HELP ! Compression on 87 Johnson 50hp VRO.

[skelly]

I have a 87 50hp VRO Johnson that has rough idle problems, I have been messing with it for the last 3 years, I have rebuild carbs 3 times changed plugs 2 times- champion QL77JC4 - Using fresh fuel - use decarb foam spring-fall & mid season sence new. Had sink & link done twice in the last 3 years. Changed thurmostat last week it was stuck open, used decarb again, this helped a little, going to check reeds next! also checked compression again it is 145psi on both cylinders!! Dose this sound right, can't find comp psi in my manual.<br /> THANKS!! SKELLY.

 

[Skyhigh]

Re: HELP ! Compression on 87 Johnson 50hp VRO.

Your Compression sounds great....<br /><br />I wish i had 145 on my cylinders.

 

[OBJ]

Re: HELP ! Compression on 87 Johnson 50hp VRO.

AMEN to the 145 compression.<br /><br />Skelly....do you notice any puffing from the carbs at idle? The carbs should suck air in all the time and NOT blow out. Hold a light piece of toilet tissue (unused) in front of each carb while it's at idle. If either carb wants to blow out the tissue, the reeds may be damaged or sprung from the reed plate.<br /><br />Also make sure that ALL fuel connections are tight. Strange thing, a fuel connection can suck air in when it won't leak gas out. (still working on that one)<br /><br />Keep us posted....Thanks.

 

[clanton]

Re: HELP ! Compression on 87 Johnson 50hp VRO.

There was a kit for the fuel pump, had 2 o-rings and nipple for fuel line, to solve air leaks, one of problems is cheap o-rings, swell when gas gets on them, then will not reseal. Worth a look, but dont think your engine problem. When you do sync and link, check all small plastic rollers, if the clear plastic sleeve is missing, the timing will move around between 4/5 degrees.

 

[skelly]

Re: HELP ! Compression on 87 Johnson 50hp VRO.

Thanks for your input guys! so it sounds like my compression is good,what is normal for this motor? OUTBOARDJIM- to anser your ? about the carbs puffing, to me it is more like a sneez every now & then-acts like it wants to cut off then picks back up. Could this be a reed problem? CLANTON-I have gone over these carbs with a fine tooth comb, HELL! i see them in my sleep, air leaks too, But i know im close to fixing it. Thanks so much for your help. IF you can think of anything please reply. SKELLY.

 

[G DANE]

Re: HELP ! Compression on 87 Johnson 50hp VRO.

skelly<br /><br />I have a 1988 40 HP evin with VERY few hours, sat for 5 years too. It has 148 and 150 compression. I guess 150 was new stock.

 

[skelly]

Re: HELP ! Compression on 87 Johnson 50hp VRO.

Thanks for the input G DANE,I think your power head is the same as mine with different carbs, Have you every had any idle problems?

 

[OBJ]

Re: HELP ! Compression on 87 Johnson 50hp VRO.

Skelly....it does sound like your sucking wind from some place. Do you notice any heavy oil acumulation under the flywheel?<br /><br />Yes, damaged reeds can cause the idle problems your experiencing. You need to remove the carb cover to check for blow back.<br /><br />Just an outside thought here, have you check the flywheel key to see if it's OK? A little outa' time here can cause ya' grief.

 

[chilifriedpork]

Re: HELP ! Compression on 87 Johnson 50hp VRO.

Try the reeds, it's worth a shot.<br /><br />I have a 15 Johnson that caughs, then picks up again at lower rpm's.<br /><br />I think it may be electrical, but that's a whole nother story...<br /><br />G'Luck

 

[G DANE]

Re: HELP ! Compression on 87 Johnson 50hp VRO.

skelly<br /><br />I have had iddle problems. It was caused by overoiling at low rpms, the fuel connector was leaking, and the pump cought air at gas side at low rmp´s, but continued delivering the right oil quantity. How does your plugs look like when iddling - oily ? or black/dry. Should be dark brown or black/dry. Did you try disassembling carbs, removing floaters and needle valves and soaking carbs in cleaner solvent overnight. Then blow through with compresed air, specially iddle circuit. Be sure top of carbs are covered when soaking. It really helps. Best motor I ever had, quiet and strong.