Power tuning a Honda Z600

Mark P Hatten · Post by **Mark P Hatten** » Sun Jan 13, 2013 1:37 pm

I've been tuning for speed and power on my 1972 600cc 4 stroke Honda Z600 hot rod. I can now go 47 mph. in 1/4 mile, up from 43 mph. last week but, it still seems lethargic. I got a slight miss to go away, but am disappointed with low top speed power. Here's the back story. Fresh 20-50 wt. oil and filter. New hot NGK #6 plugs, new 7mm wires, new NGK 90* ends, plugs are clean after hard run, swapped, tested, ignition coils, new NOS points gapped correct, new condenser, vac. and mechanical advance checked and cleaned and seem good. Timing is slightly advanced. 147 psi. compression on both cylinders, timing chain is sloppy but timing marks line up. Idles smooth, revs up good. No backfires, no misses. Smooth but low power. Redlines at 6500-6700 rpm's no problem. Tried 2 carburetors, one old style, one new style, both are clean, accelerator pump works in both, float levels correct. Both carbs act the same. 2 psi. fuel pressure, clean fuel. All new exhaust gaskets, no leaks, exhaust is not plugged. Tires are new and inflated to 40 psi., alignment is perfect, brakes do not drag. Can push car with two fingers on level surface.
My Subaru 360 could run rings around this slug with half the displacement. It just don't seem right.
Most 600 owners say their cars will go 70 mph. Maybe,..... with a 5 mile head start!.
What am I missing here?
How does one increase the jet size? Do you file the taper on the carb slide plunger needle?
I know my hood scoop does not aid aerodynamics...but, this much?
Help please.
https://www.youtube.com/watch?v=tyW8KQeYsfg
Mark Portland Or.
www.mphspecialties.com

Gabriel Garcia Diaz · Post by **Gabriel Garcia Diaz** » Sun Jan 13, 2013 5:14 pm

Those wheels don't look stock the larger diameter wheel might be hurting your acceleration. My 71' redlines at approx 5000 but I feelt the acceleration is decent for an engine small. The car sports the original 10" wheels.
Gabe

On Jan 13, 2013, at 15:37, Mark P Hatten wrote:
I've been tuning for speed and power on my 1972 600cc 4 stroke Honda Z600 hot rod. I can now go 47 mph. in 1/4 mile, up from 43 mph. last week but, it still seems lethargic. I got a slight miss to go away, but am disappointed with low top speed power. Here's the back story. Fresh 20-50 wt. oil and filter. New hot NGK #6 plugs, new 7mm wires, new NGK 90* ends, plugs are clean after hard run, swapped, tested, ignition coils, new NOS points gapped correct, new condenser, vac. and mechanical advance checked and cleaned and seem good. Timing is slightly advanced. 147 psi. compression on both cylinders, timing chain is sloppy but timing marks line up. Idles smooth, revs up good. No backfires, no misses. Smooth but low power. Redlines at 6500-6700 rpm's no problem. Tried 2 carburetors, one old style, one new style, both are clean, accelerator pump works in both, float levels correct. Both carbs act the same. 2 psi. fuel pressure, clean fuel. All new exhaust gaskets, no leaks, exhaust is not plugged. Tires are new and inflated to 40 psi., alignment is perfect, brakes do not drag. Can push car with two fingers on level surface.
My Subaru 360 could run rings around this slug with half the displacement. It just don't seem right.
Most 600 owners say their cars will go 70 mph. Maybe,..... with a 5 mile head start!.
What am I missing here?
How does one increase the jet size? Do you file the taper on the carb slide plunger needle?
I know my hood scoop does not aid aerodynamics...but, this much?
Help please.
https://www.youtube.com/watch?v=tyW8KQeYsfg
Mark
Portland Or.
www.mphspecialties.com

Bill · Post by **Bill** » Sun Jan 13, 2013 7:40 pm

Gabe;
You hit it on the head. 13 inch wheels take a whole lot of power to get rolling. I had a friend that had 13 inch Toyota mag rims with 50 series tires and it took for ever to get to speed. We put the 10 inch rims back on it with 145x10 tires and it ran great.
Bill

Chas · Post by **Chas** » Mon Jan 14, 2013 5:24 am

Mark,
Have you verified the valve timing. With a sloppy cam chaim, it may have jumped a tooth or a previous owner may have assembled it wrong. A single tooth woudl not necessarrily reduce compression on a test, but woudl affect valve overlap and may be closing the valves later or releasing compression early. Just a thought.
Chas

--- In
anzhonda600owners@yahoogroups.com
, Mark P Hatten wrote:
> I've been tuning for speed and power on my 1972 600cc 4 stroke Honda Z600 hot rod. I can now go 47 mph. in 1/4 mile, up from 43 mph. last week but, it still seems lethargic. I got a slight miss to go away, but am disappointed with low top speed power. Here's the back story. Fresh 20-50 wt. oil and filter. New hot NGK #6 plugs, new 7mm wires, new NGK 90* ends, plugs are clean after hard run, swapped, tested, ignition coils, new NOS points gapped correct, new condenser, vac. and mechanical advance checked and cleaned and seem good. Timing is slightly advanced. 147 psi. compression on both cylinders, timing chain is sloppy but timing marks line up. Idles smooth, revs up good. No backfires, no misses. Smooth but low power. Redlines at 6500-6700 rpm's no problem. Tried 2 carburetors, one old style, one new style, both are clean, accelerator pump works in both, float levels correct. Both carbs act the same. 2 psi. fuel pressure, clean fuel. All new exhaust gaskets, no leaks, exhaust is not plugged. Tires are new and inflated to 40 psi., alignment is perfect, brakes do not drag. Can push car with two fingers on level surface. My Subaru 360 could run rings around this slug with half the displacement. It just don't seem right. Most 600 owners say their cars will go 70 mph. Maybe,..... with a 5 mile head start!. What am I missing here? How does one increase the jet size? Do you file the taper on the carb slide plunger needle? I know my hood scoop does not aid aerodynamics...but, this much? Help please.
https://www.youtube.com/watch?v=tyW8KQeYsfg
MarkPortland Or.
> www.mphspecialties.com

Mark P Hatten · Post by **Mark P Hatten** » Mon Jan 14, 2013 12:47 pm

Thanks gang for the overwhelming support and tips.
Update. Good News ! The "hot rod" Honda z600 is now running better than ever.
My "go-to " seat of the pants test is 1/4 mile stretch of road nearby from a dead stop, from a stop light to the 40 mph sign. The hot rod Subaru 360's will hit 62 mph in this span. While initial 1/4 mile test tuning this particular Honda Z600 started at barely 42mph, then 43mph, then 47 mph. It painfully struggled to get there. Foot to the floor... speed shifting every gear. I knew there had to be more. Now it does 52 mph in the same span !! A huge improvement. It's now actually fun to drive. I took it on I-5 super highway last night and it easily cruised at 65 mph before I ran out of road for my exit.
Read thru the list of items below that I had addressed. I forgot to mention I had adjusted the valves .005" I and E , and the 13" wheel have the same overall diameter and the 10" wheels and tires.
The one thing I overlooked was re-checking the timing after installing the new points. The timing was not " slightly " advanced, but, 35* way advanced at idle. (Quite Embarrassing !) I'm surprised it ran at all. The old set of points rubbing block was worn down to a nub from rubbing on a rusty eccentric cam. The new points made the timing much different. That's my story.... I also polished the carburetor slide piston and needle. I added a tiny E-clip to space the needle up to richen up the midrange. Runs SUPER now.
I'm ecstatic that it runs so much better
Thanks again!
Mark
Portland Or.
Mark- First off, you're comparing apples and oranges when it comes to displacement. A 2-stroke is an equivalent of a 4-stroke of 1.75 times the 2-stroke. That makes your 360 the equivalent of a 630cc 4-stroke, or thereabouts.
Next, what's the weight of the two cars? My guess is that the Honda is heavier than your 'Ru.
So, heavier car at a 5% displacement penalty is bound to be slower. And, as you said, that air brake on the hood ain' helpin' in the top speed regime, either.
One thing to be aware of- wind drag increases as the square of the increase in speed. That is, if you're going 50 and goose it up to 55, the increase in speed is 10%, or 1.1 times more. One point one squared is 1.21, or 21% more. And you wonder why you can't get that lovable but ugly little puppy to 70?
wjs

> I've been tuning for speed and power on my 1972 600cc 4 stroke Honda Z600 hot rod. I can now go 47 mph. in 1/4 mile, up from 43 mph. last week but, it still seems lethargic. I got a slight miss to go away, but am disappointed with low top speed power. Here's the back story. Fresh 20-50 wt. oil and filter. New hot NGK #6 plugs, new 7mm wires, new NGK 90* ends, plugs are clean after hard run, swapped, tested, ignition coils, new NOS points gapped correct, new condenser, vac. and mechanical advance checked and cleaned and seem good. Timing is slightly advanced. 147 psi. compression on both cylinders, timing chain is sloppy but timing marks line up. Idles smooth, revs up good. No backfires, no misses. Smooth but low power. Redlines at 6500-6700 rpm's no problem. Tried 2 carburetors, one old style, one new style, both are clean, accelerator pump works in both, float levels correct. Both carbs act the same. 2 psi. fuel pressure, clean fuel. All new exhaust gaskets, no leaks, exhaust is not plugged. Tires are new and inflated to 40 psi., alignment is perfect, brakes do not drag. Can push car with two fingers on level surface.
> My Subaru 360 could run rings around this slug with half the displacement. It just don't seem right.
> Most 600 owners say their cars will go 70 mph. Maybe,..... with a 5 mile head start!.
> What am I missing here?
> How does one increase the jet size? Do you file the taper on the carb slide plunger needle?
> I know my hood scoop does not aid aerodynamics...but, this much?
> Help please.
> https://www.youtube.com/watch?v=tyW8KQeYsfg
> Mark
> Portland Or.
> www.mphspecialties.com

Bart Schile · Post by **Bart Schile** » Mon Jan 14, 2013 3:48 pm

You should correct the looseness on the tensioner for the timing chain to kept it within specs. A loose timing chain has different effects on acceleration than at idle where you measure it. As the crank loads one side of the chain, it will effect the timing especially on acceleration. Bart

Mark P Hatten · Post by **Mark P Hatten** » Mon Jan 14, 2013 4:48 pm

Bart,
I've been thinking about this very same topic. My chain is sloppy. The cam gear teeth and tensioned roller look Ok from what I see. I think a new timing chain will make a big performance improvement. I'm not sure how to get a new chain in there ? Does the entire engine have to come apart ? or, could one just link it to the old chain and spin it through. Are new tensioners available ? I'm not sure.
Mark www.mphspecialties.com
To: anzhonda600owners@yahoogroups.com

Eric Geiger · Post by **Eric Geiger** » Mon Jan 14, 2013 5:09 pm

Oh I know the answer to this one!!!
Split your old chain by grinding down one side of it an use a chain splitter to push out one of the links. Your new chain will come with a master link. You'll attach your new chain to your old one an very carefully rotate the engine feeding the old one out and new one in.
Once your new chain has been fully fedthrough remove your old one and attach the master link to both sides of your new chain. Use some sort or block as a backing and take a small punch an hammer to just slightly Hit the master link so that a corner of the 2 pins flattens out and can't retract back trough the other side of the chain.
Eric J. Geiger
---------------------------------------
PRG Nocturne
XXX-XXX-XXXX phone
XXX-XXX-XXXX fax
XXX-XXX-XXXX mobile
egeiger@...
www.prgnocturne.com

On Jan 14, 2013, at 7:48 PM, "Mark P Hatten" wrote:
Bart,
I've been thinking about this very same topic. My chain is sloppy. The cam gear teeth and tensioned roller look Ok from what I see. I think a new timing chain will make a big performance improvement. I'm not sure how to get a new chain in there ? Does the entire engine have to come apart ? or, could one just link it to the old chain and spin it through. Are new tensioners available ? I'm not sure.
Mark
www.mphspecialties.com
To:
anzhonda600owners@yahoogroups.com
From:
Bartcory@...
Date: Mon, 14 Jan 2013 18:48:15 -0500
Subject: RE: [anzhonda600owners] Power tuning a Honda Z600
You should correct the looseness on the tensioner for the timing chain to kept it within specs. A loose timing chain has different effects on acceleration than at idle where you measure it. As the crank loads one side of the chain, it will effect the timing especially on acceleration. Bart
From:
anzhonda600owners@yahoogroups.com
[
mailto:anzhonda600owners@yahoogroups.com
]
On Behalf Of
Mark P Hatten
Sent:
Monday, January 14, 2013 3:46 PM
To:
Mini-Mircro yahoo group
Subject:
[anzhonda600owners] Power tuning a Honda Z600
Thanks gang for the overwhelming support and tips.
Update. Good News ! The "hot rod" Honda z600 is now running better than ever.
My "go-to " seat of the pants test is 1/4 mile stretch of road nearby from a dead stop, from a stop light to the 40 mph sign. The hot rod Subaru 360's will hit 62 mph in this span. While initial 1/4 mile test tuning this particular Honda Z600 started at barely 42mph, then 43mph, then 47 mph. It painfully struggled to get there. Foot to the floor... speed shifting every gear. I knew there had to be more. Now it does 52 mph in the same span !! A huge improvement. It's now actually fun to drive. I took it on I-5 super highway last night and it easily cruised at 65 mph before I ran out of road for my exit.
Read thru the list of items below that I had addressed. I forgot to mention I had adjusted the valves .005" I and E , and the 13" wheel have the same overall diameter and the 10" wheels and tires.
The one thing I overlooked was re-checking the timing after installing the new points. The timing was not " slightly " advanced, but, 35* way advanced at idle. (Quite Embarrassing !) I'm surprised it ran at all. The old set of points rubbing block was worn down to a nub from rubbing on a rusty eccentric cam. The new points made the timing much different. That's my story.... I also polished the carburetor slide piston and needle. I added a tiny E-clip to space the needle up to richen up the midrange. Runs SUPER now.
I'm ecstatic that it runs so much better
Thanks again!
Mark
Portland Or.
Mark-
First off, you're comparing apples and oranges when it comes to displacement. A 2-stroke is an equivalent of a 4-stroke of 1.75 times the 2-stroke. That makes your 360 the equivalent of a 630cc 4-stroke, or thereabouts.
Next, what's the weight of the two cars? My guess is that the Honda is heavier than your 'Ru.
So, heavier car at a 5% displacement penalty is bound to be slower. And, as you said, that air brake on the hood ain' helpin' in the top speed regime, either.
One thing to be aware of- wind drag increases as the square of the increase in speed. That is, if you're going 50 and goose it up to 55, the increase in speed is 10%, or 1.1 times more. One point one squared is 1.21, or 21% more. And you wonder why you can't get that lovable but ugly little puppy to 70?
wjs
I've been tuning for speed and power on my 1972 600cc 4 stroke Honda Z600 hot rod. I can now go 47 mph. in 1/4 mile, up from 43 mph. last week but, it still seems lethargic.
I got a slight miss to go away, but am disappointed with low top speed power. Here's the back story. Fresh 20-50 wt. oil and filter. New hot NGK #6 plugs, new 7mm wires, new NGK 90* ends, plugs are clean after hard run, swapped, tested, ignition coils, new NOS points gapped correct, new condenser, vac. and mechanical advance checked and cleaned and seem good. Timing is slightly advanced. 147 psi. compression on both cylinders, timing chain is sloppy but timing marks line up. Idles smooth, revs up good. No backfires, no misses. Smooth but low power. Redlines at 6500-6700 rpm's no problem. Tried 2 carburetors, one old style, one new style, both are clean, accelerator pump works in both, float levels correct. Both carbs act the same. 2 psi. fuel pressure, clean fuel. All new exhaust gaskets, no leaks, exhaust is not plugged. Tires are new and inflated to 40 psi., alignment is perfect, brakes do not drag. Can push car with two fingers on level surface.
My Subaru 360 could run rings around this slug with half the displacement. It just don't seem right.
Most 600 owners say their cars will go 70 mph. Maybe,..... with a 5 mile head start!.
What am I missing here?
How does one increase the jet size? Do you file the taper on the carb slide plunger needle?
I know my hood scoop does not aid aerodynamics...but, this much?
Help please.
https://www.youtube.com/watch?v=tyW8KQeYsfg
Mark
Portland Or.
www.mphspecialties.com
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No virus found in this message.
Checked by AVG -
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Eric Geiger · Post by **Eric Geiger** » Mon Jan 14, 2013 5:20 pm

also there is a nice write up here
http://autos.groups.yahoo.com/group/anz ... ers/files/
that explains the whole process. its relatively easy. hardest part i had was hammering the master link in such a manner that it was loose enough to hinge freely but tight enough not to ever back out. make sure u have a chain splitter from a bike shop or such.
Eric J. Geiger
PRG Nocturne
XXX-XXX-XXXX phone
XXX-XXX-XXXX fax
XXX-XXX-XXXX mobile
egeiger@...
www.prgnocturne.com

On Jan 14, 2013, at 7:09 PM, Eric Geiger wrote:
> Oh I know the answer to this one!!!
> Split your old chain by grinding down one side of it an use a chain splitter to push out one of the links. Your new chain will come with a master link. You'll attach your new chain to your old one an very carefully rotate the engine feeding the old one > out and new one in.
> Once your new chain has been fully fedthrough remove your old one and attach the master link to both sides of your new chain. Use some sort or block as a backing and take a small punch an hammer to just slightly Hit the master link so that a corner of > the 2 pins flattens out and can't retract back trough the other side of the chain.
> Eric J. Geiger
> ---------------------------------------
> PRG Nocturne
> XXX-XXX-XXXX phone
> XXX-XXX-XXXX fax
> XXX-XXX-XXXX mobile
> egeiger@...
> www.prgnocturne.com
> On Jan 14, 2013, at 7:48 PM, "Mark P Hatten" mphatten@...
> > wrote:
> > Bart,
> > I've been thinking about this very same topic. My chain is sloppy. The cam gear teeth and tensioned roller look Ok from what I see. I think a new timing chain will make a big performance improvement. I'm not sure how to get a new chain in there ? Does the > > entire engine have to come apart ? or, could one just link it to the old chain and spin it through. Are new tensioners available ? I'm not sure.
> > Mark
> > www.mphspecialties.com
> > To:
> > anzhonda600owners@yahoogroups.com
> > From:
> > Bartcory@...
> > Date: Mon, 14 Jan 2013 18:48:15 -0500
> > Subject: RE: [anzhonda600owners] Power tuning a Honda Z600
> > You should correct the looseness on the tensioner for the timing chain to kept it within specs. A loose timing chain has different > > effects on acceleration than at idle where you measure it. As the crank loads one side of the chain, it will effect the timing especially on acceleration. Bart
> > From:
> > anzhonda600owners@yahoogroups.com
> > [
> > mailto:anzhonda600owners@yahoogroups.com
> > ]
> > On Behalf Of
> > Mark P Hatten
> > Sent:
> > Monday, January 14, 2013 3:46 PM
> > To:
> > Mini-Mircro yahoo group
> > Subject:
> > [anzhonda600owners] Power tuning a Honda Z600
> > Thanks gang for the overwhelming support and tips.
> > Update. Good News ! The "hot rod" Honda z600 is now running better than ever.
> > My "go-to " seat of the pants test is 1/4 mile stretch of road nearby from a dead stop, from a stop light to the 40 mph sign. The hot rod Subaru 360's will hit 62 mph in this span. While initial 1/4 mile test tuning this particular Honda Z600 started at barely > > 42mph, then 43mph, then 47 mph. It painfully struggled to get there. Foot to the floor... speed shifting every gear. I knew there had to be more. Now it does 52 mph in the same span !! A huge improvement. It's now actually fun to drive. I took it on I-5 super > > highway last night and it easily cruised at 65 mph before I ran out of road for my exit.
> > Read thru the list of items below that I had addressed. I forgot to mention I had adjusted the valves .005" I and E , and the 13" wheel have the same overall diameter and the 10" wheels and tires.
> > The one thing I overlooked was re-checking the timing after installing the new points. The timing was not " slightly " advanced, but, 35* way advanced at idle. (Quite Embarrassing !) I'm surprised it ran at all. The old set of points rubbing block was worn > > down to a nub from rubbing on a rusty eccentric cam. The new points made the timing much different. That's my story.... I also polished the carburetor slide piston and needle. I added a tiny E-clip to space the needle up to richen up the midrange. Runs SUPER > > now.
> > I'm ecstatic that it runs so much better
> > Thanks again!
> > Mark
> > Portland Or.
> > Mark-
> > First off, you're comparing apples and oranges when it comes to displacement. A 2-stroke is an equivalent of a 4-stroke of 1.75 times the 2-stroke. That makes your 360 the equivalent of a 630cc 4-stroke, or thereabouts.
> > Next, what's the weight of the two cars? My guess is that the Honda is heavier than your 'Ru.
> > So, heavier car at a 5% displacement penalty is bound to be slower. And, as you said, that air brake on the hood ain' helpin' in the top speed regime, either.
> > One thing to be aware of- wind drag increases as the square of the increase in speed. That is, if you're going 50 and goose it up to 55, the increase in speed is 10%, or 1.1 times more. One point one squared is 1.21, or 21% more. And you wonder why you can't > > get that lovable but ugly little puppy to 70?
> > wjs
> > I've been tuning for speed and power on my 1972 600cc 4 stroke Honda Z600 hot rod. I can now go 47 mph. in 1/4 mile, up from 43 mph. last week but, it still seems lethargic.
> > I got a slight miss to go away, but am disappointed with low top speed power. Here's the back story. Fresh 20-50 wt. oil and filter. New hot NGK #6 plugs, new 7mm wires, new NGK 90* ends, plugs are clean after hard run, swapped, tested, ignition coils, new > > NOS points gapped correct, new condenser, vac. and mechanical advance checked and cleaned and seem good. Timing is slightly advanced. 147 psi. compression on both cylinders, timing chain is sloppy but timing marks line up. Idles smooth, revs up good. No backfires, > > no misses. Smooth but low power. Redlines at 6500-6700 rpm's no problem. Tried 2 carburetors, one old style, one new style, both are clean, accelerator pump works in both, float levels correct. Both carbs act the same. 2 psi. fuel pressure, clean fuel. All > > new exhaust gaskets, no leaks, exhaust is not plugged. Tires are new and inflated to 40 psi., alignment is perfect, brakes do not drag. Can push car with two fingers on level surface.
> > My Subaru 360 could run rings around this slug with half the displacement. It just don't seem right.
> > Most 600 owners say their cars will go 70 mph. Maybe,..... with a 5 mile head start!.
> > What am I missing here?
> > How does one increase the jet size? Do you file the taper on the carb slide plunger needle?
> > I know my hood scoop does not aid aerodynamics...but, this much?
> > Help please.
> > https://www.youtube.com/watch?v=tyW8KQeYsfg
> > Mark
> > Portland Or.
> > www.mphspecialties.com
> > size=1 width="100%" noshade color="#a0a0a0" align=center>
> > No virus found in this message.
> > Checked by AVG -
> > www.avg.com
> > Version: 2013.0.2890 / Virus Database: 2638/6031 - Release Date: 01/13/13

zinc2u · Post by **zinc2u** » Tue Jan 15, 2013 12:45 pm

Hi Mark,
I'm coming into this conversation late and I have seen the other comments. Here is some added info;
1. The Honda Inc spec on a stock 1972 USA coupe indicates it should do the 1/4 mile in 22.3 seconds and have a speed of 57 mph. This measurement is at sea level ..... which is about where you are in Portland.
2. Your compression reading of 147 psi is a bit low. It should be in the 160 to 165 psi range for a new (or rebuilt) engine.
3. The registration of the cam to the crank is important. I used to align the "witness" mark on the cam sprocket and register it to the notch on the pulley when it was at "T" on the casing. And then one day I was noticing my 1/4 mile time wasn't correct on a engine I had rebuilt (when I drove to work, I used to time myself on a road I would enter which had the 55 mph speed marker at a 1/4 mile distance from where I entered). I found that I had to move the chain on the sprocket 1 or 2 teeth.
Since then, I now use an indicator to register the cam to the crank.
Moving the chain 1 or 2 teeth in each direction made a noticeable difference in the performance of the engine.
good luck,
Dale

> I've been tuning for speed and power on my 1972 600cc 4 stroke > Honda Z600 hot rod. I can now go 47 mph. in 1/4 mile, up from 43 mph. last > week but, it still seems lethargic. I got a slight miss to go away, but am > disappointed with low top speed power. Here's the back story. Fresh 20-50 wt.
> oil and filter. New hot NGK #6 plugs, new 7mm wires, new NGK 90* ends, plugs > are clean after hard run, swapped, tested, ignition coils, new NOS points > gapped correct, new condenser, vac. and mechanical advance checked and cleaned > and seem good. Timing is slightly advanced. 147 psi. compression on both > cylinders, timing chain is sloppy but timing marks line up. Idles smooth, revs > up good. No backfires, no misses. Smooth but low power. Redlines at 6500-6700 > rpm's no problem. Tried 2 carburetors, one old style, one new style, both are > clean, accelerator pump works in both, float levels correct. Both carbs act > the same. 2 psi. fuel pressure, clean fuel. All new exhaust gaskets, no leaks, > exhau st is not plugged. Tires are new and inflated to 40 psi., alignment is > perfect, brakes do not drag. Can push car with two fingers on level surface.
> My Subaru 360 could run rings around this slug with half the > displacement. It just don't seem right.
> Most 600 owners say their cars
> will go 70 mph. Maybe,..... with a 5 mile head start!.
> What am I
> missing here?
> How does one increase the jet size? Do you file the
> taper on the carb slide plunger needle?
> I know my hood scoop does
> not aid aerodynamics...but, this much?
> Help
> please.
> https://www.youtube.com/watch?v=tyW8KQeYsfg
> Mark
> Portland
> Or.
> www.mphspecialties.com

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Power tuning a Honda Z600