Engine runs lean, old Webra 61. Who can help?

[ken hendry]

Hi Urs
    Articles by Clarence Lee in RCM Dec 82 and Robert Munn April 81 about
lean running Webras with Dynamix carbs confirm Tonys description of the
metering orfice position and also the problem of the size of fuel passages
entering the carb- the fuel nipple and following passages. My copy of the
Lee article has faded but I remember drilling our some of these passages to
make the needle allow enough fuel thru to be able to richen the mixture.
Maybe you know someone who has a good collection of RCM?
Ken
----- Original Message -----
From: "Urs Baertschiger" <ursbaertschiger at hotmail.com>
To: <discussion at nsrca.org>
Sent: Monday, December 01, 2003 4:59 AM
Subject: Re: Engine runs lean, old Webra 61. Who can help?


> Thanks again to all who offered help. - Due to poor weather and
temperatures
> below freezing point I didn't do any test runs during the weekend. If
> weather conditions improve a bit I shall try in the course of this week.
>
> Dave: Sorry, forgot to mention that. The pipe was the very first thing I
> checked and I keep watching it. No clogging, no loose baffle. Compared it
> with a almost new Hatori original I can't notice any difference in back
> pressure.
> Tank center line is about 1/2" above the needle valve. Hence I didn't
supply
> pipe pressure to the tank thinking this wasn't necessary for test runs on
> the ground.
> Lean idling and midrange due to worn brass bar/sleeve are known as you
> mention it, but so far I never noticed any impact on full throttle.
> As I disassembled the carb I had checked the fuel metering slot very
> carefully. It is OK.
> At present another Dynamix carb is fitted to the engine but, as stated
> before, the problem is exactly the same.
>
>
> Del: Yes, I think you are right. There is definitely a feeding problem. I
> sure do what Tony suggested. A check indicated that the carb was and still
> is set up as he said.
> Fuel lines are of max. diam. I can fit. - You don't sound insulting at
all.
> I very much appreciate your comments.
>
> Nedim: Thanks, good to know that the combination Dynamix carb and pipe
> pressure doesn't work. So I am not going to try that again. Also, since
you
> experienced pump problems on these engines I certainly will wach and check
> the pump as you say. The only thing that amazes me a bit is the fact that
in
> all these years past we never had a failing pump. Hence I'd never expected
> the pump to be a problem. But there again, it's been a long time ago and
> this engine hasn't been run for years in between.
>
>
> Many thanks again and kind regards
>
> Urs
> NSRCA #3069
>
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