EF2600 How to Re-Set Throttle On Reassembly?

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EF2600 How to Re-Set Throttle On Reassembly?

Meanderthal
Hi, my genny was starting to miss occasionally so I cleaned out the petcock filter (partially clogged with orange gunge = rust) and removed the carb to clean the Pilot Jet (which was somewhat blocked), and then reassembled. It ran fine for a few days afterwards then started missing again. This led me to deal with the fuel-tank rust issue, now repaired. I then re-cleaned the petcock filter and removed the carb to re-check the Pilot Jet. I opened up the floatbowl on both occasions but nothing inside was obviously amiss (to my inexperienced eye) so nothing was touched except for a quick clean out of the easily accessible jet which screws into the side of the bottom end of the central tube.
However since the second reassembly, the genny is running rough and belching smoke, which another thread suggests is a symptom of rich running - one of the possible causes being failure to "re-set the throttle on reassembly".  Does "reassembly" in this context mean reassembly of the removed carb or is re-setting the throttle only necessary if the throttle system itself was disassembled? All I did was unhook the throttle linkage (and its spring) from the carb, so perhaps "re-setting the throttle" is unnecessary in my case?
If however I do need to re-set the throttle, could someone please explain exactly what I need to do.
cheers John
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Re: EF2600 How to Re-Set Throttle On Reassembly?

Meanderthal
Further to my above post, a further thought - my genny isn't an inverter model so perhaps the throttle re-setting isn't even applicable to my genny. In which case any suggestions on remedying my "rough running and smoke" problem would be most appreciated.
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Re: EF2600 How to Re-Set Throttle On Reassembly?

Meanderthal
Further to above posts, I have now checked the oil (although changed only some months ago) - and, blow me down, it poured out (although the machine was level), has turned brown, and has a fuel smell! So it appears I've got a fuel in oil problem which has developed only since I removed the carb.

I've now read threads on fuel-contaminated oil. Possible causes I can dismiss are having tilted the machine, or the oil being over-filled. As the oil contamination has seemingly developed suddenly, I assume its not being caused by a gradually gummed up float needle/needle seat, but some sort of malfunction of the float controlled fuel control still seems a likely candidate. Or perhaps its something more sinister? (in which case the results of my inexperienced tinkering might serve as a reminder of the potential downsides of such tinkering).
I realise the need to change the oil but I first need to eliminate the cause of the contamination.
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Re: EF2600 How to Re-Set Throttle On Reassembly?

scottybye
I am having a very similar issue with my EF-2400IS
I even removed my tank and washed it out, as there were some visible debris in there.
Removed and cleaned the Petcock assembly
Removed the Carb and cleaned all jets, and float assembly, and needle valve.
Upon re-assembly found gas leaking from carb, and a soaked air filter.
Narrowed it down to the needle valve stem attached to the float.
Seems it wasn't seating in the proper position or more degris found its way there.
After 4 times removing and cleaning it seems to be holding now,,,BUT
The genny when started seems to be running higher RPMs than usual (under no load)
Produced AC power fine, but when under load the RPMs actually slow down.  (lost me)

After reading your post I would suspect a float/needle valve issue.

Lets see what other comments say about your issue.
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Re: EF2600 How to Re-Set Throttle On Reassembly?

CycleRob
In reply to this post by Meanderthal
Meanderthal,
 You definitely have a float needle valve/seat problem!
The belching smoke problem was the gasoline thinned engine oil getting by the piston rings and massive gasoline vapors in  the crankcase venting system being fed normally into the airbox . . . . then the engine.
Talent, On Loan, From God  --Rush Limbaugh--
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Re: EF2600 How to Re-Set Throttle On Reassembly?

scottybye
Thanks for the reply. 
I ended up selling the genny to a guy who needed one for parts. 
I never did get it fixed.  
But the buyer was well aware of the problem. 

On Thursday, 26 May 2016, CycleRob [via Yamaha Generator Fan Club] <[hidden email]> wrote:
Meanderthal,
 You definitely have a float needle valve/seat problem!
The belching smoke problem was the gasoline thinned engine oil getting by the piston rings and massive gasoline vapors in  the crankcase venting system being fed normally into the airbox . . . . then the engine.


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Re: EF2600 How to Re-Set Throttle On Reassembly?

Meanderthal
In reply to this post by Meanderthal
Thanks CycleRob - Sorry I didn't update.  I found the problem as soon as I dismantled the carb again - the main jet was laying in the bottom of the floatbowl!  Presumably I only tightened it finger-tight the last time I screwed it back in, and it must have vibrated out. I put it back in, changed the oil, and the genny runs normal again.  But ...
I still have a cycling issue when its idling, which goes away when I leave the choke on a bit.  I've cleaned all the jets (including the pilot jet and pilot adjusting screw as per other threads), which I guess leaves an air leak as the next likely culprit. I tightened the nuts which hold the carb and aircleaner in place, giving the nuts a bit extra, to ensure the gaskets were tightly compressed - big mistake, as the tightening caused the aircleaner plate-washer and the threaded ends of the studbolts to bend. I'm getting new studbolts and gaskets which, even if they don't resolve the cycling, should at least eliminate an airleak as the possible cause.
One thing though - the cycling doesn't happen immediately I start the genny when cold, it may take up to 20 seconds before it begins. Is this suggestive of anything?
Cheers
John
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Re: EF2600 How to Re-Set Throttle On Reassembly?

CycleRob
Meanderthal,
 Two most likely causes are a too lean pilot jet circuit and/or an out-of-adjustment/bump-bent/worn governor mechanism.

Making the easy shots first:

1--You should loosen the pilot adjuster screw while a warm (not cold or hot) engine is idling, until the cycling just stops. That adjustment compensates for minute film deposits and oxidation of the precise brass fuel metering parts. If the limiter cap stop tap is still there and you hit it in the adjustment, grind or carefully cut it off -or- cut off the carb's cast in stop tab so the pilot screw tab can pass by. That narrow minded EPA limitation, made by small handed bureaucrats decades ago, has created MORE exhaust pollution and terrible running conditions (by small one cylinder engines!!) than the old style adjustable screw had ever made . . . so do not hesitate to disable it. If that does not fix it . . . .

2--Readjust the governor mechanism like this:
 A--Loosen the pinch bolt that clamps the governor arm to the stubby governor shaft that protrudes from the crankcase just enough so the shaft position can be adjusted. Push the governor arm's other end so the carb throttle goes to the full throttle stop and HOLD it there until step D.
 B--Turn the governor shaft's stubby end (screwdriver? pliers?) in the same direction as the governor arm moved to go toward full throttle until it hits a hidden internal stop (the collapsed governor mechanism).
 C--Holding those 2 arm and shaft positions with your finger on the arm end and screwdriver to-the-stop in the shaft end, tighten the governor arm pinchbolt.
 D--You are done.

Talent, On Loan, From God  --Rush Limbaugh--
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Re: EF2600 How to Re-Set Throttle On Reassembly?

Meanderthal
This post was updated on .
In reply to this post by Meanderthal
Hi Cycle Rob

1.  Adjustment of the Pilot Adjustment Screw has no effect whatever on the cycling – the engine continued to cycle from when the Screw is fully “in” right through the adjustment range to when the Screw is so loose its about to come out.

2.  I then moved on to the Governor adjustment.  I loosened the Pinchbolt, moved the Governor Arm forward (i.e. towards the front of the machine) and held it there (against the tension of the Governor Spring). I then used a screwdriver in the screwdriver slot on the top end of the Shaft (referred to as # 8 Governor Fork on the parts list) to turn the Shaft “anticlockwise”.

(The Shaft's rotation both clockwise and anticlockwise is stopped by the presence of the R-Clip (#10 on the parts list) - your Step B indicates that rotation of the Shaft is stopped by a “hidden internal stop”, not by an R-Clip – does this mean I should remove the R-Clip to enable further rotation until it hits a hidden internal stop?)



Anyway, I rotated the Shaft anticlockwise until it was stopped by the R-Clip, and (with Gov. Arm still held forward) re-tightened the Pinchbolt. The result was instant “full-throttle” (i.e. racing) on starting the machine – no idle at all. I could reduce the revs by manually moving and holding the Gov. Arm forward (against the Governor Spring) but this seems to be the very reverse of what should be happening. So I played around with trying variations of your Gov. Arm instructions - firstly by rotating the Shaft clockwise instead of AntiCW, but this just resulted in the Gov. Arm being locked solid in the forward position; secondly by leaving the Gov. Arm in its natural backwards position, then rotating the Shaft CW, which resulted in the engine running sweetly (i.e. no cycling) but on a very very low rev, so I adjusted the Throttle Screw on top of the Carb by screwing it in a bit to hold the throttle at slightly higher revs. But when I put the genny under load, the revs drop right down rather than increase to support the load.  So, I suspect I've somehow got things connected all back to front – especially as I was under the assumption that the purpose of the Throttle Stop Screw on top of the Carb is to set a limit to “maximum throttle”, not to set a “minimum idle”?  And the Governor Spring should be pulling the Governor Arm back to idle, not back to full throttle?  So perhaps its back to my original Post - should I be doing something to re-set the throttle position when I'm re-mounting the Carb on the genny?

     



My cycling has now of course disappeared but this is probably only because the genny is now running on its main fuel circuit, not the idle circuit.
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Re: EF2600 How to Re-Set Throttle On Reassembly?

CycleRob
This post was updated on .
Meanderthal,
 Those pics really help!! The diagram you show is the wrong one as a CCW turn is needed to set that one to the "internal stop". Also, the instructions you misinterpreted were 100% correct. At the start I was using the Yamaha parts diagrams to write the directions posting and found 2 conflicting governor mechanism diagrams for the EF2600, so it was rewritten to not mention CW or CCW, but with universally correct "direction" labels that applies to all mechanical flyweight governor engines. Your confusion seems to be what the governor parts need to do and where full throttle is on the carb. That's easy and here is an even more elaborate explanation . . . . for other people too. The object of the governor adjustments is to establish that the optimal operating range of the governor mechanism is exactly coordinated with the full operating range of the carb throttle butterfly. The governor arm's external spring attaches to the throttle speed set screw which pulls it toward full throttle. When the engine is running centrifugal force acting on the governor weights of the governor mechanism "fight back" against the external throttle spring that pulls on the governor arm to actively maintain 3,600 RPMs at a dynamically smaller throttle opening. When a higher alternator wattage load slows the engine down, the spinning governor flyweights come together under decreasing centrifugal force, decreasing the throttle "push back" resistance allowing the external spring tension to immediately apply as much extra throttle needed to maintain 3,600 RPMs. That creates 60 cycles/second 120 Volts AC power. This all happens so fast that you only hear the engine get louder/softer under the heavier/lighter wattage load without you actually noticing any change in RPMs.

 From the pics I can now say for sure . . . With the pinch bolt loose, the governor arm needs to swing CW toward the carb until the carb's full throttle stop hits -and- the governor shaft simultaneously gets screwdriver rotated CW to the internal governor stop. Then tighten the pinch bolt. The throttle screw threaded into the attached L bracket attached to the governor arm spring sets 3,600 RPMs. From your responses, you "may have" turned it way out of adjustment . . . but that is OK when there is an easy solution to make it perfect. Using a Kill-A Watt you can use its Hertz function readout to very precisely set that 3,600 RPMs so a 60 cycles/sec reading on the LCD's Hz scale stabilizes. That Watt meter linked to is very useful to monitor/tabulate power functions for your home's small appliances (<1,800 Watts). I would use an 800 watt load on the genny to set that speed screw.

 I see you have an adjustable carb pilot screw and here is how to set it. After running a cold engine about 2 minutes, choke all-the-way-off, SLOWLY screw the pilot screw in CW until the RPM falters or starts cycling. Then SLOWLY loosen it CCW until the cycling JUST stops.
Good luck.


Talent, On Loan, From God  --Rush Limbaugh--