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Author Topic: 2nd 100cc APS build  (Read 68945 times)
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Peter Jack
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« Reply #15 on: December 24, 2014, 01:28:36 PM »

I wasn't sure when you decided to scrap the first bike but I see now how your thinking's evolved and I'm impressed. Keep up the great work!  cheers cheers cheers

Pete
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sofadriver
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« Reply #16 on: December 24, 2014, 08:12:04 PM »

Thanks, Pete.
I new halfway thru the first build that it could be taken to a higher level.
Who knows - I might feel the same when this one's done.
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Mike in Tacoma

"aww, what the hell - let's just do it".............

100cc APS/G #833
bones
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« Reply #17 on: December 27, 2014, 06:36:56 PM »

Hey Sofa
   Did you have any thoughts about reducing the fork travel?-- Looks like the stock rs forks.
 I know it is too late now but you could get 50mm out of the forks and mabe 50mm out of the steering stem.
 
Are you going to be looking through the forks and have your head behind the tripple clamps?

This will be a very interesting build as my son has been using a yz80  in APS-100 and now we are going BIG block with a rs 125.

Keep up the good work

Oh-- watch your l/h toes in the chain grin

   Bones
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Nortonist 592
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« Reply #18 on: December 27, 2014, 07:13:44 PM »

Here's an interesting wind tunnel video.  Somewhat relative.  At about 3:40 the smoke is held behind the machine.  Curious how much disturbance there is back there.

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Get off the stove Grandad.  You're too old to be riding the range.
sofadriver
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« Reply #19 on: December 27, 2014, 08:39:10 PM »

Bones, it's as low as possible now. I'm looking between the top of the front tire and the bottom of the lower fork tree so I've only got about 4" of windshield. 32 1/2" to the top of my helmet.
People chucle at calling a 125 a big block but, really, it's like comparing a small block V8 to a big block. Huge difference ! Are you starting with an RS125? Let me know.

Thanks Nortonist. I've studied everything that Kolb did. He really did a fantastic job on that bike. That video shows the body aeros around the rider could have stood a lot of improvement but he still needed to be able to get on and off it. He was running BUB and I don't know what those rules say about rider's speed humps. The vid shows lots of turbulence behind his head. Speed humps are only restricted by build materials under SCTA rules and I'll be taking full advantage of that. Like you, I wish the smoke operator had spent more time behind the bike. BUB rules are way different there, too, but it would have been interesting. He was narrower in back than me but I'll have full body to 10" behind the tire. We'll  see how it works out. Wind tunnel testing is not in my budget. I wish I could see the effects of an open, spinning wheel back there.
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Mike in Tacoma

"aww, what the hell - let's just do it".............

100cc APS/G #833
Nortonist 592
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« Reply #20 on: December 28, 2014, 12:18:41 AM »

I couldn't afford wind tunnel time either.  I rely on El Mirage dust to tell me what's happening behind.  The original body I built was more of a style effort but seemed to work well.  Not a lot of dust being kicked up.



Then I got the brainwave that enclosing the rear wheel would smooth the airflow.  I was surprised to see that instead of being cleaner I was towing a big ball of dust behind the rear wheel.  Needless to say the body was severely trimmed and seems to work better.  Sure would be nice to be able to get into a wind tunnel.

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Get off the stove Grandad.  You're too old to be riding the range.
sofadriver
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« Reply #21 on: December 28, 2014, 03:12:31 AM »

That's really interesting. I'm sure you questioned whether the surface condition was the same before you got out the hacksaw.
Was speed the same when the pics were taken? Any wheel spin occurring?
Any ideas on why the open wheel was better? Seems contrary to normal thinking.
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Mike in Tacoma

"aww, what the hell - let's just do it".............

100cc APS/G #833
Koncretekid
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« Reply #22 on: December 28, 2014, 11:04:25 AM »

I'd like to see a profile photo of you on the bike in riding position.  I can't fathom how you can see under the triple clamps with your hands on the handlebars. Can you get someone to take a photo like that?
Tom
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We get too soon oldt, and too late schmart!
Life's uncertain - eat dessert first!
sofadriver
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« Reply #23 on: December 28, 2014, 11:34:30 AM »

My riding position was developed after closely studying actual photos of Superman in flight.

 grin

Here's the original concept and a pic from the one of the 4 wood mock-ups I made.
I'll post more pics after the foot pegs are done.


* rsz_2014-08-16_135140.jpg (249.48 KB, 1280x960 - viewed 221 times.)

* rsz_2014-09-29_214249.jpg (155.1 KB, 1280x960 - viewed 140 times.)
« Last Edit: December 28, 2014, 12:03:38 PM by sofadriver » Logged

Mike in Tacoma

"aww, what the hell - let's just do it".............

100cc APS/G #833
Koncretekid
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« Reply #24 on: December 28, 2014, 02:13:07 PM »

I know it's an overused expression but "thinking outside the box" would seem to apply.  This is what I like about landspeed racing where innovation is rewarded.  You'll have to have a fairly close fitting front fender to keep the salt out of your face, and at 140 mph you may find those side marking flags disappear quite often (curvature of the earth, you know); I certainly do.  If only we could get the old black or blue stripe down the center of the track, I(we) think we would be more comfortable about staying in the center.
Tom
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We get too soon oldt, and too late schmart!
Life's uncertain - eat dessert first!
sofadriver
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« Reply #25 on: December 28, 2014, 03:42:27 PM »

The front fender design has been on my mind a lot. As you said, it will have to be close so as not to eat up the viewing space. Estimating tire growth is a stumbling block. I'm using Bridgestone Battlax race slicks. 90-580/17. They're small and light so growth shouldn't be too much. I don't really know how to estimate it. To mold the fender I've cut an old BMW airhead 18' front tire in half and will slip it over the tire to make a buck. I've looked thru that opening and it didn't seem too bad. I'm as concerned about my peripheral vision as much as forward vision so I'm intending for the windshield to wrap all the way around. The first build had a helmet fairing with a windshield looking forward only and as soon as I got on it I knew I couldn't ride it. Had to cut it back off. Tunnel vision is not good.
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Mike in Tacoma

"aww, what the hell - let's just do it".............

100cc APS/G #833
fredvance
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« Reply #26 on: December 28, 2014, 06:38:14 PM »

That fairing, in the video, would be illegal in SCTA. No part of the fairing can extend past the rim in front. Ask me how I know? grin
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Sporty Dan
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« Reply #27 on: December 28, 2014, 09:30:15 PM »

What size tubing are you using? Looks to be 1 1/4 inch chrome moly. Nice design to get yourself lower and out of the wind.
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sofadriver
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« Reply #28 on: December 28, 2014, 10:23:20 PM »

That's 1" chrome moly. It just looks big because the bike is so small.

BTW, this frame was designed by me but refined and built by Mike at Motorsports Unlimited in Lakewood, Wa. This guy's a truly talented frame builder. Builds mostly drag bike frames. He's a perfectionist but still realistically priced. I'm lucky to have found him. With a few years of practice and $20k worth of shop equipment I think I could be almost as good as him.   rolleyes grin
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Mike in Tacoma

"aww, what the hell - let's just do it".............

100cc APS/G #833
Sporty Dan
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« Reply #29 on: December 31, 2014, 03:44:02 PM »

Small world! I know Mike from racing at Pacific Raceways. Tell him Dan Dahl says hi! I was the guy racing a blue sportster. I almost got one of his frames for my motor, but then life got in the way and I stopped drag racing. You are right, he is amazing at his fabrication skills! You are in good hands with him.
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