OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Engines Questions On Briggs & Stratton Engines No Spark - B&S 3.0 Horsepower engine

Hi there. I found a Rover Rapid in the hard junk collection.

It has a 3.0 HP Briggs & Stratton 148cc engine - but no spark,

investigation reveals: the magneto has 2 magnetic parts - ie one at 12 o'clock and one at 6 o'clock.

one of the magnetic parts is no longer magnetic at all. the other grips the loosened coil like it's demon possessed.

Should they both be magnetised?

If so - is it worth buying and fitting a new magneto?

or should I put it out the front again...

i had one of those mowers and you just cant stop the! best mower the 70's produced in my opinion.
they are points ignition (at least if its the one im thinking of) so that could be your problem. otherwise a flywheel and even electronic ignition magneto shouldn't cost much second hand from the right mower shop.
flywheels very rarely loose there magnetism but in some circumstances its possible. before assuming the flywheel is the cause (very unlikely in the scheme of things)its best to rule out the coil and points. if you would like the procedure for checking points posted im happy to do so.
regards jay

No there's no points. it's magneto based with an air gap. I re-set the gap to .25mm using my feeler gauges (bout the same as a business card

yes please - if there is a procedure to test the coil I would love it!

One side of the flywheel is not magnetised it is simply a counterweight for the magnets on the other side.

from the magneto is there wires leading to under the flywheel? if yes there is points underneath it...

lasty ignition coils are easy enough to find, on ebay, old mowers on the side of the road, etc.

did you check the spark plug???

I checked the spark and replaced with a known working CJ8 plug.

The spark is weak / intermittent.

I am not sure there is points, I am fairly sure it is only magneto & coil that does the spark on this thing.. (at least I didn't see any points).

Good to know the non-magnetic part is only a counterweight!!

What else should I try? New Coil?

Here's a link to the images:
Serial Number



Rover Rapid


Dusty, yes

Your B&S engine - a 92502 model - was built on 22 September 1987. All B&S engines built from 1982 onward have no points, so you are correct about that. A simple ignition test procedure is to isolate the kill wire (engine stop wire) to make sure it is not grounding intermittently due to, for example, having chafed through its insulation somewhere, make sure the module has the correct air gap and is properly grounded (not loose or rusty where it mounts), clamp a spark plug with gap increased to .060" by its metal body to a grounded metal part of the engine, attach the ignition wire, remove the normal spark plug so there is no compression, set all controls in the start position, and pull the start cord while watching the gap in the modified spark plug. If you get a steady stream of blue sparks, the ignition system is good. If you get orange sparks, or intermittent sparks, there is reason to suspect the ignition module is faulty. At that point, if possible try a known good module and see if that corrects the problem. Chances are someone on this site can help you with a known good module for an early Magnetron B&S - it is a very common engine type.

on the code I cant quite make it out is it 87 or 81, cheers.

Having taken a closer look, and compared it with the other two 1s in the string of numbers, I agree with you Joe - I can't tell either. Seems like your advice was better than mine - alwayscurious needs to trace the wires from the module, in case there is one leading into the housing under the flywheel. At least he'll then know whether his engine is 1981 or 1987.

Part of my reason for thinking it was 87 is the radial pull starter - I thought they were all vertical pull in the early 80s.

Definitely an 1981 model. Checked the bigger photo - yes 1981.

So - I will try that.

I disconnected the ignition module from the spark plug, removed it - and hung on to it - gave it a pull and didn't get a big jolt. No go.

So I will double check the kill wires too. Thanks for the tips.

Anyone got a spare (known working) ignition coil - just in case my checking proves correct?

A 1981 model has points, located inside the flywheel. There are three main possible causes of your problem:
1. the kill wire is contacting ground somehow
2. the points are not working properly (need to be cleaned and reset)
3. The coil is unserviceable and needs to be replaced.
Post Edit: or 4. the ignition condenser is unserviceable and needs to be replaced.

You can simplify your ignition system, and reduce maintenance requirements, by fitting a Magnetron breakerless module in place of your breaker points ignition system. I have attached the official Briggs and Stratton instruction sheet for this rework, to this post, or you can download it from Briggs:

http://www.briggsandstratton.com/support/frequently-asked-questions/Replacing%20the%20ignition/~/media/9ADF0E828C7642A69BC9107A496A31A6.ashx

Joe Carroll has reported doing this successfully many times, using a less complicated procedure. You can probably find the thread where he describes how he does it.

There are two advantages of going this way: you don't have to remove the flywheel to check and adjust the points; and Magnetrons are likely to be a lot more common than breaker-point coils these days, being more recent.

If you decide to keep the engine original (retain the breaker points), I suggest you check the above four possibilities in whatever order you choose. If you get hold of a replacement breakerpoint-style coil, trying it may be easier than removing the flywheel to adjust the points. However pulling the flywheel is not all that hard if you make a simple puller and if you can get access to the American screws required, or if you have a 1/4" UNC tap you can use that, followed by ordinary 1/4" UNC screws.