Sneeze, Cough, Whatever...

[rodbolt17]

there are no lead bb's for accessing the fuel passage on that 115.
what the tech bulliten says is hook up a water supply to the inlet,hold the carb upside down and turn on the water.
look for equal flow from the needle seats.
however if you tilt the carb any direction it tends too change the pattern.
if your carbs do not have the clean out port it can be added with the kit from Yamaha.
mostly a waste of time in my opinion.

[Jason2tpa]

Thanks for all the responses guys.

Townsend

Do you use RingFree? If not, that would be the first thing I would try, (shock dose). If the spark plugs are oldish, change em and gap to the tighter end of spec's.

I'm a seafoam user, but you're right. Perhaps a shock treatment would clear out debris if it's the cause. New plugs were just installed when I changed head gaskets a few weeks ago.

Rodbolt

myself I would like to know what is the idle speed, what is the idle speed in gear *****ing?

Idle speed in neutral on flush AND submerged is 800 (tach only reads in 100 incriments), idle speed in gear submerged is 600.

This rpm reduction you've heard ONLY occurs when idling in neutral and slow idling in gear. It does NOT happen otherwise. No hesitation, skipping, etc, when running up through the rpms to WOT.

Rodbolt

if the idle speed is to fast or the shutters not syncd correctly that is exactly what it would sound like.

Sorry bud, never heard of shutters. If you could, please explain a little further. Because it sounds like by your words this is a timing/sync issue and I'd like to resolve it.

[99yam40]

shutters = throttle plates, butterflys

[Jason2tpa]

shutters = throttle plates, butterflys

Ok, that's what i thought he was referring to. I can come off the speed screw a tad to see if that helps. As far as the butterflies, if they are closed with neutral throttle would this be considered "synced correctly"?

[rodbolt17]

to CORRECTLY sync the butterballs dohickys shutters or what the ell ever means disconnecting the oil link,discconecting the throttle cam.
back off the idle screw until it no longer contacks the stopper,loosen the top carb sync screw loosen the cam roller screw and make sure both shutters are fully closed without the idle screw hitting the stopper.
now would be a good time to check the oil pump link rod adjustment.
then tighten the upper screw.
turn the idle screw down about 2-21/2 turns after it contacts the stopper.start the engine,adjust the idle speed to about 750.
shut it off.
connect the cam link.
move the cam roller to the correct position,this assumes idle timing is correct.
tighten the roller so it does not touch the cam but is close.
now start the engine move the throttle until the cam picks up the roller.
check pickup timing.
adjust the roller or the cam as nessasary.
the book calls for 4*ATDC plus or minus 1.
I like 3* atc-1*ATC.
we find it accelerates a tad smoother.
but all this is in your service manual.

[pstephens46]

Butterball works for me.

[Jason2tpa]

to CORRECTLY sync the butterballs dohickys shutters or what the ell ever means disconnecting the oil link,discconecting the throttle cam.
back off the idle screw until it no longer contacks the stopper,loosen the top carb sync screw loosen the cam roller screw and make sure both shutters are fully closed without the idle screw hitting the stopper.
now would be a good time to check the oil pump link rod adjustment.
then tighten the upper screw.
turn the idle screw down about 2-21/2 turns after it contacts the stopper.start the engine,adjust the idle speed to about 750.
shut it off.
connect the cam link.
move the cam roller to the correct position,this assumes idle timing is correct.
tighten the roller so it does not touch the cam but is close.
now start the engine move the throttle until the cam picks up the roller.
check pickup timing.
adjust the roller or the cam as nessasary.
the book calls for 4*ATDC plus or minus 1.
I like 3* atc-1*ATC.
we find it accelerates a tad smoother.
but all this is in your service manual.

Sweet step by step detail, thanks bud. And yes, these steps are in the manual. However, they are not listed in a sequential order as you have detailed. I'm sure your experience is why you go about timing/syncing in this order.

I'll keep y'all updated with the outcome after adjustment. Thanks all for the support.

[throrope]

Yea - sounds just like our two stroke and others I've heard on the web. I had the lean sneeze and that ain't it.

I feel your analysing based on no load operation. I suggest following rodbolt's lead, put the rig in service. If it performs consistently and reliably, get used to the sound, don't fix what isn't broke and spend your time on the water.

[Jason2tpa]

to CORRECTLY sync the butterballs dohickys shutters or what the ell ever means disconnecting the oil link,discconecting the throttle cam.
back off the idle screw until it no longer contacks the stopper,loosen the top carb sync screw loosen the cam roller screw and make sure both shutters are fully closed without the idle screw hitting the stopper.
now would be a good time to check the oil pump link rod adjustment.
then tighten the upper screw[/COLOR].
turn the idle screw down about 2-21/2 turns after it contacts the stopper.start the engine,adjust the idle speed to about 750.
shut it off.
connect the cam link.
move the cam roller to the correct position,this assumes idle timing is correct.
tighten the roller so it does not touch the cam but is close.
now start the engine move the throttle until the cam picks up the roller.
check pickup timing.
adjust the roller or the cam as nessasary.
the book calls for 4*ATDC plus or minus 1.
I like 3* atc-1*ATC.
we find it accelerates a tad smoother.
but all this is in your service manual.

After reading your steps a little closer there are 2 steps I want to be sure I know what you're referring to. I highlighted these 2 steps above in red.
"Top carb sync screw"? and "Upper screw"?

I'm assuming these 2 screws you're referring to are the same screw, right? I've attached the parts blowout for my carb. What number on the diagram are you referring to as the carb sync screw (top carb)?

[rodbolt17]

actually, they kinda are listed in almost that order.
use your manual for the specs as I am going off memory.
I may have done 2 or 3 115/130 sychns.

[Jason2tpa]

Yea - sounds just like our two stroke and others I've heard on the web. I had the lean sneeze and that ain't it.

I feel your analysing based on no load operation. I suggest following rodbolt's lead, put the rig in service. If it performs consistently and reliably, get used to the sound, don't fix what isn't broke and spend your time on the water.

All due respect my man, I don't abide by your perspective when it comes to engines, especially aged ones. Does my engine perform consistently and reliably? Absolutely, it does. But to turn a blind eye to something small will eventually become something big. My engine didn't always idle like this, so I know something is off. Sure it's probably something small, yet I prefer dealing with the small ones before they become the big ones. And so does my pocket.

[Jason2tpa]

actually, they kinda are listed in almost that order.
use your manual for the specs as I am going off memory.
I may have done 2 or 3 115/130 sychns.

That order is the disassembly order. As you go further into the chapter with adjustments the order skews. No prob, I'll follow their specs.

You didn't mention anything about adjusting the mix screws, so what other carb sync screw are you referring to on the top carb?

[rodbolt17]

get a good shot of your carbs on the stbd side.
post it.
wait until someone opens the pics and posts them.
if you have a way label every screw with diagrams and arrows .

the carbs have throttle plate sync screws.
they are the first step.

[Jason2tpa]

Box diagram. Is #3 what you're referring to as the top carb sync screw? They are calling it the throttle lever securing screw. If so, I like your name for this screw better.

[rodbolt17]

my machine does not open thumbnails.
like my cell phone it is about 9 yrs old.
in fact AT&T cut me off yesterday.
they no longer support 2G tech I guess, that is what they said at AT&T.
tomorrow I will be at the Verizon store.

I have a star trek communicator