65 100hp Mercury bogs at wot after cleaning carb

[smanis94]

I have a 19ft Larson with a 1965 100hp Mercury. Before cleaning carb it would run about 15 mph with 3 people in it and after cleaning carb it only runs about 7 mph. I am new to this site so could anyone please help, I have tried everthing I can think of.

 

[usskydvr]

Re: 65 100hp Mercury bogs at wot after cleaning carb

What kind of RPM can you get on the muffs (hose) (not in the lake)? If you don't have the hose adapter take the prop off and run in the lake.

 

[usskydvr]

Re: 65 100hp Mercury bogs at wot after cleaning carb

p.s. just a quick rev-up nothing more than a sec or two

 

[smanis94]

Re: 65 100hp Mercury bogs at wot after cleaning carb

What kind of RPM can you get on the muffs (hose) (not in the lake)? If you don't have the hose adapter take the prop off and run in the lake.

Dont know much about boat motors the boat dont have a RPM gauge.

 

[usskydvr]

Re: 65 100hp Mercury bogs at wot after cleaning carb

Without a tach it will be just wild guesses.
You could have fried a piston. (Check compression)
The boat could be over propped ( too much pitch) Could try a lower pitch prop.
You could have broken some gunk loose which is now clogging up one of the carb orifices. ( Need to rebuild the carbs)

 

[smanis94]

Re: 65 100hp Mercury bogs at wot after cleaning carb

Without a tach it will be just wild guesses.
You could have fried a piston. (Check compression)
The boat could be over propped ( too much pitch) Could try a lower pitch prop.
You could have broken some gunk loose which is now clogging up one of the carb orifices. ( Need to rebuild the carbs)

Thanks i will check compression and let you know. The prop is 2 blade and 21 pitch i have a 3 blade with 23 pitch.

 

[usskydvr]

Re: 65 100hp Mercury bogs at wot after cleaning carb

Both those are too much pitch for that 19 footer. Should be a 19 3 blade or even a 17 if you normally have 2+ folks

 

[Fuzzytbay]

Re: 65 100hp Mercury bogs at wot after cleaning carb

If you removed the carbs and worked on them , you now need to do a link and sync. Heres a link to a thread on how to do this.
http://forums.iboats.com/showthread.php?t=168855

I would think a 100 should move a 19ft a bit more than 15mph, seems to be a proping issue too.

 

[smanis94]

Re: 65 100hp Mercury bogs at wot after cleaning carb

Without a tach it will be just wild guesses.
You could have fried a piston. (Check compression)
The boat could be over propped ( too much pitch) Could try a lower pitch prop.
You could have broken some gunk loose which is now clogging up one of the carb orifices. ( Need to rebuild the carbs)

I check compression #1 120 #2 120 #3 120 #4 120 #5 122 #6 120. Put on hose and rev-up sounds like it opens up good.

 

[smanis94]

Re: 65 100hp Mercury bogs at wot after cleaning carb

If you removed the carbs and worked on them , you now need to do a link and sync. Heres a link to a thread on how to do this.
http://forums.iboats.com/showthread.php?t=168855

I would think a 100 should move a 19ft a bit more than 15mph, seems to be a proping issue too.

Thanks will try a link and sync and thanks for link to the thread.

 

[smanis94]

Re: 65 100hp Mercury bogs at wot after cleaning carb

Cant find timing marks to do a link and sync.

 

[Fuzzytbay]

Re: 65 100hp Mercury bogs at wot after cleaning carb

There are no timng marks on your motor.
http://www.maxrules.com/timingindex.html
That is the start page go to 850-100 link and follow the link and sync, you will need a dial indicator to measure the BTDC degrees.