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Old 04-06-2019, 12:43 PM
  #39951  
the Wasp
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Originally Posted by Glowgeek
That's what .0001" dial indicators are for. . For a mounting jig I used a 3-1/2" x 3-1/2" x 6" chunk of hard maple, dado a slot for case clearance, drilled and tapped engine mounting holes, clamped it on the mill, milled the top off, mounted the engine, mic'd it and milled it. In my case it measured on perfect plane with the engine mounting ears and dead flat except at one of the cylinder mounting holes, probably from an over tightened cylinder mounting screw.

Edited: There are better ways to ensure parallelism between the deck and crank centerline but so far the way I did it seems fine.
I have a very nice Peacock Indicator that goes down to 1/2 a thousand, and the graduates on the dial are far enough apart that will allow me to get down even more

Jim
Old 04-06-2019, 12:47 PM
  #39952  
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Originally Posted by the Wasp
I have a very nice Peacock Indicator that goes down to 1/2 a thousand, and the graduates on the dial are far enough apart that will allow me to get down even more

Jim
Probably close enough, you're really just looking to jig the case in the mill where an indicator doesn't move when swept over the deck surface.

Read the edit to my edit for a better way to ensure perfect alignment regardless of Saito's deck machining tolerances.
Old 04-06-2019, 12:59 PM
  #39953  
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Originally Posted by Glowgeek
Thanks Jim, good info

no problem, I love mod'ing things, every thing LOL.. when I was a kid of 6 or 7 I wanted to take every thing apart just to see how it was made and worked, every thing. my mother had a gold colored clock that had a diameter of 5 or 6 inches, it had a gold colored horse standing on the side of the clock, well one day my mother said that the clock didn't work. boy I jumped on that, I asked her if I could take it apart,,,, no,,,, for about a week I was on her about it, I told her if it didn't work then it was no good and worth less, she agreed but still would not let me take it apart, well mom you are not going to have it fixed,,, no.. cut to when I was 33 and my mom cleaned out the basement and there was the clock, she sold it in a lawn sale for $5,,,, $5??? boy was she mean to me, I told her she should have let me take it apart. $5 ??? LOL

Jim
Saito Engines, they got it, all over.

Last edited by the Wasp; 04-06-2019 at 01:05 PM.
Old 04-06-2019, 01:11 PM
  #39954  
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Pizza time, I got to go get it, every Saturday the wife HAS to have it, like a ritual for her !!!

Jim
Old 04-06-2019, 01:23 PM
  #39955  
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Originally Posted by Glowgeek
Now now Gary, some of your type A is leaking out, not as bad as the oil leaks on older Hogs but still leaking out some.
Naw, a type A would ride a Harley and say they are the only "real motorcycles"

Great paint job though...

Your burette tube and 12mm muffler are on the way.
The muffler is plain vanilla 6061 Aluminum.
Old 04-06-2019, 01:24 PM
  #39956  
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Lol, Pizza! Sunday is pizza day here.
Old 04-06-2019, 01:30 PM
  #39957  
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Originally Posted by Jesse Open


Naw, a type A would ride a Harley and say they are the only "real motorcycles"

Great paint job though...

Your burette tube and 12mm muffler are on the way.
The muffler is plain vanilla 6061 Aluminum.
You're the best Gary! Thanks.
I ordered a stopcock for the burette, should be here Tuesday.

Now all I need to find is an fa100 carb and intake tube. Might as well open up both ends of the pig! Lol
Old 04-06-2019, 02:37 PM
  #39958  
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Originally Posted by Glowgeek
Now now Gary, some of your type A is leaking out, not as bad as the oil leaks on older Hogs but still leaking out some.
Harley guys just keep ridin and smilin with pride.

I looked over my Saito 182-T, it needs to be run. I have an 18 x 6 for it.

Last edited by Hobbsy; 04-07-2019 at 03:46 AM.
Old 04-06-2019, 03:42 PM
  #39959  
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Originally Posted by Hobbsy
He just gets careless with his low ball cheap shots, Harley guys just keep ridin and smilin with pride.

I looked over my Saito 182-T, it needs to be run. I have an 18 x 6 for it.
Familiar pattern
Dave outnumbers me on low ball cheap shots by quite a margin.
I make a comment, Dave doesn't like,he goes personal.


Good on the stop cock, the burrete is graduated in .1 mm.

Last edited by Jesse Open; 04-06-2019 at 03:51 PM.
Old 04-06-2019, 04:51 PM
  #39960  
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Regarding the 100 carb; I think that the last of the 100 parts went out a while back . Will double check.
The 100,115 and 125 are not plentiful in the parts loop!

I may have a 91 carb under foot ...

And that paint job is outstanding.

Last edited by Jesse Open; 04-06-2019 at 04:58 PM.
Old 04-06-2019, 05:09 PM
  #39961  
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LOL OK-OK guys LOL, give me a few, I will pull off the 115's carb, I had it off the other day, I think it's the same carb as the 100, but can;t remember the numbers

Jim
Old 04-06-2019, 05:40 PM
  #39962  
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OK guys, I just measured the 115's and 125 Carb Barrels

FA115,,,,,,,,,, .332
FA125,,,,,,,,, .344

so with my numbers above in my first post I have to believe that my 100 and my 115 has the same size Barrels.

NOTE that all the venturi's I measured were a bit oval, by .002" to .004"

I was surprised the 115 Barrel was not larger than the 100's

I will edit my post above, and to add I have these numbers written down, you can ask for them again if needed

Jim
Old 04-06-2019, 05:45 PM
  #39963  
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Originally Posted by the Wasp
OK guys, I just measured the 115's and 125 Carb Barrels

FA115,,,,,,,,,, .332
FA125,,,,,,,,, .344

so with my numbers above in my first post I have to believe that my 100 and my 115 has the same size Barrels.

NOTE that all the venturi's I measured were a bit oval, by .002" to .004"

I was surprised the 115 Barrel was not larger than the 100's

I will edit my post above, and to add I have these numbers written down, you can ask for them again if needed

Jim
The 100 and 115 share the same carb part# , just as the 82 and 91 do. All 4 intake manifolds are different part #'s.

Last edited by Glowgeek; 04-06-2019 at 06:19 PM.
Old 04-06-2019, 06:19 PM
  #39964  
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Originally Posted by Glowgeek
The 100 and 115 share the same carb part# , just as the 82 and 91 do.
thanks!

I have to say that it look's like the 125 Carb is not going to be too big for the 100, just big enough. and for that mater it wont be too big for the 115 too, but it's going on my 100, I can't wait to get the 100 broken in on the stand, I need to order that fresh fuel this coming week.. in the air I am hoping to spin the APC 13X10 or something else in that range. it's the Midget Mustang and I am no real acrobatic pilot, I'm just a guy that gets a real kick out of these things and I like the basic maneuvers because they are smooth, and of course I love fly-bys at all speeds

Jim
Saito Engines, I said I had enough, but I would like 4 more
Old 04-07-2019, 02:57 AM
  #39965  
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Originally Posted by the Wasp
OK guys, I just measured the 115's and 125 Carb Barrels

FA115,,,,,,,,,, .332
FA125,,,,,,,,, .344

so with my numbers above in my first post I have to believe that my 100 and my 115 has the same size Barrels.

NOTE that all the venturi's I measured were a bit oval, by .002" to .004"

I was surprised the 115 Barrel was not larger than the 100's

I will edit my post above, and to add I have these numbers written down, you can ask for them again if needed

Jim
Carburetor size is supposed to be a ratio of the cylinder bore size.

The FA-115 should have the same carburetor bore as the FA-125.

They both share the same piston and valve part numbers.

The FA-115 should have the same size carburetor and share the same manifold I D. as the FA-125.

I may experiment with that at some point.

Originally Posted by the Wasp
thanks!

I have to say that it look's like the 125 Carb is not going to be too big for the 100, just big enough. and for that mater it wont be too big for the 115 too, but it's going on my 100, I can't wait to get the 100 broken in on the stand, I need to order that fresh fuel this coming week.. in the air I am hoping to spin the APC 13X10 or something else in that range. it's the Midget Mustang and I am no real acrobatic pilot, I'm just a guy that gets a real kick out of these things and I like the basic maneuvers because they are smooth, and of course I love fly-bys at all speeds

Jim
Saito Engines, I said I had enough, but I would like 4 more

The FA-100 has a bore that is only .8mm larger than the FA-91S
with the stroke of the FA-125. Therefore, it should use a similar size carburetor to the FA-91S.

Changing to a larger carburetor on the same size intake manifold I D on either engine cited above will accomplish little if any improvement in power.

Last edited by SrTelemaster150; 04-07-2019 at 03:15 AM.
Old 04-07-2019, 03:12 AM
  #39966  
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Originally Posted by SrTelemaster150
Carburetor size is supposed to be a ratio of the cylinder bore size.

The FA-115 should have the same carburetor bore as the FA-125.

They both share the same piston and valve part numbers.

The FA-115 should have the same size carburetor and share the same manifold I D. as the FA-125.

I may experiment with that at some point.

The FA-100 has a bore that is only .8mm larger than the FA-91S with the stroke of the FA-125. It should use a similar size carburetor to the FA-91S.
I wonder why that is, one would think the carb size is directly related to the cylinders volume rather than it's diameter. Interesting.
Old 04-07-2019, 03:27 AM
  #39967  
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NEW Saito FA-120S four stroke - RCU Forums

Something to think about.
Old 04-07-2019, 03:59 AM
  #39968  
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Well
the only engine that have see a substantial change in , was put the 80 carb and intake on the 65.
What I don’t know, is yeah you’re putting a big carb on. Does that help the torque or the horse power.
My thought is that if you want more torque you increase competition, so you can turn a bigger prop. if you want to go fast you increase the horsepower to increase the rpm’s so you need more fuel hence the bigger carb.
So what say you.
Old 04-07-2019, 04:03 AM
  #39969  
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Originally Posted by Hobbsy
I wonder why that is, one would think the carb size is directly related to the cylinders volume rather than it's diameter. Interesting.
I fully agree and other factors must be considered as well. The formula for calculating how much CFM (cubic feet per minute) an engine requires is: CFM = Cubic Inches x RPM x Volumetric Efficiency ÷ 3456. Now that sounds all cut and dry however engine loading (prop), mid range fuel metering and transition from idle must be considered; not to mention we don't even have carb cfm specs for our little engines. The cam profile, valve sizes and nitro content are also big players.

I feel we are just stuck with the trial and error method. I'm good with that, now someone let me borrow a 100 carb and intake for a week......lol

Last edited by Glowgeek; 04-07-2019 at 04:06 AM.
Old 04-07-2019, 04:03 AM
  #39970  
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The old saying,"you can't beat cubic inches" is as relevant today as ever.

Last edited by Hobbsy; 04-07-2019 at 04:04 AM. Reason: Spelling
Old 04-07-2019, 04:07 AM
  #39971  
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Originally Posted by Hobbsy
The old saying,"you can't beat cubic inches" is as relevant today as ever.
"There's no replacement for displacement"
Old 04-07-2019, 04:13 AM
  #39972  
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Yeh, dat too.

And don't forget, "if it won't go, gear it."
Old 04-07-2019, 05:01 AM
  #39973  
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Originally Posted by Captcrunch44
Well
the only engine that have see a substantial change in , was put the 80 carb and intake on the 65.
What I don’t know, is yeah you’re putting a big carb on. Does that help the torque or the horse power.
My thought is that if you want more torque you increase competition, so you can turn a bigger prop. if you want to go fast you increase the horsepower to increase the rpm’s so you need more fuel hence the bigger carb.
So what say you.
Generally speaking raising the CR of an engine increases the efficiency over the entire rpm range. That of course has limitations especially when using glow ignition. If you want to up the overall torque "There is no replacement for displacement". You can "move" the torque curve however by changing the velocity of the incoming air/fuel charge. A more restrictive inlet (smaller carb/intake) will move the torque curve lower in the rpm range whereas as less restrictive inlet will move the torque curve higher up in rpm. If say my 82 stock carb/manifold is a little too small to acieve max hp and I elect to up the size to the 100 carb/intake I might see an increase in rpm/hp at peak rpms but it won't likely come without some sacrifice. This is a "Rob Peter to pay Paul" scenario because the larger inlet size of the 100 carb/manifold will negatively affect lower rpm torque. I may find that the mid range runs way to rich or that I can't get a good transition off idle. Impossible to say without trying.

If we had different cam profiles to choose from that would change everything. We could then dial in our desired performance by swapping carbs and cams.

Using higher nitro content has a similar effect as putting a larger cam and carb on your engine but without sacrificing low rpm.
Old 04-07-2019, 05:17 AM
  #39974  
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Originally Posted by Hobbsy
I wonder why that is, one would think the carb size is directly related to the cylinders volume rather than it's diameter. Interesting.

The cylinder bore/carburetor bore relationship comes straight from the Saito 4-stroke manual. They even carry that ratio over to the multi cylinder engines. The FA-450R3 had the same 10mm carburetor bore as the FA-150.


2 engines with equal displacement, one is smaller bore with longer stroke, the other has the larger bore with a shorter strike..

The more over square engine will have better volumetric efficiency and all other things being equal, the larger bore engine will make more HP due to improved breathing.

Compare a 302 SB Chevy to a 305 S Chevy. Both are similar displacement but the 302 is 4"bore x 3" stroke, while the 305 is 3.736" bore x 3.48 stroke.

Last edited by SrTelemaster150; 04-07-2019 at 05:36 AM.
Old 04-07-2019, 05:33 AM
  #39975  
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Originally Posted by Glowgeek
Generally speaking raising the CR of an engine increases the efficiency over the entire rpm range.
Higher compression rations also promote better breathing and allow more benefit from a larger carburetor. Note the highlighted section below.

Originally Posted by SrTelemaster
Over the last few days I had the opportunity to test performance of 4 different versions of FA-180 engines, all burning 15% Cool Power fuel lit off with CDI. The initial advance setting for the spark was 35* BTDC. A Dynathrust 18X8 propeller was used for all tests.

The base version was an otherwise stock FA-180 with CH-Ignitions CDI.

A few days ago I did a baseline pull of 7800 RPM. This was off about 200 RPM from the best previous performance of this engine. Cold damp weather was obviously putting a damper on performance. I also did a control pull with my 12.7:1 high compression version FA-180 with the 12mm Big Bore carburetor, ported intake manifold & Bowman ring set up with .002" end gap. That engine pulled 8400 RPM with the same propeller.

Since those test runs, in the stock engine, I installed a Bowman ring on an FG-57T piston with the end gap set up at .002" just like the high compression engine.The FG-57T piston has a .016" taller compression height to maintain the same 3.4cc combustion chamber as an FA-180 in the FG-57T engine that utilizes the bore of the FA-180 on the FA-150 based stroke of gas twin.

The taller FG-57T piston in an otherwise unmodified FA-180 results in a compression increase to 10.7:1 from the stock CR of 9.6:1.

Here are the results:

Stock FA-180 CDI---7800 RPM

FA-180/FG57T piston 10.7:1 CR---8050 RPM

FA-180/FG57T piston with 12mm carburetor/manifold--- no performance gain

FA-180/.035" case deck reduction 12.7:1 CR---8200 RPM

FA-180/.035" case deck reduction 12.7:1 CR with 12mm carburetor/manifold---8400 RPM

The fact that the 12.7:1 CR engine pulled the same RPM as it did on the day that the baseline test with the stock FA-180 CDI validates the comparison of the data from the 2 different test sessions.

Conclusions:

The CR boost to 10:7:1 using the FG-57T piston with the Bowman ring was good for a 250 RPM power gain.

Although the 12mm carburetor/manifold is good for 200 RPM withe the 12.7:1 CR engine, the breathing ability of the modest 10.7:1 CR was not improved enough to benefit from the improved induction.

Increasing CR from 10.7:1 to 12.7:1 resulted in another 150 RPM gain.

The 12.7:1 CR improved breathing to a point where the 12mm carburetor/manifold induction improvement resulted in another 200 RPM.

The FG-57 piston is an easy "plug & play" modification that is a simple bolt on modification that does not require any clearance checks.

I will tear down the engine with the FG-57T piston to have the case deck reduced by .020". This will have the same result as reducing the deck by .035" with the stock FA-180 piston. The CR will be increased to 12.7:1 but valve notches will have to be checked & most likely clearanced. I will also port the manifold & employ a 12mm carburetor.

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