jkross Posted January 8, 2009 Report Share Posted January 8, 2009 I leaned out and blew a hole in my piston. Just split the cases last night, and the crank shaft is discolored. It obviously got really hot. The top of the rod is scored. there are metal shavings EVERYWHERE! A guy I trust said the center bearings can be flushed out with mixed gas. Should I trust him? Has anyone ever done that? Do I need a new crank shaft, or is the dis-coloration a minor deal? It was a trued and welded crank. I'll be running a Cool head with 19cc domes, an extreme port job with advanced timing, k&N Pods, and CPI inframes. Please tell me I don't have to spend another $500.00 on a crank shaft...that I can just rinse it out and it'll be ok. Thanks. Quote Link to comment Share on other sites More sharing options...
nitroburner13 Posted January 8, 2009 Report Share Posted January 8, 2009 (edited) i would def advise to get a new one. that thing looks like it got toasted pertty good and the metal shavings are another red flag. if you put it back together and blow it up with that crank then youll spend a lot more than the 500 you will spend now. get the new one and dont worry about it. Edited January 8, 2009 by nitroburner13 Quote Link to comment Share on other sites More sharing options...
BUILDER Posted January 8, 2009 Report Share Posted January 8, 2009 I leaned out and blew a hole in my piston. Just split the cases last night, and the crank shaft is discolored. It obviously got really hot. The top of the rod is scored. there are metal shavings EVERYWHERE! A guy I trust said the center bearings can be flushed out with mixed gas. Should I trust him? Has anyone ever done that? Do I need a new crank shaft, or is the dis-coloration a minor deal? It was a trued and welded crank. I'll be running a Cool head with 19cc domes, an extreme port job with advanced timing, k&N Pods, and CPI inframes. Please tell me I don't have to spend another $500.00 on a crank shaft...that I can just rinse it out and it'll be ok. Thanks. You can get a stock stoke crank for a lot less that 500 and if you are worried about it at all i would replace it. Not worth doing twice. Quote Link to comment Share on other sites More sharing options...
jkross Posted January 9, 2009 Author Report Share Posted January 9, 2009 Yeah...I guess I needed to hear that. I think you guys are right...dammit. Thanks for the honesty. Nobody ever talks about what money pits these things can be. $1,300 for the port work and all the upgraded parts (labor, V-force 3 Reeds, cool head, domes, bearing kits, gasket kits, etc...etc...) $200.00 for new chain and air filters and rear sprocket. $640.00 for New CPI's $500.00 (give or take) for the crank shaft $2,640 by my math - and no Cub kit! Bought it for $3,850.00. I believe this is what you call - upside down - equity wise. Sorry for the negativity. Quote Link to comment Share on other sites More sharing options...
AKheathen Posted January 9, 2009 Report Share Posted January 9, 2009 i'm not sure about the banshee crank, but the welded crancs on sno-go twins can be rebuilt twice, but if you're goin all in with port work on a new top end, you could probably get a stroker, and be money ahead Quote Link to comment Share on other sites More sharing options...
bansheejoel Posted January 9, 2009 Report Share Posted January 9, 2009 (edited) Yeah...I guess I needed to hear that. I think you guys are right...dammit. Thanks for the honesty. Nobody ever talks about what money pits these things can be. $1,300 for the port work and all the upgraded parts (labor, V-force 3 Reeds, cool head, domes, bearing kits, gasket kits, etc...etc...) $200.00 for new chain and air filters and rear sprocket. $640.00 for New CPI's $500.00 (give or take) for the crank shaft $2,640 by my math - and no Cub kit! Bought it for $3,850.00. I believe this is what you call - upside down - equity wise. Sorry for the negativity. $1300 for porting and the other small add ons? Wow you must have gotten ripped off. A new crank isnt near $500, kevin has NEW 4mill cranks for $435. Fun isnt cheap, dont like it..........sell it.....you can get good used stock cranks for $150 all day long Edited January 9, 2009 by bansheejoel Quote Link to comment Share on other sites More sharing options...
AKheathen Posted January 9, 2009 Report Share Posted January 9, 2009 4 mill cub drop-in $750.00 in the for sale sec. here jump on it! Quote Link to comment Share on other sites More sharing options...
Dick Wheels Posted January 9, 2009 Report Share Posted January 9, 2009 I got a stock crank laying around here with a broken rod. Appears to be in good shape minus the 1 broken in half rod. Should only need a rebuild. $75 bux shipped Quote Link to comment Share on other sites More sharing options...
Darthwall Posted January 9, 2009 Report Share Posted January 9, 2009 If you half to replace the crank I would do a stroker kit the port work is a bitch to compensate for but sell off the cylinders! spend the money on a new or used crank and get yourself some good used cylinders with porting already done most of the times you get a decent set might half to be honed for about 1/3 of the price if you want power you have to spend money Quote Link to comment Share on other sites More sharing options...
Darthwall Posted January 9, 2009 Report Share Posted January 9, 2009 But if you are really wondering about it just look around REALLY GOOD if all the bearings spin free and are within the right clearances then I wouldnt worry about it get a manuel and check it out Quote Link to comment Share on other sites More sharing options...
jbooker82 Posted January 9, 2009 Report Share Posted January 9, 2009 Where exactly did the crank shaft get discolored. I dont seen anything out of the ordinary. If it didnt egg the wrist pin end out of the conecting rod, I would just clean it up real good, and run it. I dont think anybody changes the crank every time a piston lets loose. Quote Link to comment Share on other sites More sharing options...
deckheight Posted January 9, 2009 Report Share Posted January 9, 2009 (edited) I'm thinking the same thing. Burning a hole in the top of a piston is not what I would consider a major catastrophy. Did you chunk up a ring? What do the wrist pin bearing surfaces look like? Where exactly is "the top of the rod scored"? How do the mainbearings feel and sound? What do the mains look like under magnification? Seen some pretty bad seizures where the crank was A-OK. Also had a few where a main bearing got nicked by a peice of ring and everything seemed fine, but the bearing slowly came apart. Also had a few where the rod twisted or bent, but thats pretty rare as the piston boss usually lets go before that happens. Still needs to be checked out though. Just from what I read in this post and past experience I would say you have about a 1 in 6 or 1 in 8 chance of even having a problem. Really hard to narrow down the odds via the internet... You feel lucky today? on edit: I have seen brand new cranks come right out of the box w/heat discoloration. for what it's worth... Edited January 9, 2009 by deckheight Quote Link to comment Share on other sites More sharing options...
jkross Posted January 9, 2009 Author Report Share Posted January 9, 2009 hey Everybody...thanks for the info. Feeling much better about things after reading all these posts. Lots to consider. I was being a whinny little bitch when I wrote this last night. thanks for setting me straight. You all usually have lots of common sense advise. We'll see how it goes. going to try and clean it up. Wrist pin looked fine. When I say the Rod was scored, I mean that the top of it is rough...like metal has either been welded to it, or scraped from it...not sure which. the rod bearing...hole?...is perfect...not deformed at all. I'd just hate to spend that money and not be sure. I'll let you know what I decide to do. Thanks again. Quote Link to comment Share on other sites More sharing options...
dajogejr Posted January 9, 2009 Report Share Posted January 9, 2009 I'd like to see more pics of that crank. I had the top of a piston let go on me...I pulled the cylinders off, flushed the bottom end out with gas/oil (20:1) 4-5 times until no more metal came out. Put used pistons back in...and still run that crank. I'm talking hundreds of passes on a drag motor bike...not a single issue. As long as the bearings are tight, flush them real good....run it. oh...and figure out why it smoked in the first place, fix that. Once a crank is trued and welded correctly once, they're a real bear to split and you risk splitting a web. Quote Link to comment Share on other sites More sharing options...
blowit Posted January 9, 2009 Report Share Posted January 9, 2009 I agree with D. inspect well but from the looks, I would not think it is that bad. The important part is the big end rod bearing. If all the Al is in flake form, you can simply flush and roll but if it was vaporized and deposited on the bearing pins (will look like splotches),you might need another. We call this "justification for modification". Brandon Quote Link to comment Share on other sites More sharing options...
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