Saito 25cc Gas engine
10-08-2010 | 06:25 PM
#1
Saito 25cc Gas engine
About 6 yrs ago I was roped into taking a Saito 150 in a horse trade. The engine appeared to be about 1999 and had been flown a little but was in nice shape.
I ran it some at the time and oiled and put it away.
I converted it to CH ignition last week. I ran it today. Had the HS needle at three turns. Started right up but was very rich on 20:1 gasoline and Pennzoil Air Cooled. I adjusted the HS needle to 1 1/4 turns and it seemed to run decent. I turned the LS needle in about 1 turn from the glow setting. I was well pleased. It will run a long time on a 270cc (9 oz) tank.
The ignition change over was more or less plug and play thanks to TKG and bcchi . I'm using the RCEXL 1/4-32 plug.
I was using a APC 16 X 8 prop and it seemed about right.
I was well pleased considering the original Saito carb. But there was a rich mid range.
The needles didn't seem so sensitive to adjust but the carb was sensitive to the level of the fuel in the tank as it burned down.
The engine is not the high compression version. I did not use any head shims and I heard no back firing tendencies.
The last 1/4 of the throttle seemed to have little effect.
No smoke trail so needle setting is by sound.
The only black grunge came from under the exhaust valve cover and out the crankcase vent.
I got a few ideas I want to try yet so I will be playing with it some more.
I ran it some at the time and oiled and put it away.
I converted it to CH ignition last week. I ran it today. Had the HS needle at three turns. Started right up but was very rich on 20:1 gasoline and Pennzoil Air Cooled. I adjusted the HS needle to 1 1/4 turns and it seemed to run decent. I turned the LS needle in about 1 turn from the glow setting. I was well pleased. It will run a long time on a 270cc (9 oz) tank.
The ignition change over was more or less plug and play thanks to TKG and bcchi . I'm using the RCEXL 1/4-32 plug.
I was using a APC 16 X 8 prop and it seemed about right.
I was well pleased considering the original Saito carb. But there was a rich mid range.
The needles didn't seem so sensitive to adjust but the carb was sensitive to the level of the fuel in the tank as it burned down.
The engine is not the high compression version. I did not use any head shims and I heard no back firing tendencies.
The last 1/4 of the throttle seemed to have little effect.
No smoke trail so needle setting is by sound.
The only black grunge came from under the exhaust valve cover and out the crankcase vent.
I got a few ideas I want to try yet so I will be playing with it some more.
10-09-2010 | 11:12 AM
#2
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From: Riverton,
WY
RE: Saito 25cc Gas engine
If your into fiddling and have some machine tools, you can reshape the slot in the throttle barrel to lean out the mid range. Think of an expo curve.
10-09-2010 | 07:50 PM
#3
RE: Saito 25cc Gas engine
ORIGINAL: w8ye
About 6 yrs ago I was roped into taking a Saito 150 in a horse trade. The engine appeared to be about 1999 and had been flown a little but was in nice shape.
I ran it some at the time and oiled and put it away.
I converted it to CH ignition last week. I ran it today. Had the HS needle at three turns. Started right up but was very rich on 20:1 gasoline and Pennzoil Air Cooled. I adjusted the HS needle to 1 1/4 turns and it seemed to run decent. I turned the LS needle in about 1 turn from the glow setting. I was well pleased. It will run a long time on a 270cc (9 oz) tank.
The ignition change over was more or less plug and play thanks to TKG and bcchi . I'm using the RCEXL 1/4-32 plug.
I was using a APC 16 X 8 prop and it seemed about right.
I was well pleased considering the original Saito carb. But there was a rich mid range.
The needles didn't seem so sensitive to adjust but the carb was sensitive to the level of the fuel in the tank as it burned down.
The engine is not the high compression version. I did not use any head shims and I heard no back firing tendencies.
The last 1/4 of the throttle seemed to have little effect.
No smoke trail so needle setting is by sound.
The only black grunge came from under the exhaust valve cover and out the crankcase vent.
I got a few ideas I want to try yet so I will be playing with it some more.
About 6 yrs ago I was roped into taking a Saito 150 in a horse trade. The engine appeared to be about 1999 and had been flown a little but was in nice shape.
I ran it some at the time and oiled and put it away.
I converted it to CH ignition last week. I ran it today. Had the HS needle at three turns. Started right up but was very rich on 20:1 gasoline and Pennzoil Air Cooled. I adjusted the HS needle to 1 1/4 turns and it seemed to run decent. I turned the LS needle in about 1 turn from the glow setting. I was well pleased. It will run a long time on a 270cc (9 oz) tank.
The ignition change over was more or less plug and play thanks to TKG and bcchi . I'm using the RCEXL 1/4-32 plug.
I was using a APC 16 X 8 prop and it seemed about right.
I was well pleased considering the original Saito carb. But there was a rich mid range.
The needles didn't seem so sensitive to adjust but the carb was sensitive to the level of the fuel in the tank as it burned down.
The engine is not the high compression version. I did not use any head shims and I heard no back firing tendencies.
The last 1/4 of the throttle seemed to have little effect.
No smoke trail so needle setting is by sound.
The only black grunge came from under the exhaust valve cover and out the crankcase vent.
I got a few ideas I want to try yet so I will be playing with it some more.
I have a 180 and am thinking of converting like you did. I have a number of Walbro carbs, including some from 4 stoke Ryobi 26cc trmmers. I will use the RCEXL ECDI, What Walbro carb size and type would you recommend? Also, would 1:20 gas to Pennzoil be ok? What prop to use and RPM to expected? Would Coleman camp fuel be OK?
Thank you very much.
Sincerely, Richard
10-09-2010 | 08:06 PM
#4
RE: Saito 25cc Gas engine
ORIGINAL: tkg
If your into fiddling and have some machine tools, you can reshape the slot in the throttle barrel to lean out the mid range. Think of an expo curve.
If your into fiddling and have some machine tools, you can reshape the slot in the throttle barrel to lean out the mid range. Think of an expo curve.
Except for the narrow rich area, it ran great. Just as good as the FG-20.
I put a Perry oscillating gasoline pump on it tonight with a Cline regulator. I'll have to remount the engine as the pump is below the level of the crankcase.
I think the wedge slot is the problem as you run the idle needle in farther and the tip is in the wrong place in the Vee?
10-09-2010 | 08:21 PM
#5
RE: Saito 25cc Gas engine
ORIGINAL: spaceworm
I have a 180 and am thinking of converting like you did. I have a number of Walbro carbs, including some from 4 stoke Ryobi 26cc trmmers. I will use the RCEXL ECDI, What Walbro carb size and type would you recommend? Also, would 1:20 gas to Pennzoil be ok? What prop to use and RPM to expected? Would Coleman camp fuel be OK?
Thank you very much.
Sincerely, Richard
ORIGINAL: w8ye
About 6 yrs ago I was roped into taking a Saito 150 in a horse trade. The engine appeared to be about 1999 and had been flown a little but was in nice shape.
I ran it some at the time and oiled and put it away.
I converted it to CH ignition last week. I ran it today. Had the HS needle at three turns. Started right up but was very rich on 20:1 gasoline and Pennzoil Air Cooled. I adjusted the HS needle to 1 1/4 turns and it seemed to run decent. I turned the LS needle in about 1 turn from the glow setting. I was well pleased. It will run a long time on a 270cc (9 oz) tank.
The ignition change over was more or less plug and play thanks to TKG and bcchi . I'm using the RCEXL 1/4-32 plug.
I was using a APC 16 X 8 prop and it seemed about right.
I was well pleased considering the original Saito carb. But there was a rich mid range.
The needles didn't seem so sensitive to adjust but the carb was sensitive to the level of the fuel in the tank as it burned down.
The engine is not the high compression version. I did not use any head shims and I heard no back firing tendencies.
The last 1/4 of the throttle seemed to have little effect.
No smoke trail so needle setting is by sound.
The only black grunge came from under the exhaust valve cover and out the crankcase vent.
I got a few ideas I want to try yet so I will be playing with it some more.
About 6 yrs ago I was roped into taking a Saito 150 in a horse trade. The engine appeared to be about 1999 and had been flown a little but was in nice shape.
I ran it some at the time and oiled and put it away.
I converted it to CH ignition last week. I ran it today. Had the HS needle at three turns. Started right up but was very rich on 20:1 gasoline and Pennzoil Air Cooled. I adjusted the HS needle to 1 1/4 turns and it seemed to run decent. I turned the LS needle in about 1 turn from the glow setting. I was well pleased. It will run a long time on a 270cc (9 oz) tank.
The ignition change over was more or less plug and play thanks to TKG and bcchi . I'm using the RCEXL 1/4-32 plug.
I was using a APC 16 X 8 prop and it seemed about right.
I was well pleased considering the original Saito carb. But there was a rich mid range.
The needles didn't seem so sensitive to adjust but the carb was sensitive to the level of the fuel in the tank as it burned down.
The engine is not the high compression version. I did not use any head shims and I heard no back firing tendencies.
The last 1/4 of the throttle seemed to have little effect.
No smoke trail so needle setting is by sound.
The only black grunge came from under the exhaust valve cover and out the crankcase vent.
I got a few ideas I want to try yet so I will be playing with it some more.
I have a 180 and am thinking of converting like you did. I have a number of Walbro carbs, including some from 4 stoke Ryobi 26cc trmmers. I will use the RCEXL ECDI, What Walbro carb size and type would you recommend? Also, would 1:20 gas to Pennzoil be ok? What prop to use and RPM to expected? Would Coleman camp fuel be OK?
Thank you very much.
Sincerely, Richard
Try it with the 180 carb first just so you can see what it does.
I was using the 20:1 gas to Pennzoil aircooled today, the same as I use in the FG Saitos. It hasn't burned the rod out yet.
After running the engine again today, I notice a little fine black oil mist over the engine that has come from the front seal if you look at it in the sun. This is a 10-12 yr old engine but it was never used much. Appears to have had a few flights on a plane and crashed but there were no marks on the engine or crankshaft. The crank is straight. I've had it for 6 years but other than trying it out on the test stand, I have not used it until yesterday.
I'm using the Chinese RCEXL 1/4 -32 spark plug.
I've been using a Tower Heavy Duty 180 starter on it. Seems to work fine. I have several Sullivan Dynatrons but I just wanted to see how the Tower HD did. I have arthritis in my fingers and do not hand prop anymore.
10-10-2010 | 06:27 PM
#6
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From: Newport News,
VA
RE: Saito 25cc Gas engine
I have just finished a gas/ignition conversion on my OS 91FS surpass. It is using muffler pressure with the stock carb and 20:1 oil. The ignition is a Rcxcel with thier 1/4-32 plug. It runs great. Starts easily without any kickback (handstart).
The carb needles were pretty sensitive. After some time and fine adjustments, it starts, idles and runs to full song nicely. However, It does have some intermitant stumbles and midrange hickups.. But when cycleing the throttle from idle to ful in succession 2 or 3 times it smoothes out.
I have a Perry pump and Oscilating pump on the way from Tower. I also have a Ironbay regulator and a couple Cline regulators to play with.
I am mentioning my OS91FS only because I am also planning on converting my Saito 150. The Saito is currently in a 25% scale Cub. What I am learning from the OS91FS I will apply to the Saito.
The carb needles were pretty sensitive. After some time and fine adjustments, it starts, idles and runs to full song nicely. However, It does have some intermitant stumbles and midrange hickups.. But when cycleing the throttle from idle to ful in succession 2 or 3 times it smoothes out.
I have a Perry pump and Oscilating pump on the way from Tower. I also have a Ironbay regulator and a couple Cline regulators to play with.
I am mentioning my OS91FS only because I am also planning on converting my Saito 150. The Saito is currently in a 25% scale Cub. What I am learning from the OS91FS I will apply to the Saito.
10-10-2010 | 09:40 PM
#7
RE: Saito 25cc Gas engine
I have installed the Perry Oscillating gasoline pump and a Cline regulator on my Saito 150 but have not mounted it yet for running with the pump and regulator.
This should make the needle valves stay the same no matter the attitude or the fuel level.
But this does not address the rich spot in the mid range. One way to approach this is not run the engine in the rich area?
According to TKG this is caused by the position and shape of the cam groove in the carb barrel.
I found the Saito 150 to run very nice on gasoline with the stock carb except for the rich spot around 4000 rpm
This should make the needle valves stay the same no matter the attitude or the fuel level.
But this does not address the rich spot in the mid range. One way to approach this is not run the engine in the rich area?
According to TKG this is caused by the position and shape of the cam groove in the carb barrel.
I found the Saito 150 to run very nice on gasoline with the stock carb except for the rich spot around 4000 rpm
10-11-2010 | 06:12 PM
#8
RE: Saito 25cc Gas engine
Hi Jim, I've done two Saito 91's now and one 180 and none had the rich midrange although they were sensitive to the fuel level as you describe. It not real bad though and I can easily get a 10 to 12 minute flight in before needed to land and retune or refuel. Let us know how the Perry pump and regulator work out. I might be interested in trying that out.
10-15-2010 | 07:04 PM
#10
RE: Saito 25cc Gas engine
Thanx W8YE for the response concerning my Saito FA270T & the conversion information. Was just wondering if the Walbro carb from the FG36 might be a viable alternative to the stock glow carb? Still garnering info & working on getting ducks in a row. Did search forums for new Enya plug I've seen reference to, that's how I came across this thread. Thanx again Mike Brennan aka T-man49
10-15-2010 | 09:28 PM
#11
RE: Saito 25cc Gas engine
the 270/300 twins use the old Saito 120 carb on the single carb versions. Being as the cylinders are alternate firing, the carb the correct size for one cylinder is big enough as only one cylinder fires at a time. So the carb for the FG36 may be a little large???
The FG30 carb may be better?
On a twin ignition set up, there is only one trigger point and it simultaneously fires both plugs. Therefore each cylinder is firing an extra time during the overlap stroke which doesn't hurt anything as there is nothing to combust in the cylinder.
The single cylinder four strokes also fire every time the piston comes up. Most cars do this also now days. I had a 1987 Cavalier 4 cylinder with two dual outlet ignition coils and no distributor.
Try your 270T with the dual outlet ignition and the original carb on gasoline first and see how it runs before trying a WYD Walbro. You could also use a WT-457 Walbro from a Ryobi four stroke?
The FG30 carb may be better?
On a twin ignition set up, there is only one trigger point and it simultaneously fires both plugs. Therefore each cylinder is firing an extra time during the overlap stroke which doesn't hurt anything as there is nothing to combust in the cylinder.
The single cylinder four strokes also fire every time the piston comes up. Most cars do this also now days. I had a 1987 Cavalier 4 cylinder with two dual outlet ignition coils and no distributor.
Try your 270T with the dual outlet ignition and the original carb on gasoline first and see how it runs before trying a WYD Walbro. You could also use a WT-457 Walbro from a Ryobi four stroke?
11-01-2010 | 05:14 PM
#13
RE: Saito 25cc Gas engine
ORIGINAL: Kostas1
Muffler pressure on gasoline filled tank ?[
]
Muffler pressure on gasoline filled tank ?[
]
