OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Engines Questions On Briggs & Stratton Engines Briggs & Stratton 3.5 over revs

Thanks for that Grumpy, no rush for the pictures, just next time its convenient.

I will make sure to get a look, and a few pictures, of the coil on mine, and see if we cant find some answers.

With there later electronic Ignitions, have Briggs moved to a transitorised coil, or do they use a seperate coil and ignition module.

This looks like it could be an electronic ignition module to me:



What is it?

Yes, it's electronic. There are not any points.

Ty, Briggs moved to an all-in-one ignition unit (Magnetron) in 1982 and haven't used points since. The unit replaced the coil - it was a coil with a little electromagnetic sensor attached to it, to trigger the ignition as the flywheel magnet passed by, so no points were required. It can be fitted to older engines without modification of the engine. I'm not familiar with the appearance of the later electronic units - the original Magnetron was electrically rather crude, though they seem to have been reliable. sparker's unit looks just like the early coils, but doesn't seem to have the external Magnetron sensor attached.
Post edit: the ignition unit in the picture is a Magnetron, and the electronic unit is the black part which Mr. Davis has circled.
Perhaps they made the device more compact. Anyway, all of them look the same: same coil, attaching to the engine in the same place, and in the same way. The only change was in how the coil primary was triggered.

Ok, that's a bit differend to what I'm used to seeing, When Victa moved to electronic ignition, they used the same coil, but replaced the points with a module that controlled the timing. I imagine with the Victa module, it operated by the pulse from the coil itself, as the magneto passed. It was certaily not close enough to the flywheel to sense the movement itself.

In recent years, this moudule has been moved, and is now cast inside the form of the coil, creating a square plastic lump. i have also seen this with a number of brushcutter coils, thoug i imagine some of them would also use the system you are describing with briggs.

I could specuilate that the victa version is cheaper, as it seems to be adopted more widly by manufacturers as they move to China, however, the above engine pre-dates Rovers move to china i think, so that would not reflect on it.

I'm getting really curios now, so tonight I will try and check under mine, hopefully what i see there is the same, and i can pull it off and get some good shots and any markings noted, and post them up.

Ty, these 3 pictures are of my 3 May 1983 B&S 92508. It has a plastic (Minion) VacuJet with automatic choke, and the original version of the governor we have been talking about in this thread.




The third picture shows the coil. It is a very late points-type coil - I thought they changed in 1982, but it appears it must have been a bit later.
Post-edit: The coil in the picture is a very early Magnetron

Thanks for that Grumpy, I'll have to have a look through some of my recent donations from that era, Looking at the records i have with me, i dont have a 92508, but I have a few models from 1980 - 1988, so maybe one of thos may have one.

Since i have branced out, I have been trying to get my hands on as many different engines, and carby's as possible, to get my experience up and work out as much about the engines, and thier histories as possible. So if i dont have a Minion yet, i now know what to look out for!

With the coil, is it possible there was an overlap, maybe they started relesing the magnetron on some models in 82, and ran the points out till the next year on others?

Ty, a 92908 (i.e. basically the same engine with a PulsaJet instead of a VacuJet) from the same period was likely to have a carburetor made from Minion plastic, it wasn't only the VacuJet.

On the introduction of the Magnetron breakerless ignition, note that there is an official B&S way to retrofit these to breaker-point engines:
http://www4.briggsandstratton.com/miscpdfs/RNT/magnetron_retro-fit.pdf
Joe Carroll's way seems quicker and easier.

I have only found vague references to the changeover date to Magnetron on the internet. Some say 1982, some say it was mostly done by 1983, and some say it happened progressively over quite a few years (this last assertion might have been referring to changing the large industrial models to breakerless ignition, I think). I fully expected to see a Magnetron coil on the 92508 in the pictures - I've never needed to take the cowl off it before today. This diagram shows where the Magnetron module should be visible (the coil installs with it underneath, toward the engine, not on top, where it would be easy to see):

In the third picture in my previous post you would be able to see it up near the air vane, on the opposite side of the coil from the HT lead. And I agree, that was the object you circled in red on sparker's coil: it appears to be a standard Magnetron, just like in 1983. Maybe I should get my glasses replaced.

Well, Excluding a few from the late 90's and the last decade, I have (Going by by records it this point)

-1981 93508
-1980 92908
-1977 92502
-1989 100708
-1975 100902
-1985 92908

there is also one more, i havent noted its model yet, but i can remeber it, it's a 197s Rover Pedigree with the original 148cc Briggs on it.

I will look for the Minion when i get a chance, and as i go through restoring the above engines, i will document the restorations in a thread. (Looking forward to the 75' 100902, thats the Rover Super Four 21, From Redeye)

I know this is an old topic but I have a Pope mower with the minion plastic carb with 2 govenor springs.
Motor on this is a 098902-2030-B1
I have attached some pics on how the springs are meant to be connected.
Sparker's second spring seems to be connected incorrect and is overstreched causing the over revs.
Pics 1 & 2 are with govenor closed at 2 throttle positions.
Pics 3 & 4 are with govenor wide open using a screwdriver to actuate govenor arm.

Here is the B&S doctrine on how the single and double spring governors should look:



AS you can see, Fig 93 shows a dual-spring 98902 and Fig 96 shows a single-spring 98902. It seems both versions exist. In the older series such as 92908, only single-spring versions exist.

FWIW I only posted the reply in case someone wanted to hook the springs up properly, changing the control bracket isn't an option for most people.
I originally had a problem with the engine hunting at idle but couldn't find an answer anywhere on the net.
I finally figured that the idle spring needed a slight bit more tension and bent the tab to raise the idle speed and the problem went away.

I do believe that the 98892 after year 1996 have the 2 spring setup, B&S removed the manual idle screw on the throttle bellcrank and added in the idle govenor spring to increse the idle speed.
The only way to adjust the idle now is to bend the tab where the idle spring attaches too.

The way sparker installed the idle spring to the tab is incorrect as he has constant tension on the spring causing it to be on with almost full throttle irrespectively of the controller position.
The way it is meant to be installed is there is only slight tension when it is the idle position

Andy, B&S call the system that has the idle speed controlled by the governor instead of the idle stop screw, "governed idle". I agree that if you have a governed idle engine, you can't delete the feature without providing some form of idle stop on the carburetor, if it doesn't already have one.