logcutter429
ArboristSite Operative
Don't think i want the jug comeing off and hitting me under the chin neither, its fixed right.
anyone had this happen before 2nd try
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Weatherby
ArboristSite Operative
Dennis, the problem with duck tape is it doesnt stick that well when surfaces are oily. So I guess we have combine this thread with the one on cleaning cylinders, so that our duct tape now has a clean surface to stick to. See everything is always inter-related here on this site. The hard part is getting the duct tape down in between the fins to seal everything up. And make sure its the waterproof 200mph duct tape so no wateror air gets in.
An 084 carb on a 394? How exactly did that work out? Maybe you could try JB Welding an adjustable carb on one of those fixed jet 026's we've been hearing about. Well I guess you could use duct tape as well.
An 084 carb on a 394? How exactly did that work out? Maybe you could try JB Welding an adjustable carb on one of those fixed jet 026's we've been hearing about. Well I guess you could use duct tape as well.
How would water in the crankcase cause this condition?
Rotax Robert
Addicted to ArboristSite
Ben my thoughts exactly, if water can get in, so could air. Maybe they should not be using the impulse line as a siphon hose.
Dennis
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Weatherby, my apologies...it was a 3120 carb on the 394...and it worked pretty good...until the corner of the jug busted out. And of course the carb was not fully adjustable..I do have an 084 carb on a Super 930 that I am working on.
I can't see it being water either...
I can't see it being water either...
ben,
in the case of my cr250, i think it sucked in a lungfull of water through the carb. i had an aftermarket air filter on it, no airbox or nothing. i hit the creek full bore in second gear. i remember it put the fire out, but the momentum of the bike kept the motor spinning, thus causing the hydraulic lock. as i'm sure you know, water does not compress worth a darn. again, i ain't saying this is what happened to logcutters saw, as the real cause may be difficult and expensive to ascertain. i met a guy in phoenix, az. when i lived there, i was racing rc hydroplanes at the time, and he raced these little hydroplanes that you drive on your knees, all crouched down. he was selling these racing outboards, not sure what size, but 2 cylinders, and one day he says that the manufacturer claimed the engine could be thrown into the water at full throttle and come out with no damage. so we challenged him to that claim, as we had seen a lot of racing rc engines in boats that had flipped, get the whole cylinder blown off by hydraulic lock. of course these little rc engines run on nitromethanol and spin 25,000rpm's.well one day he brings one out, fires it up, tapes the throttle open and drops it into the pond at the edge. it abruptly stopped in a very quick way, and when we pulled it out, the whole cylinder assembly had pulled away from the block. actually pulled the studs right out of the aluminum. we laughed like heck, but several weeks later, he came back with the repaired engine. but he wouldn't do it again! i'll always remember that .
in the case of my cr250, i think it sucked in a lungfull of water through the carb. i had an aftermarket air filter on it, no airbox or nothing. i hit the creek full bore in second gear. i remember it put the fire out, but the momentum of the bike kept the motor spinning, thus causing the hydraulic lock. as i'm sure you know, water does not compress worth a darn. again, i ain't saying this is what happened to logcutters saw, as the real cause may be difficult and expensive to ascertain. i met a guy in phoenix, az. when i lived there, i was racing rc hydroplanes at the time, and he raced these little hydroplanes that you drive on your knees, all crouched down. he was selling these racing outboards, not sure what size, but 2 cylinders, and one day he says that the manufacturer claimed the engine could be thrown into the water at full throttle and come out with no damage. so we challenged him to that claim, as we had seen a lot of racing rc engines in boats that had flipped, get the whole cylinder blown off by hydraulic lock. of course these little rc engines run on nitromethanol and spin 25,000rpm's.well one day he brings one out, fires it up, tapes the throttle open and drops it into the pond at the edge. it abruptly stopped in a very quick way, and when we pulled it out, the whole cylinder assembly had pulled away from the block. actually pulled the studs right out of the aluminum. we laughed like heck, but several weeks later, he came back with the repaired engine. but he wouldn't do it again! i'll always remember that .
If it did indeed hydrlock it would have bent the rod for sure and also it would have broken or stretched all the mount bolts in stead of just blowing out the back of the cylinder. I am thinking it was just a bad casting that strees cracked. I could be wrong(have been before), but that my take on it.
Tony Snyder
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To bad you fixed it, you might have been able to turn it in to that independant (non-NASA) investigation board and told them it was shuttle debris and they could have told you what caused the failure.
logcutter429
ArboristSite Operative
I think i'll go with the bad casting theory, cause the morning it happened it was about 15 degrees out and clear , ihad just stumped 5 trees about 30" and was about to work them up when it started sucking air and i shut it down and traded saws.
after looking a little closer at the pic, i think we should consider excess heat as a possible contributing factor in the failure. no offense logcutter, but that jug is extremely gunked up. it looks to me like it has never been cleaned off. go to the "cutting in hot weather" thread to read more on this subject. the gunk greatly interferes with the aluminums ability to dissipate heat, and over time may lead to metal fatigue. i have seen many saws like this. this is poor maintenance at its worst. i can't believe this saw was rebuilt shortly before this happened. this kind of baked on crud takes awhile to get this bad. if a mechanic reassembled this saw with the jug in this condition, then he wouldn't get no more work from me.
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