yamaha 50 wont idle below 2000 rpm

[vroom ZOOM]

Hello. I have a 50 elf motor which doesnt want to idle at less than 2000 rpm. if below that then the tach needle is bouncing and there is a lot of smoke ( running rich). cleaned the carbs and replaced the fuel pump. that helped but not a lot. anyone have ideas? it runs nice and smooth after 3000 rpm. did a compression test and it showed 120 psi in all cylinders. the carbs have been synced and set up as by service manual, and so has the oil pump.

 

[Sea Rider]

Seems the idle speed bolt/screw whichever that adjust all carbs in a row is adjusted way high. With engine sufficiently warmed up re adjust CCW till idle revs decreases to a point that when engine is geared forward doesn't die, re adjust CW a bit if was set way too low for that scenario to happen..

Happy Boating

 

[99yam40]

check the timing with a light to make sure that is in spec.
if timing is good then either the spak producing parts may have a problem or you carb cleaning and setting was not good enough

 

[vroom ZOOM]

hmmm... seems like the timing is the next thing. as for the idle speed screw, not the jet, it has been turned out all the way. the throttle plates in the carbs are fully closed. I had mechanic friend look at the spark, and he said that it was very good. is it a possibility that the oil injectioon pump is adding too much oil and it's running on oil? it is funny that at the proper mixture it runs at 4000 rpm, with the throttle plates partly open at idle position. the carb cleaning was done by a pro with ultrasound

 

[99yam40]

motor will not run on oil only.
may need to do a better job of explaining what is going on.
fully closed throttle plates will not let enough air in for it to run at idle much less at higher RPM

following link and sync procedure calls for checking timing from what I have seen

 

[vroom ZOOM]

ok I will try post a video tommorow. right now, throttle plates fully closed, 2000 rpm, smoke. if no smoke, then 4000+ rpm, throttle plates at what should be normal idle position
there is no misses at any time and it seems to be firing quite consistently

 

[vroom ZOOM]

sorry, cant post a video now, lost my laptop charger. I looked at the timing and it seems totally out of wack. have a look. the first picture is what it is set at - look at the stopper screw - that seems funny that it is turned all the way. could that be the source of problem? set for higher speed? also, what are the dashes on the cdi? in the service manual the timing procedure doesn't use a timing light or dial indicator. could i time the engine based on these dashes and adjustment of the link rod? there is no other mechanisms for timing advance on the motor. the second picture is what I think it should be, but I am not sure, and would like to double check with you out here before starting up the motor

 

[vroom ZOOM]

*RESOLVED* 99yam40, you were right about the timing. when I bought the motor the idle was fast, and it turns out that the screw in the above picture (idle timing adjustment) was set way too advanced. read in the service manual that it has to be set at 20mm. someone before me turned it to 50mm! I wonder how the engine didn't blow. anyways, setting at 20mm lined up the pointer with the lower center dash, and now I had to open the throttle plates a bit. now it runs as it should.

 

[99yam40]

follow the link a sync procedure in your service manual and then check with a timing light to make sure it is really at spec
idle and WOT
be careful and get someone to help drive the boat

using something like a dial indicator to verify TDC of pistons and timing marks line up/are correct also