1965 Ducktwin won't fire

[cajuncook1]

Re: 1965 Ducktwin won't fire

You assess the temperature of the motor on same side of the freeze plug (round identification plug with model and serial number). The reason for this is that the exhaust plate on the opposite side gets blazing hot as well as the cylinder head. You can use a infrared/laser digital thermometer or a temp stick. (You can get infrared/laser digital temp read for about $20 at Harbor Freights or even an Automotive store.) Running temp on the core plug side should not get hotter than 155 Degrees. There is not thermostat so water is constantly circulating around those water jackets.

 

[1946Zephyr]

Re: 1965 Ducktwin won't fire

You may have to drop the lower unit to make sure there are no blockages in the water tube, as well. I usually use a flex housing, that is used for a lawnmower throttle cable, or something of equal size. Run it through the water tube, while you have the head removed and then try to run some water up the tube. You should see water flow freely out into the water jacket, since the head is removed.

It may be necessary to remove the powerhead to look for debris in the water passages, as well

 

[nwcove]

Re: 1965 Ducktwin won't fire

stupid question, but things can easily go wrong........is the new impeller clocked right?

 

[Daviet]

Re: 1965 Ducktwin won't fire

Even if you install the impeller backwards, the vanes will flip over when the engine is started.

 

[cajuncook1]

Re: 1965 Ducktwin won't fire

Hey mark38090,

You could unscrew the water flush plug and if the water pump is working it would shoot right out of the water plug hole just below the exhaust plate. Now the water from the water flush plug( if I am correct) is pre power head. Just start it up and if water shoots out of the water flush plug hole then your water pump is functioning properly. ***** Once you verify then shut down, because you will overheat your motor****. Replace the water flush plug/screw and tighten it.

If your power head is still overheating then your obstruction is with obstruction prior or within the water jackets, then you may have to remove the cylinder head and inspect. If you remove the cylinder head, you have to replace the gasket with a new one.

Please look at the previous post that I made about where to check the temperature of the power head. The exhaust plate and cylinder head cover will get hot.

Here is a video/picture of the water flush screw. It was leaking because it need a gasket and tightening. The exhaust plate is just above it, that thing gets super hot because there are exhaust gases behind there and it is not water cooled. Those plates over time get discolored and the paint peels because of the intense heat behind the plate.

Click on the thumb for the video.

 

[1946Zephyr]

Re: 1965 Ducktwin won't fire

Oh yea. I forgot about those flush screws. My old HD-20 has one too.

 

[mark38090]

Re: 1965 Ducktwin won't fire

Ok, so I pulled the head and water jackets are full of water and very little crud. I cleaned up the water jackets, resurfaced the head, replaced the head gasket and took it to the lake. My new problems; the fuel flow from the tank seems very restricted, even with the petcock removed. I see on the schematic there was a filter in there at one time but it doesn't come out with the petcock, is there a way to get it out without damaging the tank? Next, the low speed needle turns itself while the engine is running. I made sure the screw was tight, I know I put the packing in according to the schematic with the carb rebuild, what am I missing?

 

[Daviet]

Re: 1965 Ducktwin won't fire

Add another packing and try it again.
I have, in the past, had problems with the filter screens in the tank. The filter is supposed to be attached to the valve, and come out with the valve. If someone has removed it I would suggest installing an inline fuel filter. If it came off and is jamed in the hole use a small pick and try to pull it out.

 

[mark38090]

Re: 1965 Ducktwin won't fire

I tried several different types of picks, hooks and the like to no avail. What about trying to drill it out slowly and just using an inline filter?

 

[mark38090]

Re: 1965 Ducktwin won't fire

Ok, got the screen out; not really a screen. Not sure what you would call this. Anyhow, inline filter and 6 hours cleaning tank and she runs great. Went to the lake and rode for about an hour with no problem. I have another question though, On the back of the carb there is a hole that blows out air. It doesn't change the way the engine runs when plugged but am I missing a part?