Weirdest Problem Ever

[SpeedRacer88]

ok well i was helping my buddy do a top end rebuild on his bike(added timing plate +4, t5's 30mm oko's, removed tors) we got it all 2gether and it started the first kick then all of a sudden while it was idle it shot to half throttle i turned off the key and off switch pulled the plug wires and turned off the gas and it kept running for about 1min 30secs WTF!? so i turned on the gas jus long enuff to fill the bowls a little and started it back up again 1 kick. then noticed a lot of white smoke on left side... no coolant leaks even if revved the right side hardly put out any pressureso i let it idle and pulled up on jus the right carb slide still no pressure(i put my hand over the exhaust) out the back but the the engine did rev up...any ideas? im stumped carbs are synced also(i have nitrotate's video)

[peterlocal22]

ok well i was helping my buddy do a top end rebuild on his bike(added timing plate +4, t5's 30mm oko's, removed tors) we got it all 2gether and it started the first kick then all of a sudden while it was idle it shot to half throttle i turned off the key and off switch pulled the plug wires and turned off the gas and it kept running for about 1min 30secs WTF!? so i turned on the gas jus long enuff to fill the bowls a little and started it back up again 1 kick. then noticed a lot of white smoke on left side... no coolant leaks even if revved the right side hardly put out any pressureso i let it idle and pulled up on jus the right carb slide still no pressure(i put my hand over the exhaust) out the back but the the engine did rev up...any ideas? im stumped carbs are synced also(i have nitrotate's video)

 

from the first part of your story it sounded like an air leak.

Check the intakes for cracks and whatnot.ts leaking it could be revving b/c of the extra (high combustible) "fuel"

think they call it dieseling??? the throttle can remain open when motor is shut which gives the hot engine fuel to run w out spark plugs. Carbon build up can remain red hot and act as an igniter.

not positive this is correct so check into it or maybe some one else will chime in.

good luck

 

peter

Edited December 10, 2008 by peterlocal22

[2001Stroker]

Yup, air leak. Leaned out and ran away.

[Michael Jackson]

isnt that called "dieseling" ? where it starts combusting with compression instead of spark and wont stop? i think i read about that on here somewhere

[2001Stroker]

Dieseling is usually caused by the timing being WAY off. When that happens though, it does stay running for a while, but only at like 100 RPM's. And when it does it, it sounds like the engine has a horrible rod knock because the detonation is so loud. An air leak will make it run at high RPM's while it's running, AND after you cut it off.

[SpeedRacer88]

Dieseling is usually caused by the timing being WAY off. When that happens though, it does stay running for a while, but only at like 100 RPM's. And when it does it, it sounds like the engine has a horrible rod knock because the detonation is so loud. An air leak will make it run at high RPM's while it's running, AND after you cut it off.

 

so u think we had a leak? where shud i look? how? wat about the smoke ?

[Michael Jackson]

Dieseling is usually caused by the timing being WAY off. When that happens though, it does stay running for a while, but only at like 100 RPM's. And when it does it, it sounds like the engine has a horrible rod knock because the detonation is so loud. An air leak will make it run at high RPM's while it's running, AND after you cut it off.

 

ty for explaining

 

 

by the way i had a similar problem with my blaster liek 5 year ago, shut it off, pulled the plug cap, etc, and it kept revvin to the moon, it was a crank seal, a friend replaced for me and it was all better

Edited December 10, 2008 by Michael Jackson

[SpeedRacer88]

anybody? help please

[Dick Wheels]

Dieseling is usually caused by the timing being WAY off. When that happens though, it does stay running for a while, but only at like 100 RPM's. And when it does it, it sounds like the engine has a horrible rod knock because the detonation is so loud. An air leak will make it run at high RPM's while it's running, AND after you cut it off.

 

 

I know that sound all to well. The 427 in my Camaro did it when the lifters finally wore enough of the cam lobes away. Damn chevy big blocks and $13k engines

[flyhighprerunner]

I know that sound all to well. The 427 in my Camaro did it when the lifters finally wore enough of the cam lobes away. Damn chevy big blocks and $13k engines

 

Wonder if his cam went flat..........jk had to throw that in there........try checking around the bottom of the cylinders around the intakes or you can make your own leak down tester and find out exactly where its coming from....

[SpeedRacer88]

ok everyone thanks for the replys imma look for a leak 2day wen he comes back over but would a leak cause only one pipe to put out white smoke and the other pipe is just abiut dead read my original post for full story

[dajogejr]

WAY back in the day....we had a Jet Ski do the same thing. Luckily, out of water on a stand.

Kill switch didn't work, we ended up pulling the gas feed line/cap off...and letting it run out of fuel. (It sucked the fuel down like water from a straw)

 

Needless to say, after we leak down tested it and found a bad intake gasket, no one was jumping at the opportunity to be the first to ride it on the lake.

 

Alky bikes are good for doing that...running away is what we call it.

 

Normally..what we do is click up as many gears as we can, FLOOR the throttle...STAND on the brake and dump the clutch to kill it.

 

First time it happens to you...you damn near shit yourself....

 

Leak down test it. What happens is due to the air leak, it gets SO hot in the cylinder that it no longer needs spark to ignite the fuel/air. It ignites off the heat and compression (yes...just like a diesel)

 

Funny thing is...a top fuel dragster makes half the pass down the track like this, every time. They burn off the spark plugs and literally diesel half way down the track...

[desertdeweller]

as mentioned check for air leaks also pull the flywheel and see if you sheared the key on it. maybe something happened when you installed the timing plate oh and check the air gap on the pick up.

[SpeedRacer88]

thanks guys so u guys think the smoke on one side is bcause of the air leak

[KEVSWS6]

ok everyone thanks for the replys imma look for a leak 2day wen he comes back over but would a leak cause only one pipe to put out white smoke and the other pipe is just abiut dead read my original post for full story

 

Worry about the smoke later. First check the compression to make sure the rings are ok. Go back over the work you did and check it good. Sounds like an air leak to me. We have run into this and like dajogejr said you will shit yourself when it first happens to you. The first time I thought we melted the engine down. Sounded like it revved to 15,000 RPM!