Engine basics > Four strokes only

Saito 40 run issues from "Upon Request" Thread

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Bob Reeves:

--- Quote from: Willis Swindell on June 25, 2009, 06:18:54 PM ---Walter
A few weeks ago I took my SA40 out to fly with a 11x5 zinger  15 %  18%oil at 9,000 RPM The engine easily turned 9,500. the plane flew great. My buddy Jim Welch uses 20 20   in his Saito 62 and wanted me to try some of his 20 20. I tried it on the next flight . The engine would not turn over 8,600 RPM . I let it go at 8,400 and had a flight of 10 min. on 2 1/2 oz of fuel. Landed and put my fuel back in the tank and the engine was back to normal. Who knows maybe it needs some castor. I got my old log book out and with a 11 x 7 on 10 % Nitro and 50 50 oil the engine turned 9,500 RPM
Willis   H^^

--- End quote ---

Willis,
Strainge results for sure. Dificult for me to fathom any engine not running harder with more nitro, would like to know what you are running for an intake?

Willis Swindell:
Bob
I am dumbfounded as you. It doesn’t make any since. As to your question I don’t know as I ordered a Saito CL intake system from Saito and just bolted it on with out checking anything. The engine is bolted into a plane and can’t measure it . For years I have had consistency problems with this engine, I had a home made intake system a .200 intake with a dripper type needle. The new Saito system took care of all my run problems.
Willis  H^^

Maybe wrong tack setting?

Bob Reeves:
OK, kinda suspected you were running the stock CL intake.. The hole in the spray bar isn't big enough to allow the engine to ingest enough fuel in one gulp. Remove the insert if you are using it, drill the spray bar hole out with a #56 drill bit .046 and try to find or order a Thunder Tiger 11.3 X 6.5 prop.

You can try your fuel at first but also run a couple tanks of YS 20-20. It will probably be too fast but don't worry about that at this point. What you are looking for is consistency with no sagging, try putting the insert back in for a couple flights, if it's still too fast start restricting the intake choke area till you get the lap times you are comfortable with.

Of course this is assuming setting the needle on the rich side of full boat.. I've found I can set the needle easier by ear than with a tach, find the peak then start backing it off (richer) till it starts running rough, lean it out till the rough running stops and you should be in the ball park.

Let us know the results of the above, I am really interested to see if you have the same results we did.

Willis Swindell:
Bob
To make a short story long I about 5 year ago I built a 700 sq. in. twin engine Heinkel 219 with two Saito 30’s that was a little weak in the overhead maneuvers. I bought two 40’s to replace them. I could not get any constancy with the carb. or the home made intakes. I saw how docile the CL 62 was I ordered the 40 intake from Saito. The engine ran the same for all the flights I ordered another intake for my other engine. That is the one I tried the 20 20 fuel, the engine ran great in the 109 but a little weak that is why tried the 20 20.  I have the engines in the Heinkel now. I don’t need the extra power with two 40’s, but if I do I now know how to get it . I plan to fly the twin tomorrow.
Willis

Bob Reeves:
Cool looking airplane...

It isn't just about getting more power, making them run consistently has been a major part of my development criteria. I was not able to get a stock CL intake to run as consistant throughout the flight as my base set up. If you are happy with what you have thats fine, it just didn't meet my goals.

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