carb. rebuild

phester · #1 03-12-2006, 07:01 PM

my motor,150 Johnson oceanrunner, started to run a bit rough toward the end of last season. This was only at a troll speed,in fact it stalled a couple of times. Higher speeds and WOT it's fine.Does anybody know the ins and outs or a couple of good pointers before I proceed. My brother used to be a motorcycle mech. for Kawasaki and Yamaha [inluding jetskis]so between his know how and a factory manual it shouldn't be difficult. I don't think I would take on this job myself.....the mechanic I usually deal with gets 125.00 per carb, parts extra, almost a 1000.00 to rebuild???? Insane

macojoe · #2 03-12-2006, 10:17 PM

Well it may be carbs, but I would try something different first!!
The problem wit Lg motors is they hate to troll!! They carbon up like hell and then the performance drops off!!

I would try a Decarb first, and then after that run Carbon Gaurd with every tank.

I like to spray the decarb in the night before I am going out, then when I hit the water open her up and blow all the crap out!!

I run a 175 Yamaha and they are know for carbon build up, I decarb once a year and use carbon guard every other tank. works for me.

Mulv80 · #3 03-12-2006, 11:33 PM

Rebuilding carbs really isnt that difficult as long as you have a factory manual. Buy the factory rebuild kits that come with the float instead of the off brand kits. You will also need a can of decarb. I used Berrymans, they sell it buy the aerosol can or in a large can for dunking parts, I bought the aerosol can. You will also need an air compressor or a can of compressed air for blowing out all the orifices after soaking them in carb cleaner. The hardest part of rebuilding carbs is the float adjustment and the link and synch procedure when the carbs are put back onto the block. In the manual there should be a procedure for the link and synch. Hope this helps.

willy · #4 03-13-2006, 01:47 AM

Phes I would do the decarb routine MJ is talking about before I would get into the carb routine. Unless you have already done that.
I have the 99 115 johnson and I was having trouble getting to proper max rpm when I first bought the boat from Fillet1 . I bought the stuff I needed for a full decarb, did it the right way and ran a special fuel conditioner cleaner on the heavy side of the mix requirement, ran it like MJ said and it was like I white fogged the neighborhood for awhile. When I was done I put new plugs in and took it to the ocean and I was running 5600-5700 rpm no problem. Previously I was told I needed a carb rebuild by a mechanic ::) I think the stuff I have been using since is called Sea Foam to keep it from carb ing up again and keeping the carbs clean, recommended highly by several boat people and a few guys on this site

Skools Out · #5 03-13-2006, 02:02 AM

hey Phes rebuilding them most likely won't fix the problem. The air jets are bad about getting stopped up and that will cause them to idle rough or none at all. take an air hose and blow out the 3 air jets that should fix your problem. i do mine every spring and then about the mid to end of summer.

Skools Out · #6 03-13-2006, 02:07 AM

i'll get a pic of where to blow them out tomorrow.

willy · #7 03-13-2006, 02:12 AM

Good Skools we all need to see that

phester · #8 03-13-2006, 01:00 PM

thanks fellas ,yeah, I'm gonna monkey around w/ it befor I pull the trigger on a rebuild,Skools those pics you're talking about just might do the trick

Geekie1 · #9 03-13-2006, 01:38 PM

Phester, I agree with doing the de-carb before doing anything else. IMHO, Carbon buildup causes alot of problems including low compression etc. I use seafoam and add it to 3/4 gallon of gas in a small (3gallon) external gas tank. If you go to Iboats forum website (www.iboats.com) and do a search on decarb you will see the processes in detail. There are two Seafoam decarb products. One is a spray in the cylinders I think named Deep Creep or whatever and another is just "Seafoam" that gets added to 3/4 gallon of gas and running the engine using the mixture or vice-versa. Don't do it in your driveway unless you like cleaning up a horrendus black mess or explaining to the fireman that your boat isn't on fire. I do it on the water on a remote beach or some other isolated location. After de-carbing, replace the spark plugs. I have a home made spark checker that I use to check that the spark on my Yammie can jump 7/16". (Yammie spec.) There is a thread on Iboats forum that describes the homemade spark checker. I wouldn't start with the carbs until after the above has been done. I hope this helps!!

Ed G.

Crusher · #10 03-13-2006, 09:45 PM

Hey Geekie1, I live in Crosskeys two houses up from Grosses Chicken? Crusher