Yamaha 115 V4 questions

[robf7]

I recently purchased a 1995 Lund Pro V 1775 Tournament Series boat with a Yamaha 115 V4 motor and stainless prop. The motor starts, idles and runs great, but I noticed when I first give it a little gas it runs rough and shakes more than it should. As I give it more gas, it cleans up and runs smoothe. The motor also has a noticable ticking noise all the time, not loud but still there. I took it to an authorized repair center and they told me there is nothing wrong, and the problems I stated are common with the motor. I don't agree with them and am now asking for your help. Any suggestions?<br />Thanks,<br />Rob

 

[rodbolt]

Re: Yamaha 115 V4 questions

without seeing it I cant comment, but that motor is normally smooth at all RPM's. however its a two stroke and will never be as smooth as your car engine.<br />what RPM is the range it shakes at?

 

[robf7]

Re: Yamaha 115 V4 questions

Sorry, I did not look at the rpms. I know it is very low, when first taking off, just above idle speed. I will check the rpm's this weekend and add to the post if you would be so kind as to reply.<br />Thanks

 

[carljh]

Re: Yamaha 115 V4 questions

Sorry robf7 - not hijacking the thread but..<br />I have a 1991 Yamaha V4 as well and mine does not like running between 1500 and 1900 RPM. Within this range it feels "lumpy" and underpowered - I suppose it could be a flat spot. My solution is just go to WOT straight away but it is a hassle when returning to the mooring.<br /><br />Any ideas rodbolt?

 

[skiwake130]

Re: Yamaha 115 V4 questions

Rob, the motor should be smooth at any throttle position. My V4 started hesitating off idle becoming worse to the point I could not get it off idle without stalling. Thanks to this fantastic site and posts by Rodbolt and others, I knew what the problem was - rubbish in the carb. I gave it a go and pulled the carbs and found one of the idle jets completly blocked with crud. A quick clean with carb cleaner, new gaskets and reassemble fixed the problem. The motor now runs better than ever before. Total time from removal to reinstall took about 3 1/2 hours. They're really not hard to work on if you take your time and take note of how they come apart and go back together again.<br /><br />Good luck<br /><br />David

 

[robf7]

Re: Yamaha 115 V4 questions

Thanks all,<br />To answer the question from rodbolt, the engine is rough from about 900 - 1300 rpm's, and then cleans up.<br />My first guess was the carbs were dirty, but when a authorized repair center says there is nothing wrong, who knows????

 

[rodbolt]

Re: Yamaha 115 V4 questions

big difference between autherized and competent.

 

[robf7]

Re: Yamaha 115 V4 questions

I agree. It is pretty bad when you bring a motor in and suggest cleaning the carbs, and they charge you $100 labor, don't clean the carbs and tell you there is nothing wrong!

 

[bigbrownbuku]

Re: Yamaha 115 V4 questions

try adjust your throttle pickup cam timing. this sometimes causes rough running between certain rpm. ive found the book spec is a good place to start but every motor needs something a little different. try adjusting it slightly closer.<br />the screw that makes it slack is a LEFT HAND THREAD.<br />do not play with the throttle sync screws.<br /><br />edit : its not something you can adjust on land, it requires launching and adjusting as you go, test, repeat. dont fall in. the cam follower is located on the stb side of the carbs, small black roller.

 

[whiteman]

Re: Yamaha 115 V4 questions

August last year I went through the same thing with the same motor but mine was even stalling at idle. No less than 3 "authorised" mechanics looked at the problem and "fixed" it. Of course, 1st time in the water after each service the motor stalled. Each time I said they should look at the carbies but they didn't, of course.<br /><br />After some long negotiations, took it back to the original Yamaha dealer and he did take down the carbies and lo and behold - crud! Still charged me a small fee and he insisted the problem had changed since he looked at it.<br /><br />I have to thank Rodbolt and others on this site for giving me the confidence to keep going back with some knowledge of the probable problem. I have since found a motor mechanic who is well trained and was frustrated working for dealers so he's on his own and he comes to me for half the price.

 

[robf7]

Re: Yamaha 115 V4 questions

Thanks for all of your advice. My boat is at the lake, but I have scheduled an appointment for next Tuesday with a reputable guy that I personally know. After he is through I will post the results in case it is something else, but it looks like it will be timing or dirty carbs.<br />Thanks again, you guy's are great!