76 135 HP JOHNSON REBUILD?IS IT 2 OLD

[delsol]

i have a johnson thar has comp-155-155-155-125 new piston run bad think carbs are dirty but was thinking of total rebuild have taken power head before. if i rebuild powerhead do you thinks its worth it because its a 1976 granted i have a 18 ft crestliner78 thats in good cond. with trailer i had 3 years i got 2 yrs out of boat before trouble....if i redid powerhead myself how much do you think it would cost pistons borings etc...<br />please any advice would be aapeaciated.<br />bob in philly

 

[Solittle]

Re: 76 135 HP JOHNSON REBUILD?IS IT 2 OLD

Try to decarbon before you do anything else in case the only problem you have is a sticking ring.

 

[G DANE]

Re: 76 135 HP JOHNSON REBUILD?IS IT 2 OLD

Hi bobby 515<br /><br />Your compression seems very high to me. If the 3 cyls have 155 compression i dont think you will get them higher with any rebuild. Try to find out what happend to the fourth. If you decarb it will probably rise some, you can see on this board these have a need for decarb. Be aware a cylinder with 125 compression will run fine, just with a bit less power than the others. Lots of crossflows have compression around 100 on all. If you are experienceing any other problems than a little rough iddle, i dont think it is caused by your compression.

 

[hondon]

Re: 76 135 HP JOHNSON REBUILD?IS IT 2 OLD

Parts availability is already an issue with this engine and will certainly be more of a concern on down the road.You will be putting that money into 30 year old technology,need to use head gaskets that work with the fuel we have now,and once she is up and running,you still have that 30 year old engine that is getting more obsolete.It is hard to encourage anyone to throw money at this kind of project.

 

[delsol]

Re: 76 135 HP JOHNSON REBUILD?IS IT 2 OLD

see i put piston in it last year the cyl is 125 capared to 155 in other 3 i run good on muffs but wont start unlell i prime carbs with shot of fuel in water sometime it run good when under wot then other times it stalls and wants to go no where ..i did have bad fuel in my xtra 6 gal tank that i got rid of my main tank is good i am think that i might have to clean carbs again ...igot it to idle on muffs good but idle is very high 1500 i was hopeful that when i out it in water it will run better and i can adjust idle also new cyl 125 comp..has very little time on it will it get better it has about 3 hours on it ..i have manual if i clean carb jets do i have to remove core plugs to get under them to clean passage ways???i never did this

 

[G DANE]

Re: 76 135 HP JOHNSON REBUILD?IS IT 2 OLD

If you soak carbs in cleaner overnight and blow through with compressed air it should not be neccesary to remove plugs. Sounds like this is your problem.

 

[delsol]

Re: 76 135 HP JOHNSON REBUILD?IS IT 2 OLD

G DANE i will try to soak my carbs this weekend...<br />what do you soak them in?????crc gas ????cab cleaner what kind

 

[delsol]

Re: 76 135 HP JOHNSON REBUILD?IS IT 2 OLD

i also ran it today i ran on muffs it idled at 1500 rpm so i was able to adjust idle to 1100 sounds good idle a little rough like it always did i was able to start it without spraying gas in carb i put on choke and it started after a while...i want to change spark plugs and water teat it if if does not run ok i will soak carbs but it sounds much better on muffs today with old plugs. then i would like to soak cards over night

 

[G DANE]

Re: 76 135 HP JOHNSON REBUILD?IS IT 2 OLD

In most Autopart stores you can get carbcleaner in a small bucket with a net to soak parts in. Be sure to remove all plastic parts and gaskets first. Alternatively you can get some fuel additive that cleans carbs and even decarbs motor some, to add to fuel. I know Bardahls has some, in a small bottle suitable for 10 gals fuel.

 

[supergenius74]

Re: 76 135 HP JOHNSON REBUILD?IS IT 2 OLD

i rebuilt mine, I only payed 500 bucks for the motor and about 200 bucks on 2 new pistons and gasket kit and she runs and starts great. she fired right up this year after having sat since september of laster year. So for 700 bucks and some sweat i have a 135 outboard with tilt and trim.

 

[delsol]

Re: 76 135 HP JOHNSON REBUILD?IS IT 2 OLD

i am going to water test it sat if it does not run right i will clean and soak carbs and clean passages with air preasure...<br /><br />super i will find out about prop sat boat is 15 min away

 

[dkondelik]

Re: 76 135 HP JOHNSON REBUILD?IS IT 2 OLD

'mornin' bobby,<br /><br />"parts concern" shoud not be a big issue for you. There a plenty of parts around. you just have to look.<br /><br />"High" idle? You might be running a bit lean. if so, this is very dangerous and hard on the engine. I'd remove, clean and service those carbs and run a "decarb" on the motor as suggested above.<br /><br />let's find out where we are before moving on.<br /><br />Good Luck

 

[delsol]

Re: 76 135 HP JOHNSON REBUILD?IS IT 2 OLD

went for ridein boat today adjusted idle runs at 900 rpm at idle in nutrel the boat only goes wot 4500 rpms i dont ever think it did much more not sure what prop...but it ran stedy for 1/2 hour weather was raining it stalled once in water a little hard to start supect carb trouble ..but it came back to dock and only stalled 2-3 times but has nice idle with old plugs....my question is do you think if i run my old gas out that i could have 2 much oil in it and it will clear itself out without removing carbs... it did run ok for a while then bogged then back to normal

 

[supergenius74]

Re: 76 135 HP JOHNSON REBUILD?IS IT 2 OLD

I would say its old gas and old plugs. every old outboard i ever encountered ran better on fresh gas/oil and new plugs every summer. Not sure if you buy premix but i recomend against it, unless you have a small boat and motor, i always mix my own and use good oil. I have a johnson shop manual for my motor and it says the original prop is a 13" x 19p and i measured my prop and its 13" diameter but have no way of determining pitch.