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Post by roy on Aug 18, 2017 11:38:45 GMT -5
I did a search and found some good suggestions here that I will relay to my mechanic later today. Just wondering if the cdi could be the culprit. Here's the story.
Customer brings in 2T 2013 Kymco Super 8 with 4200 km. States he purchased used and told it only needed a carb. They replaced that, road it 3 miles and it died. Could only restart with starting fluid, then the rpm's would max out.
We see the EGR tubes have been disconnected and blocked. We can get it started by blocking the air intake, and it'll idle but when you give it gas it will rapidly increase in rpms to running full throttle. Can not turn off with key or kill switch. Only shutting off air supply will stop it. We have checked for stuck float, tried his old carb and a new one.
At this point I will tell him what I found here, ie. check all vacuum lines, that bolts are tight, etc. He usually does these things first. We stopped last night with only the thought of could it be the cdi. I will have to order one. I do see pictures showing 8 wires and talk of cutting 1 or 2 to derestrict, etc. BUT ... the cdi on this scoot does have the 8 pins, however only 6 wires with the other 2 slots blocked.
Once source told me it will Not be the cdi, but looking for you guys thoughts and suggestions.
thanks!! Roy
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Post by pistonguy on Aug 18, 2017 18:44:47 GMT -5
The Crank Seals are Leaking Big Time. Classic Symptoms, Big Time Air Leak, 2-T Group "A" Room # 101.......................
2-T Runaway Throttle.
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Post by cyborg55 on Aug 20, 2017 9:55:04 GMT -5
I'm in pistons camp on this one,,,air leak of epic proportions,,crank seals
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New Rider
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Hello from Va.
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Post by roy on Aug 21, 2017 9:39:08 GMT -5
Thanks for the ideas. I will pass it on to the mechanic. RE: carb, my mech. also did put the original carb. back on, and gets the same issue.
In the meantime I took the idea of crank seals and with youtube, etc. seems like that would typically lead more to bogging down by bringing in too much air. But - crank seals, piston I will share with him.
Any other ideas!! ?? Hope we can get this thing done :-)
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Post by pistonguy on Aug 21, 2017 12:10:15 GMT -5
Not Just the Crank or Crank Seals but the Intake Boot or Spigot itself or anywhere there is Air Available to leak.If ya can get it running Spray with some WD-40 and the when she sucks that it should slightly bogg or some use Contact cleaner or Sketchy but I like Starting fluid, the rpm will jump when the engine smells the Ether Starting fluid. Be careful....
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New Rider
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Hello from Va.
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Post by roy on Aug 21, 2017 13:17:01 GMT -5
Okay ... I bought some starting fluid and carb. cleaner to isolate the air leak. We'll see. BUT .... I just re-read my original Post, AND want to make sure my actual issue is known. The scooter is racing full rpms. Can only stop it by choking it.
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New Rider
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Hello from Va.
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Post by roy on Aug 21, 2017 14:18:18 GMT -5
Oh --- I just learned something (I think) --- again, I mainly know 4T's. But, now I've read 2T's need a vacuum below the piston. So - a seal would screw that up. My mech. will probably know this, just did not put it together yet.
Am I thinking right? Other ideas? Again .. we have to cover the intake to start. It will idle a few seconds, then the rpms will start increasing. In 10 seconds it's like full throttle. Have to cover intake to stop it, kill switch, key will not work (they do at idle).
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Post by pistonguy on Aug 21, 2017 15:23:14 GMT -5
Oh --- I just learned something (I think) --- again, I mainly know 4T's. But, now I've read 2T's need a vacuum below the piston. So - a seal would screw that up. My mech. will probably know this, just did not put it together yet. Am I thinking right? Other ideas? Again .. we have to cover the intake to start. It will idle a few seconds, then the rpms will start increasing. In 10 seconds it's like full throttle. Have to cover intake to stop it, kill switch, key will not work (they do at idle). Yes a 2-T Crankcase Is Pressurized, A Runaway Throttle on 2-T is Classic Massive Air Leak. If Not the Intake Spigot even the Case halves themselves maybe leaking around the Crank Area. #1 If it Smokes its Sucking Transmission Oil. (white smoke). #2 If the Throttle Runs Away its a Massive Air Leak. Good luck |
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Post by roy on Aug 30, 2017 17:05:59 GMT -5
Well Piston Guy, looks like you got it on your first answer.
I found out from the customer that they had put a 47mm bore in it. So, my mechanic was thinking they put the piston in upside down .... Turns out the cylinder is scored and the bottom of the piston is rough with little burrs. The top of the piston had a lot of carbon from never being on the road. It seems that maybe one of the rings was not seated correctly.
Any more comments or thoughts from anyone are appreciated. Thanks! Roy
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