Texasmark1

Well-known Member
BS 22 hp V twin, mechanical governor. Over the years the idle rpms increase drastically as temp increases. Like it idles at around 1000 and by the time I quit using it for maybe 10 minutes yesterday, 60 degree ambient temp, very light duty, all passages clean so air wasn't blocked and non contact thermometer had temps below 190F, it was sitting at 2700. WOT measured about 3750......I know BS are rated at 3600 and used to be that engine wouldn't rev over about 3500.

Ideas?
Thanks,
Mark
 
Sure.... had that problem with my 21hp. twin V. You need a new carburator. Just go on Ebay and spend around $60.oo. This has been covered on here several times. You can also have a vacuum leak where that plastic manifold meats the cylinders or the flange of the carb. The tractor I put the new carb runs like a watch now. Perfect response and beautiful idle too. Just go back about 10 or 15 pages in this garden tractor file.
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Shuold have added that I hope you dont have a trashed Gouvenor but as you said it slowly speeds up. Takes about four or five minutes? That is what mine did. Change the carb. Will be like a magic pixey tapped the engine with her wand. Really...dig back to around the beginning of summer in this file. The guy was having all kinds of trouble with a zero turn if I remember correctly. Fixed him up perfectly.
 
Thanks for the reply but I did replace the carb with the one you recommended and went to premium fuel like you recommended. Things are much much better. I had this problem before I changed carbs. Changing carbs just made the engine run better....could finally meet BS WOT rpm spec of 3600 but the rpm increase just increased up to 2700 now from 2400ish as I recall.

Thinking about the carb, could be that something is opening up with temp allowing more fuel through the engine causing the rpms increase. Will think about that.
 
(quoted from post at 17:56:51 11/15/17) Thanks for the reply but I did replace the carb with the one you recommended and went to premium fuel like you recommended. Things are much much better. I had this problem before I changed carbs. Changing carbs just made the engine run better....could finally meet BS WOT rpm spec of 3600 but the rpm increase just increased up to 2700 now from 2400ish as I recall.

Thinking about the carb, could be that something is opening up with temp allowing more fuel through the engine causing the rpms increase. Will think about that.

It is unlikely, adding more fuel by itself will increase the RPM from 1000 to 2700, likewise for just adding more air. For that large an increase I would think the carburetor butter fly is opening allowing more mixture to the engine.

Verify the throttle is sitting against the idle stop screw at idle. With engine cold and at idle, push the throttle shaft against the stop screw - the idle speed should not change. Allow the engine to warm up and repeat the test - the engine speed should decrease to 1000 RPM indicating the governor is allowing the throttle to open.

Perhaps some one is familiar with this engine and an adjustment procedure for the governor that could correct this....?
 
"Verify the throttle is sitting against the idle stop screw at idle. With engine cold and at idle, push the throttle shaft against the stop screw
- the idle speed should not change. Allow the engine to warm up and repeat the test - the engine speed should decrease to 1000 RPM
indicating the governor is allowing the throttle to open."

That's a good idea. Would tell you right quick if it's the governor or the carb.

Assuming it's the gov, don't know the solution for that...adjustment, how-where.

If the carb, and the fact that the control is a rigid (adjustable for desired operating rpm) cable, where is the mechanism for the butterflies
to open an additional amount, especially for that kind of rpm change.....possibly a weak return spring.....that just dawned on me and may
be the culprit and add to the fact that the problem has gotten worse as operating hours have increased on the engine. Engine was bought
back around 2006 best I can recall, maybe 600ish hours on it.

Thanks for the input,
Mark
 
Update: Worked through the possibilities this AM and came up with a bent sheet metal bracket between the governor shaft and the carb butterfly lever/control rod. Bending that slightly toward the block casting, about mid way up did the trick. Holds steady at 1800 +/- 50 which is a good number for me considering it's an air cooled engine. The spring actions were not in the direction of being weak....just the opposite.

Smoking gun: Possibly too much pressure on the throttle lever. This is a DR Pro-Z and the throttle lever is about 10" long, pivoting in the center. Plenty of room there to put some whoopie on the other end which I have done in the past....will be more "delicate" in the future.
 

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