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Post by mojo89 on Aug 21, 2014 10:12:08 GMT -5
2012 taotao atm50, about 14k on the odo.
I replaced the piston, cylinder, and head at about 11k due to low compression and it ran great for a few months. I used a 60cc piston/cylinder instead of a 50cc when I replaced it.
Some punk pushed my bike over one night and pulled my cdi out of the frame, but I reattached and it ran. The rubber holder for the cdi was broken, and allowed it to touch the frame and would bog when it did because it was short circuiting, but I have since replaced it.
It sat for a week after that incident, then it wouldn't start. I did valve adjustments and replaced the air filter and carb, before I had it compression tested and found that I only have 40 psi of compression. Could it be anything other than head/valves, cylinder, piston, or their gaskets?
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Post by scotttx on Aug 21, 2014 11:41:37 GMT -5
re-torque your head? double check your valves?
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Post by mojo89 on Aug 21, 2014 21:26:01 GMT -5
Will do sunday. I set my valves to .005 mm and head was torqued to 20 ft/lbs when I did the job, per the manuals I obtained from this forum. Basically going to do a cylinder tear down/build up inspection again.
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Post by geh3333 on Aug 21, 2014 22:07:10 GMT -5
2012 taotao atm50, about 14k on the odo. I replaced the piston, cylinder, and head at about 11k due to low compression and it ran great for a few months. I used a 60cc piston/cylinder instead of a 50cc when I replaced it. Some punk pushed my bike over one night and pulled my cdi out of the frame, but I reattached and it ran. The rubber holder for the cdi was broken, and allowed it to touch the frame and would bog when it did because it was short circuiting, but I have since replaced it. It sat for a week after that incident, then it wouldn't start. I did valve adjustments and replaced the air filter and carb, before I had it compression tested and found that I only have 40 psi of compression. Could it be anything other than head/valves, cylinder, piston, or their gaskets? I would have did a little retuning on him and messed his compression up  ? What's with these facial expressions this site won't post any of the expressions from my iphone !!!! Lol |
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Post by onewheeldrive on Aug 21, 2014 22:35:23 GMT -5
You mean .05mm.
Definitely on the tighter side of things.
Have any of you ever checked compression with overly tight valves?
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Post by jjoshua20213 on Aug 22, 2014 0:06:10 GMT -5
If your valves are set good and you have to take it apart and inspect. Somethings leaking compression
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Post by mojo89 on Aug 22, 2014 21:16:17 GMT -5
That's what I figure. But this is twice for compression problems being my initial diagnosis, is something causing it? I've done a few basic upgrades; cdi, muffler, 60cc, cvt, but the carb and air filter are new oem stock. Would any of these be causing a specific part to go out? My old 50cc parts didn't look very bad at all, but it started right up after I replaced it.
Would you recommend opening the valves to say, .06 or .07 mm then? I haven't researched it, just going by the manuals
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Post by scotttx on Aug 22, 2014 23:00:32 GMT -5
.05 is plenty, think he was referring to .005 as you said.
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Post by JerryScript on Aug 22, 2014 23:27:09 GMT -5
Compression is only affected by the jug to head connection, the rings, the valves, and the spark plug. If you have low compression, either one of these items is not properly connected and torqued, or you have too many gaskets in place (many people add extra base gaskets to lower compression when it is too high, I assume you did not). One trick to check for leaks that might be causing loss of compression is to use a spray bottle with sudsy water, spraying it on each of the connection points, then hand turning (or kickstart turning) the engine and watching for bubbles/spray to appear. It takes a helper most of the time, one to turn the motor while the other watches.
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Post by alleyoop on Aug 22, 2014 23:44:51 GMT -5
Who is doing the compression tests and does whoever that is knows how to test for compression. Many folks do not know how to test it correctly and will always show low readings. The other thing is if you put in the rings wrong that will cause low compression so there are some things that if you did not put things on right will cause low compression. To check if its the rings pour a little bit of oil down the plug and retest the compression, if the compression is higher then its your rings. To When checking compression you have to hold the throttle wide open so it sucks in as much air as possible, If you don't the readings will be very low and you crank it until the needle stops going up. As its cranking the needle will start to climb and will not climb once it reachs the most it can put out.
Compression loss can be caused by it leaking by the plug, the head gasket, cracked piston, cracked jug, rings, valves not sealing.
Alleyoop
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Post by pauldog on Aug 24, 2014 8:47:17 GMT -5
OEM carb could be part of the issue. Check your plug. I will guess you r running very lean. This can lead to valve issues and piston ring issues. 60cc is a very very reliable set up. You will need to up jet with your mods.
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Post by mojo89 on Sept 3, 2014 16:56:24 GMT -5
So my new jug is scarred. My guess is since the air filter wasn't oiled it let in debris. Another new jug and piston.
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Post by scotttx on Sept 4, 2014 12:57:01 GMT -5
wonder if new rings and a honing would clear it up if they're not too deep?
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Post by mojo89 on Sept 4, 2014 13:40:28 GMT -5
That might work, but I'm gettin new ones for 50 bucks
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Post by mojo89 on Sept 5, 2014 8:39:40 GMT -5
The oem carb is an updated model with fuel air mix screw that isn't sealed
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..BAD TO THE BONE..