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Another 1/8 mile gearing question


Rednecklights

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Glad I was missed, LOL!

 

I've been lurking for a while. We bought another house & have self imposed no TV or Computer there for now. Plus, with my work I'm not allowed a cell phone or internet. I happened to be at our old house sick today & looks like tomorrow also. Decided to pass on a little info.

 

Angel has taken over all the quad shit & It's very nice not having the headaches anymore.

 

Good to hear from you gramps! Hope all is well.
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Do you think I can run a 521 Super Cub in the 1/8th with no pump?

 

With big bowls, pingle & proper venting should be no problem for 1/8 mile on gas or alky. We ran our 443 Cub 1/4 mile with no pump on gas & alky.

 

We have ran all the distances out to about a mile. The farther you go, you need less timing & more fuel.

 

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With big bowls, pingle & proper venting should be no problem for 1/8 mile on gas or alky. We ran our 443 Cub 1/4 mile with no pump on gas & alky.

 

We have ran all the distances out to about a mile. The farther you go, you need less timing & more fuel.

 

Thanks man. I was skeptical and I knew you'd know.
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With big bowls, pingle & proper venting should be no problem for 1/8 mile on gas or alky. We ran our 443 Cub 1/4 mile with no pump on gas & alky.

 

We have ran all the distances out to about a mile. The farther you go, you need less timing & more fuel.

 

guzzler valve or banshee pingle when on alky? Ive been wondering if a single outlet dirtvalve can feed a pump or if the guzzler is mandatory
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We used a 17/36 (2.12 ratio) for both the 1/8 & 1/4 mile using a 2.86 primary with 20" AR's. We used 5th gear for 1/8 & 6th for 1/4 mile & turned a bunch of rpm for both distances.

So, correct me if I'm wrong.... by that I should be able to get away with 18/38 gearing (2.11) and the 19" American racers 5th gear in the 1/8?

 

 

 

 

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So, correct me if I'm wrong.... by that I should be able to get away with 18/38 gearing (2.11) and the 19" American racers 5th gear in the 1/8?

 

I wish it was that easy, LOL!

 

It takes a bunch of work to launch quickly with a 2.11 or 2.12 ratio. Mainly clutch tuning, but all other tuning factors have to be spot on also.

 

Here's the best advice I can give. Front sprockets are the cheapest to buy. 18 or 19 tooth flip a coin neither will be optimum for the 41 rear. Anyway around it, it's going to be a compromise of launch or mph. I'll always lean toward the launch; lowest ET wins races, period. 18/41 (2.28 ratio) will minimize a possible bog/give a decent launch. 19/41 (2.16 ratio) good possibility of a bog/slow launch, but have some mph.

 

For a rookie asphalt member I would start with the 2.28 ratio. If you think your better than average rider & can slip the clutch good with your left hand. Then go with the 2.16 ratio.

 

The final tidbit: MINIMUM final gearing needs to put the motor at it's PEAK HP RPM @ finish line in the top gear your using for the set distance. Example: If your motor makes peak power @ 9,700, you minimally want to cross the 1/8 mile @ 9,700 in 5th gear. Real world, MOST motors/bikes are faster being final geared above that peak HP RPM. 

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Thank all of you for the replies.

 

I have quite a few passes down the 1/8 mile on various r1's , gsxr's and zx10's etc as well as a few mustangs, so this isn't completely foreign to me but this banshee/2stroke racing is a big change require a steep learning curve. Honestly , there is a ton more to this than I expected .... even with some knowledge of drag racing.

 

I expect by next summer I'll have a stack of sprockets from testing and tuning.

 

I'll try and get everything ordered and together before they shut down for the year and get a baseline number.

 

Thank you guys once again. I know questions like these have been answered time and time again. I try not to be the aggravating new fella.

 

 

 

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Thank all of you for the replies.

 

I have quite a few passes down the 1/8 mile on various r1's , gsxr's and zx10's etc as well as a few mustangs, so this isn't completely foreign to me but this banshee/2stroke racing is a big change require a steep learning curve. Honestly , there is a ton more to this than I expected .... even with some knowledge of drag racing.

 

I expect by next summer I'll have a stack of sprockets from testing and tuning.

 

I'll try and get everything ordered and together before they shut down for the year and get a baseline number.

 

Thank you guys once again. I know questions like these have been answered time and time again. I try not to be the aggravating new fella.

 

 

 

Sent from my iPhone using Tapatalk

Sounds like you'll get it figured out. Tons of info in SlowerThanYou clutch tuning thread. We don't mess with clutch much on dirt due to inconsistencies, but it's a must on asphalt if you wanna run to full potential.
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  • 3 weeks later...

Ya, Those are great. Since new pumper carbs aren't available any longer and anything used is always a crap shoot those new seats are definitely the way to go if you run a pump but like my post said I was referring to gravity carbs. Do you know if anyone has tried running them w/o a pump John? Might be a great option if they won't leak.

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Ya, Those are great. Since new pumper carbs aren't available any longer and anything used is always a crap shoot those new seats are definitely the way to go if you run a pump but like my post said I was referring to gravity carbs. Do you know if anyone has tried running them w/o a pump John? Might be a great option if they won't leak.

Ya they can be set up for gravity feed to
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