Please share your experience with getting more horses out of the 60

[misterpoopoohead]

Hi Gang,
I thought I'd start another thread!
Have any of you rebuilt the 600 engines with the specific intent of
pumping out more horses than the 35 or so that they normally get?
If I were rebuilding a Ford 351 or a Chevy 327 I would know where to
go and what to do.
But, what are the details for the little 600 engine?
Do people bore them .040 over and then install oversized TRW pistons,
roller rockers, and a mild (or 3/4) cam? :o)
What about aftermarket carbs and K&N air filters, etc?
Please share your experience with 'souping up' a 600 engine.
My plan is not to race the car. I'd just like to develop as much HP
as possible.
I look forward to your answers and the discussion!
thanks!
kev

[jpro8071]

Hi Kev,
I'm one of the people that has taken the 600 motor pretty far.
Unfortunately (or fortunately!) I've had a specialty shop sponsor for
most of the time, so I've lost touch with the true cost of the
improvements. Plus the fact that I can't run pump gas makes the car
even less logical to run.
So with 700cc's, custom pistons, high compression, open exhaust, a
custom cam, EFI and a few other tricks, a simulator (Cartest 2000)
says I'd be lucky to get a 18 second quarter mile. (I hope to get out
to the local drag strip this summer and find out.) Getting any
blistering speed out of the original block is quite a project.
But the car is already pretty impressive. A Boss 302 getting 300
horsepower back in the early 70's was a big deal - 1 HP/CID. And our
35.5 CID motors turned out 36 HP bone stock - 1 HP/CID. Honda really
knew what they were doing.
There are slightly larger pistons out there that will get you a little
more displacement and compression. Every now and then a barrel kit
shows up on eBay that will get you another 60 or 70cc's. There are
specialty shops that can get the motor up to 700 or 750cc
displacement. And a few places will weld up and regrind custom cams.
Better carbs/air filters help if you've done other things to help the
performance. I've seen other things talked about like dual intake
heads and needle-bearing conversions for cams. The roller rockers
would be interesting - but they'd be pretty custom little devices. If
I remember correct all 4 are different.
It's possible to convert to an optical ignition to get better ignition
at higher RPMs.
I'd be curious to know what a bone stock car with stock exhaust and
air cleaner dynos at (not what the reviews say - strap the bugger down
and see what is really going on) - would be interesting to to compare
to our first year with just open exhaust, bigger valves, slightly
bigger pistons and a mild cam.
Just my two cents . . .
-Eric

[Kevin Lister]

Interesting stuff. I don't plan to take it too far. I was thinking more along the lines of the following:
1) K&N Air filters
2) High quality aftermarket carb(s). Weber?
3) Free(er) flowing exhaust.
4) Improved ignition. MSD? Electronic?
Can you tell me more about the optical ignition? I don't think I've ever heard of this.
kev
jpro8071 wrote:
Hi Kev,
I'm one of the people that has taken the 600 motor pretty far.
Unfortunately (or fortunately!) I've had a specialty shop sponsor for
most of the time, so I've lost touch with the true cost of the
improvements. Plus the fact that I can't run pump gas makes the car
even less logical to run.
So with 700cc's, custom pistons, high compression, open exhaust, a
custom cam, EFI and a few other tricks, a simulator (Cartest 2000)
says I'd be lucky to get a 18 second quarter mile. (I hope to get out
to the local drag strip this summer and find out.) Getting any
blistering speed out of the original block is quite a project.
But the car is already pretty impressive. A Boss 302 getting 300
horsepower back in the early 70's was a big deal - 1 HP/CID. And our
35.5 CID motors turned out 36 HP bone stock - 1 HP/CID. Honda really
knew what they were doing.
There are slightly larger pistons out there that will get you a little
more displacement and compression. Every now and then a barrel kit
shows up on eBay that will get you another 60 or 70cc's. There are
specialty shops that can get the motor up to 700 or 750cc
displacement. And a few places will weld up and regrind custom cams.
Better carbs/air filters help if you've done other things to help the
performance. I've seen other things talked about like dual intake
heads and needle-bearing conversions for cams. The roller rockers
would be interesting - but they'd be pretty custom little devices. If
I remember correct all 4 are different.
It's possible to convert to an optical ignition to get better ignition
at higher RPMs.
I'd be curious to know what a bone stock car with stock exhaust and
air cleaner dynos at (not what the reviews say - strap the bugger down
and see what is really going on) - would be interesting to to compare
to our first year with just open exhaust, bigger valves, slightly
bigger pistons and a mild cam.
Just my two cents . . .
-Eric

[jpro8071]

--- In 2cylinderhondas@yahoogroups.com, Kevin Lister
wrote:

> Interesting stuff. I don't plan to take it too far. I was thinking

more along the lines of the following:

> 1) K&N Air filters
> 2) High quality aftermarket carb(s). Weber?
> 3) Free(er) flowing exhaust.
> 4) Improved ignition. MSD? Electronic?
> Can you tell me more about the optical ignition? I don't think

I've ever heard of this.

> kev

We ran a down-draft Weber and didn't have much luck with it. I'm
trying to remember which carb I was looking into before going EFI -
when I remember I'll let you know! (Hopefully others on the list will
share what they have used.)
(If you are handy, look into Megasquirt - that's an EFI system that
might be worth putting on the Honda for normal street use.)
I think there is a lot to be gained with a freer flowing exhaust -
Harbor Freight sells some electric 12V (redundant, eh?) heating units
that might be able to be used for a defroster.
On the optical ignition, we used a Crane optical pickup inside where
the points go. A disk was put on the spinning part with two slits 180
degrees apart to trigger the sensor. This was wired to an MSD
ignition box. Wound all the way up without missing a beat.
I really need to get some photos posted of this - hopefully this
discussion will finally get me to do that . . .

[Kevin Lister]

Photos of the optical ignition would be cool. I suppose I could find that online somewhere though. ;o)
kev
jpro8071 wrote:
--- In 2cylinderhondas@yahoogroups.com, Kevin Lister
wrote:

> Interesting stuff. I don't plan to take it too far. I was thinking

more along the lines of the following:

> 1) K&N Air filters
> 2) High quality aftermarket carb(s). Weber?
> 3) Free(er) flowing exhaust.
> 4) Improved ignition. MSD? Electronic?
> Can you tell me more about the optical ignition? I don't think

I've ever heard of this.

> kev

We ran a down-draft Weber and didn't have much luck with it. I'm
trying to remember which carb I was looking into before going EFI -
when I remember I'll let you know! (Hopefully others on the list will
share what they have used.)
(If you are handy, look into Megasquirt - that's an EFI system that
might be worth putting on the Honda for normal street use.)
I think there is a lot to be gained with a freer flowing exhaust -
Harbor Freight sells some electric 12V (redundant, eh?) heating units
that might be able to be used for a defroster.
On the optical ignition, we used a Crane optical pickup inside where
the points go. A disk was put on the spinning part with two slits 180
degrees apart to trigger the sensor. This was wired to an MSD
ignition box. Wound all the way up without missing a beat.
I really need to get some photos posted of this - hopefully this
discussion will finally get me to do that . . .
---------------------------------
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Check outnew cars at Yahoo! Autos.

[MarkN]

I've managed to squeeze a little more power out of my 600.
Here's a rough outline
1. Homemade equal length (26"? x 1.25 Dia) headers going to a mandrel
bent 1.5" exhaust - required removing the vertical hood latch support
bar thingy for clearance, which in turn required hoodpins.
2. Mike in NC sells oversized pistons- they bump you up to a huge
640cc if I remember right. They're also lighter.
3. Mild port job on the head... I paid somebody with more experience
than I to do that.
4. Stock cam
5. Carefull assembly (selection of the base gasket thickness)to set
piston/head clearance as low as you dare to go (I'm at .032"), to
increase compression.
6. Loose pistons and rings to reduce friction.
7. 39mm Keihin FCR-MX Carb. This is huge. I haven't finished the
airbox/cold air intake for it yet, so it's not fully dialed in, but it
is night and day more powerful and responsive than it was with the old
CV carb.
I don't know how much power I had before/after doing this work, but
after installing the carb, I accidentally found myself at 70mph in a
40 zone while tuning the A/F ratio. I had never had speed sneak up on
me in the honda before.
-Miles E.

[Kevin Lister]

Cool! I think I may try some of this.
Thanks!
kev
wanna600 wrote:
I've managed to squeeze a little more power out of my 600.
Here's a rough outline
1. Homemade equal length (26"? x 1.25 Dia) headers going to a mandrel
bent 1.5" exhaust - required removing the vertical hood latch support
bar thingy for clearance, which in turn required hoodpins.
2. Mike in NC sells oversized pistons- they bump you up to a huge
640cc if I remember right. They're also lighter.
3. Mild port job on the head... I paid somebody with more experience
than I to do that.
4. Stock cam
5. Carefull assembly (selection of the base gasket thickness)to set
piston/head clearance as low as you dare to go (I'm at .032"), to
increase compression.
6. Loose pistons and rings to reduce friction.
7. 39mm Keihin FCR-MX Carb. This is huge. I haven't finished the
airbox/cold air intake for it yet, so it's not fully dialed in, but it
is night and day more powerful and responsive than it was with the old
CV carb.
I don't know how much power I had before/after doing this work, but
after installing the carb, I accidentally found myself at 70mph in a
40 zone while tuning the A/F ratio. I had never had speed sneak up on
me in the honda before.
-Miles E.

[friend]

Miles E.
Look at a regrind on your cam, then use lash caps on the valves (they
will have to be made). And the volume of air fuel mixture is enough with
the later carb, just need to open the jets and move the pin up on the
accelerator pump shaft. When boring for new pistons, keep the cylinders as
straight as possible and as for rings, go to the next size up and grind to
the closest gap without touching. Never had a stock set of rings come close
to what's necessary. Then torque the head to to 45 pounds feet. And,
retorque after the first warm-up. Don't forget to change out the cam chain,
you know what they say about the weakest link. Oh yea, use an oil cooler
and remote filter.
Bill
-----Original Message-----
From: 2cylinderhondas@yahoogroups.com
[mailto:2cylinderhondas@yahoogroups.com]On Behalf Of wanna600
Sent: Wednesday, April 18, 2007 3:00 PM
To: 2cylinderhondas@yahoogroups.com
Subject: [2cylinderhondas] Re: Please share your experience with getting
more horses out of the 600.
I've managed to squeeze a little more power out of my 600.
Here's a rough outline
1. Homemade equal length (26"? x 1.25 Dia) headers going to a mandrel
bent 1.5" exhaust - required removing the vertical hood latch support
bar thingy for clearance, which in turn required hoodpins.
2. Mike in NC sells oversized pistons- they bump you up to a huge
640cc if I remember right. They're also lighter.
3. Mild port job on the head... I paid somebody with more experience
than I to do that.
4. Stock cam
5. Carefull assembly (selection of the base gasket thickness)to set
piston/head clearance as low as you dare to go (I'm at .032"), to
increase compression.
6. Loose pistons and rings to reduce friction.
7. 39mm Keihin FCR-MX Carb. This is huge. I haven't finished the
airbox/cold air intake for it yet, so it's not fully dialed in, but it
is night and day more powerful and responsive than it was with the old
CV carb.
I don't know how much power I had before/after doing this work, but
after installing the carb, I accidentally found myself at 70mph in a
40 zone while tuning the A/F ratio. I had never had speed sneak up on
me in the honda before.
-Miles E.
--- In 2cylinderhondas@yahoogroups.com, "misterpoopoohead"
wrote:

> Hi Gang,
> I thought I'd start another thread!
> Have any of you rebuilt the 600 engines with the specific intent of
> pumping out more horses than the 35 or so that they normally get?

[MarkN]

Bill-
Thanks for your thoughts. The cam is stock, so no lash caps necessary.
The Keihin FCR-MX carb is a far more advanced design than even the
later stock carb. It does a better job of atomizing fuel and flowing
air than a CV carb ever could. My old Mikuni 38mm CV carb held a near
perfect AF ratio and had a bigger throat than the old early stock
carb, but this new FCR-MX just blows it away. It's using 25 years of
carb design evolution to your advantage! This design of carb is used
on almost every racing 4 stroke motorcycle engine except the fuel
injected ones.
The downside is that it's a pain to set up, machining is necessary.
Miles E.

--- In
2cylinderhondas@yahoogroups.com
, wrote:
> Miles E.
> Look at a regrind on your cam, then use lash caps on the valves
(they
> will have to be made). And the volume of air fuel mixture is enough
with
> the later carb, just need to open the jets and move the pin up on the
> accelerator pump shaft. When boring for new pistons, keep the
cylinders as
> straight as possible and as for rings, go to the next size up and
grind to
> the closest gap without touching. Never had a stock set of rings
come close
> to what's necessary. Then torque the head to to 45 pounds feet. And,
> retorque after the first warm-up. Don't forget to change out the
cam chain,
> you know what they say about the weakest link. Oh yea, use an oil
cooler
> and remote filter.
> Bill
> -----Original Message-----
> From:
2cylinderhondas@yahoogroups.com
> [mailto:
2cylinderhondas@yahoogroups.com
]On Behalf Of wanna600
> Sent: Wednesday, April 18, 2007 3:00 PM
> To:
2cylinderhondas@yahoogroups.com
> Subject: [2cylinderhondas] Re: Please share your experience with
getting
> more horses out of the 600.
> I've managed to squeeze a little more power out of my 600.
> Here's a rough outline
> 1. Homemade equal length (26"? x 1.25 Dia) headers going to a mandrel
> bent 1.5" exhaust - required removing the vertical hood latch support
> bar thingy for clearance, which in turn required hoodpins.
> 2. Mike in NC sells oversized pistons- they bump you up to a huge
> 640cc if I remember right. They're also lighter.
> 3. Mild port job on the head... I paid somebody with more experience
> than I to do that.
> 4. Stock cam
> 5. Carefull assembly (selection of the base gasket thickness)to set
> piston/head clearance as low as you dare to go (I'm at .032"), to
> increase compression.
> 6. Loose pistons and rings to reduce friction.
> 7. 39mm Keihin FCR-MX Carb. This is huge. I haven't finished the
> airbox/cold air intake for it yet, so it's not fully dialed in, but it
> is night and day more powerful and responsive than it was with the old
> CV carb.
> I don't know how much power I had before/after doing this work, but
> after installing the carb, I accidentally found myself at 70mph in a
> 40 zone while tuning the A/F ratio. I had never had speed sneak up on
> me in the honda before.
> -Miles E.
> --- In
2cylinderhondas@yahoogroups.com
, "misterpoopoohead"
> wrote:
> > Hi Gang,
> > I thought I'd start another thread!
> > Have any of you rebuilt the 600 engines with the specific intent of
> > pumping out more horses than the 35 or so that they normally get?

[friend]

I agree there are lots of bigger, better and higher performing carbs on the
shelf, but the intake is only so large. So unless you are going to a larger
intake manifold and widening the head intake along with larger valves or
cutting your cam, a larger carb is defeating the purpose. This is why I
say, work on the jets, the original carb has a variable venturie allowing
the same capabilities as a two barrel carb. The function is there. I
always look at an engine like a pump. intake equals exhaust for efficient
running. Open your intake and exhaust with an equal cut and you will
increase output. Otherwise you will be starving the intake or choking the
exhaust.
Bill C
-----Original Message-----
From: 2cylinderhondas@yahoogroups.com
[mailto:2cylinderhondas@yahoogroups.com]On Behalf Of wanna600
Sent: Friday, April 20, 2007 12:12 PM
To: 2cylinderhondas@yahoogroups.com
Subject: [2cylinderhondas] Re: Please share your experience with getting
more horses out of the 600.
Bill-
Thanks for your thoughts. The cam is stock, so no lash caps necessary.
The Keihin FCR-MX carb is a far more advanced design than even the
later stock carb. It does a better job of atomizing fuel and flowing
air than a CV carb ever could. My old Mikuni 38mm CV carb held a near
perfect AF ratio and had a bigger throat than the old early stock
carb, but this new FCR-MX just blows it away. It's using 25 years of
carb design evolution to your advantage! This design of carb is used
on almost every racing 4 stroke motorcycle engine except the fuel
injected ones.
The downside is that it's a pain to set up, machining is necessary.
Miles E.

--- In
2cylinderhondas@yahoogroups.com
, wrote:
> Miles E.
> Look at a regrind on your cam, then use lash caps on the valves
(they
> will have to be made). And the volume of air fuel mixture is enough
with
> the later carb, just need to open the jets and move the pin up on the
> accelerator pump shaft. When boring for new pistons, keep the
cylinders as
> straight as possible and as for rings, go to the next size up and
grind to
> the closest gap without touching. Never had a stock set of rings
come close
> to what's necessary. Then torque the head to to 45 pounds feet. And,
> retorque after the first warm-up. Don't forget to change out the
cam chain,
> you know what they say about the weakest link. Oh yea, use an oil
cooler
> and remote filter.
> Bill
> -----Original Message-----
> From:
2cylinderhondas@yahoogroups.com
> [mailto:
2cylinderhondas@yahoogroups.com
]On Behalf Of wanna600
> Sent: Wednesday, April 18, 2007 3:00 PM
> To:
2cylinderhondas@yahoogroups.com
> Subject: [2cylinderhondas] Re: Please share your experience with
getting
> more horses out of the 600.
> I've managed to squeeze a little more power out of my 600.
> Here's a rough outline
> 1. Homemade equal length (26"? x 1.25 Dia) headers going to a mandrel
> bent 1.5" exhaust - required removing the vertical hood latch support
> bar thingy for clearance, which in turn required hoodpins.
> 2. Mike in NC sells oversized pistons- they bump you up to a huge
> 640cc if I remember right. They're also lighter.
> 3. Mild port job on the head... I paid somebody with more experience
> than I to do that.
> 4. Stock cam
> 5. Carefull assembly (selection of the base gasket thickness)to set
> piston/head clearance as low as you dare to go (I'm at .032"), to
> increase compression.
> 6. Loose pistons and rings to reduce friction.
> 7. 39mm Keihin FCR-MX Carb. This is huge. I haven't finished the
> airbox/cold air intake for it yet, so it's not fully dialed in, but it
> is night and day more powerful and responsive than it was with the old
> CV carb.
> I don't know how much power I had before/after doing this work, but
> after installing the carb, I accidentally found myself at 70mph in a
> 40 zone while tuning the A/F ratio. I had never had speed sneak up on
> me in the honda before.
> -Miles E.
> --- In
2cylinderhondas@yahoogroups.com
, "misterpoopoohead"
> wrote:
> > Hi Gang,
> > I thought I'd start another thread!
> > Have any of you rebuilt the 600 engines with the specific intent of
> > pumping out more horses than the 35 or so that they normally get?