$100 does sound like a lot to me for a CDI swap, but that's prob because I'm used to not paying anyone. Realistically it takes time to figure things out and mechanics aren't there to work for free, so it's reasonable I think.

[tominbmore]

Thanks man!

I posted elsewhere with a fresh topic specifically directed at CDIs and value, and brands, etc. Apologies for the double-post.

You're right that some labor needs to be accounted for (they need to make SOME $$), and like you say I already have $65 of sunk costs, so even if I could walk her home and buy a $20 awesome CDI online, I would be paying $20 extra, whereas here most of that would be accounted for by the $65 already spent.

So I'll stick with what he offers, but wanted to be able to know how I can tell whether the one he wants to put on is a good one or a crappy one.

[90GTVert]

Not really sure how you will know that. I've bought CDIs for $10 that looked, felt, and worked pretty much the same as $50 CDIs from the manufacturer.

[bashan]

I don't think that price is unreasonable Tom especially when you're on this side of the learning curve. This way you have established a decent relationship with what sounds to be a good mechanic. I agree with Brent, it's impossible to tell a good CDI from a crappy one. I've always ponied up a little more for the orange ones not because they're faster but they seem a little more durable. But they could be the same thing under the skin but with an orange peel. We are talking Chinese origin here. Now Sprocket, a very nice and intelligent man once on the forums, always said buy NCY CDIs because they had superior components especially the capacitors. Do you have any thoughts on that Brent? Rich

[90GTVert]

I really couldn't tell you from anything other than experience with other parts that I'd think NCY would be more likely to be a quality part than random Chinese parts. I tend to sway the other way and buy cheap stock replacement CDIs because they've worked fine for me so far. If honest timing curves were published, that would make me more likely to spend a bit extra.

[bashan]

True that bud. How about the variable timing CDIs? A load or some validity? I've had folks say they can help with starter kickback and top end but I'm the original skeptic. Rich

[Jwhood]

I met with tom today and fixed him up carb was a dirty and jets were clogged he took it for a ride and I took for a ride all was good!!! People that don't know 2 stroke scooters should just leave them alone