Author Topic: Engine Wouldnt Shut Off  (Read 1981 times)

MrWeaselX3

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Engine Wouldnt Shut Off
« on: June 04, 2009, 07:16:52 PM »
Ok Heres The Situation. Went For A Ride. Ran It Kind Of Hard But Not Real Hard Wasnt Trying To Break It. Never Held The Throttle At Full For Long. It Was A 30-45 Min Ride. Ran Good The Whole Time. Got Back Home Idle Was Kind Of High And Went To Turn It Off From The Run/Off Switch On The Steering Wheel And It Stayed Running. Turned Off The Key And It Stayed Running. Pulled The Plug Wire And It Stayed Running. Pinched The Fuel Line And It Finally Turned Off After Burning All The Fuel That Was Passed The Pinch. I Checked The Compression And It Is At 121. Heres A Picture Of The Plug. Sorry Its Not The Best Picture. Went To Turn It Back On And It Fired Right Up Sounded Normal Hit The Kill Switch And It Turned Off Like It Was Supposed To. Working Fine. So It Seems This Only Happens After The Engine Is Warmed Up Or After A Long Ride. Can Anyone Tell Me What Might Be Wrong. Thanx

PilotHawK

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Engine Wouldnt Shut Off
« Reply #1 on: June 04, 2009, 08:52:04 PM »
Uncontrolled detonation. You need to do a leakdown check, and find the air leak that is causing the problem.

MrWeaselX3

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Engine Wouldnt Shut Off
« Reply #2 on: June 04, 2009, 10:00:26 PM »
How Do I Do A Leak Down Test?

MrWeaselX3

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Engine Wouldnt Shut Off
« Reply #3 on: June 05, 2009, 01:00:30 PM »
Why Does It Only Do This When I Ride It For A While Cause It Doesnt Do It When I Go For A Short Ride?

odypilots

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Engine Wouldnt Shut Off
« Reply #4 on: June 06, 2009, 09:20:35 AM »
It could be that the leak isn't that bad, and doesn't show itself until things get hot.
The usual 'my two cents' disclaimer applies. :)

MrWeaselX3

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Engine Wouldnt Shut Off
« Reply #5 on: June 06, 2009, 04:44:12 PM »
Ok I Did The Leak Test Using The Information Randy From Odyssey Salvage Emailed Me Here Is What He Sent Me.


There are several ways to go about this and this way seems to be the easiest and cheapest for the average guy.
 
You will need the following parts:
vacuum brake bleeder kit (Plastic one is the best because it can be reversed and blow pressure)
1/4 fuel line
     rubber plumbing plug for intake manifold
     rubber plumbing plug for exhaust manifold
 
Ok its best to take the exhaust manifold off and seal the exhaust gasket with silicone for the time being so it does not allow leakage. While you have the manifold off, clean out the exhaust manifold using an cyln. brake hone. Then coat with oil or silicone and install plug.
 
Its best to take the intake manifold gaskets and coat them with motor oil to make sure they have a good seal and can be re-used. On the intake manifold just coat with oil and install plug.
 
Use the vacuum line into the engine that runs the fuel pump to hook your vacuum brake bleeder up to. For now just use the vacuum bleeder and take it to -6 lbs. It may take up to 5 minuets for the pressure to equalize out above and  below the rings. Once that has happen then it should hold the -6 lbs for a minimum of 10 minuets.
 
 IF you do have a leak you can reverse you vacuum bleeder tool and blow pressure into the engine. Then using a bottle of soap water you can try to locate your leak.



 There Was No Leak It Held Pressure For 10 Minutes. What Else Could Be Causing This? A Friend Of Mine That Works At The Local Motorcycle Shop And The Guy That Put My Top End Together Said He Didnt Think It Was A Leak Cause He Said If There Was A Leak It Would Idle High From The Start He Said It Might Be The Spark Plug Staying Hot And Continuing To Burn The Fuel Until You Cut Fuel Or Im Running It To Lean With The Fuel/Oil Mix But Im Running It At 32:1 Or The Carb Is Not Set Right Any More Info Would Be Helpful As To Why This Is Happening It Has Happened Twice Now And Cant Figure It Out Thanks In Advance.

PilotHawK

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Engine Wouldnt Shut Off
« Reply #6 on: June 06, 2009, 05:22:31 PM »
Is the cylinder head chamber smooth? If there is a chunk missing or several pits from a previous piston failure you could have a hot spot developing in the head which is causing your problem. Also excessive carbon buildup could cause a hot spot.

Just to clarify lean or rich does not indicate how much oil you are running. Read this article on jetting.

http://www.yellowdogracing.com/techstuff.htm

MrWeaselX3

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Engine Wouldnt Shut Off
« Reply #7 on: June 07, 2009, 11:41:22 AM »
The Cylinder Dome Is Clean And No Pits Or Hot Spots I Personally Think Its Carb Related I Dont Think My Carb Is Set Right Causing It To Run At High Temperature Gonna Try Some Things From The Link You Posted Does Any Body Live In Californias Mojave Desert Near Barstow That Would Know The Carb Settings For This Area It Gets Pretty Hot Here Im Also Gonna Try A Different Fuel Ratio Adding More Oil To See If It Runs Cooler

PilotHawK

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Engine Wouldnt Shut Off
« Reply #8 on: June 07, 2009, 12:16:12 PM »
Oil at 32:1 is fine. The more oil you add will actually cause the engine to run leaner. The oil displaces the amount of fuel in a given volume.

Lean vs rich is a FUEL and AIR issue. It has NOTHING to do with how much oil you run.

Read this book. It will help tremendously with your understanding of how a 2 stroke engine works.
http://g2buggy.g2-innovations.com/gentech/manuals/2stroketunershandbook.pdf