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2008 30hp 2 stroke problems, bogging under load, please read the list so far....

M

motiondave

Contributing Member
Hi there people. I have a 2008, 30hp 2 stroke that bogs under load.
we have , as follows.

compression is perfect on both cylinders, 150 psi.

Its been to two mechanics and came back with two different answers.

We have replaced..
CDI, exicter coil, (charge coil shows right voltage) , coil for spark, recitfier. new plugs (tried different gaps)
spark overall seems good according to spark tester. no fouled plugs, they are the right colour
It was suggested we run a DVA meter, but as said, both coils under flywheel are either replaced or checked to be good.
new carby, new fuel pump, all new fuel lines,
new tank, new fittings.
Still bogs, like too much fuel, gets to 10 knots and bogs, but does not stall. (which is weird as I tried BRAND NEW carby :D ), we did try, with boat on trailer, running it in gear and spraying fuel into carby and it bogged more, so not lack of fuel.
reed plate has been inspected and checked to be ok.
prop is standard 9.9 x 11 , and we are only pushing a 9 foot boat with it.
fuel, weve tried 60:1 mix instead of 50:1, unless its supposed to be something different (70?100:1?)

we are trying, as time allows, changing the jet sizes to see if we get results.

Is there anything, apart from a full tear down of the power head , its been suggested gasket leaks between crank cases(would rather not go to that) , have we missed anything to test or check?

Kindest Regards, David Lane.
 
EDIT, it is electric start and pull start motor.
whats the chances, although Ive never heard of, that a battery might be causing the issue? its a brand new battery.
 
Not sure why you would even think about running with anything other than 50:1 mix.---But I have said it many times that the concept of mixed gas / oil is not well understood.-----And I do not believe the battery is involved with putting spark on the plugs.----Why not post what the 2 mechanics said to you ?
 
racerone said:
Not sure why you would even think about running with anything other than 50:1 mix.---But I have said it many times that the concept of mixed gas / oil is not well understood.-----And I do not believe the battery is involved with putting spark on the plugs.----Why not post what the 2 mechanics said to you ?
Click to expand...


One mechanic said, try 60:1 electrical and replace CDI, coils, check reed plate. did that, all good, no improvement
another said to replace carby, fuel pump, fuel lines, and rectifier, coils under the flywheel, Nope, didnt help.
OK. cool. battery is crossed of the list.

any suggestions?
cheers, Dave.
 
Serial # of this motor ?------Is this something that started all of a sudden ?----How did it run for you last month?-----Could it be an issue with boat ?----Too big a prop for your boat ?
 
Have you EVER got it to plane off and run at a decent speed?

Jeff

PS: That 60:1 nonsense tells me your 2 mechanics don't know 2 strokes.
 
racerone said:
Serial # of this motor ?------Is this something that started all of a sudden ?----How did it run for you last month?-----Could it be an issue with boat ?----Too big a prop for your boat ?
Click to expand...

number is 0N103053 , international , it stared after I bought it, when you go see a second hand motor, it starts , runs, pumps water, changes gears, until.......you get it in the water, and trhats where the issues began. Its been nearly 3 months, either waiting for parts, as time allows, plus wasted time with mechanics,
the boat is a 9 foot long fibreglass speed boat, a 15 hp will push it to about 16 knots no problem, but like anyone, id like more speed
the prop is standard at 9.9 x 11.
 
racerone said:
I agree----You need to install a warning on your GPS to stay away from these 2 mechanics !
Click to expand...


the suggested idea was to only test, to see if too much oil on the plugs, but yes, didnt help anyway.
theres a lot of misinformation out there, and the time and money Ive spent on this thing only to be directed to something else with no result....well....
 
fastjeff said:
Have you EVER got it to plane off and run at a decent speed?

Jeff

PS: That 60:1 nonsense tells me your 2 mechanics don't know 2 strokes.
Click to expand...
only with an old 15hp (probably more like 12hp for its age), got it to 16 knots.
the suggestion was to see if the plugs oil up, was not for long, back to running 50:1 anyway.
 
Perhaps it is running on one cylinder.----Remove bottom plug lead and test run.----Put bottom lead back on and remove top plug lead and test run.
 
racerone said:
Perhaps it is running on one cylinder.----Remove bottom plug lead and test run.----Put bottom lead back on and remove top plug lead and test run.
Click to expand...

we replaced the ENTIRE electrical system unless the leads are around the wrong way, but they both fire at the same time.
Still, thanks for the info, I will give that a run.
 
There are several 2 stroke stroke motors that use the lost spark coil.. so if it has single coil with 2 leads your good. When exactly does motor bogg??? take off?? mid range?? WOT???
 
motiondave said:
we replaced the ENTIRE electrical system unless the leads are around the wrong way, but they both fire at the same time.
Still, thanks for the info, I will give that a run.
Click to expand...
You have a Tohatsu built motor and the Japanese ignition systems are good for firing both plugs at once.
 
Yes both plugs fire at the same time.-----One is a wasted spark.-----Need to know if there is fuel mixture compressed in both cylinders for proper operation of this engine.
 
faztbullet said:
There are several 2 stroke stroke motors that use the lost spark coil.. so if it has single coil with 2 leads your good. When exactly does motor bogg??? take off?? mid range?? WOT???
Click to expand...
about mid range is day, gets to about 10 knots ish, if flat out is 20 knots, if it got there
 
racerone said:
Yes both plugs fire at the same time.-----One is a wasted spark.-----Need to know if there is fuel mixture compressed in both cylinders for proper operation of this engine.
Click to expand...

do you mean is compression on both cylinders good? we checked that, its fine on both, 100%
 
It occurred to me yesterday, my brother has been thinking about it as well.
possible wiring short
the engine is electric and pull start
we have been only using the electric start via the key.
another thing, im using aftermarket dual lever controls, one for gears, one for throttle.
also, the neutral cut out switch in the factory controls, connects when in neutral for ignition and engine to start, then it disconnects after that in gear.
It occurred to me, instead of putting a push button switch in replacement of that, Ive simply connected both those wires permanently on.
we have yet to test the motor via pull start with the key switch disconnected, but id say I still will need a temporary switch for neutral start...whats the chances of neutral switch on permanently causing electrical feedback causing the whole ignition circuit to play up?
Obviously yet to test that as there is a 30hp ol johnson in its place currently, so I will get back to the Mercury later.
 
motiondave said:
you are talking about the exhaust reliefs jut under the bottom of the cover where the cowl sits, right?

yes, the engine does not go that deep in the water
Click to expand...
What about when you are accelerating? It doesn't matter where they sit at an idle or just sitting there. Considering the weight of the motor and probably the battery and gas tank and length of the boat. The water behind your boat is pretty high during acceleration if it comes up high enough think banana in the tail pipe.
 
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