Webra 25

Tell us what you do to get the best performance from your engines.

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Air Scharnell
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Webra 25

Post by Air Scharnell »

Wondering if anyone else has a Webra that is really touchy, on the high end needle valve settings?
Running a Kombat Kan and a MA 9x4

Any info would be helpfull.

Frank
Hat Trick
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Post by Hat Trick »

Mine aren't sensative at all. I always try to take off with it set pretty rich.
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Air Scharnell
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Post by Air Scharnell »

Thanks for the input HT.
I was just wondering, iv'e got a 2nd Webra that plays the same way.
It looks like it has a newer needle valve on it.
Well maybe Horizon service can fix it, since it took a HARD dirt nap.
It doesnt turn very well now :(
Thats combat.

Thanks again,

Frank
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Post by Hat Trick »

You might try a piece of fuel line over the needle to seat junction. You seal may not be good there. Also make sure the carb to case seal is good. Backplate and head bolts are tight.
sgilkey
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Post by sgilkey »

check the head bolts! mine do loosen occaisionally, especially when new. our webras are very sensitive on the HS needle as well. maybe it has somehting to do with can placement. once in the air and set right, they are very consistent though.
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Air Scharnell
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Post by Air Scharnell »

Thanks for the input on yours Scott.
Thanks again HT as well.
I started too have same idea on the high needle this last meet.
For either fuel tubing or heat shrink over high end.
My sons got touch on the last meet as well.
Head bolts have been ok so far, thou we havent had really hot temps here yet.
As for all the other junctions with bolts or gaskets all have been checked.

Will keep trying.
As for todays run my sons Webra was still touchy.
But you can really HEAR the change when its on the pipe.

Thanks again for all the input.

ps: Mr. Gilkey I have to say I just started reading RC Report.
and truly enjoy your column.


Frank S
sgilkey
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Post by sgilkey »

we have had good luck with the OS 8 plug. when we switched to Powermaster 15% fuel (we were using Ritch's Brew) our Webras really liked it. The HS needle is still quite sensitive but the engine ran much better.
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Air Scharnell
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Post by Air Scharnell »

Thanks for the info Scott,

We have been running our Webra's with an OS 8 or a Thunderbolt #3
So far the TB #3 has had longer life so far. Just switched too the OS8
For fuel we are using Cool Power 25%. Also using Hayes tanks and 1 Dubro on a Go Devil. ALL suction draw. This hasnt seemed too be a problem. being at 6000 ft in Colorado.
We have been using Kombat Kans as well.
My Webra will turn 18.5 K with a MA 9x4
APC 9x4 drops the rpm too 16K.
Havent had a chance too experiment with the NEW APC blades yet.

Thanks again for the info on your fuel of choice, I may trying lowering our Nitro, and change plugs.
SIG has come out with a NEW plug for HEAVY DUTY use our Tuned pipes.
And there not as pricy as OS 8.
Im trying 1 in a OS 25 fx and seems too be working well.

thanks all for your input, better kill this book and go too work.

Frank
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Post by montague »

I've never had a problem with my Webra's being peaky at all.

K&B HP plugs. Mostly Omega 15% fuel, but I've also run some Powermaster, about 22.5% (mixed a gallon of 30% with a gallon of 15%),
and the Webra's loved that stuff.

MAS 9x4 tached over 20k, I'm using either the GRS yellow prop (for 2610) or the APC 9.3x3. Less RPM with the 9.3x3, but big time thrust.
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Post by montague »

Btw, the MAS 9x4 on the Webra with a mousse can is a bad idea. When I did it, I noticed the prop tips were moving all over the place, you could see they weren't tracking right. Lots of noise, not a lot of thrust. That prop just isn't made for that kind of power. Do yourself a favor, run something (APC, GRS, anything) that doesn't flex so much under that much power.
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Air Scharnell
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Post by Air Scharnell »

Thanks Kirk,
We will be giving the NEW APC blades a try by this week-end I hope barring work.
I usually get foaming problems with Omega ? Cool Power slows the foamimg down.
I will try 15% thou. I would hate too burn a piston in our hot summer runs.

Frank
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Post by sgilkey »

It's interesting that some folks find the Webra peaky and others don't. For me, one click of the needle and BAM that sucker jumps on the pipe, one more click and it's too lean. I suspect it has to do with the placement of the can on the header but have not had a chance to experiment. I set my cans based on experimentation i did a long time ago with FXs on a test stand, I moved the can in and out till i got the best rpm. Did not do any in-air testing. I've used this position ever since and it works fine but I suspect there's more opportunity there.... For me, I have always set my can so the end of the outer straight portion (before the end of the can starts tapering in) is 17mm rear of the end of the header. Not all MACS headers are the same length- I don't trim them to a specific length and that might be part of the trouble....

I would avoid the MA prop on the Webra, it is being grossly overspeeded (oversped) in that application. I have not tried the GRS props but have seen others use them and they look very good. I have tried the APC 9.3x3 and 9x3. The 9.3x3 worked very well but when there were several streamers on the wing it seemed to load up and not pull thru turns well. We then tried the 9x3, which revs about the same as the MAS 9x4. The speed is about the same, maybe slightly better, than the MA, and it pulls thru continuous turns better. When loaded up with streamers, the plane still pulled strong. That's a great prop for the Webra (the 9x3 APC).

Our Webras got a lot easier to tune with the use of Powermaster fuel. Before, I was running Ritch's Brew and Sig, which worked fine in our FXs, but the needle was very temperamental on the Webra. it got better with Powermaster, still peaky but not as bad.
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Post by montague »

I only had fuel foaming problems with the Omega a couple of times, and that was always traced back to a hard-mounted fuel tank (probond leaked in to the fuel tank compartment and glued the tank down solid after a repair). I'm using Hayes tanks if that matters.

I'm under the impression that Omega and Cool Power are identical fuels except that Omega has a bit of caster oil (~2-3%) while Omega is 100% synthetic. I'm not certain though.
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Post by sgilkey »

It's been a long time since I checked this with Morgan, but when I pylon raced and we used Morgan fuels (about 8 yrs ago at least)they told me both were 17% oil, Cool Power is 100% synth, Omega is castor/synth blend. I don't know how much castor is in Omega.
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Post by RH »

I had been using the pink Omega fuels and was always fighting foaming problems. Did all the usual remedies with marginal results. I was on the verge of going to bladders last summer when on a fluke I tried some green Cool Power 25% and all foaming went away! Been using it ever since with nary a bubble and several of the rest of us around here are having the same good results. Maybe it's another altitude thing, don't know.

rh
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