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Post by 50ccent on Nov 7, 2018 1:48:57 GMT -5
Hey all, having a little problem. Picked up a little scooter for $50. Previous owner said it was running fine until she let it sit and the battery died, then it just sat in the garage. Tag says 2010, so yeah, hasn't ran in 8 years. Odometer says only 608 km.
First things first, dumped the gas, hosed out the carb with carb cleaner, checked for spark. Kicked it over a bunch, made sure gas was flowing, sprayed it with stater fluid. Kicked it over some more and got her to fire up! Not bad for about a hours work, i'm thinking i'm on easy street.
But no. From a cold start it has smooth idle. I can go part throttle and get the revs up. Full throttle it wants to die. As it warms it starts to surge for a bit, then just putters out. Might start a couple more times, but as soon as i touch the throttle, it dies. Or it might rev a little then die. Then when it's warmish, it refuses to start.
Ok, now i'm thinking carb needs more cleaning. Watched a tutorial online, pulled the carb apart for a quick clean, found diaphragm was incorrect size and didnt fit in groove at all and I tore it stuffing it back in. Ordered rebuild kit for $14, waited week, new perfect fitting diaphragm installed, slapped carb back on lil' scoot, still no chooch. Same symptoms.
Read about crappy chinese rubber hoses and E10 gas. Noticed tiny black specks in carb bowl and no fuel filter. Replaced fuel line with nice clear hose and inline fliter. Read some more forum. Pulled entire carb apart and did supreme carb clean, new float valve, cleaned seat with drill ear swab, poked holes with bread twist tie wire, sprayed every hole with carb cleaner. Vacuum slide tested working with shop vac. Carb so clean you can eat off of it.
It still does the exact same thing as first day when I just hosed the carb while it was still attached and had misfitting diaphragm. What is this voodoo?!
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Post by tocoo on Nov 7, 2018 10:17:32 GMT -5
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Post by GrumpyUnk on Nov 8, 2018 11:56:37 GMT -5
If you get the carb all gussied up and it still wants to play dead, you may have gotten things out of adjustment to where the engine won't want to start. If you have CLEANED the pilot, not 'drilled a new one' using a too-large probe, and can blow through it, then you can adjust the carb so it should start and run. You want the fuel adjustment needle open 1.5-2 turns, and the throttle stop screw touching the cable attachment bell crank plus a turn or two. Twist the throttle a few times(with the float bowl full) and see if it will fire off on the 'squirt' of fuel. With things way out, you could be trying to start the engine on the mid-range system rather than the slow/idle system. If so, it will be hard to get running. In short, you must get it to run on the slow/idle system to be able to start it. If the throttle plate needs to be open to make it run, you are likely NOT running on slow/idle, and it will be hard starting all the time. If it bogs when you open the throttle, it is either a 1)accelerator pump or 2)pilot jet problem(likely two things). If it starts to run, then bogs, it could be the slide is not moving any more due to a vacuum leak or poked diaphragm. It will start to take off, then start to stumble/mumble/misfire due to too much fuel and too little air... tom
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Post by 50ccent on Nov 9, 2018 18:54:40 GMT -5
Thanks for the feedback guys. With out touching the throttle (maybe a twist to get so fuel in it), it will start and idle fine for a minute or so, then starts slowly surging (revs go up, revs go down), then the revs get so low it dies. I have played with the mixture needle a bit. When I first took the carb apart, i counted the turns in, was about 1 and 7/8s turns. So that's where i put it back, but have moved it around about a quarter turn up and down looking for some better results. Also played with the throttle screw trying to get the idle higher, i'll look at that again. Yes, the accelerator pump does squirt. I'm thinking maybe the auto choke is stuck or isn't shutting off or something? gonna disconnect it after i get it running and see what happens.
Also, earlier I had pulled the valve cover and checked that rockers had a tiny bit of wiggle, but i'll get my feeler gauges in there and check it right. Think I saw lash is suppose to be 5 thou, will double check the vids when i get ready to do it. Thanks again, gonna mess with it again this weekend and will update when i find something to report.
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Post by islandscrub on Nov 9, 2018 20:32:17 GMT -5
So it runs better when the auto richener is open (dead cold start), then slowly runs worse as the richener closes? If you're sure your fuel tank is clean and fuel delivery is consistent, that would mean to me maybe your pilot jet is clogged. You're on the right path with your method of disconnecting the richener wire and seeing if it continues to idle fine with no interaction, would mean you need to get more fuel in for it to stay running.
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Post by niz76 on Nov 10, 2018 0:25:23 GMT -5
Surging like you described is usually an indication of a lean condition or an air leak somewhere. Or a lean condition caused by an air leak... You can restrict the airbox some with tape to richen up the mixture and see if it responds well. If it does you know it's running lean.
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Post by 50ccent on Nov 13, 2018 0:26:09 GMT -5
Messed with lil scoot again. Valve lash is .004 which from what i saw is correct. I pulled the carb again to checked the pilot jet was clear and noticed the one included in the rebuild kit was smaller, so I swapped the old one back in and sprayed some carb cleaner up thru it. It actually ran better, but still under wide open it just stumbles and wants to die. idles way too low once warm and only stays running with a little throttle to keep the rpms up. I agree with niz76, i think its running lean like something is still messed up in the carb. And i was wrong about the accel pump working, it does not squirt. I swear it was working before the last time i took it apart, but the rubber was slightly degraded so i suppose it's not sealing well after i put it back together. Anyway, now that i know new carbs are only $20 I got one on the way. I have a feeling this will fix all my problems. Thanks for the input!
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Post by 50ccent on Nov 14, 2018 16:22:11 GMT -5
If it's not obvious, I'm working with only half a clue here. But good news! lil scoot is running great with the old carb! Good idle, good revs, i like it! Let me explain what happened. That first day when it wouldn't run i found a vacuum line lying next to the carb so i connected it to the only possible place, which i now know is the overflow drain port. What clued me in is the new carb has a cut piece of tubing connected there which got me wondering so i looked up a good carb diagram. so yeah, assumptions and all that. New question, where is the hose in the attached pic suppose to connect? Its an open vacuum leak and bike run like crap unless I plug it. Thinking about just deleting that entire tee-junction thing coming off the intake, but i've made bad assumptions before. :-) Thanks again guys, i'm having fun messing with this.
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Post by GrumpyUnk on Nov 14, 2018 17:01:03 GMT -5
Many of these China machines have a vacuum operated petcock to stop fuel flowing into the float bowl when the engine is not running. The petcock can be mounted to the bottom of the fuel tank, at the outlet, or down stream, in the 'middle' of the fuel line path. Both will have a diaphragm operated by engine vacuum which will pull open a valve to allow flow. The stand alone has 3 ports, 1 vacuum, and 2 fuel - inlet & outlet. The tank mount has two lines - 1 vacuum and 1 fuel. The other uses for a vacuum line attached to the intake are for 'smog control' or emissions control devices. To know, you would have to show the whole engine area along with all the 'gizmos' that are zip-tied to the frame such as catcb-cans and diverter valves. There are too many styles of controls to be able to state anything of value without seeing what's there. tom
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Post by 50ccent on Nov 14, 2018 17:44:46 GMT -5
Gave it a good look over, i see nothing that it could connect to. Too short to reach much of anywhere. My limited research turned up that it might be for the carb decelerator vacuum, IF it had a different style carb. This is third hand scooter (at least) with unknown history, so who knows whats been changed in the past.
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Post by kagetenshi on Nov 15, 2018 10:02:40 GMT -5
If I'm not mistaken, you could remove that entire t piece and plug all of the open vacuum ports. The only thing I see that uses vacuum pressure is your fuel petcock. It would also help to slightly reduce the amount of vacuum pressure lost.
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Post by GrumpyUnk on Nov 15, 2018 11:34:02 GMT -5
The 'valve' that the vacuum line connects to seems to have another port that may not be connected to anything. If that's the case, then you can disconnect and plug the port on the intake with no change. It is doing nothing now, and would continue if disconnected. The 'valve' looks as if it is a vacuum operated mechanism. Got no clue as to real function. I did note that your cam cover vent is open to atmosphere. You might want to add a length of tubing and route it up towards the fuel tank, in general. There should be a slight amount of venting from the crankcase, and you'd want to prevent lube from seeping out the vent. The blowby gases can travel up a length of tubing, and if any lube or lube vapor was carried out, it would have time to attach to the inner diameter of the tubing and then drip back to the cam cover. Less oily spots on the engine. tom
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Post by 50ccent on Nov 15, 2018 17:12:44 GMT -5
Thanks for the input. My first thought was to pull the tee setup and plug the intake ports, but trying to understand how this is suppose to work before I start jacking with the original design.
The valve cover vent blows a good bit of air and I have no idea if this is normal but it's more than I would expect having only worked with car motors. Before I took things apart to work on the carb there was a hose from the vent to the air filter box, which seems normal to me.
What I think the tee-device is is a PCV valve, but it has two lines from the intake manifold to each side of the device, which doesnt make any sense to me. Having no idea what to do, i jammed the open vac line on the valve cover vent, cranked up lil scoot and rev'd her out. Seems good, runs fine so far but it's still on the frame stand with flat tires so how it'll run on the street is still a mystery. ya know what I should do? Maybe I should check the valve thingy for markings or a label or something and try not to guess if I dont have to. :-) Probably in chinese.
Also found why the accl pump does't work. Gas leak from carb housing there. Replacement o-ring not sealing, will fix tonight when i'm done with work.
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Post by 50ccent on Nov 15, 2018 21:30:14 GMT -5
Broke the gizmo trying to get it off. It is now deleted and the two vacuum hoses connected together instead of plugging holes. Everything is put back together and lil scoot scoots. I hit 40kph doing a couple test runs, which i assume is blazingly slow. lol Cleaning everything up this weekend to make her pretty. She'll be for sale in the north dallas area soon if anyone is interested. 609km on the clock.
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Post by GrumpyUnk on Nov 16, 2018 11:43:52 GMT -5
Not really into butterscotch color, but other than that, looking good.
Besides blowby, remember that there's a XXcc volume displacement - increasing on compression and exhaust strokes, decreasing on intake and firing strokes - change occurring with the engine running. Given the volume of the crankcase, that's a pretty good percentage change per stroke. You'd think the pressure inside goes up and down all the time. It does. That produces pulsations on the vent port. Chuffing and puffing all that, you will of course start to carry droplets/mist of oil out that will then scatter to the winds and rustproof the engine and underside of the scoot. A length of tube, as suggested or connecting back into the air cleaner assembly will at least prevent lubing the whole thing. I would check that a full twist of the throttle opens the butterfly all the way. Unless limited by the CDI or the variator, you should exceed 40kph, which is about 24mph. Most will reach at least 30mph, about 50kph, and many will go faster than that. tom
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