Slow sluggish take off for a 135 merc, or so it seems...

[AndrewB]

Hi all,<br />I've got an 1986 135 black max merc on a haines signature 1700S, total weight around 700kgs. When I use the boat for wakeboarding or skiing it really seems to struggle on take off, even when just cruising it doesn't exactly really jump out of the hole. I had a 14 X 19p vented stainless prop on it which pulled round 5400-5500 rmp at WOT for a speed of 50-55 mph. After some advice I dropped the pitch to 17 which has made it better and it does pull a bit harder. It revs round 5900 now at WOT but still tends to bog down on take off and is really bad if the trim is down too far yet it still cavitates in some turns.<br />Should my set up be quicker off the line or am I just expecting too much. Do I have to play around with motor heights? Currently the cavitation plate is around 2 inches above the bottom of the hull? Any advice would be great.

 

[Maximum Gravity]

Re: Slow sluggish take off for a 135 merc, or so it seems...

You could try a 4 blade prop, or drop to a 15" pitch, just don't expect to run WOT. Many people around here will go as low as a 10" or 11" for skiing only, and never run above half throttle (or 5500 RPM, whichever comes first), doing so WILL damage your motor!

 

[ob]

Re: Slow sluggish take off for a 135 merc, or so it seems...

Andrewb, From your description sounds like propping and motor height is fine.Maybe a slight timing advance and carb adjustment will improve out of hole response.

 

[AndrewB]

Re: Slow sluggish take off for a 135 merc, or so it seems...

Thanks OB and Maximum Gravity for your replies. OB, is there a simple way of finding out whether the carbs need adjustment or what the timing it is set at at the moment or is it just a trial and error process, outboards are still relatively new to me, any additional advice would be great, cheers.

 

[ob]

Re: Slow sluggish take off for a 135 merc, or so it seems...

Andrewb,The only correct way to set timing is per motor specs.I would obtain manual when making this adjustment as advancing too far by trial and error could result in predetonation and damage engine.You could experiment with the idle mix ,taking note of where they are now set and enriching or leaning in slight increments and noting change in out of hole performance.Again, if you are not familiar with your specific carbs adjustment points ,a manual will be very helpful.Does motor seem to be sluggish out of hole just when pulling skiers or at all times?

 

[AndrewB]

Re: Slow sluggish take off for a 135 merc, or so it seems...

Ob,<br />It's tends to be more sluggish when pulling skiiers out which is expected I suppose however it still doesnt really pop out when not pulling skiiers out either. I have a friend who has a very old 115hp something??? with granted a lighter boat yet everytime I'm in his boat or we are out together it seems to cream mine in out intial take off, then I come back and beat him, but that's besides the point. Ive been told my motor is very strong for a 135, it just seems somethings a miss somewhere. Other boating mates have their motor trimmed all the way down for take off, should I be doing this? If so, then theres something really a miss because that is near impossible. Maybe my trims set up wrong, what should the level of the motor be trimmed all the way down?<br />Cheers.

 

[ob]

Re: Slow sluggish take off for a 135 merc, or so it seems...

AndrewB , trimming down more on take off , if your not cavitating now, will bog even more.I don't know about your paticular motors operation on out of hole situation,but I do know that some motors make power a bit different and some motors of same hp will perform better out of hole than others.If your motors top end is good and throttle response is crisp with no flat spots at midrange ,it might be as good as it gets as far as timing and carburetion is concerned.You may just be a prime candidate for a hydro fin ,as you should notice quicker lift out of hole with less cavitation when motor is trimmed higher.Each boat and motor setup has its own unique characteristics

 

[Hooty]

Re: Slow sluggish take off for a 135 merc, or so it seems...

Are your prop vents adjustable? If so, go to the larger vents and give that a try.<br /><br />c/6<br /><br />Hooty

 

[AndrewB]

Re: Slow sluggish take off for a 135 merc, or so it seems...

Thanks guys Ill have a bit of a play around and see what I come up with, maybe adjust the vents as Hooty suggested, hopefully an improvement will be the result.

 

[marion]

Re: Slow sluggish take off for a 135 merc, or so it seems...

It's not really clear from your post if you have a ventilation or a power problem. If it's ventilating the motor will rev up but you won't go anywhere because you're pushing air instead of water. Lowering the motor on the transom or changing to a prop designed for a high motor mounting will cure that problem. Lack of power is internal to the motor and could be caused by either ignition or fuel problems. One thing not mentioned that you could check is if a couple of cylinders are flooding at low speed due to either a bad float or leaking float valve in the carb or a pinhole in the fuel pump diaphragm. Once the motor burns off the excess fuel those cylinders start working and you've got full power.