80hp is only getting 7mph .. too slow any ideas?

[Bosunsmate]

Re: 80hp is only getting 7mph .. too slow any ideas?

Yes as above,
she aint sounding right, that idle is very precarious.
Try the suggestions Bob said.
You can get yourself a timing light for about $12 or so as even if its sparking ok you will want to check the timing at some point as you get her back to full working operation again.

It doesnt seem too bad so hopefully it wont take much too get it right, its not back firing and there doesnt sound like any knocking going on so keep at it

You can also put the fuel tank on a stool or something on the boat to make it higher than the motor which helps rule things out, but i dont get how the vent works on your tank at all.

 

[JRegier]

Re: 80hp is only getting 7mph .. too slow any ideas?

Dont try to run a motor WOT on muffs.
Especially in neutral.

 

[Don Hansen]

Re: 80hp is only getting 7mph .. too slow any ideas?

I wonder if a couple of plug wires got mixed up. Not familiar with 4 cylinder motors but I assume the spark wires would be marked like a 2 cylinder. Check to make sure that the wires with the band that has the word "up" on it are on the upper spark plugs.

DLH

 

[lbcboating]

Re: 80hp is only getting 7mph .. too slow any ideas?

Don I was thinking the same thing at first about the plug wires .. I do know that the person I got it from had just did a compression test on it so maybe he accidentally mixed up a couple of the wires .. it could only be 2 of them because the length of the other 2 would be hard to mistake for the wrong plug ...

Bob , you're probably right .. Because I can rev it up no problem on land when on muffs. I can rev it up in neutral in the water just fine and I get way more RPMS, I can rev it up on land in gear with muffs and I get way more RPMS.. But when it's in gear and in the water, it seems to loose power .. I thought it was natural when in water in gear to loose more RPMS , just like any motor but it wont even get half the rpms as it does in neutral or on gear on land with muffs. I usually don't like to rev it up on muffs or in neutral because I don't want to damage the motor or cause a problem ontop of another problem so the way i've been testing it is by fixing or adjusting one thing then putting it in the water to see the results.

If I move the throttle up while in gear with the motor off the carb should still open right? I tried this and the carbs opened.

One carb is blowing air, the other is sucking in air. This is normal on a v4?

i'm going to check the sparks again to make sure. I didn't know that a V4 could rev up fine with a spark out . I thought there would be more obvious symptoms like the motor knocking , hard cutting or excessive shaking.

 

[Bosunsmate]

Re: 80hp is only getting 7mph .. too slow any ideas?

Ive seen people almost get up to the plane on these with two cylinders out of commission

One Carb should not be blowing. Which carb is it?

Y

 

[Bosunsmate]

Re: 80hp is only getting 7mph .. too slow any ideas?

Is it running when its blowing or only blowing when turning over notor by hand?
Start researching reeds.

 

[Bosunsmate]

Re: 80hp is only getting 7mph .. too slow any ideas?

Is it running when its blowing or only blowing when turning over notor by hand?
Start researching reeds.

 

[Bosunsmate]

Re: 80hp is only getting 7mph .. too slow any ideas?

Were you turning the motor over by hand or was it running when you notice the carb blowing?

Wow three same posts in a row, i wasnt being bolshy, seems something happened with iboats this evening.
All fixed so quick recovery from them.

 

[lbcboating]

Re: 80hp is only getting 7mph .. too slow any ideas?

I had the motor running in neutral at about 1/4 throttle in water and decided to check the carbs. I noticed the carb on the right was blowing and the carb on the left was sucking.

 

[Bosunsmate]

Re: 80hp is only getting 7mph .. too slow any ideas?

Theres a problem. You might have a failed reed or something stuck in there keeping it open.
Dont run it anymore until you fix that as if its blowing it cant suck in any mixture to lube the internals

 

[lbcboating]

Re: 80hp is only getting 7mph .. too slow any ideas?

ok thanks i'm going to get that fixed .. I read somewhere that this could be caused by bad timing? sometimes a warn timing belt can jump and throw it off timing causing the carb to spit out air verses suck in .. is this possible?

 

[Bosunsmate]

Re: 80hp is only getting 7mph .. too slow any ideas?

Yep good point, it can be that.
Do you know which cylinders each carb feeds?
Reversed plugs could cause it in only one carb if they were both fed from that carb

 

[Bosunsmate]

Re: 80hp is only getting 7mph .. too slow any ideas?

I just looked up your motor it looks as though the starboard carb feeds both starboard cylinders, its not an up and down system like the more modern ones.
Which spark plugs wires do you think might of being swapped?

 

[Bosunsmate]

Re: 80hp is only getting 7mph .. too slow any ideas?

You might want to spray some premix into the cylinders before you go any further as some will be dry from the blow back

 

[lbcboating]

Re: 80hp is only getting 7mph .. too slow any ideas?

thanks .. where exactly is the reed in the carb? is it inside below the choke?
i'm not sure which cylinder which carb feeds , both carbs would feed 2 cylinders each?
Correct me if i'm wrong but with a 2 cycle 4cylinder motor , there are only 2 complete cycles that all 4 cylinders perform. For instance 2 cylinders move up while 2 cylinders move down, then visaversa to complete the 2 cycle motion. So if one carb is blowing air verses sucking it in , that issue would effect 2 cylinders right?

 

[Bosunsmate]

Re: 80hp is only getting 7mph .. too slow any ideas?

So if one carb is blowing air verses sucking it in , that issue would effect 2 cylinders right?

yep that parts right, thats why i suspect the starboard side if thats what you meant be right hand carb.

You could try unplugging both those leads and grounding them. Make sure you ground them.
Then see if you still get blow back and also if it runs any different.
Mark the leads so you know which cylinder they came from

 

[Bosunsmate]

Re: 80hp is only getting 7mph .. too slow any ideas?

The reeds are downstream of the carbs

 

[lbcboating]

Re: 80hp is only getting 7mph .. too slow any ideas?

i'll try unplugging and grounding them to see any difference.. I also confirmed that all plugs were in their correct places.

I did adjust the speed control on the right hand carb and it is no longer blowing and is now sucking in air just like the left carb. Would adjusting the speed control improperly effect this or do you think this is still not normal?

I also posted a pic of the motor with the carbs .. The one on the right was the one blowing out air until I moved the speed control until it tightened , i noticed the left side is not identical.

Another thing I noticed is there are two screws missing from the right carb, just above the speed control, one in front and another on top in the back , not sure if these have something to do with air flow?

 

[Bosunsmate]

Re: 80hp is only getting 7mph .. too slow any ideas?

Speed control- do you mean the throttle cam(the thing that turns the butterflys) or the needle valve?
I have no idea why changing the throttle cam would stop blow back.
Have you tried grounding all the wires, cleaning the plugs dry, then reinstalling them without the HT leads and turning it over with the starter for a few seconds then removing the plugs and checking they are all evenly a bit wet with fuel?

 

[lbcboating]

Re: 80hp is only getting 7mph .. too slow any ideas?

i meant the needle valve , just next to those two valves it say's "speed control" .. I notice when I tighten the right one the engine revs up more and the right carb begins sucking in air just like the left one.

When I unplug the plugs on the right side of the motor (2 and 4) the motor runs a lot different and begins to backfire here and there and cut .. I noticed that the plugs on the left side (1 and 3) are much hotter after idling than 2 and 4 on the right side. I also noticed plug 4 on the right side looks a little older and soiled than the other ones.

I tried swapping spark plug 1 with spark plug 4. Since I did that I can't get it to turn over. Maybe that plug or both plugs on the right side are soiled beyond repair? I'm going to put in new plugs just to make sure and then go through the steps again just in case that was a problem i overlooked ..