1988 48 special carbs

[racerone]

The 88 and 89 powerheads are essentially the same are they not ?-----So why not swap carburetors.

 

[saltchuckmatt]

Here is a video for the 89 and up link and sync so maybe there was a change in 89

 

[Crosbyman]

why not tell us if you popped the dime size plug on top to clean the low speed circuit of the carb. did you confirm carb cleaner flow via all orifices did you line up the proper carb gasket mounting holes... all of them incl. the side channel to the top half of the carb ??

 

[Tim T.]

This is the process I took I took when I got the boat home . hooked up battery and cranked it over . It stared on first crank. Only ran for 3 or 4 seconds. Drained gear oil ( no grit no water , seals good) . I filled with fresh oil. Installed proper plugs gaped at 40th. (per manual). Removed motor from boat and started redoing boat, finished boat . Reinstalled motor. Had trouble with starter not turning motor over and thanks to Crosbyman and others took starter apart cleaned surfaces with commentator stone . reinstalled and problem fixed. I want to thank everyone for the much needed help. when I finally fix this problem I will post the solution . thx agian Tim

 

[Tim T.]

to

why not tell us if you popped the dime size plug on top to clean the low speed circuit of the carb. did you confirm carb cleaner flow via all orifices did you line up the proper carb gasket mounting holes... all of them incl. the side channel to the top half of the carb ??

I did, kit came with them . I watched a video on utube an how to do it. peened in ball bearing and sealed cap with red loctite. thank you for all your help

 

[Tim T.]

I forgot to say I also replaced water pump

 

[jimmbo]

A leaky Upper Crankshaft Seal is a known cause of Idle Problems. It can cause what Racer calls "elusive crankcase compression"

 

[racerone]

Cylinder compression may be an issue with this motor.-----Head gasket is cheap.----Take head off and have a look at cylinders.

 

[Tim T.]

How can you tell if it's leaking?

 

[Tim T.]

I did an compression test and 116 and 120 on upper and lower

 

[Tim T.]

That's why I think it is a fuel problem. When I run the motor on higher than normal speed and start lowering the warm up throttle it dies.

 

[racerone]

A head gasket is cheap at about $30 or so.

 

[Faztbullet]

Cylinder can be damaged and still have good compression. A compression test only shows that a cylinder has enough pressure to support combustion but not the condition of engine. Rebuilt many a motor with good compression but bad cylinders

 

[Crosbyman]

 

[Tim T.]

Update on not idling. Finally got the rebuild kits in yesterday for the old carbs. I rebuilt the old carbs then installed . Success!!!!, first time it started and idled Yes!!! can not wait to put it in the water! Thank you guys for all the input and knowledge . So now I know for sure that 1989 carbs will not work on 1988 48hp johnson.

 

[Crosbyman]

any clue as to what in the new kit actually fiixed it all up.... was it sucking air in via the poorly packed LS needle do you think ? .

the rest is float , carb gasket orifices , donut washer etc...

 

[saltchuckmatt]

any clue as to what in the new kit actually fiixed it all up.... was it sucking air in via the poorly packed LS needle do you think ? .

the rest is float , carb gasket orifices , donut washer etc...

His motor came with the 89 carbs on it and it didn't run right, it also came with parts including the 88 carbs. He rebuilt those so he now has the conclusions above.

 

[Tim T.]

any clue as to what in the new kit actually fiixed it all up.... was it sucking air in via the poorly packed LS needle do you think ? .

the rest is float , carb gasket orifices , donut washer etc...

I think the 89 carbs have bigger jets causing it to flood out at low speed maybe?

 

[ct1762@gmail.com]

I did an compression test and 116 and 120 on upper and lower

compression tells you NOTHING about crank case compression/vacuum. 2 stroke acts like a pump. compressions tells 1/2 the story. remove head to inspect cylinders.

 

[Diplomasta]

You should be able to use the carbs. I would switch out the jets with old carbs though. What I would've suggested is checking the reeds and the fuel pump. A Leaking fuel pump diaphram will dump extra gas into the motor thru the air port that runs it.