Engine Z445/w 27HP Briggs engine surge

eldowdy · Sep 21, 2017

Been There said:
Here is a perfect example of a Brigg V-Twin engine with a pulsating governor by YouTube. Check it out at about the One minute mark on the video. Note the spring reaction on the governor arm and how it plays against the engine RPMs.

https://www.bing.com/videos/search?...FC1093D49CB89A1DB99CFC1093D49CB89A1&FORM=VIRE

Good vid. Mine doesn't pulse at low idle. It runs fine at low idle. It only pulses at full throttle with no load. Once the blades are engaged it runs fine. I'll take a look at the governor today and report back.

Ed

BlazNT · Sep 21, 2017

Information for the thread.
Carbs have 2 circuits.
The first circuit is the idle circuit. Bad name for it because it is the idle through the WOT(wide open throttle)
The second circuit is for a load. When you drive and or use the mower blades.

So with your carb surging at WOT, it is in your idle circuit. IE dirty carb or air leak.
When at WOT the engine cannot get enough fuel so governor slows the engine. Then when slow the throttle tries to get it to speed up. When it cannot run at speed the govinor slows engine. Repeat repeat repeat...

eldowdy · Sep 21, 2017

BlazNT said:
Information for the thread.
Carbs have 2 circuits.
The first circuit is the idle circuit. Bad name for it because it is the idle through the WOT(wide open throttle)
The second circuit is for a load. When you drive and or use the mower blades.

So with your carb surging at WOT, it is in your idle circuit. IE dirty carb or air leak.
When at WOT the engine cannot get enough fuel so governor slows the engine. Then when slow the throttle tries to get it to speed up. When it cannot run at speed the govinor slows engine. Repeat repeat repeat...

This is exactly what ILengine and I were talking about last year. His answer (after a long and very helpful conversation) was to replace the carb. That's a good solution, except I don't want to spend $257.00 on a new carb. I rebuilt the carb I have. Problem is still there, but it only happens when not mowing. Like I said in a previous post. I didn't change the o-rings on the jets when I rebuilt the carb. I'm going to do that. I think ILEngine hasn't chimed in this time because he and I beat this horse to death last year. All the input here has really appreciated.

Ed

BlazNT · Sep 21, 2017

I too would replace the o-rings as carb cleaner in a can has a bad effect on them sometimes. If you know someone with an Ultrasonic jewelry cleaner you could borrow, you could put your carb there and clean it out even better. It seems to be the best fix for dirty carbs. I would buy a blown engine and pull the carb off it before I purchased an expensive carb.

eldowdy · Sep 21, 2017

I did an experiment today. Inspired by Bert. I don't have enough time to tear into anything today. I did this. I let the mower warm to operating temperature and start pulsing. As all the shields are in place I can't get my finger to the governor lever. So. I took a long thin screwdriver and put enough pressure on the governor lever to stop the pulsing. I then released the pressure. It took a couple minutes for the pulsing to start again. I did it again, but this time the pulsing didn't resume. I had to throttle it back to low idle and back up to wide open to get it pulsing again.

Here's my theory. I think the governor lever has slipped on the shaft and is not turning the shaft far enough clockwise. I'm probably wrong, but I thought I would throw that out there.

Ed

bertsmobile1 · Sep 21, 2017

eldowdy said:
I did an experiment today. Inspired by Bert. I don't have enough time to tear into anything today. I did this. I let the mower warm to operating temperature and start pulsing. As all the shields are in place I can't get my finger to the governor lever. So. I took a long thin screwdriver and put enough pressure on the governor lever to stop the pulsing. I then released the pressure. It took a couple minutes for the pulsing to start again. I did it again, but this time the pulsing didn't resume. I had to throttle it back to low idle and back up to wide open to get it pulsing again.

Here's my theory. I think the governor lever has slipped on the shaft and is not turning the shaft far enough clockwise. I'm probably wrong, but I thought I would throw that out there.

Ed

Excellent.
Not quite what the doctor ordered but as it ran smoothly when you were holding the shaft that confirms a governor problem.
They can be tricky little buggers to adjust but yes, start with resetting it and remember to do the clamp nut up tight.
Then if it still surges, get the Dremel tool out and modify an old Allan wrench.
Never met a real mechanic who did not have a 1/2 dozen incomplete sets of them but do take the effort to find one that will go in and have enough clearance to twist the anchor point.
I have a couple with the slot at different orientations to the short end cause no matter which one you grab, the handle will foul on something a natt's nacker before the exact right spot.

eldowdy · Sep 21, 2017

bertsmobile1 said:
Excellent.
Not quite what the doctor ordered but as it ran smoothly when you were holding the shaft that confirms a governor problem.
They can be tricky little buggers to adjust but yes, start with resetting it and remember to do the clamp nut up tight.
Then if it still surges, get the Dremel tool out and modify an old Allan wrench.
Never met a real mechanic who did not have a 1/2 dozen incomplete sets of them but do take the effort to find one that will go in and have enough clearance to twist the anchor point.
I have a couple with the slot at different orientations to the short end cause no matter which one you grab, the handle will foul on something a natt's nacker before the exact right spot.

I have more Allen wrenches than I know what to do with and a Dremel tool. It will take longer to take all the protective covering off. Than to actually do the deed. It's all hidden under here.

Ed

eldowdy · Sep 27, 2017

Reset the governor today. Although I didn't notice any movement once I had it loose. Once I had everything tight. I let it run long enough I knew it should be pulsing. No longer pulsing. I was flabbergasted. Movement that was imperceptible to me had done the trick. I need to mow today. We'll see if it is still fixed after I'm finished.

Ed

Been There · Sep 27, 2017

eldowdy said:
Reset the governor today. Although I didn't notice any movement once I had it loose. Once I had everything tight. I let it run long enough I knew it should be pulsing. No longer pulsing. I was flabbergasted. Movement that was imperceptible to me had done the trick. I need to mow today. We'll see if it is still fixed after I'm finished.

Ed

This is my post way back earlier in the thread that you had problems, and I wrote this,

"You have a Governor setting problem, and it will take a very high experience carburetor person to get it right. I had the same problem on my John Deere 345 years ago and I fixed the problem with a spring like the one you have on the governor-carburetor by attaching it so the governor will not move at high idle.:

However, I was wrong on..it would take a very high experience carburetor person to get it right... Been There done that.

eldowdy · Sep 27, 2017

Been There said:
This is my post way back earlier in the thread that you had problems, and I wrote this,

"You have a Governor setting problem, and it will take a very high experience carburetor person to get it right. I had the same problem on my John Deere 345 years ago and I fixed the problem with a spring like the one you have on the governor-carburetor by attaching it so the governor will not move at high idle.:

However, I was wrong on..it would take a very high experience carburetor person to get it right... Been There done that.

I did have a governor setting problem, but it doesn't appear to have been the spring. I haven't mowed yet today. Coffee became more important.

As soon as I do I will report back. Thanks again for everyone's input!

Ed

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