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10-03-2018, 10:15 AM

Jimmy Murdock

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Ive got a 1986 Yamaha Moto 4 200 that won’t start. I’ve replaced the starter,carb,coil,spark plug and wire and the valves seem to be set right but still won’t start. Turns over fine. Seems to be getting fuel and good spark that’s what is confusing. Any help would be greatly appreciated.

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10-03-2018, 04:42 PM

Kymco 450i

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Needs compression...run a comp check, if below 75lbs it will never run. If comp is good then look at ignition timing, spark needs to happen at the right time and a good spark is needed. Check spark gap.. should jump a 3/16"gap and be bright blue. If dull orange spark may be weak.

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10-04-2018, 08:36 AM

Jimmy Murdock

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i messed with it yeasterday and got it running now it seems to have a little back fire I guess you would call it or a hick up? When it does this sometimes it dies sometimes it doesn’t. Is there something that needs adjusted? If it makes any sense it doesn’t sound like a backfire from the exhaust more from the front of the engine that’s why I’m not sure it’s a back fire.

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10-04-2018, 12:07 PM

Jered651

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Could be the boot from carb to the head. get it running and spray carb cleaner on the boot all over take your time doing it if the motor changes you have a leak on it. Could clean the carb good and adjust the valves too that might help I have 3 of these machines and they are tough.

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10-04-2018, 01:30 PM

Jimmy Murdock

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i tried the spraying carb cleaner on the boot from carb to head but it showed no change? I changed the carb and it also changed nothing. Thinking now it maybe the valves?

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10-05-2018, 10:05 AM

Jered651

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Check the valve lash yes I have had one where the spark was inconsistent and would do that also and needed a new cdi box. If that is the case buy a oem one off ebay and not a Mr electric after market one.

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10-05-2018, 04:30 PM

McBuckNasty

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Hello I need a little help. I have an 80cc Yamaha Raptor. I recently replaced the carburetor do two valves getting bit and all that and now I'm wondering what I could do for lack of power any suggestions

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