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chuckvan

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Greetings, newbie here, I have an older Sears 647D David Bradley chainsaw (917.60041). I need recoil spring and some parts. Are most 917 series models the same? Where can I find parts?
 
With time on hands now, I finally got into this 647G. I got it to run, but only for a few seconds with fuel I squirted into the spark plug hole or carb throat. I dug into the carb again and found that the balloon-type fuel pump was punctured and also cracked right at its top cap - see picture. No wonder it would not draw fuel from the tank. The carb is a Lauson. Unfortunately its not a Tillie. Any of you have a balloon-type fuel pump or a Lauson carb that you would be willing to part with? BTW, this is a very frustrating saw to deal with. The rewind is extremely problematic. I ended up rope-starting it to get it ot run. Thank goodness there was notch to connect the rope.
 

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Do a search (ebay or wherever) for a Tecumseh 631893A carb kit. I can recommend the Oregon 49-239 kit as I have used them before, are good quality and always come with the fuel pump diaphragm, bulb or whatever you want to call it.

Not shilling for this seller but there is a good picture of the kit here.. https://www.ebay.com/itm/Oregon-49-239-Carburetor-Repair-Kit-Replaces-Tecumseh-631893A-/321458400717

As to the starter, the Fairbanks Morse starters can be a pain if you not used to them. Make sure the friction washers are not worn bad and are clean and dry (no oil on them) or they wont ratchet out to grip the cup properly. Also make sure you re install the dogs the proper direction.
 
Oh and another thing, at least you found and knew about the fuel pump bulb, but in case you don't know, there is a check valve in the fuel inlet fitting of the carb that works along with that bulb to pump fuel. Make sure its working properly.

Thank you very much for this information. I really appreciate it. Yes, I pulled the pressed-in fuel inlet fitting from the carb and saw that check valve. It looked OK but it is darn hard to be sure because it is so small and locked into position. It looks to be without any openings or holes. Is that is correct, how does the fuel get past it and into the metering chamber? Lastly, I did figure out that rewind's engagement mechanism. I had obtained a second complete rewind unit from eBay. I have chosen and cleaned the best components from each unit. The only thing I'm concerned about is the rotational direction. The one from eBay has the rope wound clockwise on the pulley when looking at the pulley from the inside of the rewind housing. The one from my saw has the rope wound counter clockwise when looking at the pulley from the inside of the rewind housing. Of course that means the underlying springs are laid in place opposite also. What is the correct direction for the rope to be wound onto the pulley? Isn’t the rotation of the engine supposed to be clockwise when looking at the rewind side of it?
 
Your saw is a gear drive without a idler gear so they will turn the opposite way of the direct drives. Most of those covers were reversible simply by flipping the recoil spring over and the same with the starter dogs.

As to the inlet check valve, its been a few years since I have done one and can't picture it right off. Its pretty simple though and only lets fuel in and holds pressure the opposite direction. I usually never take them out you can check them in place.
 
The kit has been ordered via the link you provided - - thanks again. For that check valve, I removed the inlet fitting and used my reliable lung pressure to test in/out from both ends of the fitting. Nothing is perceived to be happening from that air flow. There's a tiny hole in the center of the + shaped metal retainer - see pic. Can't tell if there is a hole in rubber behind that hole in the retainer. If there is, that's a mighty small passage for fuel to flow thru. Still wondering if the fuel goes around this check valve or through it. I've got the rewind assembled properly. The dogs are engaging the cup and the engine's rotation will be counterclockwise when viewed from the rewind side.
 

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I told you it had been sometime since I messed with one of these. I usually avoid what I call "assembled lawnmower motor saws" but I have done my share over the years. I went and looked and I have a couple NOS inlet check valves. Hard as it was to try to hold them firm to my pressure tester , I found they do flow freely going in. When going the other way I could feel some resistance so they are working. Like I said they are hard to check but they usually work and yours probably will too. 20200410_175817.jpg20200410_175824.jpg
 
I checked it with my pressure and vacuum testers (instead of my mouth). It seems to be functioning properly; slight but free flow in the right direction and resistance in the oposite. Carb kit estimated to arrive on Monday. It'll be an intersting day.
 
This thread and a second parts saw got me messing with mine again today. Not sure what is up with it. It runs, but it is pig rich. (Or the ignition is breaking down) the spark plug lead is taped where it passes through the recoil housing and I'm certain I can feel it shocking me when it's running so I'm gonna swap the ignition from the parts saw. If that doesnt do it, I will order another carb kit.
When I tried getting this running a couple years back @Modifiedmark clued me into that check valve and I replaced it along with the carb kit including the "pump element". Very strange carb design. Also impossible to adjust after it is installed.

Sent from my SM-G950U using Tapatalk
 
I put a tansistor/chip in mine. So, I have the points, condenser etc. available. I would send 'em to you (no charge) if you want them. I also have a spare coil with a spark lead that's in good shape; could sent that too.
 
I told you it had been sometime since I messed with one of these. I usually avoid what I call "assembled lawnmower motor saws" but I have done my share over the years. I went and looked and I have a couple NOS inlet check valves. Hard as it was to try to hold them firm to my pressure tester , I found they do flow freely going in. When going the other way I could feel some resistance so they are working. Like I said they are hard to check but they usually work and yours probably will too. View attachment 816649View attachment 816650
 
Your saw is a gear drive without a idler gear so they will turn the opposite way of the direct drives. Most of those covers were reversible simply by flipping the recoil spring over and the same with the starter dogs.

As to the inlet check valve, its been a few years since I have done one and can't picture it right off. Its pretty simple though and only lets fuel in and holds pressure the opposite direction. I usually never take them out you can check them in place.

It's running. The rewind is still a work in progress. However, the rope would do fine for this saw's life as a show & tell item. Idling is a bit erratic and fussy to optimize. I have not had the saw in my hands yet to do a whip-around test for the seals.

The next post has the video of it running.
 

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