Twin 1987 30hp Yamaha's

[Andrew Leigh]

Hi, please help me help a friend.<br /><br />He and his brother own a 16' fibreglas twin hulled fishing boat. Recently the performance of the one motor started to drop off so they serviced both. The cleaned the carbs, fitted new kits, checked for spark, poor leads etc.<br /><br />When on the muffs the motors appear to be fine but when under load the one is sweet and the other not. The poorer motor is hard to start and does not get the revs up as quickly as the first. At higher revs it really performs poorly and will often die whereafter it is extremely difficult to start.<br /><br />My friend commented that when using just the good motor at WOT with the poorer motor at idle the boat runs O.K. but the minute you apply throttle to the poorer motor it actually appears to retard the performance of the boat?<br /><br />Any ideas<br />Cheers<br />Andrew

 

[rodbolt]

Re: Twin 1987 30hp Yamaha's

hello<br /> are they 2 or 3 cylinder 30 hp motors?<br /> in anycase check the compression of each, test the spark on each with about a 1/2 inch gap. and carefully test the fuel pump diaphrams.<br /> if you can get me a model number however if its an international motor I may not have much info. after that check that the timer bases move freely and dont touch the flywheel.

 

[Andrew Leigh]

Re: Twin 1987 30hp Yamaha's

Hi Rodbolt,<br /><br />thanks for that.<br /><br />He will be bringing the boat around tomorrow so will only get the dope then. Will check the timer bases and will take caution. When you say 1/2 inch gap by that do you mean that the spark generated should be strong enough to flash across free air of 1/2 inch.<br /><br />Will give you more feedback after tomorrow.<br /><br />Cheers<br />Andrew