CrankShaft Dis-Colored-Do I need to Replace?

[jbooker82]

I was thinking that the discoloration he may have been seeing was from when they heat the webs up to press the crank together. Some times they have a little blue or purple color on the webs.

 

josh

[dajogejr]

We call this "justification for modification".

 

 

Or Divorce Court....

 

:yelrotflmao:

[jkross]

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.

 

 

Here's another pic. it's only letting me do one at a time. I'll do a couple separate.

[jkross]

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.

 

 

Here's one of the f'ed up top of the rod

[dajogejr]

Flush it and run it.

[kawiking]

is it already trued and welded ? if not get it done...

[notsed]

i like your sig, much easier to read

[jbooker82]

Flush it and run it.

 

Whoa Dajogejr I didnt realize you had your TORS removed. I guess now I know thanks to your sig.

[jkross]

Flush it and run it.

 

 

Best advice I've read all day.

 

Thanks man.

[AKheathen]

Whoa Dajogejr I didnt realize you had your TORS removed. I guess now I know thanks to your sig.

woah, all new zip ties :woot: ....but what color? :ermm:

 

custom mustard---that's great :biggrin:

[FireHead]

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

 

I couldn't have said it better myself...............

 

Dave,

 

I hate your signature. I may need to come up with something more annoying. :ermm:

[deckheight]

Probably good to go. Inspect the mains, clean all the melted aluminum as best you can, duche the whole thing out and maybe check the phase.

So what do you figure caused the "lean condition", exactly?

[jkross]

Probably good to go. Inspect the mains, clean all the melted aluminum as best you can, duche the whole thing out and maybe check the phase.

So what do you figure caused the "lean condition", exactly?

 

 

So - What cause the lean condition - that's a good question. I'd like to bounce this off you all.

 

A guy I trust at a shop in Oregon took one look at my piston and was able to tell me exactly what I was doing when it blew. He said, "oh, interesting - found the flats did ya, I hope you won." Huh, I replied. He then said, "yeah, you can't do that. Banshees like the hills. If you're going to drag race, hit the top and let off. Don't keep running or you'll lean it out - sometimes as much as two jet sizes."

 

Well, that's exactly what I did. I was drag racing on the flats, and basically kept it open for a while after I hit the top of top. I'd back off for a second at a time, but then I'd get back into it. I guess that's a bad thing.

 

Does this track with what you all know? or should I look for addtional causes of the leaning?

[blowit]

A banshee engine runs very nice WFO but MUST be tuned for it. Yes, the Banshee can absolutely handle wide open straights for long durations. You would want to switch to 24:1 oil ratio and and jet up for it. That means you fatten jetting to the point it stutters, back off just a hair, and you are there. You also cannot run quite as much timing.

 

Remember, the Banshee engine was originally designed as a street bike engine.

[LS1Inferno]

a banshee with the proper main can run fine for a while WFO. BUT not if the carb bowls run down. that usually the piston killer in these situations. and the top of the rod its just melted aluminum stuck to the top of it. if it doenst scrape off just hit it with file. another thing if the fuel is low there is less pressure forcing fuel into the bowls. if your going to race like that make sure you have plenty of gas in the tank.