Mojo 40/extra sting!!

[notorious_benny]

Yes its just another Mojo, but check out the nice donk!!!!

Motor is a Dubb Jett BSE 0.76L two stroke. BSE stands for Bar Stock Edition, yep thats right the whole shebang is turned from bar stock, even the cylinder fins and head.

Check out the individual signature and numbering on the crankcase

Should turn a 14x4 wide prop at 10,500 rpm's

Weighs 470grams/15.2 ounces including muffler = 10 grams less than an OS 46FX.

Hopefully I will have this model flying within two weeks, I will be able to let you guys know how these lesser known sport motors perform. I am hoping it kicks butt!!!!

[Billy Hell]

I had my hands on one of these at Toledo and it was hard to put down.

[notorious_benny]

I have only ran it on the bench so far Billy. But the guy who I bought it off had it in a Ucando 3d fatty and reckoned it hovered at half throttle.

One thing I can say is its a noisy little bugger on that lite muffler and I can see it's going to take a bit of gettin used too at first tuning wise.

[BubbaGump]

That is a **** load of power. I have friend in Cincy with a webra 50 on a OMP Edge and it hovers at two clicks of power. And it has instant throttle response.

[Wind Junkie]

I'm having some trouble tuning my Jett .76L. The motor starves when I punch out of a hover. It doesn't do this in level flight. No combo of high/lo speed needle settings are good for the whole tank from full to empty. If I set it rich enough so it's good near empty, it's a real dog when it's full.

I wrote to Scott (Texan) on the Pro Bro site and to Dub Jett this weekend. I'm now waiting for Dub's reply.

I think it's because my tank is on the CG (actually, the nose is really short and the tank centered on the CG puts the front of the tank about 2 inches behind the motor cylinder). I even switched to a bubble jett tank but it wasn't any better than the hayes. Hopefully you won't have this problem with your tank on the nose of your Mojo.

I hate to say it, but so far my Saito .82 kick's it's butt, even if it does get really bad gas mileage compared to the .76L and is a couple oz heavier.

[notorious_benny]

Soundls like you have some sort of issue there. Twostrokes in profiles are quite finicky unless you set up your tank well!!

I have had issues running an OS in a previous profile and tracked the problem all the way back to the tank.

[Wind Junkie]

yea, tell me about it

The funny thing is the plane was fine with a Jett 30, an OS .46 FX and a Saito .72. Same airplane, tank -- everything.

It's got to be the carb. Scott said he had problems with high G maneuvers and he got a special oval bore carb for his .76L from Jett.

Even with all the shaking of the 4 stroker and some extra foaming, the consistency is just so much better than with the .76L. On 30% nitro Cooper fuel, it's hard to tell the diff in performance with the same prop as the .76L-- a MAS 13x6 scimitar. I'm only using 15% powermaster in the Jett. The Jett runs smoother, a little louder, but sips the fuel for twice the run time. In the sweet spot of the needles for the .76L, I think the .72 is only marginally better in the low end and not quite as good at the high end. But the .82 takes the ball game with that prop in all aspects except the fuel usage and vibration -- even cost!

I really do hope Dub can figure this out cause I love all the rest of his motors. I must own 7 of them now. I just find it super ironic that he calls it the "hover special" and that's absolutely the ONLY achilles heel I've been able to find about this motor. It will hover, just don't try to punch out of one with an empty tank if the tank isn't on the nose.

Please, if anyone has experience contrary to this, I'd love to hear what you're using.

[YNOT]

I have tried 2 Jett motors on 3D planes and I was dissipointed in both. They SCREAM wide open, however I have been very unhappy with the transition.

Neither were the BSE motor. I am curious of how it will work. Keep us posted.

[Wind Junkie]

This motor is a lot different than the typical Jett. It's designed to turn big props slow.

What really intrigued me was that this motor will turn the same prop at the same RPM as my Saito .72. Think about it -- nearly the same displacement, same RPM. Only the torque characteristics differ.

The Jett .30 I had on there was really only for R&D and that behaved like you're talking about. I've got two of those dragons for combat and those motors like the 10x4 props, but that prop is just too small for a 4.5 lb 3D plane, even if it does have great transition. The air just can't move fast enough through the prop like it does with a bigger prop moving more air slower. Too much "slippage".

I'm now wondering if my .76L isn't broken in yet. That would be possible, but it is just SOO friendly in all other aspects. It idles at ~2100 RPM forever, the transition is breathtaking, and although I haven't measured this yet, it seems to hold the same MAX rpm for as long as I hold the throttle there, and reaches that same max RPM anytime I want. It did this right out of the box!

I had planned to break in the motor in the air by just flying really big pattern loops, cuban eights and other high speed stuff for a week or so, but when I saw this motor idle and behave so good right away, I thought maybe since it was designed to turn at low RPM (~9200 w/ a 13x6 right now), and doesn't feel as "tight" as the racing motors, maybe that long break in wasn't needed. I may be wrong here.

[notorious_benny]

Break in is important on any motor. Jett specifies that the 0.76L be bench run initially.


Here are some pics of the hardware I have decided to use on my Mojo. You think these linkages will be up to the task on a 40 size profile????????

[Boulder]

I don't know benny, I don't you have near enough throw on those surfaces...

[YNOT]

The control horn you have on the rudder is good, however put lock nuts on either side of the linkage. If not it will slip in a short amount of time and your rudder will always be out of trim.

[notorious_benny]

OK I got about 10 flights on the Mojo today. The motor is a screamer but is definitely a little tricky around the midrange.

I get a fantastic low idle and really sharp transition from idle to about 1/2 throttle, then she gets a bit lumpy and rich and can have a tendancy to cut, especially if its been idleing on a long descent ect.

The tank was foaming horribly at the beginning making a consitant tune almost impossible. AFter replacing the cable ties holding the tank on with elastic bands I got five good flights in where I was able to try and get the Jett to transition through the midrange.

At the end of the day I was getting close. I think the top end needle has a fair way to come in yet which would probably explain why it dosnt want to transition in the upper mid range.

It looks like the 13x4 APC is the best prop so far.
Also tried a 14x4 wide blade and a 12.25x3.75 as well. the little prop really screams but gives very fast throttle up.

I think the motor needs a bit more running before trying the big prop, it got hot turning this prop and cut out so I just flew with the little props for the rest of the day.

Power is definitely more than adequate and signifiacanlt more than a 46 on a similar model (as you would hope) you need to be turning the 13x4 to really tap into the potential.

In summary the verdict is still out on the motor. It is definitely a beast I will have to learn to tame. I was becoming increasingly encouraged towards the end of the day though.

On a side note I actually crashed the Mojo today due to a cut out as I transitioned into a hover. It was at what I considered to be a safe height in case it stopeed. The motor did indeed die, but the model did not simple nose over and glide away.

It fell tail first for about 10 feet or maybe more while I watched, with dumb thumbs doing nothing. It wasnt going to flip over nose first!!!! Eventually with a bit of up elevator it flipped to a nose down attitude and with about 2 feet left I let it gain a little speed and pulled to crash land at a 40 degree angle!! No real damage to write about. Dusted her off and kept flying.

[notorious_benny]

Wind Junkie. I didnt notice any inconsistancies between a full tank or an empty tank.
Also once you were in a hover it would hover for minutes on end and then punch out without hesitation.

I only get hesitation when doing really low throttle manouvres like elevator to harriers to hover.

Afler lengthy idleing it will still pick up well initially, but stumbles at above 1/2 throttle. I am sure I will be able to tune this out.
I dont own a tachometer and have been flying my DA 100 for almost 12 months without messing with glow. So my ears arent used to listening to a 2 stroke glow and full noise. I am probably way too rich on the top needle but am still too sacred to wind it in as I am not confident of hearing the engine drop off peak on the lean side.

[SBR_RV]

hey benny wheres your CG?