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Discussion Starter · #1 ·
Have any of you found the need for billet cranks or 2nd gear sets in your 10 mill cubs? We are getting ready to get the second bike going and just kicking around ideas. Thinking 10 mill cub or 4 mill supercub. I want to keep cc's under 465, thats why not thinking DM yet. Thanks for any info.
 

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Discussion Starter · #2 ·
That should have been 475 cc's.
 

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No need for billet as said.
I have a used, forged 10 mil in my cub, it was freshened up with a TZ bearing early 07, and it has literally hundreds and hundreds of runs on it. Even a smoked piston....still going like a champ.

No need for billet 2nd gear, unless you're a big guy and going to asphalt, then it'd be good insurance, but not a necessity....
 
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QUOTE (dajogejr @ Oct 16 2008, 06:27 AM) index.php?act=findpost&pid=13244No need for billet 2nd gear, unless you're a big guy and going to asphalt, then it'd be good insurance, but not a necessity....

I have a 710 DM 20mm stroker. Racing on asphalt. I'm not using a billet 2nd gear. It's still a stocker.
Just make sure the transmission is always moving. No back loading it. Then you will never have a problem with it.
 

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QUOTE (Fouledout421 @ Oct 15 2008, 08:15 PM) index.php?act=findpost&pid=13234No need for billet cranks and billet 2nd on the 10 Mil cubs.. maybe if you were putting a big shot of NOS to it.. Then it would be good insurance.. but not necessarily needed


That's what I was going to say, verbatim, lol...if you don't plan to put nitrous to it, forged crank and stock tranny gears should be fine. And Dave brought up another good point about asphalt, if you plan to run it, you may want to consider going ahead and putting a billet second gear in there...I wouldn't risk the stock gears on asphalt with anything larger than a 4mil cub
 

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Discussion Starter · #9 ·
Thanks for all the quick replys. No plans right now to run asphault, strictly sand/dirt. Now...decisions ,decisions. I think I'm leaning toward the 10 mill cub.
 

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QUOTE (REDLINE @ Oct 16 2008, 11:58 AM) index.php?act=findpost&pid=13260Don't most of the asphalt guys launch in 1st? if so they can prolly get along without a billet 2nd better. But if you try to launch a big motor in 2nd, in the sand, you get this........

View attachment 1026
oops!!! nice pic.

Yeah I was wondering if you took off in 1st why you would need a billet second?!
 

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QUOTE (badassbanshee479 @ Oct 16 2008, 09:05 AM) index.php?act=findpost&pid=13267oops!!! nice pic.

Yeah I was wondering if you took off in 1st why you would need a billet second?!

I was told (and this is just hearsay from "reputable" folks) that even though you may not leave in second, the transition from first to second can be rough on the gear, enough to break it if you're getting traction w/ no wheel spin. I think there is just a fine line of need it/don't need it...some folks can get away with no billet, others can't. I think it more so depends on setup, rider, and track.

I still believe that you shouldn't spray a 10mil cub without a billet second (leaving in second) no matter what surface you're on....it's just asking for carnage, lol
 
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There is a lot of asphalt draggers out there not using the billet 2nd gears. Motors bigger than a 4mm stroker.
There is a 611 DM out there that has a uncut stock transmission and having no problems at all.
He is using a shift kill setup on his air shifter.

Like I said before. Start in 1st and just keep the tranny moving and you won't have a problem.
 
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QUOTE (banshee332 @ Oct 16 2008, 02:25 PM) index.php?act=findpost&pid=1327610mill cub did this starting in 1st. I have a billet crank going on 5 years no problems, never rebuilt still strong as the day I got it.

Hey Brad,
I see the problem. You should of had 6th gear on the shaft or a spacer next to 2nd gear.
When a shaft is missing a gear in between gears. It throws the shaft off balance.
My first 1-5 tranny had no 6th gear and it did the same thing. These day I have a 6th gear with on the shaft.

I have seen that same setup with no 6th gear on the shaft and the 2nd gear broke the c clip.
 
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QUOTE (dajogejr @ Oct 16 2008, 02:22 PM) index.php?act=findpost&pid=13275I would rather be safe than sorry...after a 7 to 12 K motor build, I'm having a hard time figuring out why you'd skimp on a few hundred dollars...for peace of mind.

Knowing 2nd gear is the weakest in the motor, launching in it or not...

Change your primarys. Less stress on the transmission and clutch.
I'm using 2:36 primarys. That why having no probelms with a stock cut 1-5 auto and using $50 clutches.

Why I skimp on spending 100's more.
Just showing, you can still do it old school.
 

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Discussion Starter · #17 ·
One more question. Which rod are you guys running? 115,120 125? I found a good deal on a crank with a 115 rod. But cp website lists 120 and 125 for the 10 mill cubs.
 
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QUOTE (RJ65 @ Oct 22 2008, 01:21 AM) index.php?act=findpost&pid=13663One more question. Which rod are you guys running? 115,120 125? I found a good deal on a crank with a 115 rod. But cp website lists 120 and 125 for the 10 mill cubs.
On my 710cc 20mm DM rods are 137.5 (1982 YZ490 rods)

Go with a 120 on a 10mm stroker.
115 is not good with that much stroke.
 
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