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1987 Johnson Fires Only On Top Two Cylinders

C

camsore

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Hello All
1987 110 V4 will on

Hello All
1987 110 V4 will only fire on the top 2 cylinders. It had not been run for 6 months. I rebuilt the carbs and have 110lbs on all cylinders and very good spark. Could this be a reed valve problem??? VRO problem??? It run great the last time I used it.
 
"ok im confused..........you s

"ok im confused..........you say it isnt runnin on the bottom 2 cyls but it has spark?

if this is the case i would suspect you made some error in the carb rebuild...bottom carb of course.

if if guesssing right you can start the eng and it misses and barely runs.......then you can pull the 2 bottom plugs and they have fire but make no difference in the way it runs..............right?

if this is so dont run it like that much as your fuel (pre-mix) is the only lunrication you have...ie no fuel no lube that will do damage real fast..

no spark is better that no fuel....as far as damage control goes...as far as cost i would rather have no fuel.

have you loosed the carb drain screw to see if it has fuel?

did you manually clean al the orifices?.....or just spray them with carb cleaner?

you really need some small wire, carb cleaner, and compressed air to clean one properly..............i cant remember who said it on here but it was right on...."jsut because the inside is shiny doesnt mean its clean""
 
"Yes, I loosened the drain and

"Yes, I loosened the drain and gas came out. Yes I cleaned carb with a small wire, carb cleaner and compressed air and checked float level.Yes I can pull the bottom plug wires and it makes no difference. I did get to run on all 4 clinders for a short time be now it's back to 2. What is the correct level of gas in the filter? If I have low fuel pressure would gas only go to the top carb?"
 
"the correct level of fuel in

"the correct level of fuel in the filter is debatable ..... it depends on the size and angle.

i run one single fule filter now.....water/fuel separator

have you checked for an air leak around the carb to intake gasket?........you can start the eng and spray some carb cleaner around the base...if its lekaing you will know it.



what did you do when it did run on all 4cyls?

sounds like you may have an intermittent spark prob....

you can inspect the reed valves if you suspect this is the problem......you are looking for warped, broken, cracked leafs.

also ,im sure you have already done this but just to be safe, check all your wire connections for corrosion..especially the coil...and make sure none of your pins are pushed back."
 
I don't know what I did to

I don't know what I did to make it fire. I have always had the same spark. I also sprayed a little premix gas in the bottom carb and nothing. I am going now to check VRO pump pressure. Will try the carb cleaner around the carb. How will I know what will happen?
 
"if you sprayed pre-mix into t

"if you sprayed pre-mix into the bottom carb with no effect you are either losing spark or you have some issues elsewhere....now isee why you think it may be the reeds.

what does your spark plugs look like?

usually the carb cleaner will drag the motor down because it doesnt burn as well as gas........i doubt you will get any effect from the carb cleaner since spraying fuel directly into thecarb didnt help.........sounds like your reeds are stopped up.

i have seen the cyl sleeves come loose and spin....but you have good compression and it actually worked at one time....and 2 cyls would be rare..to me anyways.....and usually when a sleeve turns you will end up with some broken rings.

we may have to have some more help......im an auto mechanic and still a lil green on obs......i do however work on any and everything...especially my friends obs, dirt bikes, chainsaws, etc......you get the idea.

this one has just about got me stumped........but i have torn one down only to fine a buuunch of grass in the reed valve ...but it tried to run..just poorly"
 
Larry check the pulse line fro

Larry check the pulse line from the block to VRO...if you pull the line of the plus limiter which is screwed into the block and prime fuel up you should not have any fuel coming out of that line...if you do you have a problem.

The other problem can be an air leak somewhere...intake area or lower crankcase seal (last resort)
 
"Found it <[img]"http://www.ma

"Found it
happy.gif

David, I was sure it was not the carbs. I checked the fuel presure and it was fine. You said take a look at the bottom carb. Took it apart and found a small amount of lint pluging the bottom of the small vertical tubes. Thank you David and all of the others that post here for the help. Sometimes others can see what I was overlooking."
 
yep those tubes and orifices c

yep those tubes and orifices can get you......it dont take much to cause problems....even varnish can cause problems...

i over look things too......sometimes i have to step back and tell myself: dont over diagnose the prob and start with the most basic steps first......some of the stuff i overlook reminds me of carl in slingblade ------- mmmmmmmm aint got no gas in it......ive actually been guilty of the no gas deal lol....and notice i said above i now only run 1 filter?....i had a prob with water in the fuel on one of my small obs (i am boat poor--got 4) and i jerked on that rope for what seemed like an eternity before i figured it out.

glad you got her going!!
 
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