G2-A yamaha spark breaks down at high rpms.

[nineiron6]

I have a G2-A yamaha

when you step on the gas the engine rev's normally until you put the gas to the floor and then it cuts out .... when the timing light is attached the light works perfectly until the gas pedal is put to the floor then it cuts out . I have replaced the coil , installed the igniter on another cart same age it works perfectly no cutting out ... Thanks for any suggestions

[Michael Eddie]

When the cart dies, pull the spark plug out and check for spark.

[nineiron6]

The spark is working until the gas pedal is depressed to the floor and then starts missing .... when you attach a timing light the light stops pulsing or working at the high rpm's ..works great at low rpm's no misses the carb has been cleaned gas filter is new lots of gas to the carb . gov has been disconnected for testing air cleaner has been cleaned.

[nineiron6]

the cart is moving with the gas pedal fully depressed when this happens and is going about 6 or 7 mph ... if the cart is stationary and the shifter is in neutral the engine starts falling off as soon as the gas pedal is depressed to the floor and the engine reaches the higher rpm's this is with no mechanical governor attached

[Michael Eddie]

With the governor attached were you still getting this problem?

[wesison]

wes ison

i have a simular problem with a g1 will start will run normal at very low speeds as soon as the vehicle is accelerated or floored the engine boggs way down but surges back up like engine is turning off and back on same
condition exists when rear wheels off the ground and and running-clutch engages engine speed slows up then re-engages constant and rythmatically, i have disconnected exhaust and ran to eliminate clogging of exhaust causing back pressure-have drained fuel tank cleaned and replaced fuel-replaced fuel filter-replaced fuel and vacuum lines-removed fuel pump disassembled completely cleaned thoroughly-replaced carburator-replaced spark plug-cleaned fuel tank vent-eliminated fuel tank vent-eliminated air filter element with air box closed-ran with no air box/filter connected-ran the engine with fuel in a funnel direct to carburator fuel intake-removed and cleaned check ball valve in vacuum hose then air checked-removed valve cover visually inspected valve train-turned engine over apears to operating
correctly-engine will back fire when forced to run under this condition-pulling choke when running does not change condition at all-has good vacuum and great fuel delivery when running on jack-tested vehicle for spark and is good when cranking engine disconnected have not tested at high speeds-all efforts have lead to no results-i have exhausted all atempts of common sense-any information you could share that will point me in the right direction will be appreciated.

[macch7]

G9-A same problem

My G9-a is experiencing the exact symtoms as your G2. I will try replacing the coil first , have one in stock. What does the igniter look like and where is it located? Have you cured your similar problem? Macch

I have a G2-A yamaha

when you step on the gas the engine rev's normally until you put the gas to the floor and then it cuts out .... when the timing light is attached the light works perfectly until the gas pedal is put to the floor then it cuts out . I have replaced the coil , installed the igniter on another cart same age it works perfectly no cutting out ... Thanks for any suggestions

[macch7]

Hi Wesison,

Is the G1 a 2 stroke or 4 stroke, my G9 is a four srtoke and seems to be loosing spark under heavy load demand, the same thing that happened to ninearon. What I am saying is I have no experience with the two stroke engines. Wish you luck.

i have a simular problem with a g1 will start will run normal at very low speeds as soon as the vehicle is accelerated or floored the engine boggs way down but surges back up like engine is turning off and back on same
condition exists when rear wheels off the ground and and running-clutch engages engine speed slows up then re-engages constant and rythmatically, i have disconnected exhaust and ran to eliminate clogging of exhaust causing back pressure-have drained fuel tank cleaned and replaced fuel-replaced fuel filter-replaced fuel and vacuum lines-removed fuel pump disassembled completely cleaned thoroughly-replaced carburator-replaced spark plug-cleaned fuel tank vent-eliminated fuel tank vent-eliminated air filter element with air box closed-ran with no air box/filter connected-ran the engine with fuel in a funnel direct to carburator fuel intake-removed and cleaned check ball valve in vacuum hose then air checked-removed valve cover visually inspected valve train-turned engine over apears to operating
correctly-engine will back fire when forced to run under this condition-pulling choke when running does not change condition at all-has good vacuum and great fuel delivery when running on jack-tested vehicle for spark and is good when cranking engine disconnected have not tested at high speeds-all efforts have lead to no results-i have exhausted all atempts of common sense-any information you could share that will point me in the right direction will be appreciated.

[Michael Eddie]

wesison,

Check to make sure the air filter box, hoses and pipes are 100% sealed, there must me no holes or air getting in anywhere. Check for dry rotting around the rubber carburetor bracket.

macch7,

wesison has a 2 stroke, actually the first model Yamaha made the G1A which was a gas 2 stroke model. Check all the intake hoses for a perfect seal, Yamaha's are infamous for not running right with even the slightest leak. Make sure it is indeed a spark problem and not a gas problem, I’ve seen what you are explaining when there is a problem with the needle in the carburetor.

[macch7]

simple fix

Matti,

I want to thank you very much for your suggestion about air leaks to the carburator. After reading your response to my question, I noticed a loose clamp on the hose between the air filter and carburator . I tightened the clamp and walla, problem solved.

Thanks again,

Macch

[Michael Eddie]

Glad to hear it macch7, happy carting!