Webra 160 Problem

[Dean Pappas]

Emory,
Lengthen the pipe. It widens the sweet-spot, at the expense of all-out power in level flight.
If the sweet-spot is very narrow, you may even be too short for best power in the vertical.
Actually, there is a best length for horsepower after a two or three seconds of warmup in the vertical climb,
and just a quarter or so of inch longer will produce better grunt for the first two seconds of climb.
That's the length I usually prefer.
Also try this test: fly at wide open throttle for a good four or five Mississippi count.
If the engine does not go just a little bit rich, lengthen the pipe a quarter inch.
If the engine goes solidly rich, then that's too long.
Alternatively ...
Sometimes a hotter plug allows you to run richer.
 
Hope this helps,
 

Dean Pappas 
Sr. Design Engineer 
Kodeos Communications 
111 Corporate Blvd. 
South Plainfield, N.J. 07080 
(908) 222-7817 phone 
(908) 222-2392 fax 
d.pappas at kodeos.com 

-----Original Message-----
From: discussion-request at nsrca.org [mailto:discussion-request at nsrca.org]On Behalf Of Emory Schroeter
Sent: Tuesday, February 15, 2005 12:54 PM
To: discussion at nsrca.org
Subject: Re: Webra 160 Problem


OK Matt and others,
 
I have a question also. I have two Webra 1.60's with the MC carbs that do run well. The only thing I don't like is that the adjustment seems real critical (there is a small window from lean to rich). How can I adjust the engine or pipe to make that window larger so that I am not so close to being too lean? Do I need to change the pipe length or increase the pump pressure? Here is the set-up that I am running...
 
20% Cool Power fuel
Greve pipe set at 31 to 31.5 inches (measured from glow plug to rear of pipe where the stinger starts)
 
What do you all think?
 
Thanks, Emory Schroeter

----- Original Message ----- 
From: Rcmaster199 at aol.com 
To: discussion at nsrca.org 
Sent: Tuesday, February 15, 2005 11:30 AM
Subject: Webra 160 Problem


Hey folks, thought I'd pass on a problem I experienced with my new 160 this past weekend and share the apparent solution.
 
Extremely strong engine, easy starting just like its small brother. However, it did something very annoying this past weekend. Rich running on theground and for the first couple passes around the field. But after about a minute of running, the moment I would point the nose up at partial throttle, the engine would sag to lean, and then catch and run fine again. It did this continuously at partial throttle but not at full throttle. Oil on the exhaust stinger was darker than I would like to see, indicating lean
 
Fuel delivery was compromised somehow after the first minute or two. I did some playing around with making certain the pump wasn't being blocked from cooling ram air, re-plumbed the tank and everything else, used large bore tubing throughout, etc. Problem persisted.
 
Took a close look at the vent's one-way valve (standard YS valve) and saw that this was sticking. Removed it. To avoid syphoning of fuel through the vent, I looped the vent line and secured with a tie strap forming a P trap.
 
Also increased pump pressure about 1/4 turn. These changes have helped richen the engine to normal levels. 
 
MattK
 
 

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