Dynajet Starting Video

[Eric]

I got a dynajet off of ebay and decided to make a little tutorial video about them, and post some pics.

As usual it decided to thunderstorm so I was kind of rushed and resorted to using some old gas with 2 stroke oil since I couldnt get the methanol to go because of the horrible humidity, and I think the #4 metering jet is way to restrictive for pure methanol, I will have to dig out the old metering jet set I made.

Made a little stainless mounting stand for it, fires up pretty easy despite the 2 stroke oil.

Here are a few pics, I will post a link to the video once its done uploading.

Eric

[Eric]

Ok heres the video

http://www.youtube.com/watch?v=IJqkHJ2zWPY

[Mark]

They sure look pretty when they are new. Nice seams on that one Eric. I was just looking at the difference of the metering jet on my Dynajet compared to the 3 sizes that came with my Bailey Jet. The hole is considerably larger in all three of Earls. Mr. Bailey's manual mentions that methanol does a better job of cooling the head and it is less thermal stress on the reeds and engine. It goes on to say that gasoline has a relatively narrow range of flammability, too rich or too lean, the jet will flame out during maneuvers exceeding the limits. "Narrow fuel/air mixture flammability range may also cause more difficult starting."
Methanol can be fussy too, in hot, humid air as mentioned or very cold days you have to warm up the engine a little. And if you are flying in AMA competition there is that mix of 80% methanol and 20% propylene oxide that is used still I suppose and it's what is recommended for the Bailey Jet too the manual says. Of course we all know you need more fuel flow with methanol, thus a larger metering jet, but if you really want to see the extreme, I just now looked at my Tigerjet metering jet. Man, that's one tiny hole for the gasoline to flow through, just a little dot of a hole! And again, even the smaller Tigerjet is a screamer.
If you have a tire pump Eric, it would be neat to hear a single backfire, sometimes they really sound impressive, not always but just out of the blue when you puff in some air, the sudden report is inspiring. Also, if you can capture some machine-gunning/false starts, those are entertaining too. I think it is funny how so small a jet can frighten uninitiated grown adults, causing them to back up a considerable distance from the roar, or even the backfiring can cause them to anxiously wonder what the heck is going to happen when it starts. ha
One time I was misting methanol in the tail end of my Dynajet just playing around and then lighting the tail and it would weakly bark or burp. This one time though, just holding the jet level in one hand, (so as not to let the little bit of methanol I primed the throat with drip out) and lighting the tail, it caught and reved up quite furiously. Talk about being startled. It's really hard to do because I was never able to repeat it. I think if you corked the tail and sparked it after priming, you might could do a start without using air. I used to start my plumbing pipe jets that way, no starting air. The cork gives you more of an impulse/compression. Just some boring accounts most of you have heard me tell before. When a Dynajet is hot it is often quite easy to restart too, a puff or two of air and it's off and running again.
Great pictures Eric.

[Mark]

A good narrative Eric. You made it look easy as pie.

[noclassmac1972]

Eric you will have to bore out the holes in the flow jector to about 1.5mm and the metering jet will have to be about 1.5mm as well or 58 thou which ever you have to run methanol.
Regards
Robert

[Mark]

I have two packages, one is labeled .057 and the other .058 that came extra with my Bailey Jet. I wonder what size the third metering jet is, the one that came installed in the jet out of curiousity? I guess I could get out some of my drill bits and put the smooth end in the hole to find out?
One time I ran my Tiger Jet on methanol by hooking/slipping a fuel line over the starting air fitting to overcome the too small of metering jet made for gasoline. It ran fine on methanol even with such a ghastly fuel feeding method, all the fuel ingested from the off-to-one-side "air pipe." It wasn't fussy about running at all, even though the port was way larger than it should have been. On my Dynajet the air pipe broke off one day when I tried to unscrew it and the head was still hot. So to run it on methanol, I just slipped a silicone fuel line over the center stalk with the metering jet removed. And I used an air compressor to puff air in, making sure to angle it so that the fuel would get sucked out of the two final exit holes. Methanol isn't very fussy, as long as you give the jet enough of it.

[noclassmac1972]

59 thou Id say!! I cant remember exactly without going trough my bits at home hard to do when you are at work !!

Robert

[Mark]

Here is a crude way I ran methanol in the Dynajet which is made to run on regular gasoline. My old Dynajet manual says to use unleaded gas only. I remember seeing an entire collection of metering jet sizes from some flying group member from Down Under.

[Mark]

Here is a really silly way to run methanol in a Tigerjet but it works fine for a static running. You have to use an air compressor now to puff in air of course because you have taken over that feature to flow fuel instead of air through the blow pipe.

[Mark]

59 thou Id say!! I cant remember exactly without going trough my bits at home hard to do when you are at work !!

Robert

I just unscrewed the one in the Bailey jet and held it next to the other two. To me, seeing which is a thousandth larger or smaller was/is perplexing! I didn't realize the sizes were so close to each other. You should see the Tigerjet metering jet, it's a wonder it can get enough gasoline the metering jet hole is so very small.

[Mark]

Not really worth posting but here's a Bailey, Dynajet, and then Tigerjet metering jet side by side. If you can make it out, the silver metering jet in the middle is the Dynajet's. You can barely see the Tigerjet leaning into the Dynajet part. It was hard to hold them straight.

[Eric]

Hey Robert,
I made an entire set through the whole dynajet metering jet size ranges years ago when I was only focusing on valved engines.... cant find it for the life of me though.

I just realized I know where I have a meth flowjector and high flow metering jet... Cause this #4 metering jet is fused into the steel flowjector and I dont want to destroy it just yet.

Actually ran the engine with one of your valves, looks good sofar. I'll probably try torturing them a bit more tomorrow.


Mark,
The methanol is such a pain in this humidity, walking around feels more like swimming. I'll probably run a mix tomorrow 90 meth 10 gas to give it a little kick for starting.

Having an engine like that not connected to anything just running in your hands must be exciting I was happy when I pinched the fuel line and pulled it up, that the engine just kept on going and sucked down what was left of the fuel in the fuel line like nothing was wrong.... though a bit of a delay for shutoff response....


Thanks for all the kind words

Eric

[dynajetjerry]

Eric,

I congratulate you on a most excellent and informative video. However, may I offer a suggestion?

You would be well-advised to install the anchoring hose clamp on the p-j further forward, perhaps in front of the spark plug. The reason is that where you placed it, the 1500F temperature renders the combustion chamber very soft and weak, as well as causing a loosening due to the heat-caused expansion of the tube. As can be seen on your video, the front remains much cooler and stronger.

I don't recall the size of the gasoline orifice in the Tigerjet but can give you numbers for stock D-J metering jets: #2 is U. S. #63 drill bit, .037 in.;
#3 is #62 bit, .038 in.; #4 (standard) is #61 bit, .039 in.; #5 is #60 bit, .040 in.; #6 is # 59 bit, .041 in. I think the stock cross hole in the flojector is the same as a #5 or 6 metering jet.

Jerry

[Eric]

Thanks Jerry,
I'll put the clamp on the front next time, also I think Im going to run it with a leaf blower blowing air over it.

Eric

[francisco]

hi

in my alpha (pl-35) and starjet, the inyector its comose for 4 hole of .019 (0,5mm) and he running very good... but.... if the holes (2) were of .039 to be runing more easy??

tanks

F. cooreman