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Old May 21, 2010, 08:20 AM
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Gary Cee's Avatar
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I believe both of the Enya 120s outperformed the Saito 120 according to Mr Lee's tests.

I am still interested aquiring an Enya 155 .

As far as the stand off issues ,What to do ? Perhaps the thread starter already checked the valve adjustment as suggested ? Get some RPM measurements ? What fuel ? What glow plug ?
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Old May 21, 2010, 11:42 AM
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According to what I've been able to dig up the Saito 1.20 turns an APC 16x6 at 9,000.
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Old May 21, 2010, 11:45 AM
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Quote:
Originally Posted by Gary Cee View Post
I believe both of the Enya 120s outperformed the Saito 120 according to Mr Lee's tests.

I am still interested aquiring an Enya 155 .

As far as the stand off issues ,What to do ? Perhaps the thread starter already checked the valve adjustment as suggested ? Get some RPM measurements ? What fuel ? What glow plug ?
Can you post Mr. Lee's tests for the big head 1.20 Saito and/or the Saito 1.20S.

I've used all three engine The big head1.20 the 1.20S and Enya R1.20. At 6K feet of altitude the big head Saito with the carb insert would turn the heavy MAS props (like18x6) faster than the Enya and it had better tractability with one exception.

The Saito 1.20S was a little weaker than the Enya at higher rpm up to 12K rpm. Reworking the big head Saito 1.20 (milling 1 mm off the case deck, some mild porting and adding the "S" cam) she would run with the Enya R1.20 (some props faster some props slower).

To the OP,
The failure mode I saw with the Enya was worn valve guides. If the engine was fitted with a muffler (back pressure) oil would tend to back flow, up the worn guide and "flood" the rocker box. This might be what you are seeing. With the valve half open you should not feel (see) any side to side movement in the stem as you put some side loading on the valve stem.

Cam timing marks should look like this.
http://www.modelrectifier.com/resour...EnyaRevRot.pdf

P.S.
The tractability issue I had with the big head Saito on heavy props was that if I pulled back on the throttle suddenly you could hear the flame go out . As the prop windmilled down to the speed that throttle was set to (low power or idle) she might relight. Even with on board glow I never got 100% reliability.
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Old May 21, 2010, 06:18 PM
Whatever works well .
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K'rad, check out page 4 on the review of the Enya 120-4C
The same review is in the RCM 4 Stroke Anthology book from many years ago. Mr Lee reports the Enya running about 300 RPM stronger on larger props . This was the Saito 120 of that time against the small valve Enya 120. You may also see the power gains at higher revs with the R120-4C.

From page 1 ,this thread:

Quote:
Originally Posted by gkamysz View Post

Valve guide wear as well as general valve related wear are suspect. This is why I referred to starting out by checking lash. Hopefully he did not get himself a clapped-out used and abused engine !
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Old May 21, 2010, 07:01 PM
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Thanks,
As I don't see a date on the review and that he mentions the OS I'm confident that Mr. Lee was comparing the Enya 1.204C to the old pre "S" Saito 1.20 and the pre Surpass OS 1.20. The Enya was why OS finally conceded that the market wanted powerful four cycle engines, not just quiet engines for "Sport/ Sunday fliers".
As I recall the OS surpass was the stronger engine until the YS came on the scene

I'm sorry to say I no longer have the notes from my four cycle experiments. Thinking back I think the Saito S1.20 was on par and my reworked big head actually stronger than the R1.20 Not that this is a fair comparison as I had tuned the Saito for my flying conditions, 6K feet altitude. As I recall the stock OS Surpass 1.20 out ran all these stock engines when it came out.
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Old May 21, 2010, 07:39 PM
Whatever works well .
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The OS Surpass lived up to it's name and was pretty much top of the heap for a time. The Enya R120 and Saito were pretty well matched as I recall. The Enya 120 geared pump with it's huge carb was quite a contender but a bit troublesome. I never owned a GP Enya but a very capable friend did...not for very long. Could have been a fun one to play with.

The Enya 120 review is also in my RCM book dated 1985. Pre OS 120 Surpass as well as being Saito FA-120, Pre 120-S era.
I for one would like to have one of the smooth running pre "S" 120 Saitos. Some of the old ,soft tuned 4 strokes have a real charm .
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Old May 21, 2010, 07:41 PM
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I am hesitent to say much in this part of the discussion since I've never owned a Saito 1.20 but i I did have an Enya 1.20GP which I sold to a guy in Turky. It and the 1.55 I had had a really irritating exhaust note. It had a sharp bark to it compared to the Saitos deep throb. I may try to put a Saito muffler on my Enya .90 and see if that improves the exhaust note.
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Old May 21, 2010, 07:59 PM
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Originally Posted by I TOBOR View Post
I am hesitent to say much in this part of the discussion since I've never owned a Saito 1.20 but i I did have an Enya 1.20GP which I sold to a guy in Turky. It and the 1.55 I had had a really irritating exhaust note. It had a sharp bark to it compared to the Saitos deep throb. I may try to put a Saito muffler on my Enya .90 and see if that improves the exhaust note.
Talking about four cycle exhaust systems, we often added a 2 cycle "tuned pipe" I think it was the MACs pipe sized for the 2.5 cc engine. We would tune the length to allow for the negative pressure from the diverging cone to be present at the time of valve over lap. One can't use the pressure pulse to super charge the engine as the four cycles timing does not allow for this. The rest of the pipe was then used just as a standard expansion chamber. Later one could find purpose built tuned 4 cycle exhaust systems. These systems did lower the exhaust noise and added noticeable power (nothing like a 2 cycle on a tuned pipe). The only down side was that the "sport" fliers didn't like the long exhaust system. But if you hid it in the tuned pipe tunnel that most pattern ships had it look fine.
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Old May 21, 2010, 08:11 PM
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Generally speaking there is not a whole lot of power to be found tuning 4 stroke exhausts.
On the other hand, there are many different sounds.
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Old May 21, 2010, 08:33 PM
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I am partial to these TurboHeaders, on most Saitos they are good for an average of about 220 rpm. On a Saito .50 the TH gave a 210 rpm increase but on the 1.00 twin a pair of them provided a 270 rpm boost. Not double the increase on the .50 like you'd think. Interestingly on the Saito 1.25 the TH provided no increase in rpm. It would be interesting to try a TH on the new Saito 125 engine as it has the valves angled out more and larger cooling fins.
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Old May 21, 2010, 09:19 PM
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Everett Wa.
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Originally Posted by I TOBOR View Post
I am partial to these TurboHeaders, on most Saitos they are good for an average of about 220 rpm. On a Saito .50 the TH gave a 210 rpm increase but on the 1.00 twin a pair of them provided a 270 rpm boost. Not double the increase on the .50 like you'd think. Interestingly on the Saito 1.25 the TH provided no increase in rpm. It would be interesting to try a TH on the new Saito 125 engine as it has the valves angled out more and larger cooling fins.
On what principles do those THs work on?
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Last edited by Konrad; May 21, 2010 at 09:45 PM.
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Old May 22, 2010, 07:53 AM
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K-man, they are a tuned chamber with a beveled end in the chamber. If you buy a 12mm one for a Saito 1.00 it is an open chamber but if you specify it for an .80 or .82 than it comes with a reversion cone in the end. The reversion cone has four holes in it to let the exhaust out. Here ya go. I'm headed for the flyin field.


http://www.rcspecialties.net
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Old May 22, 2010, 10:14 AM
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Dave,
I have been doing pretty much the same thing with an open ended, plain tube outer and the anti reversion inner. It is a practice I picked up from racing 4 stroke karts with my son 25 years ago. The peak gains have been minimal but tractability improves . Lots of room for tinkering. I have one on a 7 year old Saito .56 at present.Sounds great.

I will post a photo in the next few days. I am going off to help my late friend's widow today. Flying tomorrow
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Old May 22, 2010, 10:23 AM
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Everett Wa.
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Thanks IT,
I was not aware of these. Reading your description it sounds like they are trying to control the reversionary pulse (positive pressure wave) from reintroducing contaminating exhaust into the combustion chamber during valve overlap.

Reading the TH site it looks like they are touting the looks and sound of the header more than the performance. I did not see and data showing sound level comparison with the original engine's OEM muffler nor did I see any comparison data for performance such as open stack, OEM muffler and the TH.

Do you know if they (TH) have a white paper on this device?

Again thanks for the link,
Konrad
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Old May 22, 2010, 10:48 AM
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K'rad
That is the basic principle. It was quite the vogue with racing four stroke karts from long ago.(Around here anyhow) A web search should bring up some info on the anti reversion kart exhausts.
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