Logo

72 johnson, 25 hp, setting points, wot or idle? still dying at idle

dkonrai

Regular Contributor
im confused, when setting points, should the throttle be in the wot or idle position? i have this off idle issue still. so off with the flywheel to reset the points. what i found was the points were way off.
i used the ohm meter method. i pulled the coils disconnected the condensers and used the kill wires to test the points. at idle one of the points were near the mark, but the other was way off. when i went wot the test was reversed.
i set the points in the wot position (ok?) vs at idle. the alignment marks are rather strange. the lower throttle cam has two marks, flywheel has a pointed arrow, followed by a line. i lined up the line to the throttle cam marks. motor does run but i still cant get it to idle less than 600-700 with out dying. when the throttle is to the shift mark it dies. i believe the motor should run / idle when the butterfly on the carb is closed?
question wot or idle? when setting points.
thank you very much
dino
 
This is a magneto and the points need to fire at the same time relative to the magneto plate !!-----It does not matter whether the points are set at idle or full throttle.
 
i will post some picts tomorrow. i left the motor on the stand outside. camera takes crappy picts at night. thanks for all the replies.

@ kim, seems that when i move the armature (?) plate so does the timing marks. tm are on the armature plate plate that advances with the throttle. so i am not sure if i should time the motor at idle or wot? also will this affect the low idle issue?
 
here is the armature at idle
DSCN0166_zps68efbecc.jpg

again at wot
DSCN0165_zpsc8547dbe.jpg

or do i line up with the roller?
DSCN0163_zps4c604df8.jpg

the factory guide only shows the use of the timing tool or using the 0.020 setting. i would set the points at .020 and call it done, however, wanted to see if i could get the idle nice and low like how a johnnyrude should run. seen some vids on youtube of the same motor and most seem to idle nicely.
any comments?
thanks again
dino
 
.020 will make it purr like a kitten. I noticed you post it as a 25hp now evidently you put in the larger high speed jet the motor should scream at WOT. You may need a prop with more pitch depending how heavy your boat is I believe michigan wheel still has new props available for your motor. Used prop are allways risky after 40 years the hub has a tendency to spin in the bushing. Especially with a nice healthy motor it has been around 12 years since I had a new bushing pressed into a prop it aint cheap either.

thanks kim, i will give it a go tomorrow. i bought a 25 hp carb of fleabay. figured 50 bucks! delivered in three days from pa to norcal. yah im itchy to get this on my 14 foot duroboat. boat weighs about 200. im about 170. motor is 82 (?) pounds. should be interesting :)
dino
 
When you put a timing light on any motor with that universal type magneto ,the points will always fire the coils between the 2 vertical marks on the magplate.-At idle or full throttle !!-----If a motor will not idle then some basic trouble shooting needs to be done.----What is the compression ?-----Will spark actually jump a gap of 1/4" or better.----Are the reed valves closing properly.------I have seen motors scrapped because a small screw held one reed partially open , easy fix on those.
 
Last edited:
When you put a timing light on any motor with that universal type magneto ,the points will always fire the coils between the 2 vertical marks on the magplate.-At idle or full throttle !!-----If a motor will not idle then some basic trouble shooting needs to be done.----What is the compression ?-----Will spark actually jump a gap of 1/4" or better.----Are the reed valves closing properly.------I have seen motors scrapped because a small screw held one reed partially open , easy fix on those.

compression is 120/120
semi new coils, i have plenty of spark
new plugs
carb is clean (yes i pulled the plugs and cleaned everything, blew out the carb with a compressor
how do i check the reeds?

dino
 
Remove carburetor and inspect reed valves found inside intake manifold.--------Once again , it is called a magneto and this means that the points must open at the correct time.That is governed by the position of the coils on the magplate and the magnets sweeping by the heels of the coils.----------The timing of the spark in the cylinder is governed by the ROTATION of the magneto plate.----------The maximum spark advance is limited by a mechanical stop for the magneto plate !-----At idle the timing is retarted as the magneto plate rotates, if it goes back far it means you have an engine in good condition.--------The throttle should open when the roller is lined up with a single mark / line on the throttle cam.----The 2 vertical lines on the magneto plate have nothing to do with throttle opening timing.
 
Last edited:
as for the opening of the points, i dialed in the points to open exactly 180 degrees apart using the static timing method.
 
If you have spark that will jump a gap of 3/8 then ignition is not the problem.----If you have compression at 120 PSI then the cylinders and pistons are not the problem.----That leaves crankcase compression ( totally seperate from cylinder compression ) with reed valves or lower crankcase seal to be inspected.--------The other area then is carburetion related problems.----Have you set the carburetor throttle plate to open at that mark on the throttle cam ?---Post a picture of the single mark/ marks on the throttle cam.----Post a picture of where exactly the throttle opens.
 
If you have spark that will jump a gap of 3/8 then ignition is not the problem.----If you have compression at 120 PSI then the cylinders and pistons are not the problem.----That leaves crankcase compression ( totally seperate from cylinder compression ) with reed valves or lower crankcase seal to be inspected.--------The other area then is carburetion related problems.----Have you set the carburetor throttle plate to open at that mark on the throttle cam ?---Post a picture of the single mark/ marks on the throttle cam.----Post a picture of where exactly the throttle opens.

racerone,
i dont know if you can see in the picture above, but yes the throttle cam is aligned with the carb. just slightly opens when it is between the two marks (TM),
thanks seems to be pointing to either a reed problem or powerhead gasket?
 
Are you looking at the 2 vertical marks on the magneto plate or a mark on the throttle cam ?----There is a difference here.
 
Are you looking at the 2 vertical marks on the magneto plate or a mark on the throttle cam ?----There is a difference here.
i lined up the roller to the throttle cam the two little marks. is this correct? reference the last picture.
thanks
dino
 
http://www.ebay.com/itm/314842-0314..._Accessories_Gear&hash=item43b1009e16&vxp=mtr This is the throttle cam there are two marks on it you use to sync the timing with the carb opening, you want the throttle butterfly to begin to open as the roller passes center of those two marks.
http://www.ebay.com/itm/Johnson-Evi..._Accessories_Gear&hash=item2c6b56dc1d&vxp=mtr Does your points cam look like this put the fibre lift part of the points on the O in top and adjust the gap to .020 and do that for the other set of points get them both as close as possible and start the motor and adjust the idle screw for a nice smooth idle in gear in the water and add 1/8 to 1/4 turn rich for cold starts. If there is no fuel spitting back out of the carb the reeds are probably just fine all that timing light crap is keeping you off the water.

ok good i got the carb sync'd like it should. i will give the points a go tomorrow. i am in construction (plumber) work is slow. had to work on my daughters car so i could get the boat. she parked behind the boat and the starter died.
i dont have fuel spitting out the carb so thats a good thing :)
dino
 
Once you get it running have you tried pulling the plug wires one at a time. Run it at a high idle and with a good pair of insulated pliers pull the plug wires one at a time if it stalls its only running on one cylinder hopefully the lower cylinder you can change the upper seal without pulling the block apart. You will note a decrease/increase in rpm as you pull and put a plug wire back on the plug. Also if it is having trouble idleing still take and with your fingers cover the carb about half way if the idle smooths out your running lean or you also may have a vacuum leak. The best way to isolate a vacuum leak is with a piece ov vacuum tubing put one end up to your ear and search around with the other while the engine is running the closer you get to a leak the louder the hissing gets. search everywhere there is a gasket intake manifolds and intake port covers.

kim,
ok thanks for the advice. will let u know the results. may take the boat out for a spin.
dino
 
hmmm good one. i havent checked the tstat. i know i have really good flow but didnt check to see when the stat opens. will look at this later today.
dino
 
**update**
had some time and got the needle bearing i needed. bought them from a local shop. well original 20hp carb is shot (?) but the good news is that the used 25 hp i got from omcjoe, works pretty good. got the motor to finally idle.
my guess is there was something wrong with the original carb?
thanks for all the tips. i did recheck the points, and she was pretty darn close to .020 . immediate plans are to finally run the motor on the 14 foot duroboat. next is a reseal, then a full tune up.
thanks again!
dino
 
Back
Top