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  #1  
Old 09-30-2005, 08:10 PM
AmeriKan MX's Avatar
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Default AMA Rules questions...

     

In chapter 3 Equiptment, section 12-a it states "A guard must completely enclose the primary drive, The counter-shaft sprocket and primary back drive are not considered parts of the primary drive" I have a CR250 with a stock chain guide, is that OK? My next question is, what's a good kind of fuel to race with?

If someone can answer these I'd appreciate it.

Thanks

Last edited by AmeriKan MX; 09-30-2005 at 08:41 PM.
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Old 09-30-2005, 11:39 PM
Michael Parker's Avatar
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Default Re: AMA Rules questions...

that guid sentence makes no sence but you should be good with the stock guid. I race with VP ultimate 2 race fuel and am very hapy with it.
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Old 10-01-2005, 06:27 AM
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Default Re: AMA Rules questions...

Your primary drive gear is your counter shaft sprocket, the one up front.
That gear needs a cover.
The stock cover fills the requirement.
What the rule means is the front sprocket always needs to be covered.

All bikes should have this. Ever get something caught in the front sprocket under the chain? You will not like the results.
The possibilities can cause a mild chain derailment to an exploded case and possible leg injury.
Yes, I have seen it happen.

That is the reason for the rule
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Old 10-01-2005, 09:13 AM
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Default Re: AMA Rules questions...

right now im running super premium at the pumps with demonde tech premix oil, but come march were going to be runnning VP race gas with some castor oil, i love that smell

how much does it cost you guys for your VP per gallon?
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Old 10-01-2005, 10:17 AM
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Default Re: AMA Rules questions...

for the ultimate 2 that i run it is 11 dolars per gallon but it is very good gas
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Old 10-01-2005, 11:45 AM
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Default Re: AMA Rules questions...

That is a very poorly-worded rule if the intent is to require a countershaft sprocket cover, but I don't think that is what they mean.

The primary drive in a motorcycle engine is the geartrain between the crankshaft and the clutch basket. The gear ratio between these two is referred to as the "primary reduction" in every factory service manual I've ever read, street or dirt. On a dirtbike, this is inside the engine. The only bikes I know of with exposed primary drives are some "Harley" customs with the exposed belt or chain drive between the engine and transmission.

My reading of that quote is that those exposed primary drives are not permitted. The rule explicitly states that the countershaft is NOT part of it. As for the stock plastic cover, I know what Mainjet is getting at, but I've never, ever seen a pro bike with one of those in place. Cycle news prints photos of pro racebikes in it every week and all of them have ditched that part. Yes, there is a slight risk of getting your foot caught in the chain (very slight, in my opinion), but the stock guard is a major mud-catcher and a pain in the butt as a result. Looking at the countershaft area on any dirt bike, you'd be hard-pressed to get a foot between the chain and sprocket.
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Old 10-01-2005, 08:22 PM
AmeriKan MX's Avatar
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Default Re: AMA Rules questions...

Thanks for the response guys. How about a handle bar pad, is that required? I didn't see anything about that in the rules, but I think I heard it somewhere.
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Old 10-01-2005, 08:41 PM
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Default Re: AMA Rules questions...

Not sure if a bar pad is required, but its not a great idea NOT to have one.

I value my teeth. So if and when my face hits the bars... ill be glad its there.
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Old 10-01-2005, 09:28 PM
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Default Re: AMA Rules questions...

Good point!
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Old 10-01-2005, 10:06 PM
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Default Re: AMA Rules questions...

Quote:
Originally Posted by mtk
That is a very poorly-worded rule if the intent is to require a countershaft sprocket cover, but I don't think that is what they mean.

The primary drive in a motorcycle engine is the geartrain between the crankshaft and the clutch basket. The gear ratio between these two is referred to as the "primary reduction" in every factory service manual I've ever read, street or dirt. On a dirtbike, this is inside the engine. The only bikes I know of with exposed primary drives are some "Harley" customs with the exposed belt or chain drive between the engine and transmission.

My reading of that quote is that those exposed primary drives are not permitted. The rule explicitly states that the countershaft is NOT part of it. As for the stock plastic cover, I know what Mainjet is getting at, but I've never, ever seen a pro bike with one of those in place. Cycle news prints photos of pro racebikes in it every week and all of them have ditched that part. Yes, there is a slight risk of getting your foot caught in the chain (very slight, in my opinion), but the stock guard is a major mud-catcher and a pain in the butt as a result. Looking at the countershaft area on any dirt bike, you'd be hard-pressed to get a foot between the chain and sprocket.
mtk.....
You are absolutely right.
I'm guilty of charging off without thoroughly reading the post. Something I usually give others a bad time for. What is that message board saying..."my bad"?
However remember we all don't ride major mud and most desert/dual sport riders will use the guard to keep rocks out. The injury I spoke of was from a rock into the chain between it and the countershaft sprocket and the cases exploded.
I also never heard of anyone getting their foot caught if they were wearing riding boots.
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