4 cycle or 2 cycle  
View related threads: (in this forum | in all forums)

Tower Hobbies
Enter up to 4 keywords or Tower stock numbers
Logged in as Guest



Users viewing this topic: none
  Printable Version
       

All Forums >> Glow Engines, Gas Engines, Fuel & Mfg Support Forums >> Glow Engines >> 4 cycle or 2 cycle
Page: [1] 2   next >   >>  

Login
Message << Older Topic   Newer Topic >>
4 cycle or 2 cycle - 8/20/2007 12:21:25 AM   
rheauljj



Posts: 64
Joined: 6/15/2007
From: Bridgewater, VA, USA
Status: offline 		I am considering purchasing a Saito .82 (same physical size of the .72) for a BTE Venture 60 I'm currently building. I've never owned a 4C engine, but they intrigue me. Should I make the purchase or should I consider another more appropriate engine?





Why buy a 4C versus a 2C?




_____________________________

John Rheault
email: rheauljj@jmu.edu
       Post #: 1

RE: 4 cycle or 2 cycle - 8/20/2007 12:58:47 AM   
khodges


 

Posts: 5143
Joined: 7/3/2003
From: newton, NC, USA
Status: offline
quote:

ORIGINAL: rheauljj

Should I make the purchase or should I consider another more appropriate engine?

Why buy a 4C versus a 2C?



What's appropriate? Depends on your preferences. If you want all out speed, go two stroke, but that's the only time I'd pick one.

Reasons to buy a 4-stroke:

1-Cooler looking

2- Cooler sounding

3-use less fuel

4-turn a bigger prop per displacement size (more torque)

The .82 is a good engine. It actually lighter and has a shorter stroke than the .72, should rev well. I've got a .72 and a .91, both great engines. Can't go wrong with a Saito.

Reasons to buy a 2-stroke:............................................................................ I'm thinkin', I'm thinkin'

_____________________________

Club Saito #2, WACO Brotherhood #20. What other trouble can I get into?

(in reply to rheauljj)
       Post #: 2

RE: 4 cycle or 2 cycle - 8/20/2007 1:06:33 AM   
Don41



Posts: 420
Joined: 9/4/2006
From: El Dorado, CA, USA
Status: online 		I'm presently breaking in my Saito 82. Be prepared for a lot of vibration on the first two or three tanks. She'll smooth out a lot more once you start running leaner.

Even with leaner settings I still get a fair amount of vibration in the 5 to 6000 rpm range but nothing too serious. With all of that vibration though I'd definitely use a bench mount for the breakin period.

I now have about 1.5 hours on mine and plan to go at least another half hour before mounting in my plane.

(in reply to rheauljj)
       Post #: 3

RE: 4 cycle or 2 cycle - 8/20/2007 1:08:10 AM   
Don41



Posts: 420
Joined: 9/4/2006
From: El Dorado, CA, USA
Status: online 		BTW: Check out Donald's Hobbies in Texas before you buy. I got a heck of a deal compared to most sites.

(in reply to rheauljj)
       Post #: 4

RE: 4 cycle or 2 cycle - 8/20/2007 1:27:41 AM   
onewasp


 

Posts: 1369
Joined: 12/11/2002
From: USA, USA
Status: offline
quote:

ORIGINAL: Don41

I'm presently breaking in my Saito 82. Be prepared for a lot of vibration on the first two or three tanks. She'll smooth out a lot more once you start running leaner.

Even with leaner settings I still get a fair amount of vibration in the 5 to 6000 rpm range but nothing too serious. With all of that vibration though I'd definitely use a bench mount for the breakin period.

I now have about 1.5 hours on mine and plan to go at least another half hour before mounting in my plane.



I have run Saitos for some time ----- if the engine vibrates then you've got it too rich -probably the low end especially. I have 82a through 180.
Every single one has been run from start number one in the appropriate airframe. Every one flew before one tank had been completed on the ground.
If you like to fuss with engines on a stand that is your choice, go for it.

This is the second time in a week I've read about vibrating Saitos.
See post #16 here-----same response -- http://www.rcuniverse.com/forum/m_6236784/mpage_1/key_/tm.htm

If it is vibrating then the chances are that it is your set up that is off.
Properly set up they are as smooth as four stroke singles get.

Just think it through, ----- vibration is not a break in expectation/phenomenon.
It is the set up!



_____________________________

The ground reached up and smote my airplane

(in reply to Don41)
       Post #: 5

RE: 4 cycle or 2 cycle - 8/20/2007 1:30:00 AM   
rheauljj



Posts: 64
Joined: 6/15/2007
From: Bridgewater, VA, USA
Status: offline 		Will use engine test stand... I have access to a PSP mfg engine test stand...seems solidly built. Will bolt to my kid's swing set...they've out grown it.




_____________________________

John Rheault
email: rheauljj@jmu.edu

(in reply to Don41)
       Post #: 6

RE: 4 cycle or 2 cycle - 8/20/2007 2:07:05 AM   
blw



Posts: 4619
Joined: 3/15/2004
From: Auburn, AL, USA
Status: offline 		Don41,

If you set your needle valves as directed by the Saito manual, the vibrations you mentioned are normal. As you said, they will smooth out before the 4th tank of fuel as recommended by Saito. There are many references to this on RCU.

_____________________________

The ultimate responsibility of pilots is to fulfill the dreams of the countless millions who can only stare skyward...and wish.

(in reply to rheauljj)
       Post #: 7

RE: 4 cycle or 2 cycle - 8/20/2007 2:37:02 AM   
rlmcnii


 

Posts: 443
Joined: 7/3/2005
From: Pocomoke City, MD, USA
Status: offline 		rheauljj,
I have built and flown two Bruce Tharpe Ventures, both powered by Saito.82s. It is a very nice match for the airframe and is actually several ounces (6, I think) lighter than the OS two-stroke around which the airplane was apparently designed. In mine the batteries had to be mounted in front of the servos for proper balance.
The Saito .82 will not give the Venture unlimited vertical, but is more than sufficiently powerful for sport flying. So far, my flying of the Venture is limited by me and not the engine.
There seem to be many reports of how badly the .82 vibrates. I have not found that to be true with either of the two I have operated. As BLW states in a previous post, Saitos will shake when improperly tuned. The solution is to tune them properly. It is not difficult to do, but it needs to be done.
One very nice property of the Saitos is their fuel efficiency. With the 16 ounce tank in the Venture and a well tuned .82 you will easily get two 12 or 14 minute flights out of the tank and land with a nice reserve. Fuel burn is just not an issue with that engine.
Mine are run on 15% Omega (the consensus seems to favor a bit of castor in the fuel) and fly with a 13x6 Pro Zinger. Plastic props may work better, but I just like wood. A 14 inch prop is a little too large for a Venture...not enough ground clearance. A lot of people fly with fuel of a higher nitro content. That may give you some more power. Might try that someday!
Saitos sound a lot different than 2-strokes. Your preference is your preference.
Many people at the field where I fly have commented on what a pretty plane the Venture is and nobody could believe it was not an ARF. There is another guy at our field building one now and at least one fellow has offered to buy mine.
If you are neither a 3-D disciple, nor a contest-winning-level pattern flyer, you will probably be very pleased with your Venture. If you are either of these and just want a nice sport plane, you will also probably be pleased.
Hope yours goes well, regardless of your choice of engine. But, it needs a Saito!

(in reply to rheauljj)
       Post #: 8

RE: 4 cycle or 2 cycle - 8/20/2007 3:14:26 AM   
onewasp


 

Posts: 1369
Joined: 12/11/2002
From: USA, USA
Status: offline
quote:

ORIGINAL: blw

Don41,

If you set your needle valves as directed by the Saito manual, the vibrations you mentioned are normal. As you said, they will smooth out before the 4th tank of fuel as recommended by Saito. There are many references to this on RCU.


blw
---and just what did the (unnecessary) vibrations accomplish??
Just what occurred during break in that made the vibrations disappear?
If you've a lucid answer I would love to hear it.

YOU are an engine engineer as I remember it----LARGE stationary engine types right?
Did you ever hear excessive vibration that was forceful AND desired?

Had one of my race engines done that I would have "died a thousand deaths" in outright embarrassment.
Why?
Ain't supposed to happen-----we tuned into the teens and it didn't happen-----anywhere along the line.

I'd love to see the engineering evaluation on how vibrating and pounding helped an engine.

I've talked to a current engine builder-----I'm now out of date on that front----- and told him of this ----shall we politely call it a "phenomenon" of vibration you seem to experience and accept as "normal" (which it isn't).

He was as horrified as I and he is still building race engines as well as IMAC twins on a custom order basis.
He has never seen it happen either -----except a) with a horrible imbalance/design or b) with a fouled up set up on the induction system.

Just what do you feel it could possibly help??

I simply do not understand the acceptance of an obvious anomaly which I can make disappear with set up i.e. proper tune.

I much prefer "stirred and not shaken" if 007 will allow me.

_____________________________

The ground reached up and smote my airplane

(in reply to blw)
       Post #: 9

RE: 4 cycle or 2 cycle - 8/20/2007 4:24:54 AM   
Don41



Posts: 420
Joined: 9/4/2006
From: El Dorado, CA, USA
Status: online 		onewasp: I'm not complaining about the Saito (I also have a 125).

I presume the factory knows a little about the subject and their manual leans towards using a stand for break in and they call for a VERY rich setting for the first ten or so minutes. That richness seems to translate into a vibrating Saito. I personally wouldn't care to have it mounted during this shaking period.

The more time I get on the engine the leaner I'm willing to run it and the smoother it gets. In my case though I'm still getting a little more vibrating in the 5 to 6000 rpm range than I'd like to see. Based on all that I see on the forums I assume that the 82 will eventually start to purr,,, at least I hope it does.

I'll know for sure once I'm confident it has enough run time to live with leaner settings for extended periods. I realize I'm more cautious than a lot of people but since I'm in no hurry I see no reason to rush the process.




(in reply to onewasp)
       Post #: 10

RE: 4 cycle or 2 cycle - 8/20/2007 10:55:50 AM   
NikolayTT


 

Posts: 575
Joined: 9/29/2002
From: Tampere, FINLAND
Status: offline 		If are looking for Scale model building, and have the cash, might be better to look at Laser. Most of their models have
the Valve-controls at back of the engine head and thus permits you to make what ever you want at the front. Also they
are known to be very reliable. Check on RC Scale Competitions who is flying what and you might change from YS.

Anyway, to my honest opinion, 4S is a kind of self-cheating or torture; I am staying steadily with 2S until some
puts on the market 4S with fuel injection which is in the price range of good 26cc 2S. Surely, that won't happen
soon.

(in reply to Don41)
       Post #: 11

RE: 4 cycle or 2 cycle - 8/20/2007 11:20:00 AM   
j.duncker



Posts: 1228
Joined: 6/22/2004
From: Where I park the RV, AK, USA
Status: offline 		One other factor to consider is maintenance/repair costs. There is more to go wrong on a 4st.

[ You can tell I am Scottish somehow. ]

_____________________________

The dreamers of the day are dangerous men, for they may act their dreams with open eyes, to make it possible.

(in reply to NikolayTT)
       Post #: 12

RE: 4 cycle or 2 cycle - 8/20/2007 12:13:57 PM   
NikolayTT


 

Posts: 575
Joined: 9/29/2002
From: Tampere, FINLAND
Status: offline 		Well, I am not Scottish still anyway I would bet that 4S were introduced in RC as one of the best ways
for bigger money "leakage" from User's pocket to the Manufacturer and Marketing Pockets.

(in reply to j.duncker)
       Post #: 13

RE: 4 cycle or 2 cycle - 8/20/2007 1:08:13 PM   
Gringo Flyer



Posts: 2249
Joined: 1/16/2004
From: Formosa, ARGENTINA
Status: offline 		Yes they are more expensive but really when you compare the useful life of a 4 or 2 stroke engine the price of the engine is almost negligible. You can easily expect several hundred hours out of any engine. Your fuel costs will add up to way more than the engine.

Personally, I really like 4 stroke engines. I am in the process of selling most of my 2 strokes to replace them with 4 bangers. 2 strokes are great and have their applications but for me and the kind of models and flying I do the 4 stroke generally fits the bill. I will always keep a couple of 2 strokes around (I love my TTpro 46 and ST 90) but after that its going to be 4 strokes from here on out.


_____________________________

"Courage is being scared to death...and saddling up anyway."---John Wayne

(in reply to NikolayTT)
       Post #: 14

RE: 4 cycle or 2 cycle - 8/20/2007 1:28:26 PM   
Hobbsy
<