outboard work's better in preignition??

[benathlete]

My mercury 40 hp 2 stroke 1992 have a big problem, but very hard to find!!! the compression is good , fire is good, timing is good , just replaces the stator , i checked the two carbs too, the motor goes very well at low speed, but still can't reach more than 3100 rpms in wot, the fact is that when i advance the timing (pre ignition) until 36 degree , suppose to be 30 , it goes faster and i can reach about 4100 rpm.

Do you have any idea what that reaction means?? could it be the reeds valves? it's about the only thing that hasn't been checked! the rectifier and the gaz pump either hasn't been touched! thank's

it's make me sick, need help please!!

Benjamin

 

[j_martin]

Re: outboard work's better in preignition??

My mercury 40 hp 2 stroke 1992 have a big problem, but very hard to find!!! the compression is good , fire is good, timing is good , just replaces the stator , i checked the two carbs too, the motor goes very well at low speed, but still can't reach more than 3100 rpms in wot, the fact is that when i advance the timing (pre ignition) until 36 degree , suppose to be 30 , it goes faster and i can reach about 4100 rpm.

Do you have any idea what that reaction means?? could it be the reeds valves? it's about the only thing that hasn't been checked! the rectifier and the gaz pump either hasn't been touched! thank's

it's make me sick, need help please!!

Benjamin

Most likely the stator high speed winding. Verify the diagnosis with a DVA before you commit to buy.

hope it helps
John

 

[sschefer]

Re: outboard work's better in preignition??

Humm, I'd guess the bias circuit on the switch box.

 

[j_martin]

Re: outboard work's better in preignition??

Humm, I'd guess the bias circuit on the switch box.

I don't think so, but if he keeps running it like that, he can get into the details of a major overhaul.

 

[sschefer]

Re: outboard work's better in preignition??

I don't think so, but if he keeps running it like that, he can get into the details of a major overhaul.

Didn't he say he just replaced the stator?

 

[Faztbullet]

Re: outboard work's better in preignition??

Check that all cylinders are firing at WOT, it sounds like you are dropping one cylinder due to defective switchbox or a trigger problem This is the 4 cylinder 40 correct?

 

[j_martin]

Re: outboard work's better in preignition??

Didn't he say he just replaced the stator?

How would it act if he accidentally swapped the low speed and high speed stator connections?

 

[sschefer]

Re: outboard work's better in preignition??

How would it act if he accidentally swapped the low speed and high speed stator connections?

I don't think the high speed coils can produce the voltage to charge the cap to 200vdc before the trigger tripped the scr at 600-800 idle RPM. Its' that ole EMF thing. If it ever got past 2500 RPM they'd do just fine. 48vdc on that 12V starter might work for at least one quick run.

Just kidding aroung benathlete don't try the 48v thing.

 

[benathlete]

Re: outboard work's better in preignition??

so the guy that repleaced my stator also tried another switchbox to see if their is any difference on voltage, and it was the same, Wich were good on both! could it be the switchbox even if dva tested right??? didn't try it on water with another switchbox.