RC51 & Superhawk - Gear vs. Chain driven cams
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MotoGP
Joined: Aug 2007
Posts: 5,942
From: Lake View Terrace, CA
The answer is 42......
With gear driven cams you have more accurate cam timing but you have more spinning mass to deal with.
Chain drive, not quite as accurate as gear driven cams but much lighter.
So they both are good and both have their applications.
With gear driven cams you have more accurate cam timing but you have more spinning mass to deal with.
Chain drive, not quite as accurate as gear driven cams but much lighter.
So they both are good and both have their applications.
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Superstock
Superstock
Joined: Apr 2007
Posts: 321
Gears=no way to adjust head squish. At least has been cited as a limitation to the VFR's engine modification possibilities.
Side question, is it common to alter the VTR's compression? Done with pistons only?
Side question, is it common to alter the VTR's compression? Done with pistons only?
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Squid
Joined: Aug 2011
Posts: 75
From: Austin, TX
I assume the central part of the gear that transfers the force from the crank to the cam doesn't have to deal with any torque, and so can be made pretty lightly with lots of excess metal removed. Plus there is no need for Cam Chain Tensioners or the chain for that matter. With that in mind I'm going to go out on a limb and say that I'm pretty sure gear driven cams are not much (if any) heavier than chain driven ones.
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MotoGP
Joined: Aug 2007
Posts: 5,942
From: Lake View Terrace, CA
Well for a street bike, is there really any other answer.... 
Though I do like the sound they make but then I like the straight cut primary gears on a VTR also and how many people ask about that noise....
Well here is a RC51 gear drive:
Honda, ATV Parts, Scooter Parts, Motorcycle Parts,CRF,CR,MX Parts, Goldwing parts
You can see it takes 3 gears to get from the crank to the cams. Then you also need the 2 plates they mount in and also the bearings they run on. So yes it is much heavier than a comparable chain driven cam set up.
Though if you are spinning high RPM (and a VTR's meager 10.3K rev limit really isn't all that high) they are the only way to go.
Though I do like the sound they make but then I like the straight cut primary gears on a VTR also and how many people ask about that noise....
I have a '99 VFR800 and I love the gear driven cams, they are noisier, but they are a purposeful noise.
I assume the central part of the gear that transfers the force from the crank to the cam doesn't have to deal with any torque, and so can be made pretty lightly with lots of excess metal removed. Plus there is no need for Cam Chain Tensioners or the chain for that matter. With that in mind I'm going to go out on a limb and say that I'm pretty sure gear driven cams are not much (if any) heavier than chain driven ones.
I assume the central part of the gear that transfers the force from the crank to the cam doesn't have to deal with any torque, and so can be made pretty lightly with lots of excess metal removed. Plus there is no need for Cam Chain Tensioners or the chain for that matter. With that in mind I'm going to go out on a limb and say that I'm pretty sure gear driven cams are not much (if any) heavier than chain driven ones.
Honda, ATV Parts, Scooter Parts, Motorcycle Parts,CRF,CR,MX Parts, Goldwing parts
You can see it takes 3 gears to get from the crank to the cams. Then you also need the 2 plates they mount in and also the bearings they run on. So yes it is much heavier than a comparable chain driven cam set up.
Though if you are spinning high RPM (and a VTR's meager 10.3K rev limit really isn't all that high) they are the only way to go.
Out of my mind, back in 5
MotoGP
Joined: Nov 2006
Posts: 6,109
From: Skurup, Sweden
Well... You'd need a bigger top end on the engine... And bit of goop to seal the edges, but other than that it's more or less a fair bolt on mod... 
Serousily though... Now you guys got me thinking... And that's usually a bad thing... I have a VFR engine somewhere, whom somebody tried running without oil... The cam gears in that will have to go on a field trip I think...
Serousily though... Now you guys got me thinking... And that's usually a bad thing... I have a VFR engine somewhere, whom somebody tried running without oil... The cam gears in that will have to go on a field trip I think...
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Wild Man
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Joined: Oct 2011
Posts: 189
From: California Central Coast
...or you can install these HRC billet gear drive units and lightweight rods.
No chain lash. No slight timing retardation. Just a positive exact time. No worries forever.
I'll let you know.
Edit: Now I need some block off plates for the CCT holes. Hmmm.....
No chain lash. No slight timing retardation. Just a positive exact time. No worries forever.
I'll let you know.
Edit: Now I need some block off plates for the CCT holes. Hmmm.....
Last edited by Matt_Hawk; Nov 21, 2011 at 03:08 PM.
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Squid
Joined: Dec 2011
Posts: 1
From: Winchester, UK
Anyone done it?
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Joined: Mar 2008
Posts: 229
From: Massachusetts
Well if you are going to change the valve train completely anyway...
CSRV vs. Poppet Valve - Coates International Ltd.
CSRV vs. Poppet Valve - Coates International Ltd.
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Superstock
Joined: Mar 2009
Posts: 277
From: south nj (philly area)
...or you can install these HRC billet gear drive units and lightweight rods.
No chain lash. No slight timing retardation. Just a positive exact time. No worries forever.
I'll let you know
Where did you get these? How much were they?
Edit: Now I need some block off plates for the CCT holes. Hmmm.....
No chain lash. No slight timing retardation. Just a positive exact time. No worries forever.
I'll let you know
Where did you get these? How much were they?
Edit: Now I need some block off plates for the CCT holes. Hmmm.....
Junior Member
Squid
Joined: Jan 2007
Posts: 17
they look like sp1 / sp2 cam gears except HRC ones. i think this would work since the firestorm has the two random bolt holes in the head that bolts the periphery to the block. i think they could be used to bolt down the cam gears. then all you would need to do is rotate the inlet cam 180 degrees. job jobbed
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