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V4 CyclePath...
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Discussion Starter #1
WSBK 2011 Rule Changes Include An End To Aprilia's Gear-Driven Cams
Submitted by David Emmett on Sat, 2010-07-31 21:33.

As is common at world championship motorcycle racing events, the Superbike
commission - the World Superbike series' rule-making body - gathered to
discuss rules to be introduced for the 2011 series. After the meeting, a press
release was issued detailing the changes to be made for next season, and
they make interesting reading.

The biggest change was the scrapping of the loophole which has allowed
Aprilia to drive the camshafts on their RSV4 World Superbike machines using
gears instead of the chains fitted on the production bikes. The rule had
originally read "The method of cam drive (chain, belt or gears) must remain as
on the homologated motorcycle unless a complete kit is available through
normal commercial channels" but the last part of the sentence - "unless a
complete kit is available through normal commercial channels" - has been
dropped.

Aprilia's use of gear-driven cams has been controversial from the start. The
original cylinders are supplied with the machining required to fit the gear drive
as standard, but use a chain drive to keep production costs down. The
Aprilia's V4 configuration makes this even more costly, requiring two sets of
gears for each bank of cylinders, and so fitting gear-driven cams to the road
bike would add considerably to the basic price. Fitted as an aftermarket race
kit, the gear-driven cams allow the RSV to attain higher revs and allow for
more precise cam timing. The RSV4 has been fast from the
start of the season, but since the Alitalia Aprilia started using the gear drive,
the disparity with the other bikes has grown.

To put an end to the arguments, the Superbike Commission has prohibited
fitting aftermarket kits, and all World Superbike machines must use the cam
drive fitted as standard. Of course, this does not prevent Aprilia from using
gear-driven camshafts completely, but it does require that the RSV4 be sold
with the gear drive as standard, something which Aprilia may be less keen to do.

(Titanium Rods and two sets of cam gears are some of the reasons why the
RC45 cost so much...)
 

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Panigaliscious
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So Aprilia makes the Factory version with gear driven cams stock and sells it for a couple thousand more.

Perhaps they could call it the "Suck It, Japan" edition.
 

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He with the senior member
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I think the issue is not so much the cost (it really would not be a huge difference in real manufactured cost), but rather the balance of power offset by the NOISE increase as a result of the gears.....requiring a quieter exhaust or intake system and thus reducing power for the street bikes. Remember...manufacturers have to meet VERY tough noise regs in the USA these days....and so they try to keep mechanical engine noise DOWN as much as possible, in order to ALLOW some exhaust and intake noise, which is what helps make power. The more the exhaust and intake noise has to be quietened, the larger (and heavier) the systems to allow the same power. This is a major part of the reason for the VERY heavy new exhaust systems you see these days.

So.....on the track, with MUCH higher noise limits, the cam gears make sense...on the street, having to meet the very tough noise regs....not so much. The chain driven motor may actually make MORE power...or at least the bike will be lighter with smaller exhaust and intake systems than what might be required with a gear driven cam motor with all those extra noise making straight cut gears.

Remember...the noise regs are very different today than what the RC45 or early VFRs faced....
 

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It's all about money really.
Gear-driven cams were dropped from the VFR on economical reasons alone. The VTEC was the first VFR which actually made Honda good money and that was only after drastic cost-cut measures, of which the removal of the much beloved gear-driven cams was just one.
The Aprilia RSV4 Factory has a retail price of 20,000€ (and many dealers will give you a discount without too much haggling). A Ducati 1198S will set you back at 22 grands, a 1198R will sell for a ridiculous 38,500€. Aprilia had to make decisions to offer such a good bike at such a price. Again, fitting cheaper chain-driven cams was part of the deal.

You won't believe the lengths manufacturers will go to cut costs.
Take my BMW for example. The first series came with a superb dual pitch horn lifted straight from the old 5 series sedan. In late 2006 BMW, in a cost cutting measure, replaced it with a regular pancake beeper. Fitting the old horn is a straight swap (the wiring harness is exactly the same, they just plugged the connectors) and the dual pitch horn itself, bought as genuine spare from BMW (and hence covered by the usual two years warranty), will cost as much as most aftermarket horns. It must have saved BMW no more than a handful of euros on each bike but it saved them money nonetheless.
 

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He with the senior member
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It's all about money really.
Of course costs are a factor....but I am stating an opinion that they're not the only factor here (or probably not the MAIN factor). You are more than welcome to disagree.

I KNOW that multiple straight cut gears are a key factor in engine noise and thus have a negative performance impact on a modern street bike.

I expect that Aprilia will tweak their top models to have these gears standard, and spend a lot of money to re-engineer their noise profiles to help meet the latest noise regs, while reducing the negative impact on performance. Whether they do and whether they succeed in meeting or even exceeding the stock performance of the current street motors, is yet to be seen. I think we all would love to see it happen....there's not much cooler than the sound of straight cut gears whine coming through to our ears!
 

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Panigaliscious
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I think the issue is not so much the cost (it really would not be a huge difference in real manufactured cost), but rather the balance of power offset by the NOISE increase as a result of the gears.....requiring a quieter exhaust or intake system and thus reducing power for the street bikes. Remember...manufacturers have to meet VERY tough noise regs in the USA these days....and so they try to keep mechanical engine noise DOWN as much as possible, in order to ALLOW some exhaust and intake noise, which is what helps make power. The more the exhaust and intake noise has to be quietened, the larger (and heavier) the systems to allow the same power. This is a major part of the reason for the VERY heavy new exhaust systems you see these days.

So.....on the track, with MUCH higher noise limits, the cam gears make sense...on the street, having to meet the very tough noise regs....not so much. The chain driven motor may actually make MORE power...or at least the bike will be lighter with smaller exhaust and intake systems than what might be required with a gear driven cam motor with all those extra noise making straight cut gears.

Remember...the noise regs are very different today than what the RC45 or early VFRs faced....
The bike would have a restrictive but quiet exhaust and electronic limitations that would make the bike street-legal. The $2000 extra for the SIJ edition would be for the "real" exhaust and chip to unleach the power for Off-Road Use Only ;)
 

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Dr. Carbon
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Of course costs are a factor....but I am stating an opinion that they're not the only factor here (or probably not the MAIN factor). You are more than welcome to disagree.

I KNOW that multiple straight cut gears are a key factor in engine noise and thus have a negative performance impact on a modern street bike.

I expect that Aprilia will tweak their top models to have these gears standard, and spend a lot of money to re-engineer their noise profiles to help meet the latest noise regs, while reducing the negative impact on performance. Whether they do and whether they succeed in meeting or even exceeding the stock performance of the current street motors, is yet to be seen. I think we all would love to see it happen....there's not much cooler than the sound of straight cut gears whine coming through to our ears!
or they could just choose not to export the cam driven model into the US and have them avail to the other markets where they may not face such scrutiny?!
 

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Premium Member
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I think the issue is not so much the cost (it really would not be a huge difference in real manufactured cost), but rather the balance of power offset by the NOISE increase as a result of the gears.....requiring a quieter exhaust or intake system and thus reducing power for the street bikes. Remember...manufacturers have to meet VERY tough noise regs in the USA these days....and so they try to keep mechanical engine noise DOWN as much as possible, in order to ALLOW some exhaust and intake noise, which is what helps make power. The more the exhaust and intake noise has to be quietened, the larger (and heavier) the systems to allow the same power. This is a major part of the reason for the VERY heavy new exhaust systems you see these days.

So.....on the track, with MUCH higher noise limits, the cam gears make sense...on the street, having to meet the very tough noise regs....not so much. The chain driven motor may actually make MORE power...or at least the bike will be lighter with smaller exhaust and intake systems than what might be required with a gear driven cam motor with all those extra noise making straight cut gears.

Remember...the noise regs are very different today than what the RC45 or early VFRs faced....
Barry, while i understand your valid points, i also wonder about the RC51?

Honda used a flapper to close in the intake to help lower that very noise issue you are speaking about and used some rubber skirts along the airbox to help quiet down the noise too.

Are we sure they could not have made it quieter with like $50 worth of plastic and rubber and given the goddies:rockon
 

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He with the senior member
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Are we sure they could not have made it quieter with like $50 worth of plastic and rubber and given the goddies:rockon
No, not sure. They might be able to do it, but given the increases in weight for the majority of sport bikes recently (other than Honda who did a great job on the CBR1000RR), the primary reason for these higher weights, is noise and pollution regs. It's NOT easy to meet the levels prescribed with such high MEP engines as we see today.
 

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No, not sure. They might be able to do it, but given the increases in weight for the majority of sport bikes recently (other than Honda who did a great job on the CBR1000RR), the primary reason for these higher weights, is noise and pollution regs.
How the hell do all those shitty Harleys leave the showroom floor then?:wtf Those damn noisemakers are earpiercing!
 

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Premium Member
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No, not sure. They might be able to do it, but given the increases in weight for the majority of sport bikes recently (other than Honda who did a great job on the CBR1000RR), the primary reason for these higher weights, is noise and pollution regs. It's NOT easy to meet the levels prescribed with such high MEP engines as we see today.

i know it is tough for sure, i am just curious if they could have used a flapper or butterfly like the BMW or R1 etc:rockon
 

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How the hell do all those shitty Harleys leave the showroom floor then?:wtf Those damn noisemakers are earpiercing!

Stock Harleys are actually very quiet . Unfortunately , in that sorority it's a right of passage to get obnoxious pipes within seconds of purchase .:rockon
 

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V4 CyclePath...
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Discussion Starter #20
Of course costs are a factor....but I am stating an opinion that they're not the only factor here (or probably not the MAIN factor). You are more than welcome to disagree.

I KNOW that multiple straight cut gears are a key factor in engine noise and thus have a negative performance impact on a modern street bike.

I expect that Aprilia will tweak their top models to have these gears standard, and spend a lot of money to re-engineer their noise profiles to help meet the latest noise regs, while reducing the negative impact on performance. Whether they do and whether they succeed in meeting or even exceeding the stock performance of the current street motors, is yet to be seen. I think we all would love to see it happen....there's not much cooler than the sound of straight cut gears whine coming through to our ears!
True... noise regs affected the import of the RC45 in 94... in order to pass
Federal Standards Honda reduced power down to 98RWHP and even
unceremoniously dented the exhaust pipes because of the noise of the cam
gear whine... but if you snipe 3 wires on the ECU full European power
returns... about 112RWHP...

Stock RC45 pipe dents...
 
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