Up Grading Carbs

[crb478]

I have read in past post where some members have upgraded their engines with different carbs, (newer carbs). Is there any advantage to doing this? I currently have a 1975 Johnson 115 which is probably only 90 some hp at the prop. Would using a pair of late 80's or early 90's carbs from a 90 up to a 115 hp engine give me any performance or fuel advantages or are the carbs basically the same? Just curious. Thanks any insight!

 

[emdsapmgr]

Re: Up Grading Carbs

All the crossflow carbs should bolt right up. Larger carbs can make a significant improvement in performance. You should be looking for carbs up through 1979, as they have the choke butterflies like our current 115 engine. 1980 and later carbs don't use choke butterflies. They will work-but you will need to modify the fuel hose, re-plumb for the choke hoses and install a new type choke solenoid.

 

[steelespike]

Re: Up Grading Carbs

Your at the prop power is maybe 5% less than the rating;probably closer to 110. Difficult to tell the difference.Carbs might give a slight improvement in economy but again not enough to measure and would take a long time to recoup the expense.You would probably gain as much with a tuneup
and careful fine tuning of your setup.If you can raise the motor an inch you could gain a couple of mph.Be sure the prop is tip top and the right pitch.

 

[crb478]

Re: Up Grading Carbs

Thanks for the replies, I sometimes see carbs for sale that are relatively inexpensive and didn't know if it would be worthwhile to try to upgrade. I think that I will stick withthe ones that I have sisnce they are not broke. Thanks Again.