Yamaha 90 control cables

[Diesel]

Hi all, I've just got back into boating after 20 years away from it. The boat I have now has a 1992 Yamaha 90 on it. I took it out and found it would only pull 4600rpm. It was just installed on the boat to replace the older motor that had been on it. Has the correct new 703 control box. <br /><br />What I am wondering is is it possible that I am not achieving full throttle? Can the cable be adjusted? It is possible that the marine shop that installed this engine for me did not check throttle throw as it was not tested on the water and in conjunction with other things I have found since,I'm not 100% sure of their work.<br /><br />I don't think it is the prop as the boat is about 2000lbs loaded and the prop is only a 17 pitch.<br /><br />Any help or suggestions would be appreciated.

 

[clanton]

Re: Yamaha 90 control cables

Remove airbox cover look at carb butterfly, when throttle open (engine off).

 

[Diesel]

Re: Yamaha 90 control cables

Will do, then I'll check back.<br /><br />Thanks.

 

[Diesel]

Re: Yamaha 90 control cables

The carb butterflys appear to be openning all the way. So I guess that's not the problem.<br /><br />This motor has a set of GT Series #1 cavitation plate fins. I've not had any experience with these before but they seem to really move the bow up and down at moderate speed (20 - 25 mph). This motor is supposedly capable of 2 degrees of negative trim, although with the very vertical transom on my Silver Streak 16 I would be suprised if it actually gave me more than 1 degree negative if that.<br /><br />When I tried the boat out in the chop the motor was trimmed fully down and the boat was riding almost perfectly level. Not at all bow up. Could the effect of the fins when trimmed down be enough to cause a loss of WOT rpm by forcing too much hull to be in the water? This boat has a deep V hull design with 4 inch reverse chine. Specifically designed for our West Coast Pacific waters.<br /><br />I'm trying to sort out the theory on this as since my first outing we have been having strong winds and I haven't been able to get back out on the water. Hopefully things will be a bit better on my next day off so I can get out and try whatever suggestions one may have. It's near impossible to try speed and rpm accessments in white caps on a 4' chop *LL*<br /><br />Thanks.