riddle me this carb experts, and trainees!!

[bob johnson]

Motor in question 1999 JOHNSON Ocean Pro 150.....J150pxees. The motor was an oily mess so I am rebuilding the carbs....I took the power head off and installed it on a 1997 Fast Strike 175 hp mid and lower section because my boat has a 20" transom( more about why that might be important later).

so I found my carb bowls are warped beyond belief...but luckily I have a blown 1997 175hp ocean runner and the carb bowls are the came!!!! and... they are flat!!! so I am taking the high speed jets about and I notice the 175s are VERY shiny and look new... and the 150s are dull and dirty....but they have different #'s!!!! so I figure I cant interchange them!!!!!!!!!!!!

no problem.... I needed to order manifold gaskets that I forgot to order .. and I looked up high speed orifices for my 1999 150 power head.....and low and behold... they offer THREE different size orifices depending on the letters after the 150!!...if you have a J150PLEES, then you order #69D. if you have the J150PXEES you order the #59D(what mine had!!!!yeah).... and.... if you have the J150JPLEES you order the #70D orifices!!!!( I am sure that is a jet lower model.)

the 1997 175hp had nice #70D's......so I find it strange that in the end they do use different size orifices based on the shaft length and wether its a jet or not.....

if I put the #70D's in my 150 carbs...will it adversely effect the air -fuel ratio????
if I bought new it would cost me over $70.....

I haven't looked it up yet, but what are the IDs of each orifice???? and does the length of the lower unit really create that much of a different flow to need a carb change?

bob

 

[bob johnson]

so I cant edit for some reason...so sorry about the poor typing and writing skills... and I found out that the IDs are the same as the # stamped on the orifice......

just an observation that the exhaust length probably is whats making the big difference in IDs of the high speed orifice......

bob

 

[gm280]

bob, those part numbers sure sound like a huge difference to me. #59 for one version and #69 for another. That is a huge change. Are you certain of those numbers? I can see the #69 and #70, those sound about correct, but not the #59 to #69. JMHO

To answer to your question, certainly changing the main jet will change the air fuel ratio. That is what they do. If the carb bodies are the same, then those jet changes will make a huge difference in the fuel air ratio. Again, JMHO But I am by no means an expert and I didn't stay in a Holiday Inn last night neither. :noidea:

 

[Faztbullet]

Since the loopers have tuned exhaust you will find L and XL and XXL are jetted different due to backpressure and exhaust pulses. Slap the 70's in and go have fun