115 vs 85 carbs?

[joe outlaw]

I was wanting to know if carbs off a 115 hp johnson would work on a 85 hp johnson? They fit right up and the bore on the inside are the same. just not real sure. the85 carbs are clean just busted one them. got the other two from a friend. the 115s have adjustable low speed and the 85s have fixed?
any input would be great?

 

[SparkieBoat]

Re: 115 vs 85 carbs?

I have heard that the 115 carbs are slightly bigger and have larger jets..you could cause a lean condition running 85 carbs on a 115..but 115 carbs on a 85 should be ok...worst case would be too rich...If you change your exhaust port you may even see an increase in HP...what year models??

 

[bob johnson]

Re: 115 vs 85 carbs?

I wonder what year you motors are.

I have a mid 90s 90 hp with issues and bought a mid 90s 115 hp to replace it, and asked a mechanic about telling if the 115 hp was REALLY a 115 and not a 90 hp with the tags switched...because both motors looked identical...he told me the bores on the carbs were different..so i measured and sure enough the 115 was easily bigger than the 90.

how did you measure the bores?? a tape measure?????

bob

 

[joe outlaw]

Re: 115 vs 85 carbs?

The 85 hp is a 1974 and the 115 is in the same ballpark by the looks of it dont really know. I had the kits for the 85 and they fit perfect on the 115s. only difference I saw was the hole dia. for the needle seat. I put the ones from the 85 kit on the 115 and like I said everything bolted up perefect. im thinking the years are pretty close. not to worried about the differance in hp just want to go fishing. thanks for the feed back any more input would be great.

 

[joe outlaw]

Re: 115 vs 85 carbs?

the bore on the inside was the same but the bore on the choke side looked bigger. looked like they reduced down. Ill measure and let you know. I dont want to have to try to find carbs to replace the one I busted.

 

[tashasdaddy]

Re: 115 vs 85 carbs?

the last year i can find a big carb with adjustable low speed jet is a 1971 100hp.

 

[emdsapmgr]

Re: 115 vs 85 carbs?

The larger 115 carbs will work on your 85, but will probably overfuel the engine. Your 85 is a 92 cubic inch block, and the 115 was probably a 99 cubic inch block. The larger carbs will probably work, but will overfuel that smaller c.i. powerhead at top end. You will probably have to rejet them downward somewhat to get them to work perfectly. I put a set of early 125 carbs on a small bore 100 and really had to fiddle with the jets. In the end the fiddling was worth the effort as the engine picked up h.p. (about 200 rpm over the stock carbs) and I had to go up one prop size.

 

[Bob_VT]

Re: 115 vs 85 carbs?

Bottom line is to stay stock and just rebuild your original carbs. The end results are not worth the efforts.