1992 115 hp 4 cyl 2 stroke missing wont iddle below 1500 rpm

[theslaters5]

ok so i just bought a new boat with this motor on it i ran it a few times but havent gotten out on the watter yet it was running fine now as soon as i rev it up to around 3 thousand rpm it starts missing and blowing big clouds of smoke every time it misses. i havent changed out the plugs or the filter yet. the other day i backed out the screw on the piviot arm on the port side of the motor and it iddled down to around 800 but now its right back to the same. i just really dont wanna screw this thing up.

 

[justchecking]

Re: 1992 115 hp 4 cyl 2 stroke missing wont iddle below 1500 rpm

Are you running it in a test tank or on muffs?

 

[CharlieB]

Re: 1992 115 hp 4 cyl 2 stroke missing wont iddle below 1500 rpm

Your 115 4 cyl is the 2 + 2 design, it idles on the top two cyls, the lower cyl's do not get enough fuel to fire until the throttle is opened. Only the top two carbs have idle circuits to pass fuel at an idle.

Carb cleanliness, carb linkage adjustment and throttle sync to timing are critical to the smooth operation of this motor. Follow the procedure spelled out in the FACTORY service manual to the letter, do not waste your time or money on an aftermarket manual, they are not near as detailed as necessary for this motor.

Remove the spark plugs and inspect their condition, excessive carbon deposits will cause problems.

 

[theslaters5]

Re: 1992 115 hp 4 cyl 2 stroke missing wont iddle below 1500 rpm

i am running muffs. well i will order a manual is it difficult to do your self or should i just have a mechanic do it.

 

[CharlieB]

Re: 1992 115 hp 4 cyl 2 stroke missing wont iddle below 1500 rpm

Just read, follow the directions, and keep posting any questions here, then you will do just fine.

 

[theslaters5]

Re: 1992 115 hp 4 cyl 2 stroke missing wont iddle below 1500 rpm

ok thanks will do the book should be here soon and ill start working on it i think the linkage needs to be adjusted as well when i move the throttle forward i have to push it almost all the way forward till it starts to rev up shouldnt the motor rev a little first before it engages so you can warm it up? And thanks verry much for all the help btw the boat is an 1985 sport craft cc 20 ft just wondering how good this will do on the ocean i live in nj and some have told me that its a great heavy stable boat. it sure seemed heavy when i was towing it

 

[Dave1027]

Re: 1992 115 hp 4 cyl 2 stroke missing wont iddle below 1500 rpm

i think the linkage needs to be adjusted as well when i move the throttle forward i have to push it almost all the way forward till it starts to rev up shouldnt the motor rev a little first before it engages so you can warm it up?

No. There should be a button or lever to push to make it rev in neutral. Why would you want it to rev up before engaging? That would slam the gear, wouldn't it?

Besides all that, it does sound like something is way out of whack.