Yet another Wyvern

[ThomasB]

At last, the Wyvern runs, well sort of.... It has been built to the original prints dating back to 1989. Where have the years gone.
It is proving difficult to start but once warmed up it will only run fairly quickly. If the lifting pin is operated running is improved. As long
the air lever is open to near full it seems to keep going. It does look like a fuel issue to me. Ignition is a CDI unit and appears to be working OK.
The plan is to run it on Propane, there is no intention to use liquid fuel. Any advice would be appreciated.

Thank you,

Thomas

[Kim]

Very nice!  Congratulations on getting it to run!

Are you going to paint it, or leave it bare metal?

And do we get to see a video of it running?

Kim

[Chipswitheverything]

This is a handsome looking engine, must be satisfying to see it come to completion and running stage. I'd with Kim in wondering if the engine will be receiving a paint job later on? Just looked back at the earlier posts about the build, I'd say that your progress has not been that slow compared with a few of my projects!  Dave

[ThomasB]

Thank you, yes the plan is to paint which will be dark green and black, traditional maybe.
Once I can get it to run better that is. The other little thing is that the crankshaft has too much lateral clearance.
The bearing fits are good, so it's either longer main bearings or or shim possibly.
A video may follow later...

Thomas

[Alyn Foundry]

Hi Thomas.
Your engine will run on both liquid and gaseous fuels equally well. You can have the option of either Butane or Propane as it has spark ignition. There are quite a few kits available with a small tank and control valve available for using the refillable lighter gas. Alternatively you can opt for the standard Propane bottle and fixed regulator.

You will need to pipe the gas into the fuel inlet needle valve and set your ignition around the TDC mark. You won’t need a great pressure, anywhere between 28 & 32 mBar. Starting from the closed needle valve, open it up a tiny bit at a time until the engine fires up. Once ticking over you can advance the ignition and set the speed to your liking. Unlike Petrol, Butane and Propane have a very narrow range of active combustion so a lot of patience is needed to find the sweet spot. Once found it’s just a matter of marking the control valve.

Photo of one of my Robinson hot air engines using the tank I mentioned earlier.

   Graham.

[ThomasB]

Thank you for the advice, I have found a couple of things wrong with the carburetor, the lift valve was oversize and the choke bore 6mm rather than 1/4" so these were corrected.
That did not really make much difference, so the Demand regulator was taken off and piped directly via a fine stop valve from a Propane/Butane mix canister.
A whisper of gas rather than the half bar delivered by the big regulator. Now it runs... there is some work needed on the Crank namely too much end float also
tightening the flywheel nut has resulted in the half speed gear rubbing against the boss, not a good thing. 

Thomas