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i give up
by: ramblinman - Apr 27, 2015 5:16:07 GMT -5
Post by ramblinman on Apr 27, 2015 5:16:07 GMT -5
ramblinman I live in Texas, and if i were closer to you i would work on it for free. I have been working on my own bikes for 30+ years........It sounds like the intake manifold has lost the seal, or it may have a crack in the rubber part of it. Take it off and look at it very closely. you may find the problem there. thx, i did get it running but it still has problems. i did install a new intake manifold and used gasket maker so i think the problem is something else. i bought a compression tester as i think it could be valves. haven't taken the time to check yet. |
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i give up
by: bulldogg62 - Apr 27, 2015 18:24:50 GMT -5
Post by bulldogg62 on Apr 27, 2015 18:24:50 GMT -5
ramblinman On these chinese scoots, it could be one or more things causing the problem. A compression check is a good idea. At least when you eliminate causes one by one it will get you closer to the problem. Just be patient, you will find it.
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i give up
by: ramblinman - May 5, 2015 21:08:35 GMT -5
Post by ramblinman on May 5, 2015 21:08:35 GMT -5
compression was about 100psi when warm. just to recap the symptoms were erratic idle making it impossible to tune and difficulty starting. after replacing many worn parts i suspected the valves were the cause. i already had the tools to lap the valves so i tore the engine apart.
when i got the head off i used a flashlight to check for valve leakage but didn't notice any light coming through. sprayed wd40 in both ports... no leaks.
took the cylinder off, immediately noticed the rings have an unusually large gap and were lined up together. didn't have replacement parts and really didn't want to wait so i cleaned up the carbon, removed both gaskets, put it back together with gasket maker and staggered the rings.
i didn't know rings could reposition over time. do you think that is what happened or perhaps they were installed that way from the factory? anyhow, i haven't checked the compression but it is noticeably better. starts easy and the erratic idle is mostly gone.
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Post by onewheeldrive on May 6, 2015 0:55:21 GMT -5
The ring gaps will look much bigger when out of the cylinder because the rings aren't compressed. The gap is measured when the ring is in the cylinder while compressed by the cylinder wall, using a feeler gauge.
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Post by bulldogg62 on May 7, 2015 19:11:46 GMT -5
ramblinman ...I'm glad you found the problem and it should last for a little while with that "gasket goop" on it. You really should get a proper gasket set for it. That stuff isn't really meant for cylinder base gasket or head gasket material. Usually if i am forced to re-use a gasket, I spray it with several coats of copper seal gasket paint. That stuff works pretty good and it's cheap. The factory in China turns out thousands of these engines a month and occasionally one goes out with the rings lined up. It doesn't happen often because they "bench run" these things before they go out, but it does happen.......
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Post by rdhood on May 8, 2015 10:10:26 GMT -5
i didn't know rings could reposition over time. do you think that is what happened or perhaps they were installed that way from the factory? anyhow, i haven't checked the compression but it is noticeably better. starts easy and the erratic idle is mostly gone. I have been doing the rings/cylinder thing too. Evidently, rings can move. From my research: honing the cylinder properly will limit ring movement, and ring movement will cease/stop once properly seated and broken in. So, it's important to hone the cylinder when you have it apart, clock the rings correctly, and get a proper break in. |
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i give up
by: ramblinman - May 8, 2015 10:43:26 GMT -5
Post by ramblinman on May 8, 2015 10:43:26 GMT -5
i didn't know rings could reposition over time. do you think that is what happened or perhaps they were installed that way from the factory? anyhow, i haven't checked the compression but it is noticeably better. starts easy and the erratic idle is mostly gone. I have been doing the rings/cylinder thing too. Evidently, rings can move. From my research: honing the cylinder properly will limit ring movement, and ring movement will cease/stop once properly seated and broken in. So, it's important to hone the cylinder when you have it apart, clock the rings correctly, and get a proper break in. yeah, if i wasn't pinching pennies right now i would do it properly. plus i don't know how many more miles i'm going to get before i'll need to split the case. the bearing on the variator side is bad so really don't want to put any more money into this scoot. i'm just hoping to get 3 more months out of it. |
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i give up
by: onewheeldrive - May 11, 2015 22:25:52 GMT -5
via mobile
Post by onewheeldrive on May 11, 2015 22:25:52 GMT -5
Are you certain the variator side crank bearing is going out? You're looking for up/down/left/right play, don't worry so much about in/out play. Your scoot's engine will sound like a diesel, too.
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i give up
by: ramblinman - May 12, 2015 6:18:14 GMT -5
Post by ramblinman on May 12, 2015 6:18:14 GMT -5
Are you certain the variator side crank bearing is going out? You're looking for up/down/left/right play, don't worry so much about in/out play. Your scoot's engine will sound like a diesel, too. yeah i'm positive, about 500km ago i changed the variator and noticed a lot of movement. i didn't try pushing in or out. its not as quiet anymore either. wish i had the money and time to fix or at least wish i knew how long before catastrophic failure. |
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i give up
by: onewheeldrive - May 12, 2015 22:17:42 GMT -5
Post by onewheeldrive on May 12, 2015 22:17:42 GMT -5
It'll go out any day now. Surprised you got 500km out of it, but in my experiences the rod bearings went quicker than the side bearings once symptoms started.
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i give up
by: ramblinman - May 12, 2015 23:46:13 GMT -5
Post by ramblinman on May 12, 2015 23:46:13 GMT -5
It'll go out any day now. Surprised you got 500km out of it, but in my experiences the rod bearings went quicker than the side bearings once symptoms started. man, don't tell me that. i don't have the money to mess with the crank. i need it to last a few months. i had the cylinder off last week, the rod seems fine. no movement in & out. |
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i give up
by: onewheeldrive - May 13, 2015 0:49:17 GMT -5
Post by onewheeldrive on May 13, 2015 0:49:17 GMT -5
It'll go out any day now. Surprised you got 500km out of it, but in my experiences the rod bearings went quicker than the side bearings once symptoms started. man, don't tell me that. i don't have the money to mess with the crank. i need it to last a few months. i had the cylinder off last week, the rod seems fine. no movement in & out. Well I'll try and be positive and say that maybe the 150cc cranks can handle a bit more abuse after a bearing begins to fail? A few months is a LONG time, though, especially after 500km or so on it already. Not good for the top end either. I didn't mean to make you worry, just have a "plan b" in case you get stranded----- once that crank goes out completely you won't be able to "limp" home. |
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Post by ramblinman on May 13, 2015 15:17:47 GMT -5
man, don't tell me that. i don't have the money to mess with the crank. i need it to last a few months. i had the cylinder off last week, the rod seems fine. no movement in & out. Well I'll try and be positive and say that maybe the 150cc cranks can handle a bit more abuse after a bearing begins to fail? A few months is a LONG time, though, especially after 500km or so on it already. Not good for the top end either. I didn't mean to make you worry, just have a "plan b" in case you get stranded----- once that crank goes out completely you won't be able to "limp" home. plan B is bicycle, walk or bus. or is that plan B, C & D? currently not working and need to get this scoot on the road so i can go find a paycheck. i guess if it holds up until i have some income trickling in then i could order the part(s). maybe it will hold up longer since it's the variator side and not the rod bearings.  or so i hope |
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Post by onewheeldrive on May 13, 2015 16:30:22 GMT -5
I wish you luck with work and the scoot! To give you an idea what a rebuild would be:
Top end ($50) your piston and cylinder are going to be scored with a bad crank, especially if you ride it until the wheels fall off.
Crank w/oil seals($50)
Flywheel Puller ($20)
Starter Clutch tool ($20)
Gasket Set ($10)
Starter Gear removal-- needs off the crank to split case, $10(?)
Quart of oil ($4)
Possibly oil pump ($15) as I've seen that it's recommended to replace when replacing crank
So you'd be looking at close to $160-$200, AFTER shipping, give or take depending on if you have a flywheel puller and starter clutch tool (then subtract $40 or so). This is just a basic idea of what it'd be. Depending on the shape of your clutch, variator, etc, it may be in your best interest to buy a new engine--- $330-$400.
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