MT 35 Looks Like a Winner
05-14-2010, 07:51 AM
#227
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RE: MT 35 Looks Like a Winner
I've got my Mt-35 mounted on a Slipstream MXS and have run a couple of tanks of fuel through it. The motor transitions well and top end is strong. However, it will not idle reliably below 2,000 rpm and intermittently surges (rpm's increase) at all throttle positions below wot. I've checked for air leaks and don't think I have any. Any suggestions as to what else may be causing this would be appreciated.
05-14-2010, 05:36 PM
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RE: MT 35 Looks Like a Winner
Yep mine did the same thing. More than likely tuning/ or timing thing. I was a Muncie a few weeks ago at the AMA field on their beautiful tar runway. The surging makes for an interesting taxi. Thing will get away on you fast on tar. Give Jody call. I will stick to just flying rather than try to figure that stuff out. Oh.. what.. I'm no good at that either. Hmm.
05-16-2010, 08:12 PM
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RE: MT 35 Looks Like a Winner
Yep it was the user. If you are currently have problems with your gas engine. Sometimes it helps to swap out the user for good used one and usually you will see exponential gains in engine power and performance. Your not going to find them on ebay and no hobby city doesn't carry them. Look through the thread and you will find one that will fit your engine. Check out my result... my rpm's went up nearly 800 rpms. Amazing. LOL 
05-20-2010, 05:03 PM
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RE: MT 35 Looks Like a Winner
ORIGINAL: mbinkley
Does MT offer a fiberglass reed set for the MT 70? Or is it already fiberglass.
Thanks Mike
Does MT offer a fiberglass reed set for the MT 70? Or is it already fiberglass.
Thanks Mike
Did your 70 come fully assembled with the carb installed?
05-20-2010, 06:07 PM
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RE: MT 35 Looks Like a Winner
In my earlier post on page nine I indicated that my MT-35 had a fuel draw problem but it appeared to have cleared up and was running at 7000 rpm so I took the plane to the field to fly it and refine the tuning. Well, the fuel draw problem returned. It would pop a few times after a choke but would not run. I could feel the kick back through the heavy leather glove I was wearing and my wife told me to quit it and she handed me my chicken stick which is 1.125 dia, 10-inch long piece of blue silicone tubing with no core inside. When I continued flipping there was a vicious kick back that took a 3-inch piece of wood off the trailing edge of my shiny new Xoar 19 3DA prop.
Now I thought it was time to check the ignition timing so went out and bought an advanced designed piston stop, commonly known as a bolt and nut at Ace Hardware. I also bought those beeping, flashing and buzzing ignition testing and timing toys that RC Extreme Power sells as a combo package. I found that the timing was set at 34 deg BTDC so I reset it to 28 deg. I also replaced the spark plug with a genuine NGK CM-6 which I found locally at Advanced Auto Parts and set the gap to .020. The original plug was set to .010.
I don't believe any of that cured the fuel draw problem but the engine was much gentler and when I finally got it started and adjusted the needles I did a 2-minute full throttle blast. It has been drawing fuel when choked and starting easily ever since. So far, I've adjusted the top end to 7200+ and adjusted the low needle to remove 4-cycling from the mid range. Throttle response is very good. The idle is a bit bumpy at 1800 rpm. The engine starts easily hot or cold but if you let it set for awhile it needs to be re-choked.
Should I be worried that the fuel draw gremlin will return?
Now I thought it was time to check the ignition timing so went out and bought an advanced designed piston stop, commonly known as a bolt and nut at Ace Hardware. I also bought those beeping, flashing and buzzing ignition testing and timing toys that RC Extreme Power sells as a combo package. I found that the timing was set at 34 deg BTDC so I reset it to 28 deg. I also replaced the spark plug with a genuine NGK CM-6 which I found locally at Advanced Auto Parts and set the gap to .020. The original plug was set to .010.
I don't believe any of that cured the fuel draw problem but the engine was much gentler and when I finally got it started and adjusted the needles I did a 2-minute full throttle blast. It has been drawing fuel when choked and starting easily ever since. So far, I've adjusted the top end to 7200+ and adjusted the low needle to remove 4-cycling from the mid range. Throttle response is very good. The idle is a bit bumpy at 1800 rpm. The engine starts easily hot or cold but if you let it set for awhile it needs to be re-choked.
Should I be worried that the fuel draw gremlin will return?
05-24-2010, 09:47 PM
#245
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RE: MT 35 Looks Like a Winner
Maiden mine yesterday in my Slipstream 30cc MXS. Had to keep the idle high or it would cut off. Still need to tweak the low end as it gurgles a lot at mid throttle.
Overall I'm very pleased with the motor. Just need to get it tuned and run a lot more fuel through it.
Overall I'm very pleased with the motor. Just need to get it tuned and run a lot more fuel through it.
05-26-2010, 06:56 PM
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RE: MT 35 Looks Like a Winner
I took the MT-35 powered Ultra RC Giles to the field a couple of days ago and sure as heck it refused to draw fuel when choked. I squirted gas into the carb air intake and the engine fired up immediately. It appears that I'll have to use solder to plug the air bleed hole in the choke plate to get a good choking action because the engine likes a wet start.
I flew the plane once and the engine ran reliably and didn't quit at idle but it did go rich in the mid range but never threatened to quit. The vertical climb was unlimited but not spectacular on this 10.75 pound plane. (By the way, the plane is 1/2 pound lighter than is was when the piped MVVS 26cc was installed.) It was a hot day, around 90 deg, and the rpm was in the high 6000's which was down from the 7200+ rpm that was achieved last week. I didn't readjust it, I just flew it.
Since I was concerned about engine vibration I checked the Xoar 19 3DA prop before I left home and found that it was out of balance. I balanced it by spraying Krylon crystal clear acrylic on the back of the light blade and it seems to have had no effect on the prop finish. It made a big difference as it reduced the vibration at high rpm but made no noticeable difference at idle. The airframe may be resonant somewhere in the idle rpm range and amplifying the engine vibes.
I believe there is hope for this plane and engine combination.
In a quiet moment my pit crew, who is my wife, asked me, "why did you want a gas engine for this plane"? I thought really fast and replied, "well, er, because I like engines and I just wanted to tinker with a gas engine". lol.
I flew the plane once and the engine ran reliably and didn't quit at idle but it did go rich in the mid range but never threatened to quit. The vertical climb was unlimited but not spectacular on this 10.75 pound plane. (By the way, the plane is 1/2 pound lighter than is was when the piped MVVS 26cc was installed.) It was a hot day, around 90 deg, and the rpm was in the high 6000's which was down from the 7200+ rpm that was achieved last week. I didn't readjust it, I just flew it.
Since I was concerned about engine vibration I checked the Xoar 19 3DA prop before I left home and found that it was out of balance. I balanced it by spraying Krylon crystal clear acrylic on the back of the light blade and it seems to have had no effect on the prop finish. It made a big difference as it reduced the vibration at high rpm but made no noticeable difference at idle. The airframe may be resonant somewhere in the idle rpm range and amplifying the engine vibes.
I believe there is hope for this plane and engine combination.
In a quiet moment my pit crew, who is my wife, asked me, "why did you want a gas engine for this plane"? I thought really fast and replied, "well, er, because I like engines and I just wanted to tinker with a gas engine". lol.
05-27-2010, 11:57 PM
#249
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RE: MT 35 Looks Like a Winner
I don't use a degree wheel either these days.
How I do it is a method taught to me by a certain Grumpy old Ignition guy (Sorry Ralph).
I measure the diameter of the prop hub, multiply that by 0.244 and that is the 28 degree measurement around the circumference of the hub - simple as that. Place a pencil mark on the hub at that point and you are ready to time away.
I do of course have access to acouple of Dial indicators that screw into the plug holes - one for the straight plugs and a lever one for the angled plugs. - makes it much easier to get TDC that way.
For Rocketman
I just tell mine to get back in the kitchen where she belongs and stop asking questions - luckily she never listens to me anyway or I would be in a bunch of trouble
How I do it is a method taught to me by a certain Grumpy old Ignition guy (Sorry Ralph).
I measure the diameter of the prop hub, multiply that by 0.244 and that is the 28 degree measurement around the circumference of the hub - simple as that. Place a pencil mark on the hub at that point and you are ready to time away.
I do of course have access to acouple of Dial indicators that screw into the plug holes - one for the straight plugs and a lever one for the angled plugs. - makes it much easier to get TDC that way.
For Rocketman
I just tell mine to get back in the kitchen where she belongs and stop asking questions - luckily she never listens to me anyway or I would be in a bunch of trouble