1988 Yamaha 130 dies at transition to high RPM

[usna1970]

My Yamaha 130 dies when transitioning from 1600 RPM to high RPMs. Idle is fine, runs great at high RPMs (3800) but it dies during transition UNLESS I hit the choke first. If I hit the flick the choke the transition is perfect. If I do not hit the choke it bogs down and dies. I've cleaned the carbs and put in a new fuel pump but no luck. Any ideas?

[usna1970]

Thanks for the response. Carb screw settings were double checked but not the cause. Engine runs great at the higher RPMs once the throttle is opened up and it gets past the transition point. If there was any debris, I would think the engine performance would be impaired which is not the case. What else is happening in the engine at the transition point that might cause the lack of a smooth transition?

[rodbolt17]

that system does not use 12V for ign.
by tapping the choke you force the fuel mix rich bypassing all carb jetting.
there is fuel in the bowls.
fix your carbs.

[rodbolt17]

I cant remember if the 1988 used the single float mikuni carbs or the twin float. but all the circuits work as the throttle plates open.

[TownsendsFJR1300]

Each carb uses two separate floats:

1988 130ETLG Yamaha Outboard CARBURETOR Diagram and Parts

Agreed, there's still crap in the carb.

Did you pull the main nozzle (part #17) and check all the holes that you could see light thru them?

Cleaning to some folks means spraying with carb cleaner. All the jets need to come out and physically inspected so that you can literally see light thru them....

If you did do all the above already, you may try dis-assembly again and either soaking in carb cleaner solution or using a sonic cleaner..

[rodbolt17]

beats me.
I am 55 and have been rebuilding carbs since I was about 8 and have yet to use an ultra sonic cleaner.
back in the day we used a bowl of gas.
back in the day that chem dip was mean stuff.
I could dang near drink it now.

[TownsendsFJR1300]

beats me.
I am 55 and have been rebuilding carbs since I was about 8 and have yet to use an ultra sonic cleaner.
back in the day we used a bowl of gas.
back in the day that chem dip was mean stuff.
I could dang near drink it now.

I'm 58, NEVER used carb cleaner solution or a sonic cleaner when cleaning carbs since I was 12.

The larger carbs are MUCH easier than the tiny little guys as the orifices are much smaller, use a small primer built in bulb(under that bulb is a one way "valve" that IS inaccessible). If it's clogged, you cannot poke it or it's destroyed...

I posted here about buying a sonic cleaner and used it on a Poulan gas blower carb recently. Worked great, no issues. Mix was Simple Green /water, 50/50 mix.

You'd be surprised at the amount of crap (the outside was clean prior to going in the tub) that was found on the bottom of the cleaner, once done.


Any tool that makes the job easier and more effective, I'm in for it.. Wish I had one years ago...


**While on the subject, can a sonic cleaner (liquid), be used on an fuel injector? IE, can an injector be soaked or will it damage the internal electrics?

[ausnoelm]

Cleaners are OK if there is just "stuff" in the carbs, but it would want to be a pretty good ulta sonic cleaner to remove a piece of grit from a jet! lots of jets and passages get blocked by a single grain of dirt, sprays and washing, and carbs "looking clean" will not fix it.

[boscoe99]

Ultrasonic cleaners can be useful when there is "plaque" build up within a very tiny passageway. Not all carburetors need to be cleaned using an ultrasonic cleaner. But some do. How can it be determined which need the ultrasonic cleaner and which do not?

[TownsendsFJR1300]

Ultrasonic cleaners can be useful when there is "plaque" build up within a very tiny passageway. Not all carburetors need to be cleaned using an ultrasonic cleaner. But some do. How can it be determined which need the ultrasonic cleaner and which do not?

Probably the ones that were cleaned by hand and still don't work right.

IE, a "do over"..

If I have a tool in my arsenal that can help me, I'm going to use it.

To each his own...

[TownsendsFJR1300]

Cleaners are OK if there is just "stuff" in the carbs, but it would want to be a pretty good ulta sonic cleaner to remove a piece of grit from a jet! lots of jets and passages get blocked by a single grain of dirt, sprays and washing, and carbs "looking clean" will not fix it.

The carb is STILL DIS-ASSEMBLED, the jets removed, etc. Then put in the machine. Your still doing a visual inspection once done. You also have to give it a spray to remove your cleaner...

IMO, it's more for the area's you CANNOT get to...

[boscoe99]

Thanks for the response. Carb screw settings were double checked but not the cause. Engine runs great at the higher RPMs once the throttle is opened up and it gets past the transition point. If there was any debris, I would think the engine performance would be impaired which is not the case. What else is happening in the engine at the transition point that might cause the lack of a smooth transition?

Not your specific carburetor but general advice as to how a carburetor transitions from idle mode to high speed mode. I suspect your carburetors are not fully cleaned just yet.

[TownsendsFJR1300]

I addressed the nozzle in post #7 along with a link....

[rodbolt17]

just be careful.
not all main nozzles( emulsion tubes) are removable.
would not be the first monkey destroyed carb I ever replaced.
there is really never a reason to remove that exposed nozzle.

[TownsendsFJR1300]

just be careful.
not all main nozzles( emulsion tubes) are removable.
would not be the first monkey destroyed carb I ever replaced.
there is really never a reason to remove that exposed nozzle.

I busted one decades ago in an Evinrude 140. Fortunately, the shop had a spare tube laying about... It was made of some sort of composite, and pretty fragile..