88' V6 200hp merc isn't going as fast as it should

[andy6374]

I initially had a 89' V6 200hp Black Max, which burnt out and there is no need to go into it. But i bought a rebuilt 88' V6 200HP carb. It runs great but...My old engine pushed my mako 23 at 36 kts (top speed), but my new 88' only maxes out at 29 kts. What's going on?

 

[andy6374]

Re: 88' V6 200hp merc isn't going as fast as it should

Also it has the same prop and recently I have installed a new ignition system and cleaned the carbs.

 

[Coolmaker]

Re: 88' V6 200hp merc isn't going as fast as it should

Check the timiing and throttle position. Make sure the carbs are opening all the way.

 

[andy6374]

Re: 88' V6 200hp merc isn't going as fast as it should

The carbs open all the way. Well then... Does anyone have a good timing tutorial on an 88' V6 200hp merc. <br /><br />As Tim Mathis mentioned, I should do a compression check as well.

 

[KCLOST]

Re: 88' V6 200hp merc isn't going as fast as it should

Checked spark on all the cylinders?<br /><br />As well as compression? (even though it is rebuilt)

 

[andy6374]

Re: 88' V6 200hp merc isn't going as fast as it should

I haven't checked spark on all cylinders. I figured with the new stator, trigger and switchboxes I was golden. But your absolutely right a bad coil could be giving me the green banana (i didn't think to check). Could the engine still idle and run smoothly if that was the case?<br /><br />I will check for compression

 

[KCLOST]

Re: 88' V6 200hp merc isn't going as fast as it should

Possibly, but I have lost a spark on one cylinder before and didn't notice it until I tried to get on plane....<br /><br />It's worth a check to at least rule out that part of the equation...

 

[andy6374]

Re: 88' V6 200hp merc isn't going as fast as it should

OH, I get on plane just fine. It has always got me on plane. If I didn't know what max speed was on my other 200hp merc, I wouldn't even think that there is a problem with this one.<br /><br />I just remembered, I do have spark on all cylinders. I decarbed today and when I put in new plugs after, all 6 plugs were warm.

 

[andy6374]

Re: 88' V6 200hp merc isn't going as fast as it should

I am going to do a compression check today. Is there anything else to look for? Could a weak spark on one cylinder account for the decrease in speed...maybe timing?

 

[KCLOST]

Re: 88' V6 200hp merc isn't going as fast as it should

Motor height the same?<br />Do you know the WOT rpms for the old motor and the new?<br />Do you still have the lower unit from the old motor? Are you sure the gearing is the same on both?<br /><br />Just thoughts to ponder....

 

[andy6374]

Re: 88' V6 200hp merc isn't going as fast as it should

Allright is the lastest news. Ran the boat today and it ran great (idles smooth and gets up on plane just fine) but my max rpm's were only 4500, which i thought was low. I came back and did a spark check to find that cylinder 6 isn't firing. I would think it is probably just the coil, considering all ignition components are new(except the ignition coils) and the other 5 are firing just fine. This definitely explains the lost in RPM's. I must say I think this has been going on for a while. Is there anything that could have happpened to the cylinder? Would a decarb be enough?<br /><br />The new powerhead is using the lower unit of my other engine.

 

[andy6374]

Re: 88' V6 200hp merc isn't going as fast as it should

How interchangable are ignition coils? I thought there were all the same for 25hp and up. My friend is taking a good used coil off a 93 115hp merc. It should work fine on mine, right?

 

[KCLOST]

Re: 88' V6 200hp merc isn't going as fast as it should

You can switch one coil from a sparking cylinder with the one that isn't to check to ensure it is actually the coil...<br /><br />I'm not sure about the coil from the 115hp merc working on your motor...I'd have to do some research to confirm that... But surely you can determine that yourself when you check part #'s and fit etc...<br /><br />I don't think you have anything to worry about as far a cylinder damage goes.. As long as the cylinder was getting fuel/oil, you should be ok...<br />But, did you check the compression?

 

[andy6374]

Re: 88' V6 200hp merc isn't going as fast as it should

Thanks for the help. I fell for the oldest trick in the book. The ignition coil didn't have a good ground. Ran a new ground and bingo, SPARK! Now I am getting 5200 RPM's.<br /><br />I still haven't checked compression though. But I will.<br /><br />Different topic, I changed the trigger recently. Are there any timing issues to worry about. The axis of the advance spark lever is the proper dist. from the stop nut.

 

[timmathis]

Re: 88' V6 200hp merc isn't going as fast as it should

That is good news Andy. When it gets broken in I would almost bet it will go a little faster than the last one! Just make sure you dont run the timing to high. Be carefull have fun and Good Luck. Tim

 

[KCLOST]

Re: 88' V6 200hp merc isn't going as fast as it should

When you change a trigger the sync. and lync should be performed....

 

[andy6374]

Re: 88' V6 200hp merc isn't going as fast as it should

Thanks for the info. I would love to do a lync and sync, but the seloc manual's description is way too hard to follow...they bounce from one engine to the next without telling you (I just don't feel comfortable doing a lync & sync using the Seloc manual). I know Clams Casino has a great tutorial on doing a lync & sync on inline mercs, but what a about V6 mercs. I have the specs for the tune up, just need to know the procedure. If you guys have done one in the past and are willing to share with me your procedure, that would be fantastic.<br /><br />Thanks again, and again-<br />andy<br /><br />P.S. Since this is a new topic I will post a lync and sync for v6 mercs.

 

[andy6374]

Re: 88' V6 200hp merc isn't going as fast as it should

Update:<br />I've mislead you... Upon reading my notes... My speed before I had all six cylinders firing was ~23-24kts. With spark returned to cylinder #6 I get ~29-30kts at WOT. Since this cylinder hasn't had spark in a while I decarb it, and I figured after I broke it in I would be able to achieve the 36kts my other 200 HP merc would do.(NOTE: Old engine: 89' 200HP, New engine: rebuilt 88' 200hp).<br /><br />But after a full gas tank (51 gallons) of beating on the engine, I still only go 29-30kts at WOT with ~5300RPMs. No i still haven't checked the compression, my friend who has a gauge keeps on saying he will bring it over but always shows up empty handed (we all have these friends). <br /><br />Two things come to mind:<br />1.) The obvious, the discussed, the need for a lync & sync.<br />2.) Since the #6 ignition coil was not grounded for so long, hence no spark, could I have damaged the switchbox and/or coil.<br /><br />-Thanks<br />andy

 

[KCLOST]

Re: 88' V6 200hp merc isn't going as fast as it should

If you have spark going to all the coils, the switchboxes are fine.. (should be strong sparks)...

 

[andy6374]

Re: 88' V6 200hp merc isn't going as fast as it should

Here's a paranoid question then?<br /><br />If my timing is off, should I be worried about damaging cylinders or pistons? I know it is ok to have the spark advance a bit retarded at higher RPM's, but quite harmful if the spark is too advanced.<br /><br />How come you need to do a lync & sync for replacing the trigger, but not the stator. I keep the flywheel in the same position, didn't turn the crankshaft and put the new trigger in the exact same spot. Also, the distance from the axis of the lever that comes out of the trigger to the locknut (that attaches it to the spark advance throttle lever) is the prescribed 11/16"?<br /><br />I guess the first question is a concern and the second is a curiosity or rather a lack of understanding?<br /><br />-thanks, thanks, thank you...<br />I know I am a pain in the &#@ and ask tons of questions, but now that I am getting more and more comfortable working on the engine I'm getting anal and want to have everything perfect. I actually really enjoy working on it.<br /><br />SO THANKS AGAIN-<br /><br />Andy