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
Power tuning a Honda Z600
-
Mark P Hatten
- Posts: 263
- Joined: Fri Sep 17, 2010 12:55 am
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
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
-
Mark P Hatten
- Posts: 263
- Joined: Fri Sep 17, 2010 12:55 am
Power tuning a Honda Z600
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
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