Needle valve 55 HP 1980

[mlaajanen]

Hi,

I am rebuilding the carbs on a Johnson 55 1980 due to idle problems.

After disassembled the carb I noticed that there was no spring on the needle valve, usually there is a spring(I thinks its is item #29 in the link below) that brings the needle out of the seat when the float sinks due to low fuel.

Should it be a spring or not is my simple question?

http://www.boats.net/parts/search/BRP/JOHNSON/1980/J55RLCSA/CARBURETOR/parts.html

cheers

Michael

 

[racerone]

What other trouble shooting has been done ?----Compression checked ?----Yes there is a CLIP on most needle valves to pull them out of the seat.----It is not a spring.

 

[mlaajanen]

What other trouble shooting has been done ?----Compression checked ?----Yes there is a CLIP on most needle valves to pull them out of the seat.----It is not a spring.

Hi,

No I have not done much troubleshooting. It runs perfect above idle though but when started it takes just a short while before it starts to sneeze after a cold start.
I was thinking if it could be due to needle vavle being stuck at Idle due to low fuel pressure.

Also, I also been thinking if the powerpack does not supply enough power at low RPM for the sparkplugs.

You say its a clip on most needle valves, my needle does not have any place for a clip so could I have a wrong needle valve perhaps?

 

[racerone]

Correct on the needle valve.----At idle there is more time for air to leak from crankcase / cylinder.-----That is why to the untrained it seems to " run perfect " above idle..-----Test the spark by forcing it to jump a gap of 7/16' or 10 mm while cranking.----Testing is the path to take.

 

[mlaajanen]

Correct on the needle valve.----At idle there is more time for air to leak from crankcase / cylinder.-----That is why to the untrained it seems to " run perfect " above idle..-----Test the spark by forcing it to jump a gap of 7/16' or 10 mm while cranking.----Testing is the path to take.

With correct on the needle valve you means sometimes a clip sometimes not?

I will reassemble everything now and will perform compression test and the other test.

 

[mlaajanen]

With correct on the needle valve you means sometimes a clip sometimes not?

I will reassemble everything now and will perform compression test and the other test.

Hello again,

Compression is about 140 PSI on both cylinders. I did try a different approach on the spark test, I increased the sparkplugs gap twice but no difference.

The enginen runs for some 10-20 seconds before it starts to sneeze.

I should also say that I have replaced the reeds with new ones fron Chris Carson, glasfiber ones.

 

[mlaajanen]

What about the fuelpump, could it be a faulty membrane causing leakage?

But, the strange thing is that it runs fine when for short while when cold, if it was a EFI engine then I would better understand that but on a a old 2-stroke!

Here is a link to Youtube when I am starting the engine, https://youtu.be/VZMVB0h1_I8