Landracing Forum
Bonneville Motorcycle Speed Trials => Bville Motorcycle Speed Trials Rules Questions => Topic started by: Knuckbob on February 23, 2020, 01:57:35 AM
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Planning on running a flathead in vintage fuel class. Was hoping to dual plug the heads, but looking in the rules it does say OEM, or aftermarket as long as does not increase performance. So, its a bit vague in interpretation. My heads are aftermarket dixie heads that were a stock reproduction, but will be modified for my machine. Would hate to go and work them over to find them un-usable. Any pointers? Thanks
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My question is how can you set a record if you can't increase the performance? This needs to be straighten out by the rules makers.
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The rule makers are pretty smart people and I think they have worded this pretty carefully. It's very important not to read your own additions into the printed rules. Here's the relevant paragraph -
12. K.VINTAGE FUEL (VF)
The engines production date shall be prior to 1956. Flathead, OHV,
and two-stroke engines shall retain the O.E.M. heads, cylinders, and
crankcases originally installed at time of factory production. Above
components produced after 1955 and exact reproductions may be
legal in vintage class if they offer no competitive advantage.
Documentation may be required to prove authenticity of vintage
design.
Allowable overbore in this class is +0.050 inches over O.E.M.
standard bore to remain in displacement class. Further increased
displacement beyond the class limit shall place the motorcycle in the
correct class.
NO FUEL RESTRICTIONS. See Chapter 2, paragraph 2.F.
What it says specifically is you must retain an OEM or exact reproduction head on the cylinder. Note that it does not say you can't improve its performance. One of the tricks to going fast is not to read things into the rules that aren't there. If you have a specific question like the dual plug question you can get the definitive answer at tech@bonnevillespeedtrials.com. Be patient, this far ahead of the event the people who put it on often have a lot of other things going on in their lives and it can take a little time to receive an answer.
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Thank you. It is very easy to read between the lines and overthink things. But to not ask and make an assumption that hurts me later is typically what I do.
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"Above components produced after 1955 and exact reproductions may be legal in vintage class if they offer no competitive advantage."
In other words you can modify an original pre 1955 head for performance but can't modify an exact reproduction head for performance?
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You have to use an OEM head or an exact reproduction of an OEM head. Either one is acceptable. If a head design did not change from 1955 to 1956 or later, the 1956 or later head is also acceptable. You can port it, put in bigger valves, etc. to improve performance. The intention of the rule is to keep a more modern, different looking head that might have improvements you can't do to the OEM head from being put on the motor.
Once again, if you have questions about a specific head or other part, tech@bonnevillespeedtrials.com is the place for the definitive answer. My answer here is not official in any sense. I'm just trying to help understand the spirit of the rules.
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"Above components produced after 1955 and exact reproductions may be
legal in vintage class if they offer no competitive advantage."
One wonders how exact reproductions can possibly offer a competitive advantage (otherwise they would not be exact).
I would suggest that a further statement should be added that says "modifications to OEM as well as reproductions are allowed if they are consistent with period modifications." So for example in my opinion, you should be able to dual plug a head and mill the heads, but not to use modern electronic ignitions.
Now if I could just find myself a 1955 BSA DBD34 (Gold Star) motor to put in my APS bike..................
Tom
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I keep making this same mistake: assuming that more information = good.
Apparently not.
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Better late than never!!!
I have ran my KHK 3 times at SCTA/BNI Speed Week with twin sparks and twin magnetos on a vintage flat head entry.
No one has ever said a thing about the ignition during inspection...
This forum is BMST... Have they got vintage classes now?
Patrick
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BMST (well, AMA) has vintage (pre 56) and classic (pre 81) engine classes.
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Thanks Doc B for the clarifications,
I though they were fully following the FIM rules where there's no such stuff as vintage or classic!!!
Cheers from Patrick
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There are FIM classes running at BMST as well as AMA classes.
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BMST has been running vintage classes for many years as far as I know AMA classes and FIM classes both running at the event. I often wonder why more bikes don't run at BMST but choose SW etc over it. Shorter line, and lighter traffic on the track that creates less damage and rutting to the course seem to be massive positives to me.
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I'm not adverse to looking at cars and trucks, so Speed Week's for me!!!
Patrick
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lol, yep. I get that. One year I would like to make it across for SW too just to see and witness it one time. Maybe it will happen one year when the boss and I retire, which is a fair way off and over the horizon just yet.
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Better late than never!!!
I have ran my KHK 3 times at SCTA/BNI Speed Week with twin sparks and twin magnetos on a vintage flat head entry.
No one has ever said a thing about the ignition during inspection...
This forum is BMST... Have they got vintage classes now?
Patrick
During the event entry safety inspection I have not seen the ignition system listed on the tech sheet. Inspection is for safety related items. However if you qualified on a record and then backed it up thats where the ignition being legal or not would be decided. Its always best to verify any modifications being legal with the class Committee contact for the final word prior to any record attempts. Thats how we did it on any area we were in doubt about especially in a vintage class where the competition is very attentive.
Ronnieroadster
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Yer right!
Inspection is mostly all about safety requirements. Not class compliance. But, if in doubt, you can ask for that, too (and quote them and let them sign off in your Log Book). Most of the Inspectors can help, but they've also been encouraged by competitors in the same category (guilty!).