1985 V200 - HELP! random misfire moving all over the place, cant find the culprit!

[Merc 2.5]

Hi - can 1 bad pack throw the firing out all over the place? ie I probably have one good pack form b4, and one bad- Would removing the bias wire isolate the pack/bank?

tx for the misting tip - all wires new and I dremeled the insides, blew out with brake cleaner to mostly shiny color and smeared with di grease - was some black stuff in coils..

The latest video from yesterday after complete timing/link and sync check - sputtering real bad, all coils pass open gap test but the packs are firing all over the place..

What brand or where did u get the boxes ? So all 6 jumping around? Do u have plenty of good grounds from boxes to plate and plate to motor?? Gonna b trigger or boxes, next time u test advance arm/trigger and recheck, u will wanna unhook carbs if it runnin tho , if its trigger it will prob change as u advance it , but its definitely a firing issue I'd say. If u dont have extra boxes. Least swap the 2 around and see if the "bad cyl or cylinders)" swap sides.

[Krazymaan]

I had this problem before. I ended up swapping out flywheels and it worked good again. Assuming flywheel magnets had micro cracks.

[Capt.Insane-o]

pull the flywheel off and try to twist the center magnet.

[Fstarockr]

will try source a flywheel and report back.. tx all. been unending..

[Fstarockr]

ok guys - just back from the water today.. flywheel seems fine. after about 2300 she rips, superbly powerful and maintains power.. but off idle she surges/no power - tried electric fuel pump, same..

I pulled carbs again today and these are the jets:

1: 46, 78 (Vent 74)
3: 46, 78 (Vent 74)
5: 46, 80 (Vent 76)

2: 46, 80 (Vent 76)
4: 46, 78 (Vent 74)
6: 46, 78 (Vent 74)

Does this seem right?

I now realize changing from horizontal to vertical reeds means the car/cylinder numbering has changed :0 - learning sth new each day.

Also - the misfiring was my timing light! it would drop onto other wires and spun me in an endless loop! all cylinders are firing perfectly - apologies for misleading info

[Krazymaan]

A few things that happened on my engine. The stator dripped down black thick sticky goo which made the timer plate move like slow motion. After cleaning and greasing the track, it moved nicely. But back then i didn't notice that those two stainless steel tabs with the philip screws that hold them down should be straight and flat allowing the timer base to rotate freely. Someone put a 15 degree bend in mine to hold the timer base stationary. I didn't know, it was my first GT200 engine, how would i know this wasn't how it went. All this made mine run like yours sounds like its running. Thats all I got. I got tired of it all and went with the full blown digital racing setup from CDI. Anything and everything i could change out, I did. Thats when I found out you don't ever take an air hammer to the side of a flywheel to remove it faster when you can't find those three long flywheel bolts for removing.

[Fstarockr]

tx krazyman - that sounds nuts.. well i verified the 462 mark on the pointer, set everything up, idle timing is 10-12 degrees ATDC, mid to top end is perfect. Stator, trigger, packs new (cdi and sierra brand). DVA results are perfect.

I swapped in a vertical reed block and realize the carb numbering changes when u do that so my jetting is off, and I need to try figure out how to test the bleed system.. I have an oem manual and its a little bleak on exact instructions - however i do have the routing diagram so will check everything..

[Fstarockr]

Hi chaps - finally got her going! Running real nice- few closing questions..

1: How to avoid oil build up in carbs when sitting - drain all bowls after running till she stalls?

2: Also - the manual states that primary pickup is 12 ATDC, is that when the carb roller just contacts the cam? Because the idle spec is 10-12 so basically the carbs need to open immediately? (i usually have a tiny gap before the carbs open to give some advance initially)

3: I had the jets setup for vertical reeds not knowing my coworked had not swapped in the vertical reeds so had to move jets around- the top end feels like its lacking a little less power tho - like 5% or 10%..

4: Also - i removed the t-stats as i was testing in salt water and like to flush the whole head- after a hard run temp check, top plug was 189, middle 175 and lower about 165.. any thoughts? Is the upper cylinder possibly running a little lean? or rich near the bottom?

[Dave Strong]

Go back to post 20, idle timing does not have to be at spec as I said use it to set speed in gear on the water. The way the linkage is designed carbs don't start to open till 3 - 3500rpm. Below that its all timing then the carbs begin to open.

Dave

[Fstarockr]

Dave thanks - I will try and fine tune it then and have the carbs start opening around the 3k mark then and see how she runs- I appreciate the info. I just mention the idle timing as a reference point as i read it somewhere..

I also do know not to use the idle stop screw fir idle adjustment - she idles at 650 in gear in the water.. no hesitation or flat spots - I did follow the link and sync very closely, idle stop screw is there to prevent jamming the butterflies via the cable..

more curious about the carb opening setting, and didnt know about the 3000-3500 window so that really helps nail it a little more..

[Dave Strong]

Dave thanks - I will try and fine tune it then and have the carbs start opening around the 3k mark then and see how she runs- I appreciate the info. I just mention the idle timing as a reference point as i read it somewhere..

I also do know not to use the idle stop screw fir idle adjustment - she idles at 650 in gear in the water.. no hesitation or flat spots - I did follow the link and sync very closely, idle stop screw is there to prevent jamming the butterflies via the cable..

more curious about the carb opening setting, and didnt know about the 3000-3500 window so that really helps nail it a little more..

If you did the link and sync in the correct order don't touch anything other than idle timing. It will all function correctly no need to adjust anything. You can undo the throttle cable and move the timing arm manualy, watch the top of the arm as you advance the bottom where the cable connects. You will see the timing advances before the carbs open.

Dave

[Fstarockr]

yes thats what I noted.. how crucial is the rpm pickup? is that a good way to verify that I have done it correctly for example?

sorry for the entry level questions - it helps clarify some things my brain can be a little backwards sometimes

[Dave Strong]

Sounds like you followed the link and sync so you should be fine, pick up timing will vary with prop size and boat. A 21 pitch prop pickup timiming will be close to spec most times, a 28 will have more idle timing as the more pitch the more it loads the motor in gear. The only timing that needs to be at spec is the max timing.

Dave