1990 130 ETXD goes from 5300 to 4500 rpm ....

[fmt2bx98050]

Just rebuilt both carbs, one was leaking at one of the needle valve.
In the process I changed the fuel pump and hoses.

Here is what I am getting now:

Idles fine for 20+ min.
From idle to WOT, accelerates really well for about 8 sec, then when the motor reaches about 5300 rpm it quickly goes to 4500rpm.

No improvement if I prime fuel, still 4500 rpm
Changed the sparks plugs with new ones and same thing.
Bypassed the quick fuel disconnect and same result.

It really sounded like a lack of fuel, however when I got home after checking the coils this is what I found on coil number 2:
The 3 other coils checked ok. Primary and secondary.

https://youtu.be/_RQb9wITGis


Screen Shot 2017-05-17 at 9.08.18 PM.jpg





Not saying that it is the issue but this isn't normal. Fixed that but didn't have time to go for test drive.

Here is where I'd like some help. On my next trip to lake this is the plan:

- Bring portable fuel tank and run fuel from there.
- I have an extra primer bulb
- Spray bottle with gasoline , see if spraying in individual carb makes a difference.
- Going to bring the timing light.

What else could you think of I might need to troubleshoot this while on the water?
Any idea as to what the issue might be?

Thank you.

Fmt

PS: Prior to rebuilding carbs, the motor would bog down from the get go and I would get a max of 4000 RPM, acceleration was very slow too. It definitively has improved since then even got 5600 RPM for few sec today but went down to 4500 rpm.

[amahaork]

Do not spray gas into carb. It may kill you. Pump new is enough. Have you check has tank pick up and vent? Have you adjusted timing?
Light is only good to visually compare frequency of each coil.
Frequency

[fmt2bx98050]

Do not spray gas into carb. It may kill you. Pump new is enough. Have you check has tank pick up and vent? Have you adjusted timing?
Light is only good to visually compare frequency of each coil.
Frequency

Ok thanks . I haven't adjusted the timing yet.

Now do you think that the fault I found on the coil/spark plug connector could cause the motor to rev normally for few seconds then drop down to 4500rpm?

video:
https://youtu.be/_RQb9wITGis



Don't understand how it would work at all on that cylinder since there was a discontinuity between the plug connector and coil wire. Maybe enough V to jump over for few sec then with heat it stopped(?)


Thank you

[99yam40]

Do not spray gas into carb. It may kill you. Pump new is enough. Have you check has tank pick up and vent? Have you adjusted timing?
Light is only good to visually compare frequency of each coil.
Frequency

not sure where you come up with stuff like this, but it does not belong here.

Spraying fuel into a carb throat is something that is done all the time without killing people. it checks to see if that cylinder is running too lean.

timing light is the only way to see what the true timing is on a motor

[amahaork]

not sure where you come up with stuff like this, but it does not belong here.

Spraying fuel into a carb throat is something that is done all the time without killing people. it checks to see if that cylinder is running too lean.

timing light is the only way to see what the true timing is on a motor

I advise you not to do that, but I support your right to do anything you want. Just tell someone to make YouTube video.

[TownsendsFJR1300]

I advise you not to do that, but I support your right to do anything you want. Just tell someone to make YouTube video.

Plus 1 on Yam99' post above (#4).


Putting fuel in a spray bottle and spritzing into the intake is common practice (same as starting fluid) to see if a certain cylinder IS getting fuel.

It simply confirms lack of fuel being delivered thru a carb or throttle body.

Besides, being similar to starting fluid, you can control it better.
And MOST importantly, for a two stroke, you can USE PREMIX for lubricating purposes.



.

[amahaork]

Until I will find somewhere in Yamaha Shop Manual or Yamaha Owner Manual instruction for using gasoline like that, in order to avoid liability, I would not advise anything like that.

[99yam40]

apparently you have not worked on many motors troubleshooting fuel or other problems.

what about a timing light?
how do you check timing on a motor if not by using a timing light?

[TownsendsFJR1300]

Until I will find somewhere in Yamaha Shop Manual or Yamaha Owner Manual instruction for using gasoline like that, in order to avoid liability, I would not advise anything like that.

That's fine. There's also many other tests, NOT in the manual that work perfectly fine as well.

How about the liability of the manufacturer of "starter fluid"? Would they have not been sued / closed down if it was that dangerous?

That sprays out harder and faster than a spritz (spray) of fuel.

Unless the timing has jumped, an intake valve stuck open, it won't blow a flame out the carb or TB...

In any case, it is an easy / SAFE way to see if the engine IS GETTING FUEL.

Just for yourself, (for S&G's), should you have a lawn mower (weedeater, etc) run it out of fuel, bone dry.
Pull the air filter off. Try starting it, of course it won't. Now, spritz a small amount of fuel down the intake. It WILL NOW fire and run for a couple of seconds CONFIRMING a fuel issue (no gas in the tank). You'll see no flames, nothing, just the engine starting momentarily..