85 hp Johnson???

[adm1476]

I have a 1970 American CC with a 1976 85hp Johnson on it. At full throttle the boat will only go about 12 to 14 mph. It seems like it should be able to go much faster. At least 30 or so. I just got this motor and put it on this boat, so I have no idea what speed it should go. Anyone with any ideas?????

 

[boobie]

Re: 85 hp Johnson???

Do a compression test on it. Then an open air gap spark test with the spark jumping a 7/15 " open air gap. After that look into the fuel system. Carbs ??

 

[emdsapmgr]

Re: 85 hp Johnson???

As Boobie indicated, check for spark. The engine may not be firing on all 4 cyls.

 

[adm1476]

Re: 85 hp Johnson???

The compression is good on all 4 cyl. It runs smooth, but I have not done a spark test. I will try that.

 

[dazk14]

Re: 85 hp Johnson???

Does the motor rev up significantly? You may have a spun prop.

 

[adm1476]

Re: 85 hp Johnson???

No it revs fine like it is under a load. Makes a good wake. Just no speed.