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post #1 of 6 (permalink) Old 10-16-2013, 09:24 AM Thread Starter
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This may sound dumb.

I seem to recall somebody telling me when an engine floods, it drops compression. if this is true,any takers on the wears and why fors?

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post #2 of 6 (permalink) Old 10-16-2013, 10:22 AM
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I seem to recall somebody telling me when an engine floods, it drops compression. if this is true,any takers on the wears and why fors?
If you pour fuel into the combustion chamber the compression should go up, not down. Besides decreasing the volume you are also sealing the rings....

So yes, it does sound dumb....

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post #3 of 6 (permalink) Old 10-16-2013, 10:40 AM
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If you pour fuel into the combustion chamber the compression should go up, not down. Besides decreasing the volume you are also sealing the rings....

So yes, it does sound dumb....
When an engine floods, the gas washes all the oil off of the cylinder wall. No oil, low compression. And if not done often there should be no appreciable damage. However if done on a regular basis like holding the gas peddle to the floor when shutting off the engine so that there will be fuel there when restarting is a definite death sentence for the engine. And believe me there were many fools back in the old days that did just that. The only time the gas would increase the compression is right after it is flooded, because in a short matter of time the gas would bleed down around the rings.
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post #4 of 6 (permalink) Old 10-16-2013, 11:54 AM
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When an engine floods, the gas washes all the oil off of the cylinder wall. No oil, low compression. And if not done often there should be no appreciable damage. However if done on a regular basis like holding the gas peddle to the floor when shutting off the engine so that there will be fuel there when restarting is a definite death sentence for the engine. And believe me there were many fools back in the old days that did just that. The only time the gas would increase the compression is right after it is flooded, because in a short matter of time the gas would bleed down around the rings.
That all sounds good but it doesn't hold true unless you keep cranking and cranking the engine and it doesn't ever start.

The amount of oil on the cylinder wall is minuscule, unless your rings are bad to begin with. Modern engines have pretty tight tolerances so if you flood your engine ....while trying to start it...(which I believe was my take on the question). You will likely get the thing started before any fuel has the chance to wash anything away.

If you don't believe me. Go test your compression. Then pull a plug, add an ounce of gas and check it again quickly...Compression should go up if anything.

I've done this before to prove this. If you wait ten minutes and and check the compression on an older or worn motor I could see where it might go down.

Yes, back in the day unscrupulous sellers of motors would pour a tablespoon of oil into the chamber before a would be buyer checked the compression....which would hide small leaks around the rings.

But any liquid will do the same thing. Gas is "thinner" and will leak out quicker, so yes, it's a matter of how soon and how long you check the compression.
And how well your pistons are sealed...

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post #5 of 6 (permalink) Old 10-16-2013, 09:30 PM
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Using the choke (the enrichener circuit on the Vulcan) when it is not necessary can wash some of the oil off the cylinder walls, resulting in excessive engine wear. That's why I turn it off as soon as the engine will run with out it. But, considering the extremely long life of the VN750 engine, most riders would never notice it. But as for whether the compression actually drops measurably, I doubt it.

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post #6 of 6 (permalink) Old 10-17-2013, 08:17 AM Thread Starter
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Thanks Geezy.

Who walks into the Lions Den, and comes out alive?
The Lion!
12 inch apes
1986 A3 series 750
Slash cut stainless mufflers
170 rear tyre
Custom cyane blue paint, wheels included
Relocated regulator rectifier
Solo mod
Stainless washable oil filter
Six pack rack
LED indicators and flasher unit.
Replaced CDI
Coasters
Penrite 10/50
Oil pressure hot at 1000 rpm 20 psi, 4000 rpm 60 psi
Shows 67000 kms
Jets 38 idle Mains 120 changed to 40 idle 135 main.
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