JIMARRINGTON

The one Ken showed me that he had has a Walbro on it. He said it was one he had laying around but that it was really too big. If memory serves it was an 11mm bore carb. He said it ran fine but was a little rich at idle. I would suggest a 9-10mm carb. I have a couple of 10mm carbs. I believe thay are WT-414s. They have a built in choke but they also have a priming port.

Jim

thisoldman

My Feedback: (29)

i have a s tigre 3250 im converting over to gas.. trying to find adapter to put a walbro on.. have a wt158a and a wt644.. going to see how they work as soon as i find a adapter. that engine should handle a big plane...

JIMARRINGTON

I think you can get the carb adapters at CH Ignitions. http://www.ch-ignitions.com/


Jim

Jezmo

I put another hour and fifteen minutes on the 51 today and it ran flawless. According to the data acquisition unit it runs just shy of 90 mph flat and level and out of a slight dive will run just over 110. I ran it on the ground with a Jett-Stream pipe on it and it picked up a considerable amount of r's over the tower muffler (kinda expected that) but I didn't fly it with it on there. I think I am going to quit tinkering with it and just fly it for a while. Just enjoy it.

JIMARRINGTON

What size spark plug would you get to put in place of a glow plug?

Jim

Jezmo

Hi Jim,

I use a 1/4X32 spark plug that I buy from CH Ignitions and he has two different ones that he sells. One is made overseas and is slightly less expensive than the RimFire that is made here stateside. I think the overseas one is $9.95. They hold up very well using Pennzoil Two Stroke Air-Cooled oil, Redline Two Stoke Racing oil, or Motul 800 oil. I have used some other synthetics that put a VERY hard carbon on the plug and piston crown. Won't be using those any more. I currently have one RimFire plug with over 35 hrs on it and it still runs great. Hope that answers the plug Q.

JIMARRINGTON

Thanks Jezmo. I have an extra XYZ ignition laying around. Will one of those plugs fit the ignition cap. The XYZ has a shielded cap and wire. I have used them on my weedeater conversions with good success. I cant remember the exact size of the cap but I do remember that it is smaller than the stock plug that comes on a Poulan weedeater. It fits a RDJ8J Champion plug that I use. Will it fit the smaller plug?

Thanks
Jim

oldtimer2

My Feedback: (19)

Hi, Try airpowertechnologies.net click on Gaint scale engines, services. They make conversion parts for Moki and ST engines, reasonable prices too.

gkamysz

My Feedback: (19)

The supplied plug caps on the RCexcel and XYZ ignitions will not fit the small 1/4-32 plugs. The hex on these is only 5/16" (8mm). CH sells 45° or 90° 1/4" plug caps for $13 or so. I'm going to try making one from a McDaniel plug. If that doesn't work I'll buy them from CH.

Jezmo

Greg is right on the special size for the 1/4X32 plug caps. The cap that Bill at CH sells is the McDaniel and like Greg said above they are available in both 60 deg and 90 deg angles. I use the 90 deg ones on my two strokers and the 45 deg works real nice on the four strokers.

Edited to correct angle from 45 to 60.

JIMARRINGTON

Looking at CH Ignitions website, I see the Rimfire 1/4 x 32 plug. Is this the plug I need? And can you tell me which one of the plug caps I will need?

Thanks for the info.

Jim

gkamysz

My Feedback: (19)

You will need to call for the plug cap. They are not listed on the site. The Rimfire plug is the right one. Bill(?) will also tell you that the Chinese ignitions do not use resistive spark leads so you will need to add a resistor.

Jezmo

Bump. A question was asked and I am making it easier for him to refer to.

mac2286

I would like to do this conversion on an OS50, and put it in a Century Hawk 30 size helicopter. Just a few questions, how did this do in the long run? I have a case of Penzoil air cooled 2cyl. oil that I use in my ultralight, is this the oil you were using?  The oil mixture of 16:1, you are looking at about 8oz / gal? Any help would be greatly appreciated.

Jimmy

Jezmo

Yes the ST51 still runs fine and I have since converted a couple of ST90's and a Saito 91 as well as a Saito 180. All are still running as good as day one. I have begun using Redline Two Stroke Racing Synthetic oil as there is considerably less wear and absolutely NO carbon buildup. Stihl UP Ultra is at least equal to the Redline. As you already have the Pennzoil I would certainly use it as it is the best "Dino" oil out there. A word of caution, keep at least the minumum of 16:1 oil to fuel and if you run lean often a little extra wouldn't hurt especially with the Dino oil. The OS is a ringed engine so that won't be an issue but cooling on a heli is marginal at best hence the need to run slightly rich so you can place a finger on the back of the case to check the temp. As long as you can keep it cool you should be good. The only other issue might be the carb since it doesn't have a true idle needle. There are 3 needle OS carbs available that should work really nice to keep the mid range from getting too rich. Set the initial timing to 28 degs and you should have a fun little project. Good luck with it.

John C

Jezmo,

Could you expound on what you are running the Saitos for fuel and timing? I've got a 125 I'd like to consider for this conversion.

Thanks,

John C

Jezmo

Sure John, the fuel is pump premium 93 oct with the ethanol removed and the timing is set at 36 degs in the 91 and the 180 is 34 if memory serves correct. Hope that helps and good luck with yours.

John C

Jezmo,

Thanks for that. Now to get some parts pulled together.

John C