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Brigss & stratton "ready start system", I'm stumped

#1

M

mr.farmall

B.S. Engine 128m02-1612-f1-12041958 DOM Apr 2012
190 cc Platinum 7.25 on a 22" walk behind mower

I've worked on a lot of engines, but this ones got me stumped!
This engine has a very weak spark when started with starter rope. With a neon tester connected to the spark plug, it barely glow while pulling the rope starter. If you pull it moderately, there is no spark at all. only at the fastest pull will it generate a pulse.
Compression at the spark plug is less than 4 lbs,(It has a compression release built in to the cam wheel), so it' easy to spin over,but the engine will not start with pull rope.
When starter rope is removed and flywheel exposed, using a drill and socket on the flywheel to generate a higher starting speed, the engine will start and run well but only after higher rpm,s than can be generated with pull rope. The spark is great while it is running. Engine runs very well after it is started.
Have serviced carburetor ( that was clean to start with but cleaned it any way), checked valves and lashing, changed out spark plug, changed out Magnetron (coil pack) and set at 10 thousandths inch. Checked 途eady start system ( auto choke mechanism with thermostat on exhaust that interfaces with auto choke), checked all carburetor linkage and governor. These are all functioning correctly.
I suspected a problem with the magnetron coil pack, but Engine runs great with new and old magnetron, once you get it started. Also checked that the kill switch connection is not grounded and it works the same with it connected or disconnected from the Magnetron.
Starting speed of engine is only factor that changes. Once the starting speed is increased, the engine will start and run great, but pull with all my might, I cannot get enough speed to start the engine with the pull rope, let alone someone not as strong or big as I.
I have tried to prime the start with a little gasoline in the carburetor, but it just fouls the spark plug.
I have also pulled the plug after a lot of unproductive pulls with the starter to find the plug moist and fouled with gasoline.
This has been a real problem. What can be done to fix this issue?
Briggs and Stratton have been of no help, only telling me that it take one of their specialist to adjust the ready start system.
One last observance, it take 4-5 seconds of turning with the drill before the first pop of the engine, followed by a couple more hit and misses, then it starts
CONCLUSION:
the magnetron will produce a good spark, but only at rpm,s above about 600-700
The extremely low compression must be ok becuase it runs great once it's started.
If anyone has had experience correcting these symptoms, I would be very thankful for any advice.


#2

lzn197

lzn197

Less than 5 lbs. compression? Oh man! I'd focus on that. You've got a compression problem.


#3

EngineMan

EngineMan

Less than 5 lbs. compression? Oh man! I'd focus on that. You've got a compression problem.

Why don't you read the post again....he say's it has "(It has a compression release built in to the cam wheel)" so it will not have high compression on start..!


#4

lzn197

lzn197

Why don't you read the post again....he say's it has "(It has a compression release built in to the cam wheel)" so it will not have high compression on start..!

I did read the post. Engines have had compression release mechanisms for years. 5 Lbs. compression is not enough.

I find it interesting that someone would slam MY comments but add NOTHING to help the guy. :smile:


#5

EngineMan

EngineMan

You may have poor (low) magnets on the flywheel.


#6

T

tybilly

I don't know much about tjose engines,but I have heard they had problems with the coils at one time,but I imagine that they've figured that out,when you swapped coils out .did you clean the mounting post up with sandpaper or a light filing with a file?i was taught corrosion can accumulate at that spot,wich could lead to a weak spark,i have one of tose engines on my pressure washer and im not too impressed with them,especially trying to restart when its hot. a compression test reading wont tell you anything on an ez spin cam,spinning the flywheel backwards and watching it bounce is probably the only test you could do for compression


#7

EngineMan

EngineMan

I did read the post. Engines have had compression release mechanisms for years. 5 Lbs. compression is not enough.

I find it interesting that someone would slam MY comments but add NOTHING to help the guy. :smile:

Reason why engine's have compression release is to aid the starting, and has for helping him out, I like to check the depth of the water before I jump in.


#8

pugaltitude

pugaltitude

Couple of things to try.

You need a proper spark tester as a neon light does not load a coil as if its under compression related conditions.
forget the colour. Its either sparking or not.

It should have the newer style coil fitted with a blue ring which is a higher voltage output coil only 250RPM to allow spark (going off memory).

That engine will have the newer sparkplug so it will be a Champion RJ19LMC and not RJ19LMR or briggs part number 591868.
It will have to be set to 0.020" instead of 0.030" as it was on the older model.

Other thing to try would be the metal suppressor caps on end of coil let were bad for failing.
Pull the metal cap off and see what happens. Usually that can cause a bad starting issue. Just fit a normal rubber boot and terminal briggs part numbers 493880S and 66538S.

Is you OPC cable allowing the micro switch to pull away from the earth contact when pulling the mowers bail arm?

Is the flywheel key sheared?

This is as long as the ready start system is set up properly with the thermostat and choke lever set correctly.

Good luck:thumbsup:


#9

M

mr.farmall

=pugaltitude;147819]Couple of things to try.
Is the flywheel key sheared?
no the fly wheel key is in great shape, it looks like new

That engine will have the newer sparkplug so it will be a Champion RJ19LMC and not RJ19LMR or briggs part number 591868.
It will have to be set to 0.020" instead of 0.030" as it was on the older model.

the original plug is a champion RJ2YXLE and has the B.S. symbol imprinted on it.
I have also tried to use RJ19LM no "R" nor "C" on it. And have tried other plugs that I had. They all seem to work with the same results. I don't know the difference between the RJ19LMC and RJ19LMR and the RJ19LM.

It should have the newer style coil fitted with a blue ring which is a higher voltage output coil only 250RPM to allow spark (going off memory).
Both the old and the new coil I have used look identical and neither one has any blue on it. The new coil part # is 590454. Do you have a part # for the coil with a blue ring?

You need a proper spark tester as a neon light does not load a coil as if its under compression related conditions.
forget the colour. Its either sparking or not.
I don't have a gap tester but I did try putting a second plug in line (series) with the first plug. I was able to vary the plug gap on the test plug, but after I finished, it occurred to me that the 30 /1000 on the installed plug was the limiting factor and changing the test plug gap was meaningless. I'll redo the test again tonight after I change the gap to a close 15/1000 on the installed plug.
The installed plug is under pressure, but the test plug is not. It can at least give me a clue!
One thing I noted was that it started to give a very weak spark at about 250-300 rpms. as the rpms speeded up, the spark became stronger and at 600 rpm's it was a sharp snap and a wide spark, not the narrow, almost invisible spark at 300 rpm's. This is the same results I noticed with the neon tester, a very dull glow at low rpm's to a bright flash at higher rpm's


Other thing to try would be the metal suppressor caps on end of coil let were bad for failing.
Pull the metal cap off and see what happens. Usually that can cause a bad starting issue. Just fit a normal rubber boot and terminal briggs part numbers 493880S and 66538S.
I'm not sure what you are getting to with the caps. Both coils look identical and have no caps by the coil. There is a rubber cap at the plug end of the wire. Ihad to remove the rubber cap to install it on the new coil. I took it apart to have a good look at the connection from the coil wire to the metal plgu that connect to the spark plug. It has a good solid connection and you can see the wire double back under the metal to form a good connection. It's not loose nor does it have any corrosion at all.

Is you OPC cable allowing the micro switch to pull away from the earth contact when pulling the mowers bail arm?
Yes the earth ground is completely gone, I even disconnected it at the magnetron to make double sure.

This is as long as the ready start system is set up properly with the thermostat and choke lever set correctly.
It appears that at a cold start, the thermostat doesn't even come into play. From the Briggs web site, it says that as the engine warms, the thermostat lever moves forward stopping the auto choke from going to the choke position as the engine stops. This prevents a choke with a warm engine. This thermostat is doing just as it was stated from Briggs. But I still have trouble whether the engine is warm or cold.


#10

M

mr.farmall

Further testing;
I set up a gap using two screws pointing at each other through the sides of a u shaped piece of nylon. I was able to vary the gap by unscrewing them a little to separate the points. the connection came from the magnetron spark plug lead to one of the screws and then across the air gap to the second screw then to the installed spark plug with a 15/1000's gap on the plug. This was very interesting to watch.
At 15 / 1000's, I got a spark at 250-300 rpm's. it appeared to be very thin, almost needle like, but it was a spark. It looked stronger as the speed increased.
At 76 /1000,s got the same spark at the same rpm's
At 90 / 1000's The same thing. This is almost a 10th of an inch, much wider than any plug would ever be set at!
I got a spark clear up to 150/ 1000's.
Then I changed the installed plug to 40/ 1000's and reset the air gap test to 60/ 1000's
I still got the same results. I think this clears up the issue of whether the Magnetron is bad or not. Definitely not.
But the starting results are still the same. It takes about a 600 rpm for a few second to get it started. A lot more than a pull rope can generate.
Also, I got info on the magnets from the Brigs and Stratton web site to test their strength. It says that with the fly wheel vertical, a 10 inch #3 screwdriver should not fall off when placed horizontal across the magnet.
On this one, the center magnet held very strong, the two outside magnets wouldn't hold a 4 inch screwdriver. I'm not even sure they are magnets, just getting some magnetic attraction from the center magnet.
To verify this, I got another fly wheel from the parts house and tested it. It was identical!
the magnets and the magnetron generate the spark. I'm satisfied that both of mine are in good shape. I now need to look elsewere.
any further ideas would be greatly appreciated.


#11

I

ILENGINE

I went back and read through the list of post and from the description of the problem you have a compression problem. Even with compression release anything below 60 would be suspect. 600 rpm should be achieveble with a rope starter, that is only 1 rev per second. the original magnetron was set up to fire above 600 rpm. the newer systems are set up for 250-300 rpm on briggs. the origian tecumseh and kohler CDI are 300 rpm systems.

Sounds like you need to do leakdown test to determine cause of low compression. Most likely valve leaking issue. I have seen valve seat not be cut square with the valve face on brand new engines. As well as improper valve clearance gaps.


#12

M

mr.farmall

ILENGINE:
Thanks for the specs on this engine.
600 rpm should be achieveble with a rope starter, that is only 1 rev per second.

I'm not sure I can get up that high with a pull rope. I think 600 rpm's = 10 revolutions per second, you must have mistyped a "0". When I use a drill to get it that high,it is spinning quite fast and it still takes 4-5-6 seconds to get the first pop , then another second or two to get it started.

the original magnetron was set up to fire above 600 rpm. the newer systems are set up for 250-300 rpm on briggs.
I must have one of the newer ones since I am getting a spark at about 300 rpm's

Even with compression release anything below 60 would be suspect.
I spun the engine over with the compression gauge attached at different speed. Up to 250 rpm's I hardly got a reading, at 400 rpm's It was about 6,PSI, at 600 rpm it had climbed to about 30 psi, and at 800-900 rpm's it topped out at 62 psi. It never increased from that point no matter how fast it spun.

Sounds like you need to do leakdown test to determine cause of low compression. Most likely valve leaking issue. I have seen valve seat not be cut square with the valve face on brand new engines. As well as improper valve clearance gaps.

I don't have the leak down tool, but I do have an air adapter that screws into the spark plug hole. I set the pressure at 60 PSI to try it out. It immediately spun the fly wheel moving the piston to the bottom position. At 60 psi it was hard to hold the flywheel from moving except at the TDC location. Any slight movement wold set it spinning back to the bottom without some leverage to hold it in place.
At TDC I could hear and feel air coming out of the Exhaust. All the valves should have been closed at that point. It looks like I'll revisit the valves again to see if something forieng is on the seat or valve holding it a little open.
Were can I get info on the seat angle for these valves?
Thanks



#14

M

mr.farmall

Less than 5 lbs. compression? Oh man! I'd focus on that. You've got a compression problem.

Took the valve system apart again today. Clearances are 6/1000's and 9/1000's. Seem to be good until I decided to re-seat the valves with a little re-seating grit compound. The exhaust valve cleaned up in only one small section, about 1/6th of the valve's circumference, but all of the valve seat had a nice seating mark left. I have a bent valve. I placed a bright flashlight in the exhaust port of the block and you could see light coming out of 5/6th of the valve seat with the valve in the closed position. This must have came from the factory this way. Their are no marks on the head nor any on the valve seat. I thought they started every engine after they were assembled. Maybe things have changed now that many are built in China.
It helps to pay attention to the facts from the testing!
Thanks LZN and all others
I have a new one on order and should be hear by the weekend.


#15

lzn197

lzn197

You might as well go ahead and fix it. You are almost there!

Another issue that is quite common with smaller, push mower engines that causes compression loss is the valve seat. The poor thing gets cocked in the bore and now the valve cannot seal. Why does this happen? I have found it is because customers either overload the engine with tall grass and a dull blade or never clean the cooling system and the engine gets hot. It also can be the seat or the bore were not to specs and with use over time, the seat comes loose.

I am happy you found the problem. It takes Air, Fuel, Compression and Spark to get an engine to run. Any kind of disturbance with any of them, and the engine (as my Daughter says) will not GO.

Also many thanks to ILENGINE for backing me up and the additional information he shared that was right on!

Gordon


#16

M

mr.farmall

You might as well go ahead and fix it. You are almost there!

Gordon

The parts came in today, The exhaust valve looks good, but the plug they sent, the one on their look up screens, it is a RJ19LM, the wrong spark plug. Looks as if they need to upgrade their info. I called Briggs support just to make sure and the lady on the other end of the line verified that in deed it was now a RJ19LMC, so she is sending one out, should be here the first of the week. By the way, the original plug RJ2YXLE is very elusive. It's not on the Champion plug chart and even the Briggs people couldn't find it on their records. No matter, it is now superseded with the new one. I'll let you know how it all works out next week.
Thanks Everyone, your help is very much appreciated.
Rex


#17

wjjones

wjjones

I got nothing that is a very strange issue though I hope you figure it out as it will help alot for future info.


#18

M

mr.farmall

A big thanks to everyone:
LZN197 pointed at the compression, but was overlooked while preoccupied with the spark.
EngineMan pointed at the Magnets a major component in the spark
Tybilly suspected trouble with the Magnetron, another major part of the spark
Pugaltitude gave info on proving the spark to be good and the new info on the spark plug. (much needed)
Ilengine re-pointed back to the compression and the leak down test (Invaluable)
rivets had the manual for the valve info.
and Wjjones, Yes it is fixed! Yeppi!
I got the valve clearance set by grinding the valve stem to allow 8/1000, then seated the valve with lashing compound. It seated very true, no valve seat problems.
After it was put back together, the compression was 37 psi @ 100 rpms, 70 psi at 300 rpms, and it topped out at 110 psi @ 600 rpms and above. With a new and correct spark plug, I prepped the engine and it started on the first pull. Not even a hard pull, but something my Lovely wife could do!
For a new machine that was given up as Junk after just a few lawn mowings, I think it has many years of service left in it.
Thanks everyone and I hope this will be of help to someone in the future.
Rex


#19

EngineMan

EngineMan

Nice one Rex....:thumbsup:


#20

M

mr.farmall

Re: Brigss & stratton "ready start system", I'm stumped----- now a follow up

[/B][/B]A follow up after using the mower for half the summer!]
This engine starts incredibly easy. My wife loves it!!
But their is one problem I have found, and it is very annoying; starting the engine after it has set in the sun on a hot day. It will not start. It just floods itself until the plug is fouled.
I have tried removing the plug to dry it off, but it just fouls again. I let it set in the shade for a couple of hours and it starts right up again.
To over come this, I hooked a wire over the wind vain arm of the choke mechanism, pulled forward to operated it as if in the hot engine position ( doing the same thing the thermostat would do on a hot engine) and had my wife pull the rope. It started on the first pull.
I have had this experience 5 or 6 times now and am convinced that the engine needs no chocking when the outside temperature is this hot and sunny, but the engine is still cold, (relatively for and engine). The ready start system is still not hot enough to stop the chocking.
Once started and ran for as little as 30 seconds, the engine heats up, the thermostat operates, and the chock is removed just as it should. Re-starting now works great.
I'm about to permanently connect a pull wire that can be temperately latched to hold the chock open and then be released after start up, but would not interfere with the ready start system unless it is latched open. This would greatly reduce my frustration on these hot sunny days, allow me to start the engine by myself, and also let the system work normally on all other days.
I hope this might be of help to someone experiencing this problem on their engine.
Thanks Rex


#21

D

dennis morris

I GOT THE SAME THING. I THOUGHT I WAS THE ONLY ONE. I WENT TO THE LOCAL DEALER AND TALKED TO THE THEIR SHOP FOREMAN AND HE SAID THAT HE HAD NEVER HAD THAT PROBLEM, (GREAT HELP). I WAS THINKING OF PUTTING A COUPLE OF SMALL WASHERS BETWEEN THE COIL AND ENGINE MOUNT SO THAT THE COIL WOULD HAVE A HIGHER LIFT ON THE FLYWHEEL MAGNET. I HAVEN'T DONE IT YET BUT I'M AT A LOSS TOO.


#22

B

Blaine B.

Sounds like too much complicated garbage on a lawn mower!


#23

M

mr.farmall

I GOT THE SAME THING. I THOUGHT I WAS THE ONLY ONE. I WENT TO THE LOCAL DEALER AND TALKED TO THE THEIR SHOP FOREMAN AND HE SAID THAT HE HAD NEVER HAD THAT PROBLEM, (GREAT HELP). I WAS THINKING OF PUTTING A COUPLE OF SMALL WASHERS BETWEEN THE COIL AND ENGINE MOUNT SO THAT THE COIL WOULD HAVE A HIGHER LIFT ON THE FLYWHEEL MAGNET. I HAVEN'T DONE IT YET BUT I'M AT A LOSS TOO.

Dennis; I hope you find the answer to your troubles. I did a lot of testing with the magnetron and came to the conclusion that was given in post #8 by Pugaltitude
"You need a proper spark tester as a neon light does not load a coil as if its under compression related conditions.
forget the color. Its either sparking or not.
He was right, the size and color of the spark didn't really have much bearing on the engines starting performance. What I thought was a wimpy spark turned out to be more than sufficient to start the engine. If you read through the entire postings, you will find that my trouble was entirely the compression problem from the bent valve. LNZ pointed it out right from the start but I was stuck on the spark instead and had to prove to myself that the spark was good no matter what it looked like before I moved on to find the real problem, lack of compression.
A leak down tester is something I will now put in my inventory of tools. I can see it has great potential when needed. Good Luck on your project and let us know how it goes.
Rex


#24

primerbulb120

primerbulb120

I am having this same problem on a Briggs and Stratton Platinum. I haven't turned it over with a drill, but it has 10 PSI of compression. I'm going to take the cylinder head off and see what I find...


#25

M

mr.farmall

I am having this same problem on a Briggs and Stratton Platinum. I haven't turned it over with a drill, but it has 10 PSI of compression. I'm going to take the cylinder head off and see what I find...

I'm sorry to hear you have this problem. If you read post 23 and post 18, you will see that my problem was entirely a compression problem. It was stated in one of the first posts and then again in a later post that the compression was much too low. After I got the new valve installed, I posted the results of the compression. You can see that they are much higher than originally and much higher that the 10 lbs you have stated on yours. I have since invested in a leak down tester and used it 3 or four times. It wasn't very expensive but has helped guide me to troubles and pinpoint the troubles section of compression problems, saving a lot of time. I think you can check one out for free a few days from O'rielies auto store.
good luck with your trouble, and keep us posted on what you find.
Our mower has worked great now for the second summer. still starts on the first pull no matter how long it has set without being used. it even started on the first pull this spring after filling the tank and checking the oil.
Rex


#26

primerbulb120

primerbulb120

I didn't find anything obvious, so I will get a new head gasket and do a leakdown test on the engine.


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