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Post by scooter on Jul 9, 2015 20:30:48 GMT -5
Put the right amount of oil in it, put a small amount down the spark plug hole to get it to crank over again and see if lack of oil is the problem. This is not a cure if the rings are fouled but it will make it drivable for a little while. The proper fix would be new rings or cylinder or both depending upon condition. Thanks, Todd.  I think the cylinder and rings are the problem too. |
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Post by scooter on Jul 9, 2015 19:28:26 GMT -5
Hey guys, this is my first post here but I've been following the forum for a good while. Firstly, I have a Puma Speedo 50cc Chinese made scooter. It runs the standard GY6 139QMB. It has a long case. It's got about 8000 miles on it and I've had a 80cc BBQ installed and had the engine rebuilt as it died earlier this year. They said the crank shafts was bent or something.  Sorry.  I've head this story many times. These big bore kits sound like great fun, but if you make more power, you need more strength throughout the whole system. Most recently I've begin shredding belts. I first noticed an issue when it felt like the clutch would completely disengage while I let off the throttle. Might be too much power, a problem with your variator perhaps, or your clutch. About a week later, stranded with a shredded belt. Make sure you use a good belt. I replaced the belt and it shredded again in a little less than a week. It felt like the scooter was revving high as if the belt was slipping. It wasn't getting up to speed as fast. You might need smaller roller weights. Definitely inspect your CVT parts for issues. Put this third belt on and same feeling. Scooter doesn't get up to speed and it just feels like the belt is slipping. It looks like the belt isn't ridding all the way up on the clutch. If it's not going up on the clutch then your variator may may be too closed at the bottom, or it might mean your belt is worn a lot. It also might be too short. Today I got it back together and it won't crank. It's as if the belt is binding. I squeezed the clutch to relieve tension and the motor turns fine. Make sure you have the right belt size. I tried posting a picture but am unable to. Any ideas? Try photobucket. Watch a few videos on youtube about how your variator works, how to take it apart, and how to inspect it for problems. Then look it over. You have more power with the new top end, sorry, had more power with the new top end, plus you need to know how to diagnose your CVT and learn to tune it so you can get more fun out of it. ... |
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Post by scooter on Jul 9, 2015 19:13:02 GMT -5
Get rid of the vacuum valve and use a manual shutoff . Did you see my post "50 cc won't start"? I need a specialist over there. Someone who knows about piston rings and cylinders and all that. That Jersey fellow seems to be pretty good at that stuff too. I haven't seen him on here lately though. Anyway, it looks like I'm going to be doing my first top end rebuild. Come over and check it out. itistheride.boards.net/user/2253/recent_threads |
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Post by scooter on Jul 9, 2015 19:08:44 GMT -5
I may do that, but my scoot is kind of a pain to get under, theres a rubber skirt n stuff I have to manuever around. If I get any problems with my new valve ill probably just do that though If you want to work on your scooter, it helps to remove body work. It becomes very easy to do once you do it a few times and makes your work a lot easier. It's actually a little scary how few screws these scooters have holding them together.  Embrace the removal of the body panels, not as a hassle to deal with, but as a way to make your work more rewarding and enjoyable. If the petcock is hooked up wrong, it may free flow. I would check it and prepare to put a new one in if necessary. It's probably a half hour job or less. |
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Post by scooter on Jul 9, 2015 18:56:48 GMT -5
wasn't the valves... adjusted them. I have a friend that's a mechanic he looked at it and even he is stumped. he thinks somehow too much gas is getting into it... we give it full throttle to start it an it will start then die out as we hold the throttle. he played with the screws to adjust it but it wouldn't stay started. we tried it with starter fluid in the intake and it still wouldn't start. he mentioned the fuel regulator because he thought too much gas was pouring into the carb and he tried to suck on the other hose from it and it wouldn't give any gas. so any opinions? It sounds like an overly rich mixture, assuming it's not a bad ignition, bad gas, loose wire, or other type of problem. I'd clean the carb and jets if you have not already done so. A good running scooter will usually start without opening the throttle. Usually the bowl valve is enough to control fuel flow into the carb. |
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Post by scooter on Jul 9, 2015 18:44:01 GMT -5
Almost time to think about changing the pads in the front brake. BUT THERE AREN'T ANY CALIPER BOLTS !!!!!!!!!!!!!!! Instead, there are 2 rubber things where bolts should be. Anyone have any experience with this thing?  There are bolts on the back side. The thing on the right looks like an ABS. |
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Post by scooter on Jul 9, 2015 15:33:01 GMT -5
First of all I’m not very knowledgeable when it comes to scooters (even though I have owned 2 in the past) I just know the basics. Well I decided not to ship my scooter back to SMART DEALS NOW because the shipping was too expensive. I decided to turn here. I have a new scooter that has been giving me issues for a couple months now . (2014 TaoTao 150cc Lancer) I ride my scooter to work (6miles) and every morning and it dies while riding there at least once. ( Mostly it seems when I’m accelerating somewhere during my drive it struggles) I have to pull over and about the time I’m coming to a stop it turns off. I can’t restart it right away.. it seems I have to wait a few minutes.(I turn it off and on take off the gas cap try to do whatever comes to mind while waiting) Then It starts up and seems to work the rest of the day. It appears (but I’m not %100 sure) that it has something to do with the temperature outside. I only say this because I remember 2 really warm mornings where my scooter did not die and one pretty cold morning where it died 3 times. I have changed the fuel filter, fuel pump and Intake manifold. (thanks youtube) I have even adjusted the idle (as suggested by some scooter guru) Anyways I have seen some other scooter riders with similar issues, but not exactly the same. I just wanted to ask around before I take it to a local shop for a diagnostic. I'd look in the gas tank for any debris and clean the carb. Takes about a half an hour and it's easy. I don't know what your skill level is but what I do is take the carb completely apart and spray carb cleaner in every hole and through the jets, etc. I'd also check that the plug wire is nice and tight on the plug, check the spark, and check the vacuum lines for leaks. |
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Post by scooter on Jul 8, 2015 15:40:51 GMT -5
Which leg is more macho? (non-biased edition) Left leg:  Right leg:  The left leg for sure. Being macho is painful! |
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Post by scooter on Jul 8, 2015 15:39:56 GMT -5
Hmm, almost sounds like the "Soup Nazi" of scoot parts and perfume! NO SCOOT FOR YOU! HAHA! |
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Post by scooter on Jul 7, 2015 22:17:00 GMT -5
Here's one of those things that belongs in any toolbox, especially if you need to measure things and need more than a tape measure or a caliper to get the job done. I just used the 6" spring outside caliper (third tool from the left) to measure a valve's length while it was still in the head. Just put one end on the bottom of the valve, adjust the other end onto the top, then measure the gap in the tool with a ruler or caliper. Just one of many jobs made easy by having the right tools! These tools let you measure odd shapes and get around obstacles. The set includes a 6" pocket ruler, 6" dividers, 6" outside calipers, 6" inside calipers, 6" angle and depth gauge, and a 5" analog caliper. This is a nice little starter set, and for 9.99 it's a real steal!  |
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Post by scooter on Jul 7, 2015 20:31:58 GMT -5
I came across this seller on ebay, Josh Closeouts, selling everything from scooter parts to perfume. His feedback rating was a bit low, at 98.5%, so I went to see what the trouble was and boy did I find a live one! Every negative feedback is replied by the seller that they are wrong, along with such quips as "You're Blocked! You will never buy from us again", and "You got exactly what you ordered. Pay more somewhere else. You're blocked!". My favorite one is when someone gave him negative feedback but left the comment "good items". His reply? "Too dumb to leave a negative comment. You're blocked!" If you want some entertainment, watching someone be a complete jerk, check it out! page 1 of 5 pages feedback.ebay.com/ws/eBayISAPI.dll?ViewFeedback2&ftab=AllFeedback&userid=joshscloseouts&iid=-1&de=off&items=25&interval=365&which=negative&mPg=5&page=1 |
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Post by scooter on Jul 6, 2015 18:32:05 GMT -5
A little duct tape, and a stick, and he's got a strap wrench. |
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Post by scooter on Jul 5, 2015 19:15:30 GMT -5
This isn't quite a review yet. I just wanted to share this accessory I found at HF.  It's a 2" LED lit boost and vacuum gauge with mounting hardware and even a bit of tubing and a three way connector for your vacuum lines. Use it at the shop to diagnose vacuum issues. I doubt it is waterproof, (I didn't think about that when I bought it  ) but for a fair weather scooter, it might work out as a usable gauge. It should also be able to read fuel pressure if you'd rather have that. You can keep an eye on your factory fuel pump, or that fancy electric fuel pump you put on in your last set of performance mods. This gauge comes with a classic white face. The LEDs are a nice touch. Customize and view your gauge in choice of green, electric blue, red, aqua, yellow, purple, and white by pressing the button on the face. There's a little sticker on there that says "NITROUS". How cool is that? These 2" LED lit Boost/Vacuum gauges are available at Harbor Freight right now for $17.99. I'm going to try this one out in the shop, and maybe later I'll try it on a scooter. If you try one of these, let me know how it works out, whatever you're using it for. If you want a real shop tool, this Fuel Pump and Vacuum tester is a real deal at $12.99.  |
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Post by scooter on Jul 5, 2015 18:36:49 GMT -5
I am getting cold compression readings on a 139QMB of only 90psi. Another test showed 70 psi and then, after oil was put into the cylinder, about 120 psi.
Please tell me, what is the standard psi for these engines? One source online said about 15-20 times the compression ration of 10.5:1 or about 158 - 210 psi. Several youtube videos showed 50cc compression at around 160 or so, on up to 190 with a cold engine. One source said a MINIMUM of 100psi if it's to be considered usable at all, and another said 120 MINIMUM, but a healthy engine seems to push much higher, well over 150. I am pretty sure 90psi is crap, but I want a standard number to compare it to when I tell my client what's going on with the bike. I'd also feel better with a standard number in hand before I start taking the top end apart. I think we had once discussed that a good start would be 14.696 psi times the stated compression ratio of 10.5, which would be 154 psi. 70 would only be 45% of that, and  would still only be 58% of 154.ALSO This is a Bintelli Sprint 50cc with EGR. Does anyone know if this takes the standard cheap-chinese-ebay heads and cylinders for 139QMB's? I also need to address the 64mm vs 69 mm valve length question. This one has 69mm valves, confirmed by measurements. There are videos on youtube that show you how to tell the difference just by looking at the base of the springs and the height of the valve retainers above the top edge of the head. |
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Post by scooter on Jul 5, 2015 18:23:34 GMT -5
Take your engine shroud off, look around the base of the head for oily spots. You said your dipstick read no oil, but there was some in there, that's because the dipstick doesnt touch the bottom of the oil pan. Fill it up, you need oil to run properly. I had a siilar issue with my 100cc BBK scoot, turned out the base gasket at the bottom of the cylinder had blown out and I had been losing a lot of oil through there and it was hard to start a lot of the time, after replacing it I have not lost any more oil or compression. I have not removed the entire shroud yet but I removed the fan cover and can see no oil around the base of the cylinder. My current theory is that the combustion chamber is leaking at the rings and/or the valves. (Keep in mind that the oil may not have been changed or even checked for a few thousand kilometers and may have been running on low oil for some time.) I am waiting on a part in the mail to do leakdown testing and see if I can isolate the compression problem. (If you haven't already, please see my prior update in the main post about my compression test.) |
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would still only be 58% of 154.