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Discussion Starter · #1 ·
Sorry if this is rudimentary and redundant but it seems like I've read both (can and can't)

I'm riding a 2004 vrscb and want to go bb without stroking it.

Thanks in advance
 

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Best you could do is a 1320 bore, which has been done before.
Not true you can go w/ a 4.315" bore (109.5mm) that'll get you 1358CC. It too has been done before.

Itll leave an uber thin sleeve wall which means if you motor lasts long enough, it cant be bored it will need to be re-sleeve as you've eaten all the material required for an over bore. running that thin also means youll loose some rigidity in the cylinders and with a piston exerting some pretty impressive liner velocities as well as the pressure forces from the expanding gasses, If something goes awry that sleeve wall aint stopping shit, your motor will be toast.

The largest bore that most choose is a 4.25" (1320cc) because it it requires case machine to accept the larger sleeve but it leaves the most material on the sleeve increasing rigidity and allowing for over boring in the future.

If you choose to start boring into the sleeve you've got options like the 4.285" (1340CC) or like mentioned above the 4.315" bore but again in addition to boring the case to accept the larger sleeve, youll be boring the sleeve itself. all depends on how much materiel you willing to widdle away on the sleeve.



Why don’t you want to stroke it?
Plenty of reasons.

Stroking increases the maximal piston speed thus increased wear. This is present both on the cylinder walls, piston and the wrist pin. specifically looking at the wrist pin kinetic energy is measured as 1/2 mass*velocity^2. Increasing the pistons velocity (as opposed to just the mass from say a bigger piston) increased the kinetic energy by a full fold (thanks to the ^2 term). Even minor increases to the piston velocity have a much bigger effect on the kinetic energy and the thing that's absorbing all the energy as the piston reaches is maximal speed and starts to change direction...the wrist pin

Piston rocking as the piston reaches BDC and there's less cylinder available to stabilize the piston (especially given the forces explained above) is also another source of aggravated wear resulting from stroking. specifically the rings will wear out much faster.


It's more expensive (in addition to block n piston work, you've got crank work, oil jet clearance on the revo motor, stronger rods, nitrated wrist pins to name a few)

A shorter stroke is more accepting of an over revved red-line.



OP if your serious about building a v-rod motor realize your only beginning to scratch the surface this aint a twinkiy, evo, or M8 where cylinders, pistons, rods and flywheels are readily available and be mixed and match to a preferred combo. Precision motor work is needed and i've yet to see any two builds exactly the same due to parts availability, lead time and an ever changing vendor landscape.

You really need to look good and hard into the mirror then state what functionality you want before settling on a displacement number. This is entirely to expensive of a project for you not to be painfully honest with your self. Way better to fizzle out at the start than get into it realizing you want bigger or smaller.

Also fully accept that this is your hobby you will not make money in fact you will loose lots of it. You will likely not be able to sell your big bore v-rod for the KBB+the cost of the built motor. You will loose lots and lots of hard earned dollars to pursue horse power in a v-rod but the final product's a lot fun.
 

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Discussion Starter · #4 ·
Not true you can go w/ a 4.315" bore (109.5mm) that'll get you 1358CC. It too has been done before.

Itll leave an uber thin sleeve wall which means if you motor lasts long enough, it cant be bored it will need to be re-sleeve as you've eaten all the material required for an over bore. running that thin also means youll loose some rigidity in the cylinders and with a piston exerting some pretty impressive liner velocities as well as the pressure forces from the expanding gasses, If something goes awry that sleeve wall aint stopping shit, your motor will be toast.

The largest bore that most choose is a 4.25" (1320cc) because it it requires case machine to accept the larger sleeve but it leaves the most material on the sleeve increasing rigidity and allowing for over boring in the future.

If you choose to start boring into the sleeve you've got options like the 4.285" (1340CC) or like mentioned above the 4.315" bore but again in addition to boring the case to accept the larger sleeve, youll be boring the sleeve itself. all depends on how much materiel you willing to widdle away on the sleeve.




Plenty of reasons.

Stroking increases the maximal piston speed thus increased wear. This is present both on the cylinder walls, piston and the wrist pin. specifically looking at the wrist pin kinetic energy is measured as 1/2 mass*velocity^2. Increasing the pistons velocity (as opposed to just the mass from say a bigger piston) increased the kinetic energy by a full fold (thanks to the ^2 term). Even minor increases to the piston velocity have a much bigger effect on the kinetic energy and the thing that's absorbing all the energy as the piston reaches is maximal speed and starts to change direction...the wrist pin

Piston rocking as the piston reaches BDC and there's less cylinder available to stabilize the piston (especially given the forces explained above) is also another source of aggravated wear resulting from stroking. specifically the rings will wear out much faster.


It's more expensive (in addition to block n piston work, you've got crank work, oil jet clearance on the revo motor, stronger rods, nitrated wrist pins to name a few)

A shorter stroke is more accepting of an over revved red-line.



OP if your serious about building a v-rod motor realize your only beginning to scratch the surface this aint a twinkiy, evo, or M8 where cylinders, pistons, rods and flywheels are readily available and be mixed and match to a preferred combo. Precision motor work is needed and i've yet to see any two builds exactly the same due to parts availability, lead time and an ever changing vendor landscape.

You really need to look good and hard into the mirror then state what functionality you w

Thanks everyone. Sticking with the 1320 which combined with the Trask Turbo will put me where I wanted the bike to be and yes this just became an expensive hobby.

Now I just need to find stage 2 or 3 turbo cams...Jones is out.
 

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If your going forced induction why bother bore at all? The benifit you will get from the stock bore is a more rigid case which will allow more air to be shoved in, which will make more power... etc etc etc.

What benifit are looking for from a 4.25" bore on a boosted motor?

Jan-Dirk is running a stock bore with 23 psi of boost and I believe 2 intake cams (slotted to achieve his desired overlap and duration)
 

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Discussion Starter · #6 ·
If your going forced induction why bother bore at all? The benifit you will get from the stock bore is a more rigid case which will allow more air to be shoved in, which will make more power... etc etc etc.

What benifit are looking for from a 4.25" bore on a boosted motor?

Jan-Dirk is running a stock bore with 23 psi of boost and I believe 2 intake cams (slotted to achieve his desired overlap and duration)
I currently have an 1130 and if I understand correctly a 1320 will give the power and torque off the line before the turbo really kicks in.

Am I wrong?
 

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Just put the turbo on the 1130cc engine with a set of turbo cams that will give you the most bang for the buck and as dimebag said very strong thicker cylinder liners for reliability easy to build lower boost level then later if you want more pull the engine go bigger bore with it 1250cc with the turbo that's a great combination using lower compression turbo pistons and more boost - It's a steep bell curve up in cost of time & money and proper tuning when you start stroking and boosting the Revo engine. It's definitely not easy or turn key. Most guys with turbos on basically stock engines are pretty happy with the performance they get out of them. You could start there and sneak up on the rest as you learn more thru time. Otherwise get about what 15K together to have a great V Rod machine shop build your dream turbo engine with all the strength improvements it needs to stay together - and dyno tuning otherwise you end up with blown engines and throwing more good money after bad and more time. Read the entire Turbo/SC section here to gain some insight and wisdom from guys that have been there and done with Revo turbos it's eye opening and Good Luck !! (y):cool:
 

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I agree Streetrodracer, I think OP is trying to apply generalization and over simplifications, "bigger is better" logic, which is true for the most part but there are way easier more economical ways to get the same result. If you want the biggest baddest V-rod well that's ego talking (and not necessarily a bad thing), and you should save up the cash then do it in as a single project.

What your talking about “off the line” power can be achieved on a turboed 1130, knowing how to launch and a properly sized turbo. Comparing to the sport of drag racing, your winding up and launching close to 6K RPM and by 60' on the track you'd better have that throttle pinned. By that point with a properly sized turbo, it can be spooled and compressing air.

turbo lag comes from (for the most part) larger turbos that need more RPM and exhaust gasses to get them moving. They deliver a lot more CFM of air but at the cost of longer spool times. its kind of an investment you’ll still have off the line power to get the bike moving but the power wont come on until much later in the RPM range. when it does because its moving a lot more air, hold on.

The point is you don’t need to punch the block to achieve low end grunt, a smaller faster spooling turbo might be what your looking for. Also if you stay mild enough the stock cams are pretty well designed for forced induction, it’s all about knowing what overlap, LSA and duration your after and how those translate to motor performance.

Just because it Stage 3 cams have a higher number than Stage 2 cams doesn’t necessarily mean it’s better. I hate Harley for pushing this staged progression to upgrading motors because it causes lots of mis-information. Plenty of riders have over cammed their motor by installing a Stage 3 cam into their under modified motor. Motor then runs like a shit and they can figure out whey when the used the best of the best parts.

do your home work read up on cam theory talk to people then select your cam based on what you want the bike to do.

Here’s some reading

Inside Forced-Induction Camshaft Designs With Howards Cams

The Science Behind Camshaft Design - Circle Track Magazine

Answer this OP
What peak horse power are looking for and at what RPM?
 

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Discussion Starter · #9 ·
Thanks definitely taking into account since we are in the planning stages.

I know I am not going to stroke it.
I agree Streetrodracer, I think OP is trying to apply generalization and over simplifications, "bigger is better" logic, which is true for the most part but there are way easier more economical ways to get the same result. If you want the biggest baddest V-rod well that's ego talking (and not necessarily a bad thing), and you should save up the cash then do it in as a single project.

What your talking about “off the line” power can be achieved on a turboed 1130, knowing how to launch and a properly sized turbo. Comparing to the sport of drag racing, your winding up and launching close to 6K RPM and by 60' on the track you'd better have that throttle pinned. By that point with a properly sized turbo, it can be spooled and compressing air.

turbo lag comes from (for the most part) larger turbos that need more RPM and exhaust gasses to get them moving. They deliver a lot more CFM of air but at the cost of longer spool times. its kind of an investment you’ll still have off the line power to get the bike moving but the power wont come on until much later in the RPM range. when it does because its moving a lot more air, hold on.

The point is you don’t need to punch the block to achieve low end grunt, a smaller faster spooling turbo might be what your looking for. Also if you stay mild enough the stock cams are pretty well designed for forced induction, it’s all about knowing what overlap, LSA and duration your after and how those translate to motor performance.

Just because it Stage 3 cams have a higher number than Stage 2 cams doesn’t necessarily mean it’s better. I hate Harley for pushing this staged progression to upgrading motors because it causes lots of mis-information. Plenty of riders have over cammed their motor by installing a Stage 3 cam into their under modified motor. Motor then runs like a shit and they can figure out whey when the used the best of the best parts.

do your home work read up on cam theory talk to people then select your cam based on what you want the bike to do.

Here’s some reading

Inside Forced-Induction Camshaft Designs With Howards Cams

The Science Behind Camshaft Design - Circle Track Magazine

Answer this OP
What peak horse power are looking for and at what RPM?
Thank you!
 

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A bigger bore (which reduces cylinder cooling area in the block that is machined away) along with Turbo might give you some cooling issues. I believe Jan Dirk kept his monster a 1130cc taking cooling into consideration, especially with really high boost. I also kept mine a 1130cc and went with the 4 intake cams and dropped my compression to 10.55:1. The 4 intake cam setup has more grunt down low, it pulls harder through the upper midrange and very linear to redline (9500RPM) and no more stampeding on the upper end like it did with the turbo on stock 1130. It is a whole different animal.
 

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Now there's ya some experience talking Tracy !! These guys are a great source of information that cost big bucks to develop and absorb. I've learned so much here and there's more to come - (y):cool:
 
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