DR Trimmer Pilot Won't start

labans · May 10, 2025

Would like to get the magic information to help me understand how to get a DR Trimmer Pilot started. It has a 174cc BS engine. I have replaced the following:
New ethanol free gasoline
New gas lines
New coil, with airgap adjusted to .010"
New sparkplug
New OEM BS carburettor
New primer bulb
New air filter

I have a tool to check spark and it shows a good spark. I have primed it and also used starter fluid and cannot the damn engine to even fart. Nothing at all. And this engine does not turn over easily, it is hard to pull the cord 8 times in a row and it still won't start.
What am I missing? What is the magic thing I need to do?
Help!

JoeRagMan · May 10, 2025

Did you check the flywheel key for damage? If the timing of the flywheel is off just a couple of degrees, spark timing will be incorrect to run engine. Only other thing I can think of is a possible problem with the camshaft. Depending on the model and year of manufacture, the camshaft has a plastic gear that sometimes slip on its shaft which changes valve timing. (Hope that isn’t the problem).
I picked up a nice John Deere walk behind mower which had a Briggs engine on it. Had the same problem as you are having, took the oil pan off of bottom of the engine, had a new camshaft but the valve timing was way off. Installed the camshaft, made sure the timing marks were aligned, fired right up. Hope this helps, good luck.

labans · May 11, 2025

Wow! I have encountered this type of problem with some of my customer's cars in the past that had timing belts that 'slipped a tooth or two' but did not think about that with this engine. While I deeply appreciate your help I am displeased that B&S would design a home-user engine with any possibility of having a problem with a key-way (hard to believe they let that one out the door.) Much less do I like plastic cam gears for any reason! During the seventies many engines changed over to fiber timing gears to supposedly "quiet" the engine (pure baloney) and those gearsets failed quite often.
I will pull the flywheel and see if that is causing the problem and if not then off comes the bottom end so I can look at the camshaft.
Thank you very much!!!

dieselss · May 11, 2025

labans said:
I am displeased that B&S would design a home-user engine with any possibility of having a problem with a key-way

It's a fail safe. The key will shear preventing major engine damage
And it's how they time the engine

DR Trimmer Pilot Won't start

labans

JoeRagMan

labans

dieselss

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