Motor has no power under load

[jimmbo]

I have a 1988 100 hp (upgraded to a 115). The motor always reved up like that. I was told by the dealer not to run it at that rpm so I never hold it there. There is no rev limiter mentioned in the factory manual. Perhaps it was added to later models? I never heard of piston skirts breaking on these I but have heard of crankshafts breaking if reved too high.

And how exactly was your engine upgraded?, This outa be good...

 

[Dave1027]

And how exactly was your engine upgraded?, This outa be good...

Has 115 carbs.

 

[jimmbo]

115 Carbs on a 100 Engine, does not Necessarily make a 115

 

[Dave1027]

115 Carbs on a 100 Engine, does not Necessarily make a 115

Sure it does. The carbs are the only difference.

 

[jimmbo]

Sure it does. The carbs are the only difference.

And you went thru every line in the Parts Book to verify that that was the only Difference?

 

[Hambone1983]

So my motor runs great on the muffs but on the water under load it will not get on plane and ( no Haven't replace Tech yet )and I have good compression new plugs with great pinkish spark mechanic ajusted the cables it's getting gas anyone ever had this problem.so has anyone had this problem???

 

[jimmbo]

Motor can run great on the muff, even if 1/2 cylinders aren't firing. Which it on a 2+2 motor is the Norm
Can the Spark jump a 3/8" gap on all cylinders?
Some of the 2+2 Motors had Accelerator Pumps on the Carbs(maybe they all did), if they aren't functioning, the engine can't get going fast enough for the Mains on the Hobbled Carbs to feed fuel

 

[Dave1027]

The 2+2 does have an accelerator pump but it's not on the carbs. It's connected to the linkage and injects fuel directly into the intake ports on the side of the block. You can verify it's working by idling then take a flathead screwdriver and depress the accelerator pump. The bottom cylinders should immediately fire briefly making the rpms jump up.

 

[Hambone1983]

So what should the teah be set on 6p or????

 

[Hambone1983]

So what should the tach be set on 6p or ????

 

[Hambone1983]

Now at idle All plugs have spark now today I put a tach on it the only setting that was close to the rpm's is 6p is that that right setting. Please help my mechanic thinks the prop is to small but when I get it idle down to 1000 rpm's I have to pump the ball to keep it running I don't think he is doing to good any help would be Appreciated

 

[dwitting87]

Yes Marine mechanic it was running petty good out of water but did have a miss and yes the cables were not adjusted correctly.I just got the boat 2nd time I didn't test drive one and I got robbed

Wondering, did they have a power supply hooked up on land? That would be one key difference vs in your boat with just your battery.

 

[Hambone1983]

Gro

Wondering, did they have a power supply hooked up on land? That would be one key difference vs in your boat with just your battery.

Just battery

It just sounds great out of the water.----They all sound great.----Post compression numbers .---Check

 

[Hambone1983]

Gro

Just battery

148 on all 4

 

[Hambone1983]

This was me falling asleep sorry I thought someone on here would know these Questions

 

[Hambone1983]

148,149,148 148

 

[Hambone1983]

Boat will just get up on plane then when you try to go faster triming the motor uo just a little and the motor starts to act like it wants to go then kind of like a miss but we have checked all of that and I just finished putting a tachometer in it and redoning all gas line and fitting I found 2 air leaks

 

[flyingscott]

Have you tested the stator? Not uncommon for windings to fail on them.