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Author Topic: Bonneville cc class  (Read 5742 times)

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Offline mexican jon

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Bonneville cc class
« on: October 11, 2013, 05:36:59 AM »
Hi all  :-D

Does anyone know the rules on the cc classes  :? the reason for asking is I'm planning on racing next year  :-)

So if I have a 750cc motorcyle engine that has been rebored there is a great chance that it'll be slightly over 750cc. So does it need to move up into the next class or is there a percentage over that is allowed?

Cheers Mex
« Last Edit: October 11, 2013, 06:58:38 AM by mexican jon »
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Offline sabat

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Re: Bonneville cc class
« Reply #1 on: October 11, 2013, 09:42:11 AM »
Welcome. Do you have a rulebook? If not, go here ( http://shop.scta-bni.org/ )  and get one, or a handful, they're important.

Nothing over 750cc is allowed in a 750cc class (there is one exception, in the Production class, where the limit is .5mm overbore).

good luck,
Dean
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Offline mexican jon

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Re: Bonneville cc class
« Reply #2 on: October 11, 2013, 10:27:11 AM »
Quote from: sabat on October 11, 2013, 09:42:11 AM
Welcome. Do you have a rulebook? If not, go here ( http://shop.scta-bni.org/ )  and get one, or a handful, they're important.

Nothing over 750cc is allowed in a 750cc class (there is one exception, in the Production class, where the limit is .5mm overbore).

good luck,
Dean

Thanks Dean

I've got the rule book on order  :-D I'll be running in Special Construction so will have to make sure the engine is either bang on the cc or slightly under  :x


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Offline sabat

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Re: Bonneville cc class
« Reply #3 on: October 11, 2013, 10:52:49 AM »
Sounds good, I would shoot for a few under the limit, as the bore & stroke measurement tools are not super precise, especially on the smaller end of the range (bikes). My 998cc engine came up as 983cc, but what if it came out 1013? I'd be tearing it down to the crank on the salt!
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Offline Sumner

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Re: Bonneville cc class
« Reply #4 on: October 11, 2013, 12:27:22 PM »
Quote from: mexican jon on October 11, 2013, 10:27:11 AM
....I'll be running in Special Construction so will have to make sure the engine is either bang on the cc or slightly under  :x

If this is special construction car then the J motor size is 31.00 to 45.99 cid or 0.508 to 0.753 L (753 cc).  I'd still shoot for less  :-),

Sum
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Offline fredvance

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Re: Bonneville cc class
« Reply #5 on: October 11, 2013, 01:53:17 PM »
One of my motors is a 1349.5, :-D, They usually have to measure 2-4 times. But they do get it right. :cheers:
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Offline Duck-Stew

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Re: Bonneville cc class
« Reply #6 on: October 17, 2013, 06:15:44 PM »
Quote from: fredvance on October 11, 2013, 01:53:17 PM
One of my motors is a 1349.5, :-D, They usually have to measure 2-4 times. But they do get it right. :cheers:

That's good to know as mine's 749.5cc's.
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Offline RansomT

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Re: Bonneville cc class
« Reply #7 on: October 17, 2013, 11:32:49 PM »
Y'all that know first hand can correct me, but I do believe it is the bore that is measured and not the piston.  Makes a difference when it comes to fractions of cc's.  A sloppy bore can through you out of class.
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Offline MattS

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Re: Bonneville cc class
« Reply #8 on: October 18, 2013, 01:09:53 AM »

Matt here, I have to correct a statement in a previous post.

>>
Nothing over 750cc is allowed in a 750cc class (there is one exception, in the Production class, where the limit is .5mm overbore).
>>

That is actually the opposite of the rule.
This is in regard to SCTA rules only.
Rule 7.D.3 states that in all classes other than Production, a .020" (.5mm) over-bore is allowed.
Rule 7.J.10 states that in all Vintage engine classes, including Vintage Production, a .050" (1.27mm) over-bore is allowed.
There is no over-bore allowed in the non-Vintage Production classes

I hope this clarifies the answer.

If you have any more questions, email me at motorcycletechscta@gmail.com


Matt Shuss
Chief Motorcycle Inspector SCTA/BNI

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