What Work did you do on your Mastercraft Today? - Page 258

thatsmrmastercraft · #**2571** 03-08-2013, 12:24 PM

No doubt experience goes a long way here.

CantRepeat · #**2572** 03-08-2013, 12:48 PM

Quote:

Originally Posted by Kyle

Agree 100%

I just don't have a vacuum gauge

I didn't buy one until I put a new carb on the 92. I figured I just spent $500 bucks on a carb I might as well get the 15 dollar gauge. It did seem to make a nice difference in idle and just off idle performance.

When is your birthday? Maybe TT members can chip in and get you one!!

CantRepeat · #**2573** 03-08-2013, 12:54 PM

Idle mixture screws wont change plug readings. They are for adjusting idle mixture and will normally only affect idle and just off of idle performance. Unless you have some sort of vacuum leak, plug readings normally just show WOT fuel/air mixtures which are controlled by jet sizes.

thatsmrmastercraft · #**2574** 03-08-2013, 01:01 PM

Quote:

Originally Posted by CantRepeat

Idle mixture screws wont change plug readings. They are for adjusting idle mixture and will normally only affect idle and just off of idle performance. Unless you have some sort of vacuum leak, plug readings normally just show WOT fuel/air mixtures which are controlled by jet sizes.

Many of our boats spend a considerable time at idle, and little time at WOT, so idle mixture will indeed have an effect.

CantRepeat · #**2575** 03-08-2013, 01:50 PM

Quote:

Originally Posted by thatsmrmastercraft

Many of our boats spend a considerable time at idle, and little time at WOT, so idle mixture will indeed have an effect.

Idle mixtures will have a great affect at idle, which is what I said. On the other hand plug readings aren't used to check idle mixture, which is what I said. Plug readings are used to check WOT mixtures and is an art in itself. Moreover, wide band O2s are far better then plug readings but are hard to do in wet exhaust.

But, maybe I am confused as to what people are actually talking about.

Kyle · #**2576** 03-08-2013, 02:14 PM

Tim

Bday is actually in 11 days lol.

Ok guage that I'm headed to go get now.

Hook guage to a vacuum port on carb or intake. Does it matter.

My screws are 1.5 turns currently.

Screw both ways until say port side raises vacuum to highest point. Move to starboard side and make vacuum go to highest point.

Roughly rpm should rise and both screws should be X.X turns on both sides of metering block.

Lower idle to 800

Call it good

Is this correct?

Now on my boat after sitting turned off for 5-10 min I must re pump throttle for start. I don't get that but after starting it is fine. Fuel is either evaporating or something. Basically a few squirts and all is good.

I can fix anything and build cool stuff but I never learned about carbs in tech school. It was all efi. Obd 1 and 2. I'll take any advice that you are willing to share.

CantRepeat · #**2577** 03-08-2013, 02:46 PM

You need full port vacuum, I suggest the manifold.

Make sure the engine is at operating temp and that the choke is completely off/open. You may want to check your choke adjustment, it might help with the warm start needing a squirt of fuel issue.

The reason for turning the screws all the way in and back out is to make sure they are the same, your carb 1.5 on both sides is fine.

After obtaining the highest vacuum reading by adjusting the mixture screws return the idle to the desired number and recheck the idle screws.

Attach your vacuum gauge and start by turning one screw 1/4 to 1/2 turn in. If the vacuum goes up then do the same to the other side. If the vacuum goes down then turn one screw out 1/4 to 1/2 turn out. Keep doing this until you get the highest vacuum reading.

The desired outcome is maximum vacuum at your desired idle. So once you get max vacuum and then adjust your idle you'll want to check the vacuum and idle mixture screws again. Adjusting the idle will affect the vacuum.

I think I have a howto on mixture screw adjustment on here I just can't seem to find it.

JRW160 · #**2578** 03-09-2013, 01:57 AM

Put it in the water for the first time today. Started right up. Smooth water, but still 47 degrees. Topped out at 42mph. Left it in a friend's boathouse to work on the trailer. Removed the old bunks, carpeted new bunks for the trailer, got new tires installed, changed the oil in the hubs, removed some rust from the torsion axle.