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HelicopterGasser Model RC HelicoptersEngines › Zenoah 30.5CC and Walbro WT 990 problem
10-08-2013 12:05 AM  4 years agoPost 1
yuriy

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Canada

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Hi guys.I need your suggestion regarding my Zenoah 30.5 modified engine and WT 990 carb. When I start the engine it runs with high RPM and after 15-30 sec.go to idle.When I move the throttle stick for high RPM and return back for idling, it's take about 10 sec.What kind of problem is with this carb? Low/high needles set up perfectly.No air leaking from carb. I didn't have any problems with Walbro WT 643.May be something wrong with WT990 carb?Thanks

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10-08-2013 01:41 AM  4 years agoPost 2
fastflyer20

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N. Tonawanda, NY

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That indicates it is lean

How many turns are the needles set at?
What muffler and air filter is on it?
What is the color of the plug?
What is your idle 2 engine rpm?

The 30.5 is a bear and needs lots of fuel.I broke too many helis with them!

Tom
CAUTION - my posts are based on my experiences, yours may be different.

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10-08-2013 02:10 AM  4 years agoPost 3
yuriy

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Canada

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L-1 1/4
H-1 1/2
I use a tune pipe.Plug dark and wet.

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10-08-2013 03:22 AM  4 years agoPost 4
fastflyer20

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N. Tonawanda, NY

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Did you have it running OK with a muffler?

Was the pipe length tuned to the engine/RPMs?

Tom
CAUTION - my posts are based on my experiences, yours may be different.

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10-08-2013 03:33 AM  4 years agoPost 5
yuriy

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Canada

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The same problem with the muffler.Its original tune pipe for Zenoah 26-30cc engine from Japan.I think it's some problem with carburetor.Lenght total 24 inc.Specification:
Powerful and Silent. This funtech muffler will increase the payload possibility.

Standard payload of GSR260Z is 5.5KG but with this tuned pipe, it increased to 12KG!

This pipe also produces less noise.

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10-08-2013 05:03 AM  4 years agoPost 6
RM3

rrElite Veteran

Killeen, Texas - USA

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I think your tuned pipe is the problem.

Tuned pipes are tuned to specific engine RPMs based on header length, temp and engine RPM among various other things.

Honestly for the everyday sport and most 3D "gasser" fliers, tuned pipes are more of a pain than a benefit.

There are those that love them, but put a ton of work into getting them to work just right.

when you test with a muffler use a regular one like the Century V2 or V5 or even a Zimmerman or Hatori...the stock can or "Box" muffler kills your HP alot at high RPMs and is the absolute worst in terms of performance tuning and consistant power. They work OK for planes cause of the lower RPMs on the props.

showing a preference will only get you into trouble, 90% of everything is crap...

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10-08-2013 05:11 AM  4 years agoPost 7
yuriy

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Canada

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Thanks.I will try tomorrow another carb. Will see.Also will try stock muffler.

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10-08-2013 06:02 AM  4 years agoPost 8
geomecc

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Long Island ,NY

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it's funny I have carb problems but needles are tuned perfectly. how do u know they perfect with an engine that not running properly? not tryin to be rude but thought the first statement of the thread was funny

R I P Roman Jr. Team SKOOKUM SRW EFC

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10-08-2013 12:59 PM  4 years agoPost 9
fastflyer20

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N. Tonawanda, NY

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I would put a muffler on it and get it running correctly. Tuned pipes are in a different league.

My experience with the 30.5 in a heli running mufflers was that the V2 needed to be drilled out and the RJX needed to be modified to move enough air for this engine to run correctly. It liked 13,000 - 13,500 as max RPM's and did produce lots of torque, and vibes too.

There is a post on another site where a few bought 30.5's from a car modifier thinking they would have the biggest baddest engines and ended up ripping the tails apart including breaking bolts and the boom in half, so keep an eye on the airframe.

Tom
CAUTION - my posts are based on my experiences, yours may be different.

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10-08-2013 01:51 PM  4 years agoPost 10
tomthumb

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Glendora California

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Check the throttle plate in the carb. The screw may be loose.

LOWER LOWER DOH!!!

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10-08-2013 10:20 PM  4 years agoPost 11
Toddc72

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weed,ca-usa

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What isolator block are you using? The stock one or an after market aluminum one? The factory blocks are junk and warp if you look at them funny. If it is the stock iso block behind the carb? Take it off and check it on a flat surface. If it warped replace it.

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HelicopterGasser Model RC HelicoptersEngines › Zenoah 30.5CC and Walbro WT 990 problem
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