15hp Yamaha

[hustler57]

Hey Fishos 

I bought a 15hp 2 Stroke Yamaha off a mate of mine 2 weeks ago. 

its 4 Years old and has done approx 11 Hours. I took it out last week and it didn't like full throttle and would cut out as soon as I opened it right up so I got the carby cleaned as it felt like the flow jets where a bit clogged. 

Went out for a run last Saturday night and it went perfect and took it out again today and it had the occasional splatter for about 10 mins then it ran great ? 

Questions are 

1. Why would it of had a splatter today for 10 mins ?

2. Why does it prefer to run at 1/4 Choke ? 

im running it at 100:1 as per the manufacture says but im not comfy with it as ive always ran 2 strokes at 50:1

[noelm]

Yamaha carbs are extremely hard to clean, no amount of washing, spraying or miracle stuff in a can will clean them, you need to get all the tiny passages in the carb body cleaned out, hot ultrasonic is best, but most home handymen will not have one, are the plugs good?

[hustler57]

I got the carby clean my a mobile marine mechanic but I am doubting his work as he had the carby out  cleaned and back in in around 30 mins. apparently the plugs are good according the mechanic but I will have a look at them tomorrow. 

 

[kingfishbig]

Yes you can run 50:1. It's probably a good idea if you run at full throttle a lot and if you want the motor to last. 

[hustler57]

I would feel better running 50:1 

[big Neil]

Hi Benny-Boy  I have a 15hp Yamaha which I run on UNLEADED and 2 stroke mix at 100:1. I have never had any trouble with it. I know that doesn't answer your problem, I just wanted to say that they are good, reliable motors. My mate who is a mechanic reckons NEVER run on E-10 fuel or ordinary 2 stroke oil (use marine grade). Hope you get on the water soon mate.

Cheers, bn

[hustler57]

Thanks Big Neil. I am running Caltex 95 at the moment in it. im using marine grade oil as usual in all my previous boats in the past. From my research about this model yammie I have they are a great motor but I just need to iron out this issue of it chucking a wobbly like it did for today for about 10 mins on and off. 

i bought it just last week and my mate who i bought it off . He bought it brand new and would start it up for a few mins every month and let it idle but hadn't taken it out in over a year hence why its got such low hours for it age  hence it hasn't really done much work and i expected the jets to possibly be a little clogged but I have my doubts about the work the marine mechanic who came out as it was the quickest carby clean job ive ever seen.. im going to check the plugs tomorrow myself even thou the mechanic said he checked them as well as check the air filter as it ran like a dream after the wobbly and at 1/4 choke. 

[SquidMarks]

No familiar with Yamaha carbies, but in my experience, when engines with carbies need choke to run it usually means a lean mix (too much air/too little fuel). I would say that the jets have not been cleaned properly, but i wouldn't also dismiss a possible air leak from a damaged gasket as the carby was being reinstalled... 

Give that carby a proper clean and go from there.

[kingie chaser]

13 hours ago, Benny_Boy said:

Hey Fishos 

I bought a 15hp 2 Stroke Yamaha off a mate of mine 2 weeks ago. 

its 4 Years old and has done approx 11 Hours. I took it out last week and it didn't like full throttle and would cut out as soon as I opened it right up so I got the carby cleaned as it felt like the flow jets where a bit clogged. 

Went out for a run last Saturday night and it went perfect and took it out again today and it had the occasional splatter for about 10 mins then it ran great ? 

Questions are 

1. Why would it of had a splatter today for 10 mins ?

2. Why does it prefer to run at 1/4 Choke ? 

im running it at 100:1 as per the manufacture says but im not comfy with it as ive always ran 2 strokes at 50:1

It is strange that it asks for 100:1, it is obviously a Yammy thing as all their 2 strokes are spec'd for 100:1 where as all Mercury 2 strokes are spec'd for 50:1?

But there must be a reason for it, I would be sending them an email to ask why??

Maybe their compression is higher??

 

On your carb. I agree with sqidmarks, you shouldn't need to run an engine on choke.

Being an internal tank did all the old fuel get removed & the tank cleaned out??

Either get the mechanic to recheck it or just change mechanics if your not happy! 

[hustler57]

The fuel tank is a external tank that's been cleaned. i am heading out tomorrow night to drop a  line and will see how it runs then but if running at 1/4 choke is the only issue i have then while it shouldn't need any choke im not extremely worried at this stage as yesterday was a extremely cold day on the water . I had a old 40hp Mercury years ago that ran like a dream with a fraction of choke.  but i will be emailing Yamaha to ask why they say 100:1

 

[kingfishbig]

14 minutes ago, Benny_Boy said:

The fuel tank is a external tank that's been cleaned. i am heading out tomorrow night to drop a  line and will see how it runs then but if running at 1/4 choke is the only issue i have then while it shouldn't need any choke im not extremely worried at this stage as yesterday was a extremely cold day on the water . I had a old 40hp Mercury years ago that ran like a dream with a fraction of choke.  but i will be emailing Yamaha to ask why they say 100:1

 

It's a marketing thing and a concession to the environment. If the motor has needle bearings it can run at 100:1. But the motor will probably last longer run on 50:1.

[noelm]

A few had 100:1 mix, I think it was trying to get around emissions and getting rid of smoke, most are still running the lean mix, some go to 75:1, some go to the old 50:1 mix, it's your choice, if you do a lot of high throttle long runs, a bit more oil sure won't hurt, but, for general use 100:1 is fine.

[hustler57]

I will be doing a lot of high throttle long runs . 

[jeffb5.8]

17 hours ago, hustler57 said:

 just need to iron out this issue of it chucking a wobbly like it did for today for about 10 mins on and off. 

 ran like a dream after the wobbly and at 1/4 choke. 

So after the Wobbly you say it perform well (Albeit with 1/4 Choke?)

I would phone the marine Mech and check but a slight turn of the Idle mixture to a richer setting should help get rid of the need for choke.

If the wobble has gone it may have been some residual debris left over after the clean, take it for a few warm up runs then a few full throttle runs and see how it performs, the plugs may also have caught some carbon if it hasn't seen WOT for a while, so give them a clean as well.

If Yamaha say 100:1 is the setting I wouldn't go to 50:1 but there is nothing wrong with a little extra oil like 80:1 without risking fouling the plugs on trolling. Older motors were at 50:1 as the systems weren't as advance and emissions wasn't as big a issue.

[hustler57]

When it was having the Wobbly attack i pulled out the choke 1/4 and it ran perfect. 

i wouldn't be surprised if it was just some residual debris left over after the clean . Plugs got replaced today to be safe . The engine would now of done maybe 14-15 hours in total. I spoke to a Yamaha dealer  this afternoon and was told 100:1 is the correct ratio as per instructions from Yamaha but he couldn't see an issue running it a little richer. 

[antonywardle]

I've got a 1998 and a 2004 model. Seems to be good. The 98 model I got with my new boat hadn't been run in a while, and it took a bit to get it going. For me it was pulling the carbs off three times. I've also got good at taking the leg off. Mine are all 100:1. I think it might be a bit of marketing. You'll probably find that 100:1 is recommended if you are using Yamalube 2stroke oil, but if you are using anything else then go to 50:1 or another figure. I use unleaded in mine. Does your telltail get warm? Maybe the thermostat is sticking. That can cause running issues, especially with idlin, although it doesn't sound like that you've got that.

 

 

[hustler57]

The good stream of water out the rear takes a little while to warm up but its only luke warm at best. The thought that the thermo is possibly sticking will be something i might need to look into depending how it goes tomorrow night when i drop a line in. 

Im using 95 Caltex at the moment . What are you using ? 

[big Neil]

21 hours ago, hustler57 said:

Thanks Big Neil. I am running Caltex 95 at the moment in it. im using marine grade oil as usual in all my previous boats in the past. From my research about this model yammie I have they are a great motor but I just need to iron out this issue of it chucking a wobbly like it did for today for about 10 mins on and off. 

i bought it just last week and my mate who i bought it off . He bought it brand new and would start it up for a few mins every month and let it idle but hadn't taken it out in over a year hence why its got such low hours for it age  hence it hasn't really done much work and i expected the jets to possibly be a little clogged but I have my doubts about the work the marine mechanic who came out as it was the quickest carby clean job ive ever seen.. im going to check the plugs tomorrow myself even thou the mechanic said he checked them as well as check the air filter as it ran like a dream after the wobbly and at 1/4 choke. 

Sorry Hustler 57 for calling you Benny Boy. I must have read a different post and replied to yours with the wrong user name. Sorry, tablets not working. bn

[mrsswordfisherman]

1 hour ago, big Neil said:

Sorry Hustler 57 for calling you Benny Boy. I must have read a different post and replied to yours with the wrong user name. Sorry, tablets not working. bn

@big Neil dont be sorry. 

In his first post introducing himself he said he was an active member a long time ago. I offered to merge hustler57 with Benny_Boy.

So you are correct hustler57 is Ben

[antonywardle]

The fuel that I use  is that same as my ETEC, its unlead 90. I'm using Evinrude XD50 in it after I ran out of Yamalube.

 

Thermostat is pretty easy to check. It might cost you a gasket. There are 4 or 5 10mm bolts on the front just above the top cylinder. I bought a new one, but I think that it is slightly the wrong one. I ended up cleaning the original by boiling it in water/vinegar and it came up a treat. I also tested it by putting in in hot water and it seemed to open ok. Itinitall, it was stuck half open when I took it out. My older ine doesn't get all that hot, so I think that the water jacket has a lot of build up in it. One day, I'll investigate pulling hte powerhead off and checking it all out.

 

For now, I'm using the 2004 model and it goes great.

[noelm]

Depending on the model, the tell tale will not get hot, most only get warm because the tell tale comes off the water supply before it goes through the entire motor (not all brands do this) 

[kingie chaser]

 

[big Neil]

4 hours ago, kingie chaser said:

 

Thanks for posting the video kc. Very valuable info there. Cheers, bn

 

[jeffb5.8]

6 hours ago, antonywardle said:

The fuel that I use  is that same as my ETEC, its unlead 90. I'm using Evinrude XD50 in it after I ran out of Yamalube.

 

Thermostat is pretty easy to check. It might cost you a gasket. There are 4 or 5 10mm bolts on the front just above the top cylinder. I bought a new one, but I think that it is slightly the wrong one. I ended up cleaning the original by boiling it in water/vinegar and it came up a treat. I also tested it by putting in in hot water and it seemed to open ok. Itinitall, it was stuck half open when I took it out. My older ine doesn't get all that hot, so I think that the water jacket has a lot of build up in it. One day, I'll investigate pulling hte powerhead off and checking it all out.

 

For now, I'm using the 2004 model and it goes great.

Have you tried Salt Away

i used it in my mates 2006 90hp Yamaha and my Etec.

the Yamaha definitely flowed better after two flushes.

first flush we stopped the motor and left the salt away in the motor for a week then did another flush the same.

the the following week took it for a good run up the harbour and when back home the tell tale did have more flow. 

[antonywardle]

I used viniger and water in a bucket, and threw in some detergent away a while.

 

I'll see how much saltaway costs and consider it, although based on @noelm comment above

maybe I don't now have a problem. I guess I should check it against the newer motor and then I'd

expect both engines to get to similar temperatures.  Apologies to @hustler57 if I've hi-jacked your OP