After switching power heads with Franks input this past winter on my 125 I finally got it out today to run it. It starts fine and idles great, I took it on the channel and ran it wot and in about 1/8 of a mile it just started missing real bad. Not miss,miss,miss but like you turned the key off then back on for a couple times then I'd throttle back to about half and it was smooth sailing. Also when I came to harbor it was'nt Idling quite as good. Still good but not quit. I adjusted the carbs from 1.5 turns out from lightly seated to 1.75. Same thing happened, I then adjusted 1.25 like book said. Still same thing, I adjusted 2 turns out same thing. I'm running 24-1 on the fuel ratio right now for 10 gallons to get the new, used block well lubed. And also the water flow was just hot that I could keep my hand under it for a while. Is that normal? Thanks in advance and I'll be lookin for ya all. Chris
water flow is great. Comes out full flow threw the snout. I'll check the wiring today. I have all my parts off the old powerhead so If I see something I have the part. The old powerhead had number 2 piston melted and a penny size hole burnt out of it I just am hesitant to put anything off that powerhead on this one as I don't know what caused that piston to burn. It was like that when I got it so I did'nt know any history about it. Thanks, Chris
That penny sized hole was due to detonation due to a lean run condition. With your idle mixture screws adjusted to more than one turn out from lightly seated, you should have no worry about a repeat---PROVIDED---that both carbs get the same amount of fuel. The best perventive measure would be to put a small plastic fuel filter between the carbs and fuel pump to keep a small piece of junk from clogging the inlet to one carb. See: when something causes a restiction in the fuel flow and both carbs go lean, the engine loses power and you notice before damage is done. When one carb goes lean, the other two pistons carry the engine and detonation happens before you can react. SO: The last thing that should happen to fuel before it is burned is filtering.
Water temperature in the engine is controlled to 160 degrees. Anything over 130 degrees will scald skin and cause a burn. So if you can hold your hand in it, it is not too hot. A better test is to put your finger on the powerhead near the head. It should be uncomfortably hot but not so hot that drop of water would boil off.
Now, as far as your miss, If it was missing that badly at full throttle I would not expect good running at say 1/2 throttle. Was it making a loud thump or bang as it "missed"? The boat will actually feel like it is jumping and you will see the engine bouncing. This would indicate possible dog clutch wear and the engine jumping in and out of gear. This would not happen at lower speeds, however the condition would get worse as it happened more often and the engine would jump out of gear at lower speeds.
If this accurately describes your condition, then you should take apart the lower unit and check for rounded edges on the gear dogs and/or clutch dogs. The clutch is rather expensive and the dogs can be re-ground to sharp edges as can the dogs on the gears. Since reverse gets a lot less wear and abuse, sometimes you can just flip the dog clutch over and use the better dogs to mate with the forward gear.
Then again, if this describes your condition, it could be due to improperly set shift linkage. You need to check that you have equal throw in both directions. If you have more travel in reverse, then forward dogs will not fully mate and will bounce out of gear. Below the engine pivot where the shift linkage goes into the lower unit, mark the rod in all three gear positions and measure the throw from neutral. Forward is down. The adjustment is under the bottom carb on the interlock plate. to increase forward, the top locknut is raised then the bottom nut is also raised to tighten the rod. this lowers the rod. Go small adjustments--1 turn or so-- at a time until shift travel is correct.
No Frank, you can get it to wot and shortly there after it is like you just turned the key off. There is no jumping or thumping or anything and when it fires again its a smooth transition from no fire to fire and vise verse and it does run smooth at half throttle. About the if its running to hot. I did put my hand on the block and I could keep it there. although very warm , i could hold my hand there with no problem. I had also put new plugs in so I switched back to old ones and it did the same thing. I tried it 4 times and each time it cut out at exactly the same wot and the same distance at wot before it cut out. I can't quite figure it out. Unless its the fuel pump or the 24-1 fuel mixture I'm running the first 10 gallons.
my boat says that 50:1 is the manufacture spec i run alittle richer on oil but the 25:1 might be too much oil causing it to cut out at wot ... 2 strokes are etchy on fuel/oil mixtures and are u running the same type plugs? i think u just need a good tune job with good plugs maybe a carb rebuild and deffinently a in-line fuel filter , only other thing is maybe at wot some moisture is getting in ur stator and causing it to short out...
Check the white wires from the CDI units to see if they have worn insulation that is being grounded when the timing arm moves.
Next, pull the flywheel and look for worn insullation on the trigger and grounded when the trigger is turned to WOT position. It sounds like you have a make/break electrical contact, especially if it shuts off that abruptly.
I have been chasing the same problem for a couple of years on a 96sportjet120xr. I have put new carbkits, fuel pump and diaphrams, fuel lines, primer bulb, etc.. No Help!!!!! Then, I sucked a reed into the #2 cylinder and had to get a new powerhead $3000, old parts on new powerhead = same problem!!! Accelerates then it acts like the engine is cutting out. If I throttle back, it will run ok, but if I throttle up again, surging gets more severe and engine quits if you dont back out of the throttle, it will run fine at half throttle. I am considering ordering a new stator to see if that fixes it. Please let me know if you figure this problem out. sorry I cant help.
Do you have a new diaphragm in the fuel pump? Any clogs or restrictions in the fuel system? Sometime inadequate fuel delivery will masquerade as other symptoms. The engine will surge a couple of times at full throttle then die. Yet it will re-start and will run quite happily at lower throttle settings.
when the symptoms occur on my boat, I have noticed bubbles in the inline filter. Could air be getting in the line and causing this? I have new fuel pump, new lines, new primer bulb, no obstruction in the than pickup tube, new carb kits, and the problem persists. Could it be the stator heating and failing at high rpms?
Air in the line won't cause the engine to abruptly cut out. Fuel issues don't immedialtely shut down an engine unless it is fuel injected. Carbureated engines always start to run rough as the bowl empies and doesn't get replentished.
To check your theory about something heating up, do the following.
Start and allow three to five minute warm up. Go out and open it up to WOT. Time how long it takes to start missing. It will take the engine some time to warm up so if you have problems right off, you can be pretty sure it is not something heating up.