Yamaha 25hp 2stroke hard to start pls help

[Tobiasedm]

Hello.

i got a Yamaha 2 stroke 25 nmo 1989

its really hard to start when its cold.

Next problem.

When I accelerate, it sometimes dies. but when it gets hotter it goes. but it does not accelerate smoothly, it shoots away with a delay. and then it goes well oxh evenly.Idle speed is smooth, and it goes well in free mode

I have changed spsrkplugs. New fuel.

It always start with startergas.

is it problem with carburator? Ignition?

hmm please help im going to fishing competition next week.

[boscoe99]

Choke would be the first place to start. When you pull the choke knob out do the choke plates fully close?

When a motor is being accelerated air gets in more quickly than gasoline can flow. If the carburetors are adjusted on the lean side it may stumble and/or die. Carburetors that are running lean may also be harder to start when the motor is cold.

Are you familiar with the carburetors if we suggested how to adjust them? Has this problem always been there or is it something new?

[panasonic]

I would suggest a new fuel filter and rebuild the fuel pump. And clean and adjust the carbs as mentioned already.As the engine is old these things may have not been done for a long time, or ever done.

Does the primer bulb pump up hard? And if you pump the primer bulb while trying to accelerate does this make any difference?

[panasonic]

This engine have single carb? I have a 1989 20 LG with dual carbs.

I am to lazy to look it up.

[TownsendsFJR1300]

This engine have single carb? I have a 1989 20 LG with dual carbs.

I am to lazy to look it up.

This one has two carbs, butterfly choke:
http://www.boats.net/parts/search/Ya...TOR/parts.html

Plus one on checking the butterfly's to see if their closing fully.

I'd start by draining the float bowls, catching what comes out (and contaminates, water, crud).

With the new fuel, did you add it to OLD fuel or from a known, clean container/tank?

[boscoe99]

Might be nice to know if the throttle is being advanced for a cold start or is it fully retarded.

[Tobiasedm]

boscoe99
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• Join Date: Jul 2013
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#2
11 hours ago
Choke would be the first place to start. When you pull the choke knob out do the choke plates fully close?

When a motor is being accelerated air gets in more quickly than gasoline can flow. If the carburetors are adjusted on the lean side it may stumble and/or die. Carburetors that are running lean may also be harder to start when the motor is cold.

Are you familiar with the carburetors if we suggested how to adjust


its a New motor for me.
this was the first try in water.



A freind of me will help me to fix if we just can locate the problem.
So in very thankful go give it a shoot to adjust the carburators with my freind.

Before i Will clean them ofc. Choke plate is easy to check. Does it need to be 100% closed?


so settings för carburators would be Lovely to get

thank you all

[TownsendsFJR1300]

If that engine is "new" to you, I'd be pulling those carburetors apart first thing.

The jets in them are very small and clog up easily with varnish just sitting (un-less a good stabilizer is used).

If you don't have a manual, look at the parts picture at what jets are where.

PULL them and make sure you can see light thru ALL the orifices...


*I just cleaned one on a 90cc Yamaha 4 wheeler yesterday (2016 model):
The on/off/reserve fuel valve was also fully clogged.







From a Kohler, 18HP, two barrel carb-sat for 2 years (cleaned yesterday).
The float needle was seized in the bore holding the float open (up in this pic as the carb is upside down):