Yahana 200hp txrr stumbles at idle

[Jersey Jimbo]

The outboard stumbles or intermittently cuts out does not stall. feels like an engine miss. I changed the spark plugs, cleaned out all the carbs, replace fuel filters, Fuel is fresh and clean. Verified spark with spark tester, any and all help will be appreciated thank you

 

[Kola16]

What are your compression numbers?

 

[99yam40]

possible a lean sneeze on one cylinder maybe.
did you do the link and sync after reinstalling the carbs after cleaning

 

[Jersey Jimbo]

What are your compression numbers?

compression is good 115-120 on all cytlinders

 

[Jersey Jimbo]

possible a lean sneeze on one cylinder maybe.
did you do the link and sync after reinstalling the carbs after cleaning

Did not take them off removed the drain plugs 2 on each carb cleaned out the float area with gum out, took the 2 jets in front of the carbs and cleaned them out.

 

[Jersey Jimbo]

The outboard stumbles or intermittently cuts out does not stall. feels like an engine miss. I changed the spark plugs, cleaned out all the carbs, replace fuel filters, Fuel is fresh and clean. Verified spark with spark tester, any and all help will be appreciated thank you

The outboard stumbles or intermittently cuts out does not stall. feels like an engine miss. I changed the spark plugs, cleaned out all the carbs, replace fuel filters, Fuel is fresh and clean. Verified spark with spark tester, any and all help will be appreciated thank you

also when the stumble happens it will give me a puff of smoke when it happens feels more like the ignition is cutting out for a second

 

[99yam40]

take it to a good shop to have the carbs cleaned properly.

 

[Kola16]

take it to a good shop to have the carbs cleaned properly.

This. Draining the fuel in the bowls and spraying carb cleaner in them is almost useless. The carbs need full disassembly and every square inch of the inside cleaned.

 

[Jersey Jimbo]

This. Draining the fuel in the bowls and spraying carb cleaner in them is almost useless. The carbs need full disassembly and every square inch of the inside cleaned.

ok then I will get me 3 carb overhaul kits, soak them in a carb cleaning solution and reassemble them that's not a problem. by the way I was a certified master tech with GM for over 45years. I will try the carb overhaul, will use my friends cleaning tank but my gut tells me it is an electrical issue, I am learning about these 2 strokes

 

[99yam40]

heated sonic cleaner would be better

 

[Jersey Jimbo]

heated sonic cleaner would be better

yes with air agitating to clean out the passages my friend has a machine shop and told me no problem to clean them there he uses the machine to clean up cylinder heads and manifolds thanks for thay info, his machine will do a good job on them.

 

[brodmann]

And also use compressed air to blow out all the passages. The idle circuit on those carbs has tiny holes in the top once you get those big brass plugs off of the top You've got to get those tiny holes cleaned out to get good fuel supply at idle and lower RPM's. Those big brass plugs need a really large, wide flat screwdriver and a lot of force. I bought the largest screwdriver I could find and used a belt sander to dull the tip a little so it fits really snug in the slot.

 

[Jersey Jimbo]

Got the carbs rebuilt, set them up per manual, this is crazy still does the same thing, definitely was not the carbs. It feels like it shuts off momentarily and it is random, om;y at idle and low rpm's, cannot feel it when cruising. some people say it can be the CDI unit is there a way to check that it is not cheap to replace. Others say stator, any clue this is driving me mad.

 

[99yam40]

can you get a video and post it up so we can see and hear what is happening?

a timing light might show if a spark is dropping if moved around on the different plug wires.
or maybe an inline spark tester might show if a plug is loosing spark from time to time.
Just never ran into a random spark drop before.
you can use a peak voltage meter(analog) built for these ignition systems.
digital may not be very good to show something that fast.
you can read the inputs and out puts of the CDI and see if something is doing weird things.


when you say you set cabs like manual calls for did that include syncing all the carbs linkages with the butterflys completely closed.?
and then adjust to get to an idle opening.
How about the timing?
I am not sure that is part of the procedure on these bigger HP motors, but I know on the 3 cylinder motors it is.

you need to look at them as each cylinder a separate motor tied to a common crankshaft that you have to set all exactly the same so they do not fight each other at idle

 

[Jersey Jimbo]

spoke with a Yamaha tech in my area and he told me when 2 strokes get older the reed valves get weak, he explained to me a how to check them and it turns out one is bad, does not suck in on one side of the carb, he said this is common on older engines. Now should I replace all of them or just the one set.

 

[Kola16]

If you have the money, the CCMS composite reeds are well worth it. They improve starting/idling and hole shot.

If money is tight, I am not really sure whether you should replace a set or all, but according to the Yamaha tech you talked to, you would want to replace all of them if they commonly go bad with age. Again not sure, I am just saying if you do replace them all, I would go for the CCMS reeds.

 

[Jersey Jimbo]

If you have the money, the CCMS composite reeds are well worth it. They improve starting/idling and hole shot.

If money is tight, I am not really sure whether you should replace a set or all, but according to the Yamaha tech you talked to, you would want to replace all of them if they commonly go bad with age. Again not sure, I am just saying if you do replace them all, I would go for the CCMS reeds.

Thanks for that info will have to check into them. He told me to replace them all just so I don’t have to do it again. He said to just do the reeds not the whole housing they should be good still.

 

[brodmann]

I've checked the reed valves openings and other things before, but I've never actually had to replace any before.

 

[Jersey Jimbo]

Reed valves were good. started look at all settings, linkages, fuel system, I got it to stop when I was making each carb run rich by covering the air horn (carb intake) the top carb when done the lean pop stopped. I rechecked the float level, and o rings were in place properly. I noticed then putting the top carb on I had to move the carb linkage opening the throttle plates a little. So I ran it without the linkage connected to the top carb. the popping stopped. I noticed the carb was opening a lot like a 1/4 an inch to connect it to the linkage. could the throttle shaft somehow got twisted, I had to shorten the main linkage rod, too out about 1/4 inch of metal and spot welded it back. put it all together and it works now like it should. should I get a new throttle shaft for the carb and replace the linkage rod

 

[99yam40]

in post #14 I asked if you linked all carbs with throttle plates completely closed.

was that not part of the link and sync procedure?