Big bore kit question

John,

You might want to call Dynamo Humm (now Picotte Performance after Pascal
Picotte [Canadian Racer] renamed it IIRC) about the 870cc upgrade. I
know you might not want to pay for it, but these guys have according to
sources (who shall remain unnamed until a later time) have done by far
the most big bore jobs on VFR's in North America. They have worked out
all the bugs to give a kit that not only gets you 15+% more power, but
is also reliable as well. I don't know if they'll share all their
secrets, but I'm sure you will find someone willing to talk to you about
the job.

Our friend Louie Guttilla has been there and is friends with the
management/ownership and has great things to say about them. Also
lister (former) Rodriguez, NYC or New Jersey (sorry I can't remember)
firefighter has the big bore kit on his 5th gen. I got to watch him do
roll on wheelies on a few occaisions at COTU. He was definitely way up
on power over my stock '96 (bike at the time). The big bore kit,
desnorkled and with aftermarket can sounded like one monster of a
bike---very snarly. Anyhow, I think he had his engine modded by Dynamo
Humm.

I hear you're working at a shop, but you might glean some nuggets should
you go the do-it yourself (by committee) route rather than ship the
engine to Dynamo Humm route...

FWIW

Matt Roth



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Dynamo Humm no longer does big bore turnkeys, or deals where
you ship the motor to them and they ship you back a modified
motor. They no longer have the machine shop or the room to
do it since they established themselves as Picotte racing.

The sentiments are correct in that the 840 is for the 750,
and the 870 is for the 781 (nee "800"). None involve stroke
modifications, only bore modifications.

The pistons are sourced from an outfit in England for 400
pounds sterling (Same place where Dynamo Humm gets theirs).
There are organizations here in the USA which can do the
machine work and also supply the pistons that appear to be at
least as good.

Stroking a VFR is a serious endeavor, and there are a lot of
hidden "gotchas" that I could see...there are mere hundredths
of an inch between the piston skirt and the crank throw at
BDC stock - and shortening a piston skirt in a 12000 RPM
engine is not something that I would personally like to
explore.

This is why the limit has been an overbore. The 870 will
require a Nikasil type coating in order to do it correctly,
which the better shops will be able to do for you.

I have a spare engine waiting to do this, so I've done a
little bit of research on the subject...I'm sticking with an
870cc overbore (originally wanted to do a 1000 but after a
while I realized that I would literally have to cast my own
engine cases to accomodate the longer crank throws as well as
100% aftermarket cylinders to accomodate the massive overbore
required).

It's definitely fun to think about and play around with
possibilities though :)

Joe
---- Original message ----
>Date: Mon, 30 Oct 2006 09:11:07 -0500
>From: "Mathew Roth"
>Subject: Big bore kit question
>To: ,
>
> John,
>
> You might want to call Dynamo Humm (now Picotte
> Performance after Pascal Picotte [Canadian Racer]
> renamed it IIRC) about the 870cc upgrade. I know
> you might not want to pay for it, but these guys
> have according to sources (who shall remain unnamed
> until a later time) have done by far the most big
> bore jobs on VFR's in North America. They have
> worked out all the bugs to give a kit that not only
> gets you 15+% more power, but is also reliable as
> well. I don't know if they'll share all their
> secrets, but I'm sure you will find someone willing
> to talk to you about the job.
>
> Our friend Louie Guttilla has been there and is
> friends with the management/ownership and has great
> things to say about them. Also lister (former)
> Rodriguez, NYC or New Jersey (sorry I can't
> remember) firefighter has the big bore kit on his
> 5th gen. I got to watch him do roll on wheelies on
> a few occaisions at COTU. He was definitely way up
> on power over my stock '96 (bike at the time). The
> big bore kit, desnorkled and with aftermarket can
> sounded like one monster of a bike---very snarly.
> Anyhow, I think he had his engine modded by Dynamo
> Humm.
>
> I hear you're working at a shop, but you might glean
> some nuggets should you go the do-it yourself (by
> committee) route rather than ship the engine to
> Dynamo Humm route...
>
> FWIW
>
> Matt Roth
______________________
Joe Cargal
Dalton GA
Optilink account - web access only.
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I'd just find yourself a "project bike" or donor bike to fiddle with
first--one with no front end, or you sell it and the bodywork to
"finance" your project with the rebates from the takeoffs. This way
you have a bike you can put on the dyno if you need to (do you NEED a
front end to dyno?) to see the "before" and "after" without losing your
current ride. You could even sell it after you're done if you think its
better but not your taste...

You just might get a couple bites if you develop a new "kit".

Just thinking out loud...

Matt Roth


-----------------------
JohnS wrote:
"Thanks Matt,
'gleaning the nuggets' was exactly what I was trying to do, starting
with the biggest group of consumers of the 840/870 kits,.. this list.

If I could sort that out and some other details (like the style of
rings I prefer), I might even have a kit to offer to the list.

Hell, even if this just turns out to be a cost and risk exercise, I can
always use it as justification for buying another ST bike (like the
triumph ST or the Ducati ST3). "

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