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Posted: Fri Nov 19, 2010 4:52 pm Post subject: Weird new issue: Engine races on its own & won't shut of
Still got my old '79 TS185, which I've "thought" was done now that the mag side seal & pilot jet were fixed. Was testing the bike at a stop with the gas shut off so as to drain the bowl. Blipped the throttle a few times & the engine started to race. Blipping the throttle didn't change anything.
Hit the engine off button: NOTHING. Turned the Key off: NOTHING.
Now I am concerned.. the engine is still racing, so I pull the spark plug wire. It shuts off. I restart the engine & all seems OK.
Posted: Fri Nov 19, 2010 10:49 pm Post subject: I've done some research. A number of possibilities...
Since an engine needs fuel, air, spark and compression to work I can possibly narrow things down.
Fuel: I could be somehow running lean, maybe due to a carb misadjustment, air leak or something similar. Could be a misadjusted float, plugged jet or something wrong in the carb itself.
Air: It could be a dreaded air/vacuum leak. Since I've just replaced the magneto side seal and see no loss in transmission oil or white smoke I doubt its the clutch side seal, although it could always be a possibility. I had similar issues once before, which required replacement of the clutch side seal, which was done only about 2 years/400 miles ago. I dread that, since such requires tearing down the motor, which is beyond my ability & tools. I'd need professional help. Again. Could be a leak somewhere else, such as a carb boot or gasket. I just don't know......
Spark: This is what puzzles me. How can the engine "diesel" by running without spark? The combustion chamber should be clean & the plug appears to be a decent tan. If it were loaded with glowing carbon I might understand, but so far not so good.
If I understand you correctly your bike began to rev higher after you turned the fuel petcock off. As the engine began running out of fuel it began racing higher and higher in rpms. Some of that tendency is normal for a 2 stroke. The out of control rpms can be worse if the carburetor is adjusted to an idle that is entirely too rich in fuel. As the fuel starts to run out the rpms climb because the air/fuel ratio is getting closer and closer to what it should be in the first place and the engine is running more efficiently and begins to rev up due to a cleaner burning lean air fuel ratio. A super lean mixture runs hot and will lead to a melted hole in the piston if not corrected. Just as a precaution be sure you carburetor slide and throttle cable are not sticking open.That being said.....the fact that it wouldn't shut off is a different story. If you pulled the plug wire to instantly kill the engine then I would say that your engine was not dieseling. A more likely scenario is that your kill button and ignition switch were not grounded correctly.
Posted: Sat Nov 20, 2010 7:34 am Post subject: Thanks. I remain puzzled by the inconsistency.
rdaystrom wrote:
If I understand you correctly your bike began to rev higher after you turned the fuel petcock off. As the engine began running out of fuel it began racing higher and higher in rpms. Some of that tendency is normal for a 2 stroke. The out of control rpms can be worse if the carburetor is adjusted to an idle that is entirely too rich in fuel. As the fuel starts to run out the rpms climb because the air/fuel ratio is getting closer and closer to what it should be in the first place and the engine is running more efficiently and begins to rev up due to a cleaner burning lean air fuel ratio. A super lean mixture runs hot and will lead to a melted hole in the piston if not corrected. Just as a precaution be sure you carburetor slide and throttle cable are not sticking open.That being said.....the fact that it wouldn't shut off is a different story. If you pulled the plug wire to instantly kill the engine then I would say that your engine was not dieseling. A more likely scenario is that your kill button and ignition switch were not grounded correctly.
I know the switch & kill button work. Both were tested. The carb & cables aren't sticking. Checked both. The last time this happened it was the dreaded clutch side seal.
I did pull the plug wire & it seemed to keep running. It is possible I didn't pull it far enough & there was arcing.
Still, I suspect a carb or airleak issue. Must dig deeper. Scared the crap out of me!
Posted: Sat Nov 20, 2010 2:25 pm Post subject: My mechanic friend at the local Suzuki dealer will help.
Although I could spend some time tracking this down, I'm ante up the $$ any pay the dealership to help me as the stakes are too high. Can't risk imploding a 30+ year motor! Can't get it there until after Thanksgiving, so we'll see where this goes.
Seems they call it a "runaway" engine, which can cause some real bad things.....
Posted: Thu Dec 16, 2010 8:27 pm Post subject: Update: Seems the timing may have been off.
Had a local very experienced mechanic look at the old TS185. Said the timing was off. He adjusted it. Also did an air leak test, which was supposedly OK. I need to talk to him personally to get the details, but so far so good-- I hope.
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