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3 hp Briggs and Stratton - throttle probems


ambodach's Avatar
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03-15-13, 03:46 AM   #1  
3 hp Briggs and Stratton - throttle probems

This is a 80000 side valve engine off a mower. The id. part of the serial number is 80432. The build date was 1/11/1973.

I got hold of this recently as a stand alone engine. I haven't started it yet, but it is clean, no rust of the steel work, has a good spark and the compression feels fine.

The problem is that it came without the throttle control cable. It is the two part Flo-jet carburettor. B & S have supplied me with the User's Manual and Parts List.

Where I am having difficulty is identifying from the scanned 1960's documents where and how the throttle cable attaches - I can see a clamp on the engine body below the carburettor, but not a fitting to take the cable inner.

It would also appear from the Parts List and zooming in on the diagrams in the User Manual that there could be a spring missing between the governor mechanism and the throttle arm.

Can anyone give me any help on this please

Rob

 
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03-15-13, 04:47 AM   #2  
Often the inner wire of the throttle cable has a "Z" bend on the end that you thread through the hole in the throttle arm. So, there is no separate fitting for the inner wire.


 
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03-15-13, 05:04 AM   #3  
Yes, the inner cable attaches just as Pilot Dane has shown, and the outer casing slides under the little sort of U shaped clamp that you are looking at on the engine. If you hold the casing next to the clamp, with an inch or so of the cable sticking out, it should be a straight shot to the connecting point. And yes, there should be a governor spring, just as you described, and it's not necessarily unique, but special enough that you will need to get it from one of your local small engine shops, so they can show you exactly where it goes, in case it's not obvious.

 
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03-15-13, 06:30 AM   #4  
Forgot to mention it, but along with the governor spring, I think that there is a rod that fits inside or along side of it. (Dang, wish that I could remember ANYTHING any more!) Anyway, thought that I would mention it because I know that it may be hard to see the association of the two on an exploded view, and if the spring is missing the rod very likely is as well. Am pretty sure though that the rod, like the spring, doesn't have any special clips or anything like that, so that should most likely do you.

 
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03-15-13, 08:31 AM   #5  
Hi guys, great of you to reply.

I've seen the cable configuration you show somewhere / sometime <quote> (Dang, wish that I could remember ANYTHING any more!) !!!!

The trouble is that I don't think that applies here as you can't have the throttle cable attached directly the the throttle arm otherwise the governor won't have the freedom to control the speed. I'm not sure if it's general but the two controlled speed petrol engines I have both have the throttle cable linkage to the arm via levers and a spring. The picture in the Manual seems to indicate that the cable is attached to part of the governor mechanism, and the missing spring somehow balances the leverage on the throttle arm.

Pedro - you're right about the rod; that's there OK. It's referred to as the Manual Friction Control, and I think the throttle cable attaches to it or to the lever it couples to the throttle arm with. It doesn't seem to have any friction, but it would seem to be there as an on-engine throttle control

I'm going to see if I can attached the the page with the drawings on to this post.

I put some fuel in it this morning and it kicked first pull, and ran reasonably after I wound in the slow run screw. The carburettor might be flooding as fuel is appearing at the choke and the engine gently runs to a stop, but starts again next pull - encouraging at least.

I'm planning to visit the B & S distributor tomorrow and can take the engine with me. I'm hopeful that I can get the spring - maybe I'll have to buy a throttle cable and I'll also ask about a carburettor refurb kit.

Picture ? rather than take the risk of losing this post, I'll send it and attach the picture to a follow on.

Thanks again guys
Rob

 
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03-15-13, 08:35 AM   #6  
Some, not all, engines have a very fine spring around the linkage between the governor arm and the throttle arm. It helps take play out of the linkage so the governor doesn't start to hunt. You can run it without it. It's usually a very fine wire spring.

Make sure the governor spring itself is in place. It's a much thicker spring that runs from the governor arm to the bellcrank on the throttle (not the carb).

 
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03-15-13, 08:43 AM   #7  
Here's the relevent page from the Manual. The detail as you will see is good enough for daily maintenance but not if you're pulling the thing apart or trying to work out what bits are missing !!

And DANG it I should have remembered early that I already had this page as a .jpg. 'Am bodach' means Old Man in Gaelic - justifiably chosen!

Rob

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