Landracing Forum
East Coast Timing Association => ECTA Rules Questions => Topic started by: TurboCat on May 19, 2013, 06:18:58 PM
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Another member has raised questions about my project and I'm looking for confirmation. Plans are to run a '07 Sportster 883 in P/PP 1000 class using an overbore and custom slugs for a displacement of 997cc. Is this still allowed in Production? I know an almost identical 883 set a record at Bonneville using XR1000 pistons in 2001.
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yep, as long as you stay under 1000cc and over 750cc you are good to go. You can't have a clean up overbore that goes over the class limit in production.
Making the size to class is good.
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What I thought...thanks for the verify. :cheers:
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Hey Turbocat,
Sorry for causing you confusion. I am glad to be wrong because the way I thought the new changes were was its not allowed and that would suck. Excuse me while I hit the fridge for some milk to go with my Humble Pie :-D
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yep, as long as you stay under 1000cc and over 750cc you are good to go. You can't have a clean up overbore that goes over the class limit in production.
Making the size to class is good.
I second that.
rouse
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As a caution, I read where one racer at BUB a few weeks ago was measured as too big with a 738cc bike in the 750 class. He must have had a lot of wear in that cylinder. I guess if I was ordering custom pistons I might go a little smaller as they seem to have measured his bore, not the piston size. It may not be that big a deal, but if you are doing custom, why risk it.
While we are on this subject, how are measurements done at the ECTA? If you have to tear down is it after a run, or at the end of the meet? My pushrod bike isn't bad, but with a desmo it can be an all day affair.
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Size is size... if you don't know what size your motor is you should not be racing.
bore x bore x stroke x .7854 x number of holes.
Using bike motors in car classes can cause a few seconds of WTF but the 748cc motor is 45.7 inches, still within the less than 46 inches for J class.
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While we are on this subject, how are measurements done at the ECTA? If you have to tear down is it after a run, or at the end of the meet? My pushrod bike isn't bad, but with a desmo it can be an all day affair.
No tear down at ECTA. It was considered many years ago, but not much time in a 2 day event (it's actually a 1 3/4 day event).
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however you can be protested, then the tear down will take place. and a complete inspection of the vehicle.
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As a caution, I read where one racer at BUB a few weeks ago was measured as too big with a 738cc bike in the 750 class. He must have had a lot of wear in that cylinder. I guess if I was ordering custom pistons I might go a little smaller as they seem to have measured his bore, not the piston size. It may not be that big a deal, but if you are doing custom, why risk it.
While we are on this subject, how are measurements done at the ECTA? If you have to tear down is it after a run, or at the end of the meet? My pushrod bike isn't bad, but with a desmo it can be an all day affair.
I don't know if I would read too much into that. When my engine was certified at Bub they measured it 4 times and never did get the correct measurement. Cept with mine they measured it smaller than it actually was.
I'll also add the only way I know is to measure the bore. Engine size is determined by bore X stroke.
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I'm going to take a swing from a slightly different perspective: Nobody cares what size, type, origin etc your PISTONS are (except your engine builder -might be you) so that they fit in the perfectly honed BORE you have prepared, the size of which is used, as Stainless and others have pointed out, to determine the displacement (along with stroke and some math). Difficulty measuring same is another issue. :roll:
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I agree with Jacksoni's observation above regarding the bore size versus the piston size. I am just suggesting that someone planning to build a motor visit with their engine builder to make sure their calculations are spot on. You would hate to spend all that money and have a warm motor that measures a cc too large.