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  1. #1

    Default 1985 Suzuki DT55 compression specs?

    i ran a compression test on all 3 cylinders and #1 and #2 were about 117psi and #3 was about 122psi. does this seem right? does anyone have the compression specs for these motors? im also considering running a leak-down test on them as well.

    i ran the test because when i start the motor i let it idle for 15secs, then put it into gear and give it gas and it just sputters and dies. it does this about 7 8 times then it finally wants to start going. it may be a carb issue but someone said it may be compression related. can anyone shed some light on this issue? any help would be appreciated!

  2. #2
    Join Date
    Sep 2010
    Posts
    19,577

    Default Re: 1985 Suzuki DT55 compression specs?

    I say it may be a carburetor issue.-----They idle really well when a bit lean.-----Not a problem until you want to speed up.-----Costs no coins to open low speed mixture screws 1/4 turn at a time and test run.

  3. #3

    Default Re: 1985 Suzuki DT55 compression specs?

    I ran that vintage motor for years, your compression numbers look fine. Follow racerone's advice about cleaning and adjusting the carbs. Do you have the Suzuki maintenance manual?

  4. #4

    Default Re: 1985 Suzuki DT55 compression specs?

    Quote Originally Posted by mphelle View Post
    I ran that vintage motor for years, your compression numbers look fine. Follow racerone's advice about cleaning and adjusting the carbs. Do you have the Suzuki maintenance manual?
    yes i do. i adjusted the carbs to a leaner mix and it idles much better. seems to run smoother as well. still sputters and dies out. its like its not pulling fuel into the carbs. i have to use starting fluid to get it running if i leave it off for a while but once its started it stays running.

  5. #5
    Join Date
    Sep 2010
    Posts
    19,577

    Default Re: 1985 Suzuki DT55 compression specs?

    Read post #2-----If idle is set too lean most older outboards will stall when throttle plates open !----How long have you owned this motor ?----Did this problem develop suddenly ?

  6. #6

    Default Re: 1985 Suzuki DT55 compression specs?

    i did some tuning with the boat in the water and found where it seems to run the best. at one point i did make it too lean and it barely ran. so i richened it back up.
    this was also my first time adjusting the carbs after they were rebuilt about 7 years ago.

    ive had this boat for about 13 years now. the problem started about 2 years ago but it wasnt this bad until recently.

    another sidenote, it also wont go past half throttle after i ran out of gas about a week ago. ran fine, went full speed before i ran out now i can floor it and it still only goes half throttle. related?

  7. #7
    Join Date
    Sep 2010
    Posts
    19,577

    Default Re: 1985 Suzuki DT55 compression specs?

    Do some trouble shooting here.----I think it needs more than ---" carburetor adjusting "

  8. #8

    Default Re: 1985 Suzuki DT55 compression specs?

    i bought a rebuild kit for the fuel pump cuz its never been done in all the years ive owned it. Seems pretty simple and for $18 its a good place to start. i am the 3rd owner of this boat so i dont know whats been changed if anything on this motor thru out its life.

  9. #9

    Default Re: 1985 Suzuki DT55 compression specs?

    If the carbs haven't been looked at for 7 years, I would start with a good cleaning, preferably ultrasonic, and adjustment of the carbs and throttle position switches. A couple of years ago, my lower cylinder main jet became completely clogged after only one season after a complete service. You do not want to run that motor lean, it will quickly overheat and smear aluminum across the piston rings at the exhaust port. While you have the carbs off, remove the intake manifolds and make sure the reeds are intact and seating properly.

  10. #10
    Join Date
    Mar 2019
    Location
    South Africa
    Posts
    18

    Default Re: 1985 Suzuki DT55 compression specs?

    How does it run after you rebuilt the fuel pump? I was going to suggest replacing the fuel pump diaphragm.

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