Briggs motor

I have a Magnatrac small dozer with a 35 horse Briggs and Stratton engine. It has a throttle, I usually work the dozer at about 23 or 24 hundred rpm's. When it idles down it goes to about 18 hundred rpm's. It seems to me that this is a high rpm to shut the engine off, I'm just comparing it to car engines. I have tried to contact Briggs but I get the old push 1 bs. Should I try to get a better throttle cable or is it ok to shut it off at high rpm?? Thanks, Ellis
 
It isn't best. Two reasons. !-the engine needs to cool down for 2 minutes or so before shutoff, and that speed isn't very cooling. The engine speed should be down around 1000 or 800 to allow speed adjustment when operating, or idling between activities. Jim
 
It has been SO LONG since I regularly worked on small engines. But as I recall, you can't compare them to larger water cooled automotive/machinery engines. Seems like rated/governed operating speed on most was 3600 rpm, and idle was half that, or 1800. Running below those speeds can be damaging, as you're depending on air flow off the flywheel for cooling.
 
Ellis Kinney,

Yes that is right! Newer and smaller H.P Briggs Idle 2200 R.P.M.'s or so. it will be just fine,


Guido.
 
Air cooled engines don't have the efficiency that water cooled engines have so you need to have a disproportional amount of air over the engine for idle cooling. I just ran across an idle spec a day or two ago stating 1750 idle, 3600 governed max. I will say this on current....last 10-20 years for a number, fan volume has increased or seems to have increased on my air cooled engines. Used to not notice blow by coming out from under the shroud on top of the engine. Now it's easily detected even when you aren't paying attention to it.
 
copied from the Briggs web site"
Using a tachometer to gauge engine speed, set the idle speed screw to bring the engine to 1750 RPM for aluminum-cylinder engine or 1200 RPM for engine with a cast-iron cylinder sleeve.
 
Thanks, I didn't think I was crosseyed when I saw that 1750. Going to bet you that aluminum blocks reference had to do mainly with older engines which as I mentioned, didn't seem to have the cooling capacity that current, cast iron sleeved engiones have. I remember buying a JD 110 I think was the model, 30" single blade, 8 hp Briggs, riding mower, non-cast iron liner had a non-sleeved alum. block....yeah and it wore out in no time flat too. Don't recall the idle rpm....course I had just bought the farm and it was a mess and that was my mower and yes it got worked....but when I popped the head and saw no liner, that answered that early wear out question.
 
Can you see why it will not idle down?

Could need the throttle cable adjusted.

If backing the idle stop off and manually closing the throttle still will not bring it down, I would suspect a vacuum leak, or problem with the throttle plate alignment.

My concern would be why it won't idle down. Don't want to be sucking in dirty air or have the throttle plate fall off or ingest a screw.
 
I guess my harbour freight 2.5 and 6.5 engines should be shot. Hours and hours running at an idle on an alternator charging batteries! I guess these engines don't get hot idling!
 
I suspect somebody cranked up the idle adjustment to compensate for a blocked idle passage. Have you tried lowering the idle? If the engine starts surging when you back off the idle screw, you need to rebuild or replace the carburetor.
 
Im also thinking a carb problem such as the idle stop linkage/setting,,,,,,,,its running too lean,,,,,,,,,there's a vacuum leak,,,,,,,,,gas flow or a float problem ????

John T
 
I have three small engines, 5 to 14 HP, that have no throttle adjustment at all. Start them and they run full RPM. Hit the kill switch and turn them off. I really wish they could be started and idles for a minute or two to warm up before maximum RPM. I'm wondering how long they will last.
 
Lots of newer engines don't allow for really low idle. Some of that is because of emissions and some is because the engine is only balanced to run at full throttle.

Also, 'putt-putting' them around is really hard on the compression release mechamism. It reingages below a partiular rpm so the engine will be easy to start next time.

In fact, engines made after tier-three emissions took effect are supposed to be shut down at near full throttle in order to keep them from backfiring. They want to keep the air/fuel velocity up through the muffler so it doesn't have a chance to ignite before it exits the muffler.
 
(quoted from post at 15:23:13 01/25/21) I have three small engines, 5 to 14 HP, that have no throttle adjustment at all. Start them and they run full RPM.

They actually run at the governed speed appropriate for whatever application they are being used for.

I agree that I prefer not to have any engine to run at high speed when first started especially when cold but that's the way they are set up.
 
Way back in the past somewhere, I got the idea that air cooled engines had to run at rated rpm 100% of the time. Don't remember the source. That bothered me as I wanted to idle down for whatever reason under certain circumstances on different equipment. Having the spec'd RPM in an owner's manual helps me to not worry about my initial assumption based on who knows what.
 

We sell tractor parts! We have the parts you need to repair your tractor - the right parts. Our low prices and years of research make us your best choice when you need parts. Shop Online Today.

Back
Top