Re: Big bore questions round II - Crank Grinding?

John,
I'm not sure I understand what you mean by the
following:

"Offset grinding the crank to get the additional 1mm
of radius on the journal bearing center..."

The simplified(?) picture in my mind involves shaving
metal off of one side of the throw shafts (if that's
the right terminology, the shaft section that the con
rods connect to - I'm a technical geek, but not much
of a gear head) gradually tapering the grind to keep
the shaft round. This would shift the center of the
throw shaft out by half the distance of the maximum
thickness of metal removed. If that makes sense, and
is actually what you propose, then I'm amazed that it
can be done at all, let alone be regarded as a
relatively safe approach.

I don't see how any other metal shaving anywere on an
existing the crank shaft would do anything to change
the stroke. Though I am willing to be enlightened.

Greg



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Greg, you are basically correct.

Grinding is the process, but not like you do it on a bench grinder. Very
precise "turning" of the throw to a smaller size, with the center being 1mm
further out from the center. Pretty standard when doing "stoker" engines.

Carl

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

The simplified(?) picture in my mind involves shaving
metal off of one side of the throw shafts (if that's
the right terminology, the shaft section that the con
rods connect to - I'm a technical geek, but not much
of a gear head) gradually tapering the grind to keep
the shaft round. This would shift the center of the
throw shaft out by half the distance of the maximum
thickness of metal removed. If that makes sense, and
is actually what you propose, then I'm amazed that it
can be done at all, let alone be regarded as a
relatively safe approach.

I don't see how any other metal shaving anywere on an
existing the crank shaft would do anything to change
the stroke. Though I am willing to be enlightened.

Greg

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This reduces the size of the connecting rod journal correct? If so do
you just make up the size difference with a bearing? If not what do
you use?

On 10/31/06, Walzer, Carl (.) wrote:
> Greg, you are basically correct.
>
> Grinding is the process, but not like you do it on a bench grinder. Very
> precise "turning" of the throw to a smaller size, with the center being 1mm
> further out from the center. Pretty standard when doing "stoker" engines.
>
> Carl
>
> -----Original Message-----
>
> The simplified(?) picture in my mind involves shaving
> metal off of one side of the throw shafts (if that's
> the right terminology, the shaft section that the con
> rods connect to - I'm a technical geek, but not much
> of a gear head) gradually tapering the grind to keep
> the shaft round. This would shift the center of the
> throw shaft out by half the distance of the maximum
> thickness of metal removed. If that makes sense, and
> is actually what you propose, then I'm amazed that it
> can be done at all, let alone be regarded as a
> relatively safe approach.
>
> I don't see how any other metal shaving anywere on an
> existing the crank shaft would do anything to change
> the stroke. Though I am willing to be enlightened.
>
> Greg
>
> _______________________________________________
> vfr mailing list
> vfr@xxxxxx
> For subscription and delivery options:
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That might be too much to make up with a bearing. The car projects I've
heard of either got aftermarket rods bored to size, or "resized" their
current rods. Not sure if resizing means welding up and boring again, or if
there is another process. The Chevy 383(?) is a stroked Chevy 350. Do a
search on that and you'll likely get some info.

Carl

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


This reduces the size of the connecting rod journal correct? If so do
you just make up the size difference with a bearing? If not what do
you use?
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In the car world I generally hear of putting in a different crank.
For example I see on the 'Net you take a 400 motor crank and grind the
journals to make it fit in a 350 block. This gives you your 383.

But in this case there is no other crank available.

There is an awards banquet with my racing club this weekend. I'll just
ask someone there as I'm sure they'll know.

-Chris

On 10/31/06, Walzer, Carl (.) wrote:
> That might be too much to make up with a bearing. The car projects I've
> heard of either got aftermarket rods bored to size, or "resized" their
> current rods. Not sure if resizing means welding up and boring again, or if
> there is another process. The Chevy 383(?) is a stroked Chevy 350. Do a
> search on that and you'll likely get some info.
>
> Carl
>
> -----Original Message-----
>
>
> This reduces the size of the connecting rod journal correct? If so do
> you just make up the size difference with a bearing? If not what do
> you use?
>


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The 383ci Small Block Chevy is a 350 with an unmodified 400 crank. The
most common way to resize the ConRod bearing is to weld additional
material on the outside of the journal and then grind/polish into the
desired size. It is a very common technique for rare/collector cars
then the bearing journal become too small for the smallest available
bearings. I had it done to a 1957 Alfa Romeo coupe.

Don't know how it would work on a 10k RPM motorcycle though.

Ren

On 10/31/06, Walzer, Carl (.) wrote:
> That might be too much to make up with a bearing. The car projects I've
> heard of either got aftermarket rods bored to size, or "resized" their
> current rods. Not sure if resizing means welding up and boring again, or if
> there is another process. The Chevy 383(?) is a stroked Chevy 350. Do a
> search on that and you'll likely get some info.
>
> Carl
>
> -----Original Message-----
>
>
> This reduces the size of the connecting rod journal correct? If so do
> you just make up the size difference with a bearing? If not what do
> you use?
> _______________________________________________
> vfr mailing list
> vfr@xxxxxx
> For subscription and delivery options:
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-------------------------------------------------------
"Luigi follow only the Ferrari"
-Luigi, Cars
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I know welding makes the metal as one but for some reason doing what
you say just doesn't sit well with me. I don't know why....I guess
its cause I'm a crappy welder and would end up with many voids in that
weld. :)

Thanks for the info.

On 10/31/06, Ren Finley wrote:
> The 383ci Small Block Chevy is a 350 with an unmodified 400 crank. The
> most common way to resize the ConRod bearing is to weld additional
> material on the outside of the journal and then grind/polish into the
> desired size. It is a very common technique for rare/collector cars
> then the bearing journal become too small for the smallest available
> bearings. I had it done to a 1957 Alfa Romeo coupe.
>
> Don't know how it would work on a 10k RPM motorcycle though.
>
> Ren
>
> On 10/31/06, Walzer, Carl (.) wrote:
> > That might be too much to make up with a bearing. The car projects I've
> > heard of either got aftermarket rods bored to size, or "resized" their
> > current rods. Not sure if resizing means welding up and boring again, or if
> > there is another process. The Chevy 383(?) is a stroked Chevy 350. Do a
> > search on that and you'll likely get some info.
> >
> > Carl
> >
> > -----Original Message-----
> >
> >
> > This reduces the size of the connecting rod journal correct? If so do
> > you just make up the size difference with a bearing? If not what do
> > you use?
> > _______________________________________________
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> >
>
>
> --
> Ren Finley :: ren.finley@xxxxxx
> -------------------------------------------------------
> "Luigi follow only the Ferrari"
> -Luigi, Cars
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You can weld up the journal and off-set grind it and retain the original
throw size or you can save the welding and cut it down to a smaller size
that you can get a rod an bearing for.

I had my Cadillac 500 off-set ground from a 4.36 stroke to a 4.60, then
turned it on down to a big block Chevy sized bearing.

Kevin

----------------------------
IBA 23360

----- Original Message -----
From: "Chris Burgess"
To: "Walzer, Carl (.)"
Cc: "Greg Verderber" ; "vfrlist"
Sent: Tuesday, October 31, 2006 4:19 PM
Subject: Re: Big bore questions round II - Crank Grinding?


> This reduces the size of the connecting rod journal correct? If so do
> you just make up the size difference with a bearing? If not what do
> you use?
>
> On 10/31/06, Walzer, Carl (.) wrote:
>> Greg, you are basically correct.
>>
>> Grinding is the process, but not like you do it on a bench grinder. Very
>> precise "turning" of the throw to a smaller size, with the center being
>> 1mm
>> further out from the center. Pretty standard when doing "stoker"
>> engines.
>>
>> Carl
>>
>> -----Original Message-----
>>
>> The simplified(?) picture in my mind involves shaving
>> metal off of one side of the throw shafts (if that's
>> the right terminology, the shaft section that the con
>> rods connect to - I'm a technical geek, but not much
>> of a gear head) gradually tapering the grind to keep
>> the shaft round. This would shift the center of the
>> throw shaft out by half the distance of the maximum
>> thickness of metal removed. If that makes sense, and
>> is actually what you propose, then I'm amazed that it
>> can be done at all, let alone be regarded as a
>> relatively safe approach.
>>
>> I don't see how any other metal shaving anywere on an
>> existing the crank shaft would do anything to change
>> the stroke. Though I am willing to be enlightened.
>>
>> Greg
>>
>> _______________________________________________
>> 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:
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Very interesting information.

On Tuesday 31 October 2006 03:06 pm, Walzer, Carl (.) wrote:
> Greg, you are basically correct.
>
> Grinding is the process, but not like you do it on a bench grinder. Very
> precise "turning" of the throw to a smaller size, with the center being 1mm
> further out from the center. Pretty standard when doing "stoker" engines.
>
> Carl

I have been fascinated by sophisticated machines for a long time.

I have always wondered how to compensate for the wear on the grinding wheel
while doing this to a crankshaft.

I can't help but think that it would make a difference.

Unless there is no wear..............

--
Jerry

If we are here to help the other people, what are the other people here for?
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A 383 uses a 400 crank with the mains cut down the large journal small block
size. Now Scat and a few others make a 3.75 stroke crank that is a drop-in
in a 327 or 350 large journal block.

Kevin

----------------------------
IBA 23360

----- Original Message -----
From: "Walzer, Carl (.)"
To: "'Chris Burgess'" ; "Walzer, Carl (.)"

Cc: "Greg Verderber" ; "vfrlist"
Sent: Tuesday, October 31, 2006 4:34 PM
Subject: RE: Big bore questions round II - Crank Grinding?


> That might be too much to make up with a bearing. The car projects I've
> heard of either got aftermarket rods bored to size, or "resized" their
> current rods. Not sure if resizing means welding up and boring again, or
> if
> there is another process. The Chevy 383(?) is a stroked Chevy 350. Do a
> search on that and you'll likely get some info.
>
> Carl
>
> -----Original Message-----
>
>
> This reduces the size of the connecting rod journal correct? If so do
> you just make up the size difference with a bearing? If not what do
> you use?
> _______________________________________________
> vfr mailing list
> vfr@xxxxxx
> For subscription and delivery options:
> https://lists.cs.wisc.edu/mailman/listinfo/vfr
>


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I'm impressed. I usually apply A. C. Clarke's line,
"Any sufficiently advanced technology is
indistinguishable from magic" to electronic type
wizardry, but that's got to be one slick milling
machine. Thanks for the edification.

Greg

--- JES_VFR wrote:

> At 12:52 PM 10/31/2006, you wrote:
>
> >John,
> >I'm not sure I understand what you mean by the
> >following:
> >
> >"Offset grinding the crank to get the additional
> 1mm
> >of radius on the journal bearing center..."
> >
> >The simplified(?) picture in my mind involves
> shaving
> >metal off of one side of the throw shafts (if
> that's
> >the right terminology, the shaft section that the
> con
> >rods connect to - I'm a technical geek, but not
> much
> >of a gear head) gradually tapering the grind to
> keep
> >the shaft round. This would shift the center of the
> >throw shaft out by half the distance of the maximum
> >thickness of metal removed. If that makes sense,
> and
> >is actually what you propose, then I'm amazed that
> it
> >can be done at all, let alone be regarded as a
> >relatively safe approach.
> >
> >I don't see how any other metal shaving anywere on
> an
> >existing the crank shaft would do anything to
> change
> >the stroke. Though I am willing to be enlightened.
> >
> >Greg
>
> You have got the idea on the first pass Greg.
> This process is done all the time in the performance
> Automotive
> industry. The bearing surface that the connecting
> rod turns around is
> called the rod journal.
> When an engine is rebuilt and the crank refinished,
> these journals
> are often turned down to a smaller diameter inorder
> to provide a
> fresh bearing surface for the rod bearing to mate
> with. There is
> usually enough material on the rod journals for a
> couple of light
> grinding and polishing passes for rebuilds. The
> grinding tool is
> setup to grind all the journals to the same size and
> ensure that all
> of their centers are the same distance from the
> centerline of the crank.
>
> The only thing that offset grinding does move these
> centers outward
> from the crank centerline half the increase in the
> stroke and remove
> more material from the inside of the rod journal
> than the outside.
> If it is done correctly, using a tested crank or a
> new blank then
> there should be no concern.
> Just to give you an example.
> Take the 5.0l v8 that has powered ford cars and
> trucks since the late
> 60's (back when it was called the 302).
> All the way up to its end in the late 90's the bore
> was 4.00 and the
> stroke was 3.00. Now back in the late 80's when the
> EFI mustangs were
> really taking off, it was common to do a stroker
> rebuild that would
> increase the motor to 331 cubes.
> That was accomplished by offset grinding the stock
> crank journals by
> .125, which when doubled increased the stroke to
> 3.25.
> These engines could make lots of power and run for
> hundreds of
> thousands of miles, I know I helped install several
> in mustangs and
> tbirds in this area. The best part is nothing
> visible on the outside
> of the motor had to be changed for this stroked
> motor to run properly.
> Now there were guys that did not think that was
> enough of an increase
> and would offset grind it to .225 which yielded 352
> with a stock
> bore. The crank was still not the issue here, it was
> the length of
> the rods and the fire deck height of the block.
> These two dimensions
> caused a spacial conflict between the piston pin and
> piston ring
> grooves. These motors quickly had issues with
> burning oil and poor
> ring sealing, but the cranks were never and issue.
>
> Now, I'm sure that there is much less space in any
> modern motorcycle
> engine since they are so compact, but even a little
> bit of stroke
> increase would be useful.
>
> >
>
> JohnS
> A Dragon Ascending
> "Forging my body in the Fires of my Will"
>
>




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All this opens up many ????
Removing crank material changes the journal size. This means new 'babbit' bearings will be required? And the overboring of the cylinders? The walls are powdered metal aluminum composite. Not your 'run of the mill' easy to machine bore. Done wrong and can you say 'major blowby'? What about rebalancing the assemblies after all this work? Even then, all this will undoubtly affect the fine balance and reliability designed into the VFR800. How much HP are we taking about gaining? I remember the lead designer that was interviewed back in late '97 as it was being released stating many combinations of bore & stroke was tried until they came up with a 'happy motor'. Maybe there's some tuners out there that know more about Honda motors than Honda themselves, but all this time & $$$ might be better spent on making the bike lighter (remember 6 pounds per HP) and handle better. I find making bikes lighter /centralizing mass is more cost affective and yields better results than
major motor mods.

Brad
CT.

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You are right about the 400 crank. I had it confused because the last
person I spoke to was also modifying the crank to go beyond the 383. I've
been out of cars and engines too long.

As for how they get the final result, I've never seen it, so can't answer
there.

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


In the car world I generally hear of putting in a different crank.
For example I see on the 'Net you take a 400 motor crank and grind the
journals to make it fit in a 350 block. This gives you your 383.

But in this case there is no other crank available.

There is an awards banquet with my racing club this weekend. I'll just
ask someone there as I'm sure they'll know.

-Chris
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Using techniques from large mass V8's turning 7-8k (at best) for brief periods on a small low mass bike motor turning 10-12K+ sounds too much like an 'Apples-to-Oranges' comparison. Often becomes expensive and frustrating .....let us know how you make out.

Brad
CT.

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Brad,

Just thinking out loud...

That's why people call it a "Passion" with a capitol P...normally
motorcycling isn't cost effective from an insurance, safety and
maintenance standpoint anyway...

Also remember that Honda built a product. Yes, one that was engineered
carefully. Sometimes engineering involves balancing cost vs.
performance. This is a sport-touring machine...why do we go to the
expense of putting in Gold valves, adding sport oriented tires and
Penske shocks? It has no cost benefit that's for sure.

As with any overbore, there is a choice to have the cylinders sleeved or
re-lined with a alumasil (?) or nikasil coating that can be done
aftermarket. I'm not experienced enough to know first hand, but I
think with the advent of aluminum blocks this technology is readily
available to the aftermarket consumer should it be needed...at least if
I wanted to bore out my Civic or Ford econobox I think it could be done
too, but I'm ruminating not speaking from experience...someone enlighten
me...

I know that Dynamo Humm had to gain some experience to get the job done
right, and that experience is valuable, but the job is within reason...1
to 2 K$ not on the order of superbike/unobtainium levels...to get 120+
hp out of the VFR...add on a full two brothers exhaust, PCIII and
re-map the whole thing and you could be pulling 125-129 on the dyno!
That's a significant bang for the VFR buck if the bike is your baby...

With that, I'll agree the bike is still a bit of a pig...just a bit of
one...

Cheers,

Matt

Frugal Yankee wrote:
"Maybe there's some tuners out there that know more about Honda motors
than Honda themselves, but all this time & $$$ might be better spent on
making the bike lighter (remember 6 pounds per HP) and handle better."

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