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Author Topic: 1000-MPS-CG frame question  (Read 484 times)
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gowing
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« on: December 02, 2018, 09:06:50 PM »

Hello, The name is Mark and I am a Nube. 
This is my first post here, and undoubtedly the first of many questions to come.

I have been a spectator at BMST for the last 3 years and I really want to build a bike for next year.

Here's the thing....... I'm a horizontally opposed engine guy without any money. (yeah, I know  rolleyes)
However, I do have a couple of Gl1000's, a couple of GL1100's, and a Valkyrie.

I would like to build a 1976 GL1000 as my "introductory" foray into LSR.
My question pertains to the frame, swingarm, etc:

I am thinking of using a 1976 engine, but using it in a 1980 frame.
the reason is that the 1980 wheelbase is 3" longer, and the gearing in the rear end is a bit higher.
(This is the easiest option for me)

Is this legal?
If not.....
 could I just swap the swingarm ?

I have read the AMA supplemental rules and chapter 6 reads:

"MODIFIED PRODUCTION-PARTIAL STREAMLINING (MPS) CLASS
In addition to rules for the “Modified” class, (See Chapter 5,
paragraphs 5.A. – 5.I.) 

Which refers to chapter 5:

MODIFIED PRODUCTION (M) CLASS
This class is designed to advance the efficiency of production
motorcycles attempting records and increase their strength and
stability. Construction of the modified motorcycle shall retain the
original (O.E.M.) frame and not be purpose built.

Probably the first of many "stupid" questions, but I am just looking for some clarification
before I start turning wrenches.
Thanks!


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Stainless1
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« Reply #1 on: December 02, 2018, 10:07:10 PM »

When you read the rules, try not to read anything into them.... The rule says the frame and engine will be OEM same year... the swingarm is not part of the frame. 

Everyone was new to LSR sometime... a lot of us before the internet was invented...  rolleyes this site will make communication easier. 
Good luck with your project.... Have fun, be safe, go fast...  cheers cheers
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Stainless
Red Hat 228.039, 2001, 65ci, MSA Bockscar Lakester with a little N20 
MSA Bockscar Lakester #1000 my fastest mile 245 and change, 84 ci turbobusa motor... but Corey's 233 MPH H/BFL record is still 3MPH faster than mine.
gowing
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« Reply #2 on: December 03, 2018, 12:08:52 AM »

thank you for your FAST response. 
(I guess that should have expected that on a forum full of landspeed racers  grin)

Your reply was as I expected. I was looking for clarification because the term OEM was what was in question in my mind.
I mean..... a OEM goldwing frame is a OEM goldwing frame. see where I was going?

While on topic,   Do the numbers have to match, or is just the same year engine and frame good enough?

FWIW:
I know that I am not starting out with an ideal LSR motorcycle platform,  but I am not trying to set the world on fire,
I just want the experience and to see what I can realistically build.

I believe that I could get about 90 hp. out of the engine, so with some gearing, some aero bodywork and some luck,
my optimistic goal is to run as close to 150 mph as i can get.
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4-barrel Mike
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« Reply #3 on: December 03, 2018, 01:20:12 AM »

From a car guy who reads pretty everything on this site: doesn't BMST have a "run-what-you-brung" class?  If so, build what you have to meet the safety standards and run it.


Mike
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Mike Kelly - PROUD owner of the V4F that powered the #1931 VGC to a 82.803 mph record in 2008!
gowing
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« Reply #4 on: December 03, 2018, 01:39:26 AM »

I have considered "run-whatcha-brung' with my Valkyrie,
but building a LSR bike is what I want to try my hand at.

you know......., building some bodywork, chassis tuning, bench racing, etc., all of the fun stuff!
And then actually being able to race it on the salt would be the cherry on the cake.

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Koncretekid
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« Reply #5 on: December 03, 2018, 07:27:38 AM »

[quote author=gowing link=topic=17503.msg319160#msg319160 date=1543802810


MODIFIED PRODUCTION (M) CLASS
This class is designed to advance the efficiency of production
motorcycles attempting records and increase their strength and
stability. Construction of the modified motorcycle shall retain the
original (O.E.M.) frame and not be purpose built.



[/quote]

I'm not sure why BMST/AMA retain this definition of an "M" class motorcycle, as it is misleading, in my opinion.  Even the statement "increase their strength and stability" is lost in my mind, as it would be impossible to assess those attributes which are certainly not required to meet the class rules.

In any case, scroll down their requirements for this class and we find this: "The engine and frame must be from the same manufacturer."  To me this certainly implies that any combination of Honda motor for example can be used in any Honda frame, and still be allowed to run in "M" class.  In fact, at one meet I saw a very nicely constructed Triumph which sported a modern Triumph aluminum frame with a late '60's or '70's motor which was apparently allowed to run in "M" class.

Basically, keep your wheelbase within 10% of OEM (bring proof of that longer wheelbase OEM model), keep your footpegs ahead of rear axle by at least 6", use a gas tank of at least 1.3 gallons, and make sure your seat cushion is within 5" of the top of the tailpiece if used.  And of course keep your frame backbone stock and read and comply with the rest of the regulations to stay in "M" class.

Tom
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gowing
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« Reply #6 on: December 03, 2018, 10:42:04 AM »

"The engine and frame must be from the same manufacturer."  To me this certainly implies that any combination of Honda motor for example can be used in any Honda frame, and still be allowed to run in "M" class.  In fact, at one meet I saw a very nicely constructed Triumph which sported a modern Triumph aluminum frame with a late '60's or '70's motor which was apparently allowed to run in "M" class.

Tom
Thank you Tom.
We have both read he same thing.  Hence my confusion and my posted question.
I'm guessing that more research into this is required before I dive in head first.

...It must be a numbers matching frame and engine.
...It must be the same year, make and model frame and engine combination.
...It must be the same make and model frame and engine.
...It must be the same manufacturer.

I am pretty sure that the answer is one of the above.
The old Triumph lump in a new frame is interesting. Does that set a precedent?

I must say that it is a bit disconcerting that the two replies that I have received are so different.

Since the rules are written so ambiguously that they are open to such inference and interpretation,
is there an actual authority that can actually give me a definite (clearly defined) answer?

I would hate to show up and not be able to compete because my interpretation of the rules turns out to be
different than a tech inspectors interpretation.


« Last Edit: December 03, 2018, 06:54:27 PM by gowing » Logged
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« Reply #7 on: December 04, 2018, 02:47:26 AM »

Hi Mark,
If you are unsure of any of the reg's and rules it might pay to drop Drew Gatewood an e-mail. Drew being the head cheese of tech inspection will be the guy that ultimately says yes or no to your design being fit for your chosen class.
Drop him a line mate and get a definite answer. Then let everyone know what it is.
Good luck with the build. We all look forward to seeing how you get on. cheers

Cheers
John

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mtiberio
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« Reply #8 on: December 04, 2018, 11:47:52 AM »

CG? what is the C for?
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Doc B.
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« Reply #9 on: December 04, 2018, 03:28:28 PM »

C is for Classic engine - pre 1981. This means you must use original pre 1981 case, cylinders and heads. Pistons, cams, carbs, etc, can be anything you want. You can't exceed .050 overbore from the OEM bore.

The Modified frame class rules say the motor and frame must be from the same manufacturer. That's pretty straightforward. Honda motor, Honda frame. You can use any swingarm and forks as long as you stay within 10% of the original wheelbase. With a Goldwing it seems particularly straightforward, as I don't imagine a Goldwing motor fitting in some other Honda frame.

Record in class is 129 and change. I'll suggest you plug some numbers into an online aero-hp calculator. My hunch is 90 shaft hp is not gonna get you to 150 with MPS aero, but you might be competitive with some creative fairing work. There was a Goldwing running in (I think) some APS class this year, but I don't know how fast it went. I think they had a clutch problem and left early.

Drew is definitely the guy to ask about the finer details.
« Last Edit: December 04, 2018, 03:30:08 PM by Doc B. » Logged
gowing
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« Reply #10 on: December 04, 2018, 06:50:11 PM »

Thanks Doc B.
That's some good info right there!

The shaft drive is going to be an obstacle to overcome for sure.  the highest stock rearend gear available is 2.83.
The reason for choosing to build a Goldwing is that I already have most of what I need.

Building the engine shouldn't be much of a problem, but I have never built bike bodywork before,
and I am looking forwards to giving it a shot.
 
The 150 mph. goal is just that,  a number to shoot for.  

The APS goldwing's best run was 136.45 with a blower.  Yes, they had a few issues but they think that they have
pretty much reached the limit with that bike.
« Last Edit: December 04, 2018, 07:17:41 PM by gowing » Logged
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