2stroke vs 4stroke?

[glw165]

i have a 99 johnson 9.9 2stroke and my understanding it puts out 6 amps @ wot?, was thinking going to a 4 stroke 9.9, any advantages? maybe charge battery better? i know its straight gas 1 adv and quieter ???

 

[Silvertip]

Re: 2stroke vs 4stroke?

Well sir -- here are some things to chew on:

1) straight gas as an advantage: Yes - but! You now have oil and filter changes to contend with.
2) Quieter? Yes-but! At wide open throttle the 4-stroke may be a tick quieter but the difference is not as great as one might think. The sound is "different" but not necessarily a great deal quieter.
3) Maintenance? No valves, timing belts, and related adjustments on a two stroke.
4) More economical? That depends. A two stroke almost always pushs a boat faster at any given rpm. Therefore if you look at economy charts based on rpm the 4-stroke will show less fuel consumption. However, if you look at fuel economy at boat speeds, those numbers come closer together because of the RPM difference.
5) Weight? 4-strokes are heavier.
6) Nice motors? Yes.
7) Will a 4-stroke charge the battery better? Don't know that unless you know if: a) it has an alternator and b) what the output rating is.
8) 4-stroke last longer? Won't know that for another 40 - 60 years as there are a ton of two strokes still working that are that age.

 

[Home Cookin']

Re: 2stroke vs 4stroke?

they make electric start 9.9? seems like a waste of tech and weight (battery). get a 1970's vintage pull start 9.9 and run forever.

 

[Texasmark]

Re: 2stroke vs 4stroke?

Well sir -- here are some things to chew on:

1) straight gas as an advantage: Yes - but! You now have oil and filter changes to contend with.
2) Quieter? Yes-but! At wide open throttle the 4-stroke may be a tick quieter but the difference is not as great as one might think. The sound is "different" but not necessarily a great deal quieter.
3) Maintenance? No valves, timing belts, and related adjustments on a two stroke.
4) More economical? That depends. A two stroke almost always pushs a boat faster at any given rpm. Therefore if you look at economy charts based on rpm the 4-stroke will show less fuel consumption. However, if you look at fuel economy at boat speeds, those numbers come closer together because of the RPM difference.
5) Weight? 4-strokes are heavier.
6) Nice motors? Yes.
7) Will a 4-stroke charge the battery better? Don't know that unless you know if: a) it has an alternator and b) what the output rating is.
8) 4-stroke last longer? Won't know that for another 40 - 60 years as there are a ton of two strokes still working that are that age.

Just a comment about answer #4: Just yesterday or so a question was asked by a guy with a 115 hp 4 stroke and he said that he had a 2.58 or 2.59:1 gearbox. A 2 stroke, at least the Mercs I have had and read sales brochures on, runs 2:1. So, if the engine is turning 5000 rpm, which both are clearly capable of doing, the prop shaft on the 4 stroke is only turning 5000/2.58 = 1938 RPM while the shaft of the 2 stroke is turning 5000/2 = 2500.

So that right there says to me that the 4 stroke needs a higher reduction gear to produce equal work (thrust under a given load), and with the same pitch prop produces less forward motion, i.e. mph, confirming what Silvertip said in his comment.

HTH,
Mark

 

[Philster]

Re: 2stroke vs 4stroke?

Two-strokes whenever possible.

 

[Sea Rider]

Re: 2stroke vs 4stroke?

Two-strokes whenever possible.

I'll second that, what find annoying about 4 strokes is you have to adjust valves from time to time with a gauge, why hasn't any manufacturer placed hidraulic valves which does not require physical adjustment on these motors, Just speaking for portable motors as not know anything about big motores valves.

Happy Boating

 

[glw165]

Re: 2stroke vs 4stroke?

was just debating on getting 1, my cousin got 1 for his toon, he is pleased says its faster as well, we have a 9.9 limit on this lake and marina only sells gas, so if 2 stroke u have mix ur own, also they said in near future wont b allowed to have 2 stroke on lake, was out crappie fishin today and i noticed when trolling it kept setting off an alarm on control box? hit wot and it stops

 

[Silvertip]

Re: 2stroke vs 4stroke?

Just a comment about answer #4: Just yesterday or so a question was asked by a guy with a 115 hp 4 stroke and he said that he had a 2.58 or 2.59:1 gearbox. A 2 stroke, at least the Mercs I have had and read sales brochures on, runs 2:1. So, if the engine is turning 5000 rpm, which both are clearly capable of doing, the prop shaft on the 4 stroke is only turning 5000/2.58 = 1938 RPM while the shaft of the 2 stroke is turning 5000/2 = 2500.

So that right there says to me that the 4 stroke needs a higher reduction gear to produce equal work (thrust under a given load), and with the same pitch prop produces less forward motion, i.e. mph, confirming what Silvertip said in his comment.

HTH,
Mark

That is indeed why fuel economy charts must be read with a complete understanding of what you are looking at. As I said, a two stroke almost always pushes a boat faster at any given rpm than a four stroke. To make this even more obvious, you can tell from the charts how four strokes struggle to get on plane.

 

[pecheux]

Re: 2stroke vs 4stroke?

2 strokes are simply ... more fun ... less maintenance ... less weight .... less internal parts .... Yes you all figured it out, I love 2 strokes motors.. LOL

 

[roscoe]

Re: 2stroke vs 4stroke?

was just debating on getting 1, my cousin got 1 for his toon, he is pleased says its faster as well, we have a 9.9 limit on this lake and marina only sells gas, so if 2 stroke u have mix ur own, also they said in near future wont b allowed to have 2 stroke on lake, was out crappie fishin today and i noticed when trolling it kept setting off an alarm on control box? hit wot and it stops

Thats pretty good indication that the motor is starting to overheat. The water pump impeller needs to be changed out. $10 part.

 

[Silvertip]

Re: 2stroke vs 4stroke?

was just debating on getting 1, my cousin got 1 for his toon, he is pleased says its faster as well, we have a 9.9 limit on this lake and marina only sells gas, so if 2 stroke u have mix ur own, also they said in near future wont b allowed to have 2 stroke on lake, was out crappie fishin today and i noticed when trolling it kept setting off an alarm on control box? hit wot and it stops

Another very wrong statement. The lake association my outlaw CARBURETED two strokes but the current crop of DFI two strokes are every bit as clean and in many cases cleaner than a four stroke. What is the big deal about having to add two stroke oil to a resevoir or a gas tank. If you can pour a glass of milk you can add oil to an engine.

 

[Texasmark]

Re: 2stroke vs 4stroke?

Another very wrong statement. The lake association my outlaw CARBURETED two strokes but the current crop of DFI two strokes are every bit as clean and in many cases cleaner than a four stroke. What is the big deal about having to add two stroke oil to a resevoir or a gas tank. If you can pour a glass of milk you can add oil to an engine.

Down boy, down boy........nice puppy, Grin Maybe if it's a later model it's oil injected and has a built in oil tank; but maybe not on an engine of that size.
Mark