Do you need to remove the carbs to replace the low idle jets?

[Tom turkey]

I had the carbs cleaned and new needles put in my 98 bf40 by a dealer because of hearing about having to sync the carbs. The boat sat in a barn ten years Could of did as good a job myself i think. I'm not sure he synced them and he said idles rough, that i need low idle jets or something like that?? Did not have them on hand at time. Also do they affect throttling up? Sometimes it feels like its falling on its face until it gets its feet under it. Is a syncing tool cheap? Any thoughts towards better running be great

 

[hondam]

Yes you do have to pull the carburators apart to replace the jet your talking about and yes it does effect throttling up. It is one just that supplies both the idle circuit and the intermediate circuit in that carb. You pull the entire intake manifold off when removing the carbs, if you try to do it like you do on old 2 strokes you will end up breaking a lot of parts.

Syncing tools are usually pretty pricey, the one i use is digital (vacuum mate) and was $600-700. They do make some analog ones too for much less money. I just do sync carbs on a regular basis and the better tool you have the more in sync you can get them resulting in a better running motor.

Personally i would even try cleaning a set of those carbs without an ultra sonic cleaner. You usually end up doing it more than once if you do. The shop i used to work at we would replace every single one of those intermediate jets because we didnt have an ultrasonic. Figured the $20ea was less money then doing it twice. Now that i work at a shop with an ultrasonic we very rarely have to replace anything other then the intake manifold gasket when cleaning a set of carbs. IMO if you dont have an ultra sonic your wasting both the customers money and the dealers time trying to clean a set of 4 stroke carbs. Thats just one of the things you learn from working on them 16 years at a dealership that sold hundreds of carbed 50s and cleaning thousands of carbs. There would be some days i would have a dozen of them lined up on the bench. Anyways my point if that dealer doesnt have an ultrasonic, i would find on that does.

 

[Tom turkey]

Thanks hondam, that was the informative answer i was looking for. I do have another question or two. Can i put the jets in myself and then find someone to sync them or is that backwards. Also, the schematic lists the jets number 59 as either jets 99101-zv5-0880 #88 or -0900 #90 or -0920 #92. The mech replaced the needles jet set #102 16150-zv3-000 in each carb.... So, how do i know which jets to order, the # 88's, the #90's, or the #92's or do i need one of each or 3 of 1. Sorry if this is a big jumble or not making much sense, thank you for helping me get through this

 

[Sea Rider]

Get yourself a spare parts manual for that engine model, some brands, probably most use same size lower jet on upper & center carb and bit larger on lower one. There are only 2 fuel speed circuits, low and high, idle/low is when throttle cam does not exert pressure against carb roller, ralenti time. When cam begins exerting pressure against roller while throttling up, high speed circuit takes command.

Will need to have a musician ear and be expert trained to tune 2-3 individual carb configurations, will need 3 sets of analog or electronic led vacuum meters to tune properly for engine to idle smoothly, provided that each carb has a removable port to hook each individual gauge to. Once carb passes from slow to high circuit, there's no other needle to adjust on carb,

Happy Boating

 

[hondam]

There are 3 circuits in that carb, it does have an intermediate output to help with mod range and acceleration.

Needle sets and the 102 jet are two different things. If he hasn't replaced #19 then they should be replaced and the mixture screws all set at 2-1/8 for serial number 1999999 and below 2-1/4 for serial number 2000001 - 2007399 1-5/8 for serial numbers 2007400 - 3200000.

You can replace them yourself just make sure you take your time and don't break anything. That happens a lot with first timers.

The removable ports are on the intake manifold, Phillips head screw.

 

[Tom turkey]

Thx hondam, the number 19 #102 jets is what i was calling the needles, sorry about that. I'm supposing he set them correctly. I'm also guessing he didn't have the ultrasonic to clean with. At certain rpms she just purrs like a kitten but idle is rough and first bringing up the rpm's under load you have to be ginger with her. She also doesn't like starting. She purrs wot once your up but at about 52 to 5300 rpm's max. Do you think replacing the number 59 jets will help? Is that what your calling the removable ports? Appreciate you bearing with me and the redundancy. Thanks again, think I'm just about there

 

[hondam]

There is no reason you cant get the main jets(59) clean, the only time ive ever had to replace them is if they were overtightened and broke. The intermediate jets(19) are not adjustable. The adjustment is with the pilot screws on the side of the carbs. They are brass and screw striaght in from the side. The screws on the linkage are what is adjusted when balancing the carbs.

Double check the timing belt too while your at it. Make sure it isnt a tooth off.

 

[Tom turkey]

Ok, last post i believe. My buddy has a carb sync for his MG, can that be used or is it totally different for outboards. Also, are their marks making it easy to tell if timing is off? And lastly, i think he didnt have a gasket set for the carbs and manifold and i believe he reused the old ones on the cleaning, can replacing them make a big difference?

 

[hondam]

Should work, will need to have the right adapters to screw into the holes in the intake manifold. Its just a standard metric thread, you can probably make adapters if you needed to.


The timing marks are easily identifyable Just line up the T and the 1 with their respective marks.

The carb gaskets usually dont need to be replaced, usually need to replace the intake manifold gasket. If it doesnt tear apart it should be ok though, i just usually repalce them just to make sure their are no leaks.

 

[Tom turkey]

Thats great news, really appreciate the help. Now your a seaman apprentice =] I dont know what kind of shape the gasket is in but i think I'll replace the manifold gasket when I'm in there. How should i clean the 59 jets, any certain way or solution?

 

[hondam]

Find a very small piece or wire to run through the jets orfice spray through both ways with carb cleaner blow dry with compressed air then a thorough inspection. Might need a bright light and magnifying glass if you don't have good eyes.

 

[isaksp00]

I find that the thin plastic wire in floss threaders (get at drugstore) works well if you split open the loop, and seems safer to me (to not scratch the orifice). I invested $20 or so in a can of carb dip, to make sure the gunk/varnish is really gone.