Smoggyboy

I need a little help.

I have a Saito 220 GK that is, as every one knows very heavy on fuel. So, I am looking into a Gas conversion. I plan to use the Just Engines CDI System using the Glow size spark plug. What I am stuck with is the compression ratio needed. My initial thoughts are that the compression can be reduced for gas by the addition of a thicker head gasket, I just done know the starting point and how much to reduce the compression too (how thick the head gasket needs to be).
Thanks for the help guys.

nitro wing

My Feedback: (1)

You should ask Saito direct.With any luck ,they will let you in on their tech secrets.

NM2K

My Feedback: (14)

Other recent Saito engines have a one piece cylinder head and cylinder jug. While I have an FG-36 gasser, I haven't looked to see if it has a detachable cylinder head, but I doubt it. Besides, yours is the glow version.

If worse comes to worse and your engine lacks a seperately detachable cylinder head, you can shim the cylinder jug at the crankcase junction enough to reduce the compression substantially. You might even have enough pushrod length to make the adjustment without replacing the pushrods. However, you might also get away with the stock compression ratio if you use high octane petrol for fuel.

From what I have heard, you will need to replace the connecting rod with the FG-36 connecting rod. Although, I know of one fellow on the RCU engine forum than converted his 1.50, IIRC, with just an ignition system. He ran 20:1 petrol/oil for fuel and ran his successfully and satisfactorily for quite a long time, without having any excessive wear problems. Charlie, are you ought there old friend? I've often wondered if Charlie's pioneering work (I hope I got his name correct) might have served as the inspiration for Saito to pursue and develop the FG-36.


Ed Cregger

Smoggyboy

Ed,

Thats quality information. Would there be any danger of a bit of trial and error, Given that I would start with a 30-1 mix with super unleaded around 97 octane without any compression change (head shimms)as you are correct regarding the one piece head.

One other point is that this is a brand new engine so it is unlikely to run very well for the first gallon or so. I will try with a heavy prop and low pitch maybe an Master Airscrew 18x6 for run in.

Do you have any idea as to the incremental change of say one extra thickness of gasket would make?? Iam wondering of how much of a change it would be in terms of a dimention (1mm, .5mm, .25mm ect)

NM2K

My Feedback: (14)

I'm not well versed enough to have retained the dimensions of said cylinder jug shims. I am sure that there are others reading with tons of experience in this area if we can get them to step forward and offer their wisdom.

I'm hesitant to recommend running a brand new engine on 30:1 petrol/oil mix. IIRC, even my FG-36 recommends a 20:1 petrol/oil mix for initial running. Later, they say it is okay to run 30:1 petrol/oil mix, but remember that this is with the FG-36's exclusive bushing equipped connecting rod. I'd rather make more smoke than be sorry.


Ed Cregger


***I forgot to say that I would probably break-in your glow 2.20 on glow fuel, then try the conversion. Gasoline acts as a lubricant to a certain degree and it might take a lot longer to break-in the engine using petrol. Alcohol as virtually no lubricity and will make quick work of the break-in, albeit an expensive one.

Smoggyboy

Ed
More good points. Yes I made a typo regarding the oil mix. It should be 20/1 for break in (I have read that 100 times over and still got it wrong). I also agree that break in would be better using glow fuel.

I have looked at the componants needed for the conversion and the cost is not too bad, (if it works) if it doesnt all that will show my attempt is the magnet drilled into the prop drive washer and I will have a go at converting one of my older gib 2 strokes.

Some good things, I assume that will come from the conversion is less likley hood of hydraulic lock, easier starting, no mess, better MPG, reliability with that 4 stroke sound.

NM2K

My Feedback: (14)

I would check the crankshaft part numbers for the FG-36 and your FA-220. If they are the same, I can't imagine it not working okay. If they are not the same, I would find out what the differences are and take that into consideration. I'm wondering if the crankpin on the FG-36 crankshaft is hardened versus unhardened on the FA-220?


Ed Cregger

Smoggyboy

Ed
I have checked the stroke distance of both engines and they are both 32mm, sugesting the con rods are the same length. There may be changes made internaly to the one piece head, I will check the dimentions when I can find them

gkamysz

My Feedback: (19)

There is a review on the FG-36 in the current issue of Fly RC. It mentions the rod is bushed in the big end. Otherwise it is the same as the 2.20. I didn't notice if the compression ratio was any different.

hamman

My Feedback: (61)

I checked Horizon web site and the crank, rod and head all have differant part numbers for the gasser and in the photo you can see the bronze bushing in the 36 rod. Maybe the crank pin is harder as Ed mentioned. Could the head have differant valve seats because of higher exhaust temps when running on gas? Hamman

Smoggyboy

So I guess now the question is, wether its worth a try or not. I am by no means an engine expert, but it sounds like I should be getting hold of a bushed 36 con rod and maybe a crank pin.

I have probably got this completely wrong, but, I thought that the higher compression used in Glow fuel engines and the addition of nitro to the fuel would require the glow version to be built more substatial than the gas. From a practicle point of view rather than technical or is it purely down to higher temp.

tkg

My Feedback: (1)

NO crank pin, but crankshaft

captinjohn

If the cylinder and head are one part....shim under base gasket to reduce compression. Then re-adjust valve clearence. If you use 20-1 lube & Hi octane gas and run the engine easy...you should be able to see how it runs on spark ignition. If you do not like that...go back to Glow fuel or try Gas/glow. See engine converios forum on that. Capt,n P.S. CD units are a lot less expensive now.

Charley

My Feedback: (2)

Ed & Smoggy,

I'm the guy who ran the Saito 1.5 on gas for a season. I used 90 octane gas and dyno oil in a 16:1 mix. Didn't smoke and ran fine with the original carb. The ignition was CH Ignition's kit for the Saito. It included a shim to go under the cylinder to lower the compression and eliminate the kickback that the early 1.5s were prone to. I went to the ignition because I was sick of thrown props and lost prop nuts and washers. The engine ran like a watch on FAI fuel & ignition, using the shim at first. You wouldn't believe the low RPM reliable idle it had. I tried gas for the helluvvit. All I had to do was replumb the tank with Tygon and change to a gas stopper, then retune the carb. The carb needles weren't overly sensitive. Power was about the same on gas as it was on FAI fuel. The engine ran a bit hotter on gas. Oh, here's a tip : I had to use a silicone hose on the muffler tap. Attached it to a large inline fuel filter and attached Tygon from the filter to the tank. Tygon melts if hooked to the muffler. []

Smoggy, you might want to check with CH to see what they can provide for your 220.

Have fun with it. I did.

CR

avishay

Did any one has experience converting Moki 180 to gas. somone told me that i have to use only CDI ' replace the plug and can use the glow carb. ??? and that power loss is very low.

Thank's
Amir

Charley

My Feedback: (2)

Hello Amir,

I have no experience with the Moki but I can offer some general observations. If the needles on the Moki are very fine thread, then they will probably meter the gas OK. This is what I found with the Saito and SuperTigre engines. You'll have to try it out and see. Wish I could help more.

CR

Smoggyboy

Charley.

I don't want to sound Dumb, but you lost me with ''CH'' not sure who they are. Any chance of a link to their web site?

BTW Thanks for the advice.
Dave

Charley

My Feedback: (2)

You aren't dumb, just ignorant of some fact; "ignorant" means not knowing. Doesn't have anything to do with stupid or dumb. Ignorant you can fix with info, stupid is helpless.

Anyhoo, it's: <www.ch-ignitions.com/>

Cheers,

CR

mrbigg

My Feedback: (21)

Charley, how was the reliability using the ignition with the glow fuel, compared to using the glow plug? Fewer deadsticks, if they were a problem before?

Jezmo

The folks at CH are outstanding to deal with. I am using their products on my SuperTigre and Saito conversions and have experienced nothing but the best in service from them. Good luck with yours.

avishay

Thank's All

CH gave the answer at their site:

"Yes. We have conversions for these engines. We do not recommend doing this.
This gets pretty expensive and can cost as much or more to convert to gas as the engine cost in the first place. These engines on a gas fuel mix are not successful unless you put on a Walbro type carburetor. After these engines are converted you must use a heavy oil mix of least 10% oil .
This is because of the bushing type connecting rod. We do have Walbro carb adapters for the above engines"

So, conversion Moki to gas will be expensive or not efficient i believe i will buy new gas engine.

Charley

My Feedback: (2)

What I was getting on glow was detonation and thrown props. With the ignition it had a remarkably low, reliable idle. It never dead sticked on ignition. Funny thing is that when I went back to glow - just to see - it ran fine. Maybe it finally got broken in after a summer season on gas. I'm running all my glow engines on 10% nitro 2-stroke fuel. Go figure.

CR

Charley

My Feedback: (2)

That statement by CH is just them playing CYA. Also selling carb adapters. I used a 16:1 gas to oil mix.. That's a bit over 6% oil. I also used the stock carb.

As far as the cost is concerned, they're exaggerating a bit IMHO. To me the cost was secondary. I put the ignition on the engine to cure the kickback problem. My Saito 1.5 is on a Ace 4-120 Bipe that I built from a kit and I didn't want to change engines. The model loses it's character with a 2-stroke engine. Trying it on gas was just for the helluvvit and cost me little. I believe most of us doing glow to gas conversions are just playing with our hobby.

CR

tkg

My Feedback: (1)

Not really CYA, but the voice of experence. IF YOU WANT TO RUN GAS, BUY A GAS ENGINE.
Now if you have a burning need to experment or a very special need we are very happy to take your $$$ and provide you with what you need to make a conversion. BUT you have been warned...[X(]

Antique

My Feedback: (4)

Or you can be like my friend in Phoenix...I converted a ST3000 about 15 years ago...He was experimenting with oil ratios....Flying along straight and level one day the engine suddenly stopped...He got the oil ratio TOO lean, the rod froze on the big end and cracked the rod..He ONLY needed a new crank and rod...He still uses it occasionally, but with LOTS of oil in the fuel....
The reason for a Walbro is for ease of tuning, and also for the pump...The stock carb relies on crankcase suction, so if the tank is too high, too low, or too far from the carb you will have tuning problems...Or you can get a $50-$60 Perry pump or a regulator from billsroom.com...
goodf luck...