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View Full Version : O.T. how bad is using choke for speed control?



Happy
12-16-2005, 02:16 PM
The governor on my 5 year old craftsmen 25 hp intek B and S engine is broke, and engine runs wide open. This is on my snowblower, so I only use it about 2 times a month. I don't have time to fix it now. how bad is it to use the choke to keep engine speed in the normal range? Can it do permanent damage, or will it just foul the plugs?

Carl
12-16-2005, 02:34 PM
The choke should only be used for it's intended purpose. Controlling engine speed by use of an excessively rich mixture will usually lead to wash down of the cylinder walls causing, at the least excessive ring and cylinder wear, at worst seizure of the piston. Who knows, you may even have a good old fashioned crankcase explosion, always thrilling!

Evan
12-16-2005, 02:46 PM
What Carl said. That shouldn't be hard to jury rig. OK, so it won't have a governor but set it so it can't go wide open. Just block the throttle arm some way.

CCWKen
12-16-2005, 02:52 PM
Ditto above. !!!! Not only that but you'll probably burn holes through the tops of the pistons.

Where is the governor broken? It may just be a spring that has fallen off. Take the time and check it out. Those engines run about $1600-$1800. Might be worth 15 minutes to look into it...Ya think?

Happy
12-16-2005, 03:13 PM
Springs all look good. It looks like from the B and S website that the governor has many plastic parts on the inside, and the governor is calling for full throttle, overpowering the hand throttle. it of course is a pain in the butt to look at or work on, with all the important stuff being in the worse place to get at, and if you run the engine, then the hot exhaust is right there to burn your fingers if you try and do anything by feel, or attempt to manually control things while it is running. And, I only need the choke when starting or shifting, the rest of the time the engine is loaded with heavy snow, thus keeping the speed down.

Evan
12-16-2005, 03:16 PM
The hand throttle is pulling on a spring that is countered by the governor. See if you can connect it directly to the linkage with a bit of stiff wire or similar.

Kdahm
12-16-2005, 03:30 PM
Most that I have seen have a bend in the heavy wire between the governor and the throttle plate. I have had good success in bending them to raise/lower the engine speed.

OTOH, the internal guts of the governor may be shot, resulting in wide open throttle all the time. Disconnecting everything from it and moving the lever by hand should give an indication of its condition. While the engine is cold and not running, of course.

Karl

CCWKen
12-16-2005, 06:22 PM
Post the engine data (serial & date code) so I can take a look. As Evan says, you should be able to bypass the govenor and run with just the throttle. It may bog on heavy snow and you'll have to manually adjust the speed but at least you're not destroying the engine.

IOWOLF
12-16-2005, 06:41 PM
If you have to ask.........................

------------------
The tame Wolf !

J. Randall
12-16-2005, 10:06 PM
Using it like you describe I don't think you will hurt anything, go ahead and get the snow moved. If you did it a lot you would wash the cylinder walls down and do permanent damage. I don't see any way that it could cause you to burn a hole in the pistons. James

JRouche
12-16-2005, 10:28 PM
<font face="Verdana, Arial" size="2">Originally posted by J. Randall:
I don't see any way that it could cause you to burn a hole in the pistons. James </font>


I agree, that would be a lean condition or pre-ignition.

And I'll add I dont think running it choked is gonna cause the damage described above. When choked you are not running in an overly rich condition as if the float was stuck or the jets sized wrong. You are not adding additional fuel, you are reducing air. Which does produce a slightly enriched mixture but not nearly as severe as the float/jet issue.

Run it to get the jobs done. After about two tanks or a few hours of use pull the plugs and check her out. They wont be dripping or even moist so the cylinder wash down is not happening. They will, or may, look carbon sooted.

But if you did have a stuck float or wrong jetting you could run into the overly wet condition described above. JRouche



[This message has been edited by JRouche (edited 12-16-2005).]

Happy
12-16-2005, 11:52 PM
CCWKen
it was hard to see, but here is the engine data.
Model 445777
type 0129 E1
code 000824YH

Treven Baker
12-17-2005, 01:10 AM
Running choked will cause it to run very rich. That is what the choke does and that is how it helps a cold engine start.

Don't run it chocked for the reasons posted by carl!

Usually the govenor is nothing more than a flapper in the air from the flywheel fan - very simple.

Evan
12-17-2005, 02:17 AM
Another thing not mentioned is that excess gas will dilute the oil. Not an entirely bad thing in cold weather, it's used on aircraft for really cold conditions. But, too much and bye bye bearings.

Brian_h
12-17-2005, 08:11 AM
Another thing to check. Make sure your throttle butterfly hasn't fallen off.

It is a long shot but, I have experienced it. I bought a beat up riding lawn mower this summer from a guy. "The governor needs to be fixed". The engine was a Tecumseh 16hp vertical shaft OHV. All the linkage was fine.

Before pulling the motor to disassemble, I decided to pull the air cleaner and look in the carb. Suprise, no butterfly.

I found it laying on top of the intake valve. It was bent up a bit but had never made it into the valve seat.

Of course when I pulled the head, the butterfly screws had been through the seats and were firmly imbedded in the piston.

Brian_h



[This message has been edited by Brian_h (edited 12-17-2005).]

andy_b
12-17-2005, 10:06 PM
speaking of older B&S engines....
i have a log splitter with an old 8HP on it. not real old, but at least from the early 80s. the governor linkage was messed up when i got it a few years back, so i used to control the throttle with the choke and a bent piece of 10 gauge wire. the engine eventually got harder and harder to start, and now it is impossible to start, so it sits in my shed.

i pulled the head off and everything looks perfect. i attempted to rebuild the carb, and it seems okay. i replaced the sparkplug and pulled the flywheel to check the ignition and magneto coil. for the life of me i can't get the thing to run. i keep trying to start it and all it does is eventually flood the engine and the spark plug gets soaked with gasoline and it never even sputters. anyone have any ideas?

i'm usually pretty good with at least jury-rigging an engine enough to get it to sputter, but this thing does nothing. it's definitely getting fuel, and the spark looks good.

andy b.

Carl
12-18-2005, 12:55 AM
If it's getting air, fuel, compression, and a spark at the right time, it should run. You said it's getting fuel and a spark. Check for obstructed air flow and see if it has compression. Make sure both valves are closed when they should be. Take the spark plug out and put a finger over the plug hole while you crank it to check for compression. I have a B&S on a generator that won't start if it has been sitting for a few weeks or months. It seems to be fuel quality related, as a small shot of starting fluid in the carb will get it to start on the first pull and then it runs fine.

wierdscience
12-18-2005, 09:27 AM
Andy,sounds like your valves are pocketed.Check the compression first,should be at least 100psi,if it's not chances are the valves aren't sealing.Quick fix is to remove the valves and grind length off the tips until they seal with the proper tappet clearence.
Better way is to install seats and new valves,but depending on the engine it may not be worth the extra grief IMHO.

Duct Taper
12-18-2005, 06:10 PM
With an over-rich mixture you could be causing a hotter exhaust valve/muffler condition because of a longer burning charge. This could also burn the exhaust valve a bit causing a lack of compression, which would also cause hard starting.

J. Randall
12-18-2005, 09:41 PM
Andy, If the compression seems iffy, add a teaspoon of motor oil through the spark plug hole, if the ring are washed down this will restore compression. James

JRouche
12-18-2005, 10:53 PM
<font face="Verdana, Arial" size="2">Originally posted by Duct Taper:
With an over-rich mixture you could be causing a hotter exhaust valve/muffler condition </font>


Well no again. A lean condition causes a hot exhaust valve condition. The rich running engine runs cool hence the carbon covered valves, plugs and pistons. JRouche

Evan
12-19-2005, 01:12 AM
JR is right. The ideal mixture is around 14 to one air/fuel mass. Rich burn for max power is around 12 to one. The choke will make it much richer and will definitely result in unburned fuel as well as cooler burning. On a normally operating engine the choke should be able to make the mixture so rich it won't burn at all, killing the engine.

[This message has been edited by Evan (edited 12-19-2005).]