Is this a primer “bulbâ€/ plunger?
- Thread starter dlundblad
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Originally Posted by P10crew
Originally Posted by JLawrence08648
The carburetor needs to be taken apart and cleaned. The gas tank may be rusty. The diaphragm needs to be replaced, it's hard.
^ this and if it's got compression it will run.
About what should the compression be? I can test that this weekend.
Originally Posted by JLawrence08648
The carburetor needs to be taken apart and cleaned. The gas tank may be rusty. The diaphragm needs to be replaced, it's hard.
^ this and if it's got compression it will run.
About what should the compression be? I can test that this weekend.
You have to use the "bounce back" compression check on that motor. Spin the motor backwards against the compression stroke and see if the flywheel bounces back against compression. Checking it with a gauge will show low readings because of the easy spin bump on the camshaft to aid pulling over by hand.
Basically if it just spins when you pull the cord, there's no compression. A good engine will have a part of the cycle where it is harder to turn. As @andyb said the compression gauge used on cars doesn't apply to a small engine. This is something that an experienced person would just judge, there isn't a number associated with the test.
Originally Posted by AndyB
You have to use the "bounce back" compression check on that motor. Spin the motor backwards against the compression stroke and see if the flywheel bounces back against compression. Checking it with a gauge will show low readings because of the easy spin bump on the camshaft to aid pulling over by hand.
There likely is nothing on the cam on that old Briggs engine to make that engine start easier. It's only 5HP. If he can feel a reasonable amount of compression when pulling the rope, it should be capable of running. I have seen many worn out engines still run well with little compression but went to sleep when you really loaded it down.
You have to use the "bounce back" compression check on that motor. Spin the motor backwards against the compression stroke and see if the flywheel bounces back against compression. Checking it with a gauge will show low readings because of the easy spin bump on the camshaft to aid pulling over by hand.
There likely is nothing on the cam on that old Briggs engine to make that engine start easier. It's only 5HP. If he can feel a reasonable amount of compression when pulling the rope, it should be capable of running. I have seen many worn out engines still run well with little compression but went to sleep when you really loaded it down.
Most all Briggs of that era had the bump on the intake lobe. The larger displacement motors had a centrifugal compression relief that engaged at pull over speeds and got out of the way when the engine started. Raced and built many 5hp go kart motors of that model. The "easy spin" was a tech item even with after market performance cams.
The valves like to stick on these engines also. That would be the first thing to check if there is no compression.
Just an update on this.
I've been working on it here and there and was able to get it running on the original carb. Bought a Chinese version for $11 shipped, but the holes where it bolts to the engine didn't match up. One could be drilled if needed. No big deal.
Anyways, she runs. I need to figure out how the throttle linkages go back together as well as why the recoil rope mechanism squeals, stalls and eventually stops the engine when throttled up.
I've been working on it here and there and was able to get it running on the original carb. Bought a Chinese version for $11 shipped, but the holes where it bolts to the engine didn't match up. One could be drilled if needed. No big deal.
Anyways, she runs. I need to figure out how the throttle linkages go back together as well as why the recoil rope mechanism squeals, stalls and eventually stops the engine when throttled up.
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It's going to have the ball clutch starter. Remove the air shroud / rope starter assembly. On the engine shaft, remove the clutch cover (the balls will fall out) then remove the pawl drive thing and lightly grease the engine shaft where it runs in the pawl clutch. Do not get grease on the balls or they won't drop back into starting position when they need to.
Originally Posted by dlundblad
I should add that it was definitely related to the rope starter because I removed it when it was running and it was fine.
That is because the rope mechanism is no longer holding the top of the clutch. It can spin freely. It is that clutch. It is a normal problem to have happen.
I should add that it was definitely related to the rope starter because I removed it when it was running and it was fine.
That is because the rope mechanism is no longer holding the top of the clutch. It can spin freely. It is that clutch. It is a normal problem to have happen.
Yep. That's an oldie of a Briggs and that is the choke. Haven't seen one like that in a very long time.
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