So I repowered my pontoon with a 81 Johnson 90 and I am having a few issues.
First and foremost I know this motor needs rings. I tested compression when I first got it on the boat and it was low but I couldn't get repeatable results between the cylinders. So in the off season I will be re-ringing it, if not more.
So now on the water. It starts fine, idles good as long as i keep the revs up around 1100-1300. And runs out of the hole to WOT fine with no hiccups. WOT is only about 4100 right now, which could be a mix between over propped (15p on a 21ft pontoon @22mph gps) and motor health ( I hit 4100 at about 2/3 throttle, any more throttle makes no difference).
The main issues I have a question on is after running for awhile it drops a cylinder and revs drop to 3000. If i take it down to idle speed at is definitely not running on all 4 as it is bucking and shaking. Now to fix it I either can let it run like that at it will eventually pick back up or I can beach it and shut it down and after a while it might run normal or still miss. Its all hit or miss.
Ideas? Like I said, this winter I will be going through the motor, replacing the rings/pistons, cleaning carbs ect ect. I was thinking maybe one of the low cylinders was loading up and flooding out then it would recover. Anything else I can check while I am in there. I was thinking maybe one of the coils was shorting out when hot, but I don't know how to check.
First and foremost I know this motor needs rings. I tested compression when I first got it on the boat and it was low but I couldn't get repeatable results between the cylinders. So in the off season I will be re-ringing it, if not more.
So now on the water. It starts fine, idles good as long as i keep the revs up around 1100-1300. And runs out of the hole to WOT fine with no hiccups. WOT is only about 4100 right now, which could be a mix between over propped (15p on a 21ft pontoon @22mph gps) and motor health ( I hit 4100 at about 2/3 throttle, any more throttle makes no difference).
The main issues I have a question on is after running for awhile it drops a cylinder and revs drop to 3000. If i take it down to idle speed at is definitely not running on all 4 as it is bucking and shaking. Now to fix it I either can let it run like that at it will eventually pick back up or I can beach it and shut it down and after a while it might run normal or still miss. Its all hit or miss.
Ideas? Like I said, this winter I will be going through the motor, replacing the rings/pistons, cleaning carbs ect ect. I was thinking maybe one of the low cylinders was loading up and flooding out then it would recover. Anything else I can check while I am in there. I was thinking maybe one of the coils was shorting out when hot, but I don't know how to check.
