The one with the H-13 over the san pan is a IMG type post from Photo Bucket

You can also directly past a image carried in your desttop to the WYSIWYG editor

What's Photo Bucket? Is that part of RCUniverse site?
I have the WYSIWYG (HTML) selected, but paste command is still greyed out. I probably need more detail to gain this skill.

For this Saito gas conversion, I ordered from Paragon a 1/4-32 spark plug boot and shroud. (see pic). In this kit, they supply some solder. Paragon doesn't know what kind of solder it is, but I assume it's low melt silver soldera little stronger than regular 60/40 tin-lead. Anyway, no matter what I tried, I could not get this, or any solder to flow the two 45 deg chamfered shroud pieces to flow. Hi heat, low head, medium heat, flux, didn't matter. The solder would melt against the steel shroud, but would not flow. It would just drip off. Very frustrating. If I try even more heat, the silicone boot starts expanding and outgassing, ruining the joint by causing the two pieces to pull apart under pressure from the expanding boot inside. Paragon says I'm the first one to have a problem. Yeah yeah, I've heard that one before.

Anyway, here is my solution that worked fine: Sheath the steel with brass. Find some K&Sbrass tubing (that I KNOW will flow solder), cut a slot so it'll stretch over the existing steel, and braze it on. This works because the silicone boot is not present at this time. Sand and clean it, then sand down the extra protruding brass to reestablish the original 45 deg angle.

Now, just reassemble the whole thing according to the original intent, but now I'm soldering a favorable material - brass. Flow is no problem anymore. Here's some pictures:

I've experienced your problem too.

There's no way to make a nice solder joint across the two original pieces. All you can do is have a couple gobs of solder on it.

Your solution is nice

stainless steel requires a special flux, it must also be spotless clean and a fresh surface (sanded).

After I read your post, I took a magnet to the steel plug shield provided by Paragon. The metal is NON MAGNETIC, confirming that it is a 300 series stainless steel. Very little, if any, iron, and lots of chrome & nickel. I'd have never dreampt this part would be stainless steel. Talk about overkill.

You're quite right, it takes s special flux to make this work. It probably would have been sufficient for RCEXLto use nickel or tin-plated carbon steel, thus providing corrosion resistance along with solderability. That combo works for the shields for the larger plugs, so why do something different for the 1/4-32 plugs????

The worst part is the Paragon kit contains no instructions, and no mention of special flux. Research indicates the flux should contain hydrochloric acid, zinc chloride, and ammonium chloride. This is indeed a powerful mix. It's not hard to get, it's just silly for RCEXL, the makers of this kit marketed by Paragon, to not fully inform their customers.

TKG thanks VERYMUCH for your information!<font color="#292526" size="3" face="Arial"><font color="#292526" size="3" face="Arial"><font color="#292526" size="3" face="Arial"><p align="left"></p></font></font></font>

Does anyone out there have a good photo of the WT-456 carb, with the diaphragm cover off, showing the exact position of the 98-3226 spring?And the inside surfaceof the cover? And perhaps the carb body? The Walbro diagrams are so bad that it's hard to tell how the spring installs. Their diagram makes it appear as if the springassembles around the center screw,but that seems dumb.

It's quite clear that the carb shown on this Saito conversion (see previous photos)won't accept the spring at all. I have some other carbs in the drawer into which this spring might install, but it's not clear if the body or the coverneeds to bechanged to accomodate the spring.

In checking Walbro, there are a variety of diaphragm covers, all which looks the same (in their exploded views)yet have different part numbers. There could be a wide variety of differences, some of which may be there to accept that spring.

With a lot of money, one could just by a bunch of carbs and become a degreed expert. The next best thing is to use the forum. Thanks.

I have a Walbro WYD four stroke carb and it does not have the center screw on the pump cover. The screws are on the side like on the regulator cover

<div id="fancy_content"></div>

been there done that, no one listens, so you're on your own. You've been told what to do and how to do it.

The carb on the Saito FG-20 and FG-14 engines has a Saito pump carb with no separate regulator

The pump has a second diaphragm on the liquid side of the pumping diaphragm that is called a surge diaphragm. the back side of this has a vent hole to the atmosphere.

This is supposed to eliminate the need for a regulator? The end result is a weak pump. You need to have the tank right against the carb like on a glow engine.

<div id="fancy_content"></div>

The pump and surge diaphragms in the FG-20 and FG-14 carbs are clear Mylar. The Diaphragms in the FG-36 carb are black rubber looking.

Here is the pump part of the FG-20 carb showing the pump diaphragm return spring which is not available separately from Horizon

<div id="fancy_content"></div>

I agree with youthis second pump diaphragm seems a poor substitute for an actual regulator. I don't know the actual fluid/air schematic of this Saito, but it seem the only LEGITIMATE reason to to vent this second diaphragm to ambient is to compare the venturi vacuum to it, and to have the fuelmetered in response to that information. I can't be sure, but it seems hard to do this from the pump side. It almost seems more like Saito was trying to damp pressure surges, and leave the tank positioning to the user. Perhap rationalizing that model users are used to critical tank positioning.

I can tell you for a fact that ARFs do not always provide for proper tank positioning, even though a factory designed plane should. Case in point is the Hangar 9 Fokker Dvii, where you have a GIGANTIC tank, way too long, positioned by the factory well below the nominal carb position. It took me a long time to finally sort out all the fuel flow issues I had with this plane. I can tell you that just raising the tank much higher didn't do the job....the tank is just too big for the engine no matter how high it's positioned. Intuitively, one would think that tank size would be secondary to position, but it's not. I've never found a good engineering explanation for this, but it's known fact anyway.

Too bad about Saito's new gas modelsneeding critical tank positioning just like glo engines. My opinion is they've missed one of the main reasons to go to gas....less tuning woes. Some may argue about that, but once I cowl in a gasser, I never seem to have to remove it at the field for additional tuning like I do glo engines. Scale enthusiasts (read that cowled engines) hate thishassle as it takesaway from flight time. It also can lead to power loss and crashes.

Thanks for the pics of the Saito setup. At this time, I'm awaiting a WT-456-1 carb for my conversion. Should arrive tomorrow. I wonder if a different intake adapter will be necessary?The current one is for a WT-669,the carbI decided not to try. Funny, all the local lawnmower shops need 10 days to get the carb, but a guy on Ebay had itin ONEDAY and shipped it out to me. Terrific service...but why can't the shops match it? Everyonesays to "buy local", but no one wants to invest in inventory. Even the WAREHOUSES are watching their inventory. That's like asking a coal mine to not have too much coal on hand. I'd better shut up now......

The people on ebay are selling items they have on hand, the local shops have to order it.It IS asking a lot for a local shop to inventory hundreds if not thousands of carbs they may or may not sell,maintaining an inventory of carbs with the upfront cost and the tax on the inventory and storage costs would drive carb costs through the roof.

I have never had a decent deal on carbs on ebay, IE: used instead of new, not walbro while stated as such, size misrepresented etc. You have to figure any carb you get from junkbay needs a rebuild kit so spend accordingly.

I have bought a fair number of Walbro's from the fleabay and so far, knock on wood, all have been brand new (as advertised) and worked perfectly without even taking them apart. In one purchase, bought strictly for parts, I got 15 brand new Walbro's for 20 bucks. They were purchased to rob things like needles, arms, diaphragms and such from them. I have used a couple of them on engines and they ran great. They have been a great source of parts and at just over a dollar a carb I can't buy a kit that cheap. The last two I bought were WT540's for 15 bucks each brand new in the box and one was used on my MVVS 26. It also worked flawless. You can get some great deals on the bay, you just gotta be careful.

I've not yet been burned on Ebay either.  Best advise is to write emails to the seller and gage the responses.  Most crooks are illiterate and have no social graces, so you likely can tell with whom you're dealing.  Anyway, the mailman will be here soon with my carb, so we'll see.

Soapbox alert:
On local shops, and inventory, all I can say is it's not really the local shops fault.  They are a victim of poor, regressive government policy regarding inventories.  It's part of a long term war on affluence the government is conducting.

But why the 10 day's wait for parts?  Because the WAREHOUSE is not stocking parts anymore either, and that's their whole reason for existence.  Local shops might as well order from the factory directly if this is the case.  Anyway, I was just frustrated because I am on vacation now, and would like to run this motor before work starts back up and time becomes limited again.

The WT-456-1 arrived, and it's new in the box. Clearly never been used. For those interested in an Ebaywalbro sellerwho is responsive, his Ebay name is captneversail. Give him a try.

Besides getting my Saito conversion running correctly, another goal has been to understand (IN DETAIL) what Walbro did to their existing designsto marketthe intake-pulse-only carbs for 4 strokes. This 98-3226 spring is obviously a design mod rather than a clean sheet 4 stroke design.That opens the potential for budget conscious modellers to convert existing carbs to 4 stroke. The carb is $37. The spring is47 cents. Duh. It looks like the only difference is the diaphragm cover, and it only differs by the machining of the little flat bottom counterbore (see photo). The 4 stroke cover on the parts listis obsolete, but there's a replacement for $2.50. To save time or money, one could machine the old cover. The counterboreis .380" diameter, and it's .045" deep as measured from the cover mounting surface. (not the gasket ridge, but the surface just outside of that). I think this could be done on a drill press if one clamps everything tightly. Just grind the angle off the tip of a SHORT3/8 drill. It should be short to keep the drill from chattering. Grind a clearance angle behind the two cutting edges on the drill.

In the two photos below, one is a non spring-assisted 2 stroke carb, and the other is a known 4-stroke carb, the WT-456. This was used on RyobiAC trimmers. This isa line of 4 stroke products called "Air Clean" to address mounting critisizm from the greenies about 2 stroke pollution. They even made their engine designs open source forothers to copy,ostensibly toforestall government regulation. I'm showing both carbsto illustrate where the parts are common, and where they differ. And also to show how the WT-456 4 stroke spring assembles. Maybe there are other differences, but I can't find them if they exist. I add that as a caveat to innoculate myself against anyone yelling at me for an incomplete analysis.

Not true, there are patents on features used in the Ryobi, they only offered to license other manufacturers.The only one to take them up on the offer was Zenoah/Redmax, the Ryobi Gen III is the same as the 25cc Redmax, why anyone would want to copy that POS is beyond me.


It wasn't long ago someone posted a link in this forum to an auction that was offering brand new carbs, well they weren't, so my guess is that the crooks are working the forum and ebay in tandem.

The term open source I used is misapplied. I work in the computer/electronics/software field where that term is common. It means IP is usable by others, as opposed to being secret. It may still cost something to use it though. Or they may charge for the SDK to take advantage of the open-sourceness of it. They still make money. For Ryobi, I think the altruism (or greenness if you please)of their offer lies in how much money they wanted for the licenses. Do you know how much they wanted Nosedragger?

I don't know and if I knew I could not disclose how much Ryobi whacked Honda for the use of Ryobi's patented uni lobe cam shaft design.

Open source and available for license are two different things.The former suggests its technology is free for use, the latter suggests money will be involved.




Edited by Moderator

Unless you work for Ryobi, or were under contract to them for some reason, you'd not be bound by any confidentiality regarding their license fees. People who use the web to pass on already known information aren't liable.

The less Ryobi charged for the license, the less distinction there would be between open source and licensing. However, I do agree with you that there is a difference andIalready commented I used the wrong term. Their own press release made it sound like they were doing other companies, and the earth, a favor. We're wasting electrons. Happy New year.

Hello guys,

I would like to convert my saito FA82 to gas by just mounting a elektronic ignition from justengines to it.
What ignition timing is to be used for this?
What do you think of using a oscilating perry pump with the stock carburator on a Saito FA82?

Hello Evert1969,

There's a lot of guys on here more knowledgeable than I am, but I'll start. The timing is identical to a 2 stroke timing, with one caveate. Depending on the compression ratio you're starting with on the FA82, you may experience some preignition (detonation) that could be damaging. Use high octane fuel. Nominal timing for a 2 stroke is around 28 degs BTDC, so you could opt to start more retarded (the engine, not you) like say, 26 degs? If you know how to measure your compression ratio, that would help. You need to know the bore and stroke, the rest is just math. I've heard (no experience) that anything higher than 9:1 and you risk preignition.

A whole other issue is oil mix, and the lower rod bearing. Some convert to needle bearings, some convert to bronze bushing, and most use 10:1 gas/oil mix. There are some people who claim that is not necessary but why not start conservatively? I don't think it's practical on an engine that small to convert the bearing. I converted mine (see earlier in this thread) and barely made it fit with some custom machining of the crankcase. And the remaining strength of the rod journal is questionable. It may break because it's too thin. That's still to find out. So forget the bearing conversion and possibly just go with a bronze bushing or leave it as is and try it.

As for the Perry pump, I don't have any information on that. But I can help develop the right questions though. Is the perry pumpgas compatible? How will you scavenge the oil building inside the dry side of the perry pump that migrates from the crankcase? Is the existing Saito carb gas compatible? Probably not, but I'm not sure. The lower end of the Saito is lubricated strictly from engineered blow-by, so oil is supposed to collect in the crankcase. That's one reason for the barb. But that oil can find it's way up the pressure tap tube to your pump and contaminate the dry side. Eventually, it could hamper the diaphragm's motion.

Now for the kicker. Methanol fuel runs much richer than gas. You are gushing fuel through the engine compared with gas, and the needle valve angle is designed with that in mind. Now, when you run gas, you may find it hard to accurately restrict the amount of gas and the setting becomes very sensitive. Gas carbs like Walbros have a metering system that is constantly regulating the fuel air mixture based on venturi negative pressure and comparing that to ambient. They are very accurate, and the std Saito carb is not up to the challenge.

Converting to gas is supposed to allow folks to get away from the expense and tuning issues with glow fuel, so you're partially defeating your purpose. Yes, it's tempting to try (cost-wise), especially if you already have the Perry pump sitting around. No custom machining of a carb adapter, etc. I have a lathe, so this wasn't an issue.

THanks for the fast response!

I have to do it the easy way since i don't have a lathe or any of that kind of machinery. Perhaps later i can find someone to make me carb adapter for the FA82. Wich carb can i best use for this engine?

I'm using the Oscillating Perry pump VP20 wich doesn't have the pressure connection. I use this now with methanol.
Is it possible to leave the perry pump away since i have read that this type is not gas proof and use the pressure from the exhaust on the fuel tank instead just like with nitro or is that to dangerous.

Maybe someone else have the experience with the ignition timing on gas ? Because i have to drill the hole for the magnet in the prop hub i can't change to much timing afterwards.

As you see i'm seeking for wich way to go with this conversion

Many have converted glow engines to gas. In general, rods don't need any modification. The FG-14 appears to use the same rod as the FA-82. Lubrication is tricky but using it seems that 12:1-22:1 oil ratios will be suitable. Just follow the ignition's installation manual to install the ignition. You can make some changes to ignition to find the optimum setting once the engine is tuned well. If the carb is oversize you might find it doesn't draw fuel well when running gasoline. It will be very sensitive on needle settings, Just be patient and use a systematic approach to find the correct needle settings.

Here's a good thread.

http://www.rcuniverse.com/forum/m_7282593/tm.htm

The Saito prop hubs are collet type so it's easy to change timing.

The VP-22SG Oscillating pump is compatible with gasoline.


http://www.perrypumps.com/prod02.htm