Engine noise / vibration Yamaha 2-stroke 200 HP

[bart.willemsen]

Yamaha 2-stroke 200 HP GETO L 500430 X 61H with enige noise /vibration.

Both cold and warm, the engine was making a ratteling noise at a certing higher rpm, lower or higher rpm resolved the noise. Now it's making the same noise at weakboaerd speed . Does anyone have idea;s how to analyse this issue and to know if it is bearing, piston, crankshaft related? The engine can smoke heavy after a cold start and warm when starterd whithout throtle. it's gone in seconds but it look it run rich on oil. No thoughts on running on less then 6 cylinders. Anyone for the settings of the oil pump. Anyone suggestion for the maintenace of the fuel pump . reed valves?IMG_0364.jpg

IMG_0366.jpg

[amahaork]

Show me spark plugs

[bart.willemsen]

Photo sparkplug added

Hi, i have added the photos of the sparkplugs as requested. I looked into the cylinders and the look ok to me, 3 cylinders are clean ( i cloud read 46B02) 3 with a minimum of dark combustion recedu ( bit wet). Sparkplugs seems all to be ok, no recedu and the electrode is white.

[99yam40]

Bad gas could cause pre- ignition/knocking, that will destroy pistons.

how old is the fuel and what kind of fuel?

with plugs out put a wooden dowel in to look for slack in wrist pins, or bottom rod bearing

[amahaork]

try to run from external tank on pre-mix 1:50 and hear difference.

[bart.willemsen]

Thanks both for the reply. The petrol is clean 95 RON and is replaced fully several times this year by using it intensively. I wil inspect the pisons as sugested and try to clean the combustion residu carfully. I also try to use 98 ron to identify any difference and will let you know.any other suggestions to check the pison bearings, rod end whithout opening the enigine?

[amahaork]

95 RON = 87 US is OK. try to run oil rich premix to make sure piston rod bearings have enough lubrication.

[99yam40]

any other suggestions to check the pison bearings, rod end whithout opening the enigine?

as I said use a wooden dowel to look for movement of the piston or use a dial indicator.
measure the amount of movement of the piston or lack of it while hand turning the flywheel back and forth

[robert graham]

My 1999 C90 was rattling at certain RPM's....turned out to be those black plastic threaded control cable ends under the cowling....they just vibrate a some RPM's...I wrapped some elastic around them to sorta hold from rattling....no more noise!.... Check it out...

[bart.willemsen]

Ok, i checked the piston crank on excessive space by putting a woden stik into the sparkplug hole and checked it on tdc and bdc and could not feel any space. Each movement has been felt, but as its not the most secure check it only says ist not worn out. I made a video with a running ( hardly not smoking) engine, reving between 500 and 2500 rpm by my iphone but could not upload it. During the videoing the engine became overheated ( despite the water bracket on the water entry ( engine was peing water). Duo to the noice, i could not hear anything so i must repeat this execsice in the water ( hoppefully in this weekend). No of hours is unknown. Keep you posted.

[scofflaw]

Dowel test is done when the piston is on its downward stroke

[panasonic]

Have you eliminated the possibly that the LU could have problems and be causing the knocking?

Take the lower unit off and try running it.

[bart.willemsen]

It will be difficult to recognise the sound when the engine is out of the water (exhaust noise), and whitout LU it will not have proper cooling. I aim to make a sound/video recording when in the water.

[bart.willemsen]

Ratteling Nois 2 stroke 200HP 1999 (not a VMAX)

Finnaly could make a video. At 26-30 sec the video shows the best difference between the rateling en non ratteling. the noise comes up at arround 2000 rpm en disappears by reving above/beneeth 2000 rpm. Hope somebody recognise the noise. Holding a long screwdriver arround the crankshaft, the noise seem to be equal at each crankshaft piston road bearing.

https://youtu.be/F38SZSHD7Yc

https://youtu.be/HvQ-hemB1x8

[panasonic]

It will be difficult to recognise the sound when the engine is out of the water (exhaust noise), and whitout LU it will not have proper cooling. I aim to make a sound/video recording when in the water.

With the LU off clamp a garden hose on to the water tube in the midsection to supply water too the engine. I would try that before tearing into the power head.

I know it might be hard to hear due to exhaust noise. It is worth a try though.