Big bore kit question.

Like most of us, I often feel like things are never enough, in this
case the issue is vfr displacement and in someways power.

That being said, and my vfr being paid off in full, I'm seriously
considering the Big Bore Option. I say 'Option' because now that I
work behind the parts counter in a motorcycle dealership, I'm not
anxious to do a 'kit' with all it's added costs.

Having read a chunk of the available info on the web about three of
the known kits, I sat down with calculator, pen and a pad of paper to
work out the figures.
As I read it the 837cc (some call it 840) big bore is just that
boring the cylinders out to 74.5 mm and leaving the stroke at a stock
48mm. The 870cc is both a bore and stroke change to 74.5mm X 50mm.

Now this little bit of research leaves me with a few questions the
first round are these.
1. Is 74.5 the real boring limit or can we go for 75mm or 75.5 mm?
2. What is the limiting factor in stroking the VFR, material loss in
offset grinding the crank or interior dimensions of the block?
3. Are the JE pistons or Wiseco units better, and which ones are they
so that I can compare them?
4. What rods are these kits using and has anyone considered any other
brands of rods for this endeavor.



JohnS
A Dragon Ascending
"Forging my body in the Fires of my Will"

_______________________________________________
vfr mailing list
vfr@xxxxxx
For subscription and delivery options:
https://lists.cs.wisc.edu/mailman/listinfo/vfr

On Oct 27, 2006, at 8:11 PM, JES_VFR wrote:

> Like most of us, I often feel like things are never enough, in this
> case the issue is vfr displacement and in someways power.
>
> That being said, and my vfr being paid off in full, I'm seriously
> considering the Big Bore Option. I say 'Option' because now that I
> work behind the parts counter in a motorcycle dealership, I'm not
> anxious to do a 'kit' with all it's added costs.
>
> Having read a chunk of the available info on the web about three of
> the known kits, I sat down with calculator, pen and a pad of paper to
> work out the figures.
> As I read it the 837cc (some call it 840) big bore is just that
> boring the cylinders out to 74.5 mm and leaving the stroke at a stock
> 48mm. The 870cc is both a bore and stroke change to 74.5mm X 50mm.
>
> Now this little bit of research leaves me with a few questions the
> first round are these.
> 1. Is 74.5 the real boring limit or can we go for 75mm or 75.5 mm?

That is pretty much the safe limit without going to a set of Dart
Modular Deck cylinders, but that would require a huge amount of
machining. Getting a shop to do it will be difficult as such a mod
is pretty much uncharted territory.
> 2. What is the limiting factor in stroking the VFR, material loss in
> offset grinding the crank or interior dimensions of the block?

I think there is more room, but you don't want to offset grind too
much as it will weaken the crank and also increase in stroke will
raise the stresses on the crank, rods and pistons.

> 3. Are the JE pistons or Wiseco units better, and which ones are they
> so that I can compare them?

JE by far.

> 4. What rods are these kits using and has anyone considered any other
> brands of rods for this endeavor.
>
Carrillo rods are very good.

I did a bunch of research a couple of years ago to turn my VFR750
into an 1100 cc monster. I quickly determined while it was feasable,
it would quickly turn into a moneypit. I'd need either new carbs or
fuel injection to support the added displacement. The carbs would
cost about $1200 for a set, actually 2 sets because I'd need both
down and side draft carbs. Can only buy them in sets of 4. Fuel
injection was another moneypit, needing larger injectors than a
VFR800 and an aftermarket ECU, preferebly a Motec unit. An extreme
porting job on the heads, bigger valves, larger, custom ground cams,
rods, pistons, probably crank. It all adds up very fast. The
question you have to ask yourself, is how big do you want to go and
how much power do you want to make. The 837cc kit is at the limit of
the stock injectors with a PowerCommander. The 870 requires larger
injectors, but at that point, the heads become a bottle neck. A good
port job and hotter cams will be needed, along with larger valves to
take maximum advantage of the extra displacement. But now you are
talking about spending what the bike is worth on the engine.

So how much power do you want?

It's only money.

Chris Stumpf

_______________________________________________
vfr mailing list
vfr@xxxxxx
For subscription and delivery options:
https://lists.cs.wisc.edu/mailman/listinfo/vfr

At 12:11 AM 10/28/2006, you wrote:
> > first round are these.
> > 1. Is 74.5 the real boring limit or can we go for 75mm or 75.5 mm?
>
>That is pretty much the safe limit without going to a set of Dart
>Modular Deck cylinders, but that would require a huge amount of
>machining. Getting a shop to do it will be difficult as such a mod
>is pretty much uncharted territory.

okay so 74.5 is the bore limit.

> > 2. What is the limiting factor in stroking the VFR, material loss in
> > offset grinding the crank or interior dimensions of the block?
>
>I think there is more room, but you don't want to offset grind too
>much as it will weaken the crank and also increase in stroke will
>raise the stresses on the crank, rods and pistons.

I wasn't thinking of just paring down the crank journal more. I was
thinking of maybe source-ing a new crank blank and having it machined
with a stock diameter journal but a longer throw.


> > 3. Are the JE pistons or Wiseco units better, and which ones are they
> > so that I can compare them?
>
>JE by far.

Which pistons are they so I can check them out myself and price them
myself as well.


> > 4. What rods are these kits using and has anyone considered any other
> > brands of rods for this endeavor.
> >
>Carrillo rods are very good.

Okay, that's cool, how much longer than stock are they, because I
might be able to get them or an equivalent local rod.



>I did a bunch of research a couple of years ago to turn my VFR750
>into an 1100 cc monster. I quickly determined while it was feasable,
>it would quickly turn into a moneypit. I'd need either new carbs or
>fuel injection to support the added displacement. The carbs would
>cost about $1200 for a set, actually 2 sets because I'd need both
>down and side draft carbs. Can only buy them in sets of 4. Fuel
>injection was another moneypit, needing larger injectors than a
>VFR800 and an aftermarket ECU, preferebly a Motec unit. An extreme
>porting job on the heads, bigger valves, larger, custom ground cams,
>rods, pistons, probably crank. It all adds up very fast. The
>question you have to ask yourself, is how big do you want to go and
>how much power do you want to make. The 837cc kit is at the limit of
>the stock injectors with a PowerCommander. The 870 requires larger
>injectors, but at that point, the heads become a bottle neck. A good
>port job and hotter cams will be needed, along with larger valves to
>take maximum advantage of the extra displacement. But now you are
>talking about spending what the bike is worth on the engine.

Well I work in a dealership that has about four techs that all do
extreme mods of bikes (one specializes in both B&S and turbo work on
GSXR1000's), so I do have access to people that can to the head work
and tuning.
But I just got thinking that if I could stretch the stroke by another
..5mm, the VFR could be stretched to 880.

>So how much power do you want?

as much as I can afford, sometimes.



>It's only money.

I hear that, I'm just throwing it around right now. I have other more
pressing projects right now.




JohnS
A Dragon Ascending
"Forging my body in the Fires of my Will"

_______________________________________________
vfr mailing list
vfr@xxxxxx
For subscription and delivery options:
https://lists.cs.wisc.edu/mailman/listinfo/vfr

On 10/27/06, JES_VFR wrote:
>
>
> But I just got thinking that if I could stretch the stroke by another
> .5mm, the VFR could be stretched to 880.
>
> >So how much power do you want?
>
> as much as I can afford, sometimes.
>
> >It's only money.
>
> I hear that, I'm just throwing it around right now. I have other more
> pressing projects right now.


In that case, how about fitting the Vmax V4 into the chassis?!
They have been tuned to put out 150hp at the crank IIRC.

JohnA in LA

_______________________________________________
vfr mailing list
vfr@xxxxxx
For subscription and delivery options:
https://lists.cs.wisc.edu/mailman/listinfo/vfr

I also understand that superchargers have been fitted to V-maxes, adding
another 50-100hp...



_____

From: vfr-bounces@xxxxxx [mailto:vfr-bounces@xxxxxx] On Behalf Of
John Alexander
Sent: Saturday, October 28, 2006 1:32 PM
Cc: vfr@xxxxxx
Subject: Re: Big bore kit question.





On 10/27/06, JES_VFR wrote:


But I just got thinking that if I could stretch the stroke by another
..5mm, the VFR could be stretched to 880.

>So how much power do you want?

as much as I can afford, sometimes.

>It's only money.

I hear that, I'm just throwing it around right now. I have other more
pressing projects right now.


In that case, how about fitting the Vmax V4 into the chassis?!
They have been tuned to put out 150hp at the crank IIRC.

JohnA in LA






_______________________________________________
vfr mailing list
vfr@xxxxxx
For subscription and delivery options:
https://lists.cs.wisc.edu/mailman/listinfo/vfr

Maybe I've been out of the loop on this a while, but isn't the 840 the big
bore for the 750's and the 870 for VFR800? I think you are looking at 2
different things ... on different engines.

Things get expensive fast when you start going beyond standard parts.
Unless you can find alternatives that are already off the shelf, you are now
paying for custom machining and development effort. You have to ask if it
is really worth the money.

Also ask yourself if saving a few bucks by trying to do it yourself is worth
it compared to someone who really know what he is doing and can make sure it
is done right. I've built my own engines before and did pretty good, but I
will pay the money to make sure it is all done right and is built to last.

Just my 2 cents worth.

Carl
-----Original Message-----

Subject: Big bore kit question.

Like most of us, I often feel like things are never enough, in this
case the issue is vfr displacement and in someways power.

That being said, and my vfr being paid off in full, I'm seriously
considering the Big Bore Option. I say 'Option' because now that I
work behind the parts counter in a motorcycle dealership, I'm not
anxious to do a 'kit' with all it's added costs.
_______________________________________________
vfr mailing list
vfr@xxxxxx
For subscription and delivery options:
https://lists.cs.wisc.edu/mailman/listinfo/vfr

Yep, 750 goes to 840 and the 800 goes to 870. At least that was the results
on the big-bore bikes that Brian Law did. I rode them both ... very cool!

Of course, the RC30 I had was even better ...

Later,
M

-----Original Message-----
From: vfr-bounces@xxxxxx [mailto:vfr-bounces@xxxxxx] On Behalf Of
Walzer, Carl (.)
Sent: Monday, October 30, 2006 8:32 AM
To: 'JES_VFR'; vfr@xxxxxx
Subject: RE: Big bore kit question.

Maybe I've been out of the loop on this a while, but isn't the 840 the big
bore for the 750's and the 870 for VFR800? I think you are looking at 2
different things ... on different engines.

Things get expensive fast when you start going beyond standard parts.
Unless you can find alternatives that are already off the shelf, you are now
paying for custom machining and development effort. You have to ask if it
is really worth the money.

Also ask yourself if saving a few bucks by trying to do it yourself is worth
it compared to someone who really know what he is doing and can make sure it
is done right. I've built my own engines before and did pretty good, but I
will pay the money to make sure it is all done right and is built to last.

Just my 2 cents worth.

Carl
-----Original Message-----
Subject: Big bore kit question.

Like most of us, I often feel like things are never enough, in this
case the issue is vfr displacement and in someways power.

That being said, and my vfr being paid off in full, I'm seriously
considering the Big Bore Option. I say 'Option' because now that I
work behind the parts counter in a motorcycle dealership, I'm not
anxious to do a 'kit' with all it's added costs.


_______________________________________________
vfr mailing list
vfr@xxxxxx
For subscription and delivery options:
https://lists.cs.wisc.edu/mailman/listinfo/vfr

just buy an RC-51 and be done with it...

Lou
SF, CA

-------------- Original message ----------------------
From: "Mike Solace"
> Yep, 750 goes to 840 and the 800 goes to 870. At least that was the results
> on the big-bore bikes that Brian Law did. I rode them both ... very cool!
>
> Of course, the RC30 I had was even better ...
>
> Later,
> M
>
_______________________________________________
vfr mailing list
vfr@xxxxxx
For subscription and delivery options:
https://lists.cs.wisc.edu/mailman/listinfo/vfr

On 10/30/06, lguttilla@xxxxxx wrote:
>
> just buy an RC-51 and be done with it...
>
> Lou
> SF, CA


Kind of a good point Lou.

But, you could take your stock VFR and put on a nice set of Dymag carbon
wheels or Marchesinis,
do a bit of lightening up here and there, maybe a full titanium exhaust
system, have the motor blueprinted and probably be close to the big bore in
true performance.


My 2¢.

JohnA in LA

_______________________________________________
vfr mailing list
vfr@xxxxxx
For subscription and delivery options:
https://lists.cs.wisc.edu/mailman/listinfo/vfr

And spent enough money for two RC51's. :)

On 10/30/06, John Alexander wrote:
>
>
> On 10/30/06, lguttilla@xxxxxx wrote:
> > just buy an RC-51 and be done with it...
> >
> > Lou
> > SF, CA
>
> Kind of a good point Lou.
>
> But, you could take your stock VFR and put on a nice set of Dymag carbon
> wheels or Marchesinis,
> do a bit of lightening up here and there, maybe a full titanium exhaust
> system, have the motor blueprinted and probably be close to the big bore in
> true performance.
>
>
> My 2¢.
>
> JohnA in LA
>
>
>
> _______________________________________________
> vfr mailing list
> vfr@xxxxxx
> For subscription and delivery options:
> https://lists.cs.wisc.edu/mailman/listinfo/vfr
>
>


--
Check out my racing site...http://www.burgiracing.com and my blog at
http://blog.burgiracing.com

_______________________________________________
vfr mailing list
vfr@xxxxxx
For subscription and delivery options:
https://lists.cs.wisc.edu/mailman/listinfo/vfr

Did that, but want the big bore V4 too ... and an RC30 ... and a ... well,
you get the picture :)

Glad to hear from you Lou

Carl

-----Original Message-----

just buy an RC-51 and be done with it...

Lou
SF, CA

-------------- Original message ----------------------
From: "Mike Solace"
> Yep, 750 goes to 840 and the 800 goes to 870. At least that was the
results
> on the big-bore bikes that Brian Law did. I rode them both ... very cool!
>
> Of course, the RC30 I had was even better ...
>
> Later,
> M
>
_______________________________________________
vfr mailing list
vfr@xxxxxx
For subscription and delivery options:
https://lists.cs.wisc.edu/mailman/listinfo/vfr

Nah, RC51's are for pussies.

Heh,
M

-----Original Message-----
From: lguttilla@xxxxxx [mailto:lguttilla@xxxxxx]
Sent: Monday, October 30, 2006 10:33 AM
To: Mike Solace; 'vfrlist'
Subject: RE: Big bore kit question.

just buy an RC-51 and be done with it...

Lou
SF, CA

-------------- Original message ----------------------
From: "Mike Solace"
> Yep, 750 goes to 840 and the 800 goes to 870. At least that was the
results
> on the big-bore bikes that Brian Law did. I rode them both ... very cool!
>
> Of course, the RC30 I had was even better ...
>
> Later,
> M
>



_______________________________________________
vfr mailing list
vfr@xxxxxx
For subscription and delivery options:
https://lists.cs.wisc.edu/mailman/listinfo/vfr