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Mar 05, 2019, 08:59 AM
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Irvine 150 not rich enough

I picked up a nib Irvine 150 and in running it in and it won't go rich enough to find the break between four stroke and two stroke. Most two strokes I've had would four stroke when the high speed needle is opened, this one won't, had it opened to 7 turns. The instructions say start at 3 turn and turn in from there. It's not lean at 3 turns but it's not far from peaked. I like to find the two stroke four stroke break so
I know I have it good and rich for run in. With the high speed needle 3 to 7 turns out it would turn a ma 16/8 in the low to mid 8000 range and a zinger 18/6-10 low to mid 7000 with not much change as I turned it in or out from 3 to 7. As I turned it in past 3 I could get it to move toward peak. I was using 10% nitro, 20% oil, of which 20% was caster. I checked to tank and lines and carb for blockages and found none, I'm using medium fuel line. Probably the carb just won't pass enough of this fuel (10% nitro) to make it 4 stroke and I shouldn't be concerned as it's already had a tank through it and it runs pretty good. My only other experience with a glow engine this large was a satio 180 and that would go pleanty rich all though I don't know if you would call if 4 stroking, cause it's always 4 stroking. Just wanted to know what others think and if possibly my presumptions are correct (just won't pass enough fuel to 4 stroke).
Thanks Phil
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Mar 05, 2019, 09:54 AM
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pilotpete2's Avatar
I have no experience with Irvine engines, but assuming (yeah, I know) there is a low speed needle and it's not an air bleed carb. The LS needle could be turned in too far and affecting the high end.
Since the engine is NIB, there could be a bit of foreign material or glop in the carb. Take a short piece of clean fuel tubing (I hate the taste of glow fuel) and gently pressurise the line with the carb barrel open, then adjust the HS needle listening for the change in air flow. The increase in airflow should be noticeable as you open the needle.
Good luck,
Mar 05, 2019, 11:09 AM
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I TOBOR's Avatar
Backing the LS needle out one full turn should cure that, after verifying set LS needle for best transition.
Mar 05, 2019, 11:53 AM
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Thread OP
Thanks for the replies. Already turned the low speed out till it was well clear of the slot and took the carb off and blew through everything. I'm still thinking that the 10% nitro and a cold day about 35f the carb just couldn't pass enough fuel for it to four stroke.
Mar 05, 2019, 12:21 PM
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what plug? is there a head shim?
Mar 05, 2019, 12:31 PM
Sticks, Tissue & old Diesels
brokenenglish's Avatar
If it's NIB, why don't you just follow the setting up instructions in the box?
That's all I've ever done, and my Irvines run great. I must own about 8 or 10 (I haven't counted) and I'm currently flying 3.
Mar 05, 2019, 04:55 PM
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It has the idle bar plug that came with it. I did read and follow the instructions and the engine runs fine. I just found it not common to not be able to richen the high speed needle to make the engine 4 stroke. I picked up a gallon of fai fuel today so I can see how it runs on 0, 5, and 10% nitro. Always nice to be able to run a engine on less nitro. Thanks again for your replies. Phil
Mar 05, 2019, 05:42 PM
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As long as you don't allow the engine to overheat there's no need to run it so rich it 4 strokes. I ran in my Irvines (25,46,53 and 72) as per the book, one tank on the ground and then flew them. Long time since they were run in, but my 53 which had not been run for several years was recently put in a Astro Hog, started straight up and runs well on 0% nitro, synthetic (17% I think)
Mar 06, 2019, 03:25 PM
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Originally Posted by FrankS
As long as you don't allow the engine to overheat there's no need to run it so rich it 4 strokes. I ran in my Irvines (25,46,53 and 72) as per the book, one tank on the ground and then flew them. Long time since they were run in, but my 53 which had not been run for several years was recently put in a Astro Hog, started straight up and runs well on 0% nitro, synthetic (17% I think)
Great plane, always wanted an Astro Hog. They take you back. I do understand there is no need to 4 stroke it. I broke it in about 4 turns out never got above 165f the hottest part of the head, 15oz so I'm probably good to go. I'm still going to fool with it on the stand to see how it runs on low or no nitro.
Thanks Phil
Last edited by 4strokephil; Mar 06, 2019 at 04:05 PM.
Mar 07, 2019, 04:40 PM
UAS Pilot - FAA# *******HRK
CryHavoc's Avatar
I know it sounds far fetched but I had the same problem with an Enya .50CX. I just couldn't get it rich enough. It wasn't exactly lean so I tried to fly it. As soon it got airborne it unloaded, the RPMs went up and then it went too lean. Killed it and brought it in. Went through the same rigamarole you went through with the fuel tank, lines, needle valve thinking there was a blockage or something. At one point on the bench, all of a sudden it went slobbering rich. But as soon as I pinched the fuel line to start tuning the needle it did the lean thing again. Every once in a while I could make it do it again but it wouldn't stay. Throttle down and back up and it would do the lean thing again. Got to thinking about it and surmised that maybe the fuel line dia was too small. Surface tension of the fuel (YS20-20 fuel) was too much but every now and then it would break loose. It just wouldn't flow enough so I broke down and redid the fuel tank and feed line with a larger diameter. Bingo! problem solved. With a big engine like a 1.50 I would suspect that medium tubing is just too small.

I drilled out one of the Sullivan fuel tank cap assemblies to take a 3/16" OD fuel tube. (like in the pic below). That let me run the larger fuel tubing to the carb.

Last edited by CryHavoc; Mar 07, 2019 at 04:46 PM.
Mar 08, 2019, 08:20 PM
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Thread OP
Mike, I think you hit it. Today I blew everything out with compressed are and put a tank on the stand that had larger lines, then I could get the engine to richen up and four stroke. The tank was from a big super tigre I was fooling with a couple years ago. For a while I was hoping I didn't have another super tigre 3250. That gave me real headaches, the carb just wasn't right for the engine. I also found that the piece of 1/8 brass tubing on the end of the syringe I was using pump fuel in the tank had a sharp edge and it was peeling the inside of the silicone line I had on the tank, actually blew little pieces of silicone out of the lines into a paper cup with compressed air. At times a little flap would plug the line and you could hardly force fuel in with a syringe. When you blew through the lines with your mouth they seemed fine, but when you forced fuel through with the syringe they acted different. This one really had me going. Now on to seeing how this big glow engine runs.
Last edited by 4strokephil; Mar 08, 2019 at 08:31 PM.

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