Discussion in 'Engines' started by rick dazzler, Dec 18, 2011.
Well, after waiting and waiting and waiting... TWO days my motor is here!
I have questions- IS it possible to rotate the carb/ isolator block/ reed valve block 180* from the stock position? As it sits it is on the opposite side of the carb from the DA-100 I have in my plane now. I can use a longer pulse line if I can rotate the carb itself-- but I really really don't want to move my throttle servo, push rod, etc. to the other side of the airplane...
Yes It can be rotated however keep pulse line length to a minimal if you just rotate the carb. The fuel line inlet will be somewhat awkward as I don't think you can rotate it back to fire wall. Tom or Milton might know that answer. I apologize for the 2 day delivery time.
The fuel inlet fitting on the WJ-71 can easily be rotated to whatever position you need. I would recommend rotating the ambidextrous intake and reeds with the carb.
Yes it can be rotated but there are two thing that you will run into by doing this.
First as Justin said is the fuel inlet tube, It is pressed in and can be rotated but I have seen them break while trying to do it.
Second is air prop blast will be hitting the pump diagram and you will need to cover it with something so it will not effect the pump diagram in the carb.
I would suggest leaving it as it is and make the modification needed to make it work.
Some Walbro carb shafts can be taken out and put in from the other side. Not sure on the 71 carb...
How come JC didn't drill the carb bolt holes to make the shaft parallel to the cylinders ?
This is what I was hoping for. I'm just not motivated to re-do the inside of the airframe- I'm going to need to make a new throttle linkage anyway, but that's better then the alternatives. I suppose there is no substitute for actually taking it apart and rotating the reed block. I'm a little nervous about rotating the fuel inlet, so the fuel line will just make a U turn. I will block/ redirect the hole in the cowl so the airstream does not interfere with the carb diaphragm.
Thanks for the help guys-
Side by side with DA-100
Well, got the Cub out to the field today-
SO, the first start- was a bitch. I wore my arm out three times before we got it to fire. Then it only ran a few seconds and died. I progressively rich'nd the needles to about 2 turns out before she started idling and spooling up. I ran the high end needle out until it was barely running, then leaned it just so it would run WOT with a burble and went flying. I ended up covering one of the holes in the cowling just to make sure the slipstream wasn't effecting the pump diaphragm. I'm turning the same NX G3 27X10 I had on the 100. I ran the tank dry 3 out of 4 flights, and burned an entire gallon for almost an hour of flight time. First couple flights were not very peppy, but the engine started just fine between flights, and it is already idling very reliably. By the 4th flight, even running rich as hell it's putting out more power then my freshly broken in DA-100. It's not ripping the prop since she's running so fat, but that's fine with me! This engine already inspires confidence, and I look forward to more flight time! And, of course Mr. Bowmans contribution.:rolleyes2:
Oh- running WOT and super rich I drained a 32oz tank in 11 minutes flat... And I mean EMPTY! Good thing that Cub likes to glide!
Nice Cub, Who makes it.
I have been looking for a 1/3 scale to stick one of the 120cc in.
Too bad you're so far away. I have a World Models 1/3 Cub still new in the box in California.
Time to work those needles in for a little better tune. Better for the rings, the engine, and your self confidence Congrats!
That is the problem, Every time I find a deal on one they are 3,000 miles away. LOL
Will be at Joe Nall next week and maybe I can find a deal on one there
This Cub flies awesome- inverted 45 up line it's literally hands off! I recommend them to anyone! I will dial in those needles a little now that I've got some gas through it. I just didn't want to cook it first day out. Thanks TOM.
Milton- It's World Models. For ~$750.00 you can't beat it!
Mr Bowman is a very busy man, he promises to have them done sometime soon..... The cub looks great! Thanks for sharing.
Over the last couple day's I've put almost three more gallons through the motor. Mostly practicing IMAC, but today was special. The wind dropped, and it was time to hover! I don't have any RPM readings. The 27X10 is not ripping at full throttle, but I have the high end fat enough the engine is barely peaking if that makes any sense- I'm sure I can lean it at least 1/8-1/4 turn after it's broken in.
The Cub is listed at 28#'s on the World Models site. This plane has got to weigh well over 30#'s. The wings are crazy heavy. I am able to pull out of a hover now- and I'm flying a mile high! The air is thin up here! With the DA-100 WOT would keep it from descending, but it had nothing left to give. The JC can hover at 1/2-2/3 throttle, and pull out slowly at full throttle.
I haven't learned how to pop it up into a hover without gaining 50', so after it stopped climbing I started torque rolling- with authority (a truly new development) and tail-sliding slowly toward the wheat in the field before I arrested the descent. I pulled vertically about 20' before I pushed the nose over and flew out. The motor didn't fade at all in the time I had the plane hovering, which was almost a minute.
When I can lean it a bit more, and it breaks in I'm sure it will keep getting better. I really am looking forward to demo-ing the Bowman products... With a little compression boost I think this engine could be tremendous.
Oh- we had a radar gun- 81 MPH wot and level! Faster then the real thing!
I've got another two gallons through the engine so far. 8 flights last time I had it out. I had some ignition trouble, but it was unrelated to the RcExcel ignition itself. Turns out I had a loose connection on my regulator. So, following Rob Ritchey's advice from Smart fly I dropped my on/off switch. I decided to drop the regulator and am now using an A123 with voltage dropping diode to bring it down to ~5.2V under a 1 amp load.
This engine is starting to come alive- I have an IMAC contest tomorrow, and I'm going to tune the motor for the last time before my Bowman rings come in. I will try to tach it and put some numbers down for you number guys. Let me tell you- when I fly the freestyle tomorrow and it's time to pull out of a hover with my 144" Super Cub@ 5,280'- that will be the true test!
I want to drop a personal note here- for some reason the prop washer on my engine came with a diameter .050" larger than my DA's. I drilled my prop a skootch bigger- something like 7/64" I believe, and now the prop bolts lined up fine. That said, Justin at Vital-RC.com is not only sending me a new hub and washer (I didn't ask for one) he's also sending me a new pair O jugs (didn't ask for them either) with the Bowman rings we ordered so we can make an apples to apples comparison of the power difference between the stock rings after being broken in, and a motor that started out with Bowman rings. I think this is terrific. Anyone in the hobby business knows how tight margins are, and that most of the time it's a thankless job. Well, Justin, THANK YOU for taking such good care of me! I'm looking forward to getting some numbers tomorrow, and will be installing the new jugs and rings as soon as they arrive!
I am glad I could help ! Hope you do really well in the competition. Id love to see how the cub does at a mile high, post a video!
Flew the Cub in the IMAC contest today- the engine rean great, and idled down enough to sound like an idling Harley. In the freestyle it had enough power to pull out of a hover, do a KE loop, and made lots of fast fun passes. I leaned the motor out after about 8 gallons of break in fuel and we got 5,750 RPM with an NX G3 27X10 @ 5,000', with a density altitude closer to 7K'.
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