Erratic RPMS

[Chuck B]

Hi everone, new to the site.
Have a 2003 LX210 with the lst1200AB engines.
starboard engine was bogging down
comp tested both engines both have 122 to 125 all cylinders
pulled the spark plugs cleaned and re-gapped
on the ramp on the trailer Starboard engine at 4500 fluctuates to 3,000 give it a little throttle and will jump to 5000 then fluctuate, it will run at 5500 like it is up against a governor and will not fluctuate.

the port engine will only run at 5200 in this condition, however there seems to be power to the boat, in nuetral whereas the starboard engine does not try to move the boat.

on the starboard engine I am getting a popping sound in the aft carb when bringing off idle, i am getting good spark to that cylinder though.

my question and looking for input, could the couple slipping, if it is be causing the erratic RPMS, or would 1 dirty carb do all of this
thanks in advance

 

[Chuck B]

Sorry I meant, if the coupler was slipping could this be causing part of my problem, and also do the couplers get worn and slip or do they just go bad and thats it?

 

[Murf'n'surf]

I would question your spark plugs -- replace them.

Check the quality of fuel.

Broken engine mounts(s) could cause the coupler to separate.

 

[Chuck B]

Thanks will do

 

[bronze_10]

If it is a carb engine... how about the timing?

 

[4x15mph]

I think this is more simple:
- not the coupler
- replace the fuel filters. do you have fuel filters? If so, change to fuel/water separators
- rebuild the carbs with OEM kits. Have you ever had this done? when?
- are you running pre-mix?

Given your compression, it is probably that simple. Carbs (6) are the biggest consideration outside of an air leak

 

[Chuck B]

Thanks so much for the reply,
Has fuel filters, but they are in line see through clear filters.
UNK on the carb rebuilds, Maintenance history pretty much unknown.
Not running premix, I have read on other posts most have switched from the pump, it does seem to smoke a lot for even a 2 stroke.
Where would I be looking for an air leak if there was one?
Was hoping to rule out everything else before tearing it down to rebuild the carbs.
Just a couple more questions
Does each carb have it's own fuel pump?
Can I take the carbs off without pulling the engine out of the boat
Thanks again for your help.

 

[4x15mph]

- replace the fuel filters
- rebuild the carbs by buying an OEM kit. Don't change out the springs and needles.
- you do not need to take out the engines. It is actually pretty simple but you will need new gaskets and you may want to add new fuel line between the carbs
- each carb has its own pulse tube which acts like the fuel pump.
- do not convert to pre-mix if you have a working oil injection.
- there really are not a lot of variables around why it would act like it is outside of fuel delivery (carbs) and you should rebuild them anyway since you don't know the history. Reset the clock

 

[itsdgm]

Do you guys with Yamaha 2-stroke experience also reccomend changing out the oil lines on this boat? I used to see a lot of reccomendations about that a few years ago

 

[4x15mph]

@itsdgm , yes - you should make sure that all oil lines have slack, are not brittle, and that they are clamped using oetiker clamps. The oetiker clamps come as part of the oil line replacement kits. It isn't necessary to change out the lines if they are in good shape but many buy the whole oil line replacement kit and do this as a complete job. When you do this, you have to bleed the oil lines to prime them.

You are right that this is a critical preventative step. I don't know from experience other than from reading and it makes sense.

 

[Chuck B]

I feel like a dunce here, I have found a carb rebuild kit 65u-W0093-00-00, it has been my experience with Yamaha that everything is sold separately does this kit rebuild a bank of 3 or just 1

 

[M@__]

Kit for 1 is about $50
Kit for 3 is about $150

 

[4x15mph]

I ordered the kit here and it is per carb. http://www.ebay.com/itm/181261923522

Remember, if you are going to replace the fuel lines in between carbs you will need new fuel line and clamps. Also order the gaskets above and below the flame arrestor and the carb gaskets (3), and the gasket where the carb rack fits to the engine. Use boats.net to see great pictures and part numbers

 

[Ronald Dillow]

SPARK PLUG wires!!!! I had so many issues last summer with my 2002 LX2000. I replaced the plug wires and the thing runs like a champ.

 

[Yamatuf]

Changed plugs first, If they are the original wires I would replace. My original wires were all broken and corroded causing intermitant spark, adding a load on the motor increased this issue - Jet ski solutions does a great job on new wires. If that doesn't fix the issue then carbs would be next step.

www.jetskisolutions.com/

 

[Chuck B]

I am down to the carbs, but cannot see how the rack comes off, i am assuming the 3 carbs come off as 1 then rebuild from there correct? just need to know how to get the rack off.
every one's input is greatly appreciated.

 

[Ronald Dillow]

Yea Jetski Solutions did a great job with my wires. And I got them back fast.

www.jetskisolutions.com

 

[Yamatuf]

Looking straight down there is 8 nuts on the intake grate. Remove those bolts and the whole unit comes off. Then you can remove the carbs individually.

 

[Chuck B]

thanks

 

[Yamatuf]

My mistake, it's only 5 nuts to remove. I'll try to attach a picture