175HP OX66 runs like a champ. What is this broken linkage to the flywheel and why would it be broken other than old age. An additional linkage connection is cracked and there is a strange fitment between the parts. Any thoughts would be helpful. Thanks
OX66 what does this linkage to flywheel control
- Thread starter Noble Savage
- Start date
The lower linkage is for the precision oil injection pump. That pumps adjusts the oil ratio depending on revs. The oil pump linkage is spring loaded and if the linkage is not adjusted or disconnected. the pump runs at full volume all the time. That will eventually result in carbon fouled plugs especially at lower speeds.
I am not sure what the upper item in the first picture is but it looks like it is also indirectly operating the oil pump ratio lever.
I am not sure what the upper item in the first picture is but it looks like it is also indirectly operating the oil pump ratio lever.
1995TXRT is not a valid model number. I searched my files and I think I founds what the upper adjustment is but I have never worked on a motor with that adjustment. The upper adjustment that seems to be disconnected ot broken is the timing adjustment. Different models have different spark timing a nd I think the spark is changed as the throttle opens. Since the timing rod is not connected, I guess the timing does not advance as it should
Setting the timing is described in the service manual but if you motor is running well, I might leave it alone.
The lower linkage is the oil pump ratio control as I mentioned. The adjustment for that should be periodically checked. It seems that yours has a end that is cracked. Keep an eye on it. If the rod connecting the throttle lever to the oil pump breaks or becomes disconnect, the oil ratio will the highest amount of oil per gallon of fuel. At idle and low speeds that will cause excessive smoke and plug fouling
Setting the timing is described in the service manual but if you motor is running well, I might leave it alone.
The lower linkage is the oil pump ratio control as I mentioned. The adjustment for that should be periodically checked. It seems that yours has a end that is cracked. Keep an eye on it. If the rod connecting the throttle lever to the oil pump breaks or becomes disconnect, the oil ratio will the highest amount of oil per gallon of fuel. At idle and low speeds that will cause excessive smoke and plug fouling
Sorry. Mode is a 175TXRT. Thank you for the info. I think you’re correct that the linkage controls the timing. What’s wild is that we have owned this boat for five years. She runs great. But on start up it would require us to pump the throttle at high rpm for the first minute at the launch ramp to warm up. Subsequent starts were easy. I’m experienced with two stroke chain saws and lawn equipment. So I thought this was normal. I’ve now realized that the timing linkage might have been broken this whole time. Wild!!!! I’m a big believer in a thorough physical inspection, but this one got by me. Thanks again for the info. She runs like a champ again. Lol
correction. Maybe that is the one control rod. Not sure how long this thing was broken or why the engine continued to run without it
What do you mean by "strange fitment"? From looking at the pics, it seems that knurled metal end should friction fit into the fitting by your finger. You may need to glue it in, at this point.
For the cracked one... see if you can source a new one. BUT, in the meantime, put a couple zip ties around it.
For the cracked one... see if you can source a new one. BUT, in the meantime, put a couple zip ties around it.
The need to pump the throttle when cold to keep the motor running is most likely related to engine timing. It is a fuel problem that can be related to several things. The choke mechanism comes to mind first.
When you pump the throttle you are activating the high speed jet pump and than adds more gas to the mixture.
I am not sure how the choke is set up on that motor. It could be mechanical or electrical or a combination of both. Do you have a service manual for that motor? If not, send me a direct message (by left clicking on the green circle with the letter S ) on this message and select the option to Direct Message me. Include your email address and I will try to send you a copy of the service manual
enfish
Well-Known Member
- Joined
- Oct 17, 2006
- Messages
- 461
- Reaction score
- 87
- Points
- 28
- Location
- San Marcos, CA
- Model
- Adventure
Just to note, that motor is NOT an OX66. I have the same model and year motor, 1995 175TXRT... It's the first generation Yamaha Saltwater Series. I knew those photos looked familiar...
And, your startup routine sounds about normal. My normal cold start is advance the throttle in neutral, pull out the manual choke on the motor cowling, start the motor (it usually kicks over in a second or two, even after sitting for 6 months), push the manual choke back in, race up to the helm to pull back the throttle before it over-revs after opening the choke, let it fast idle at 1200-1500 RPM for a minute or so before pulling the throttle back to idle. After that, subsequent starts are easy, occasionally needing the electric choke below the key switch if it's a lukewarm or cool start.
Last edited:
enfish
Well-Known Member
- Joined
- Oct 17, 2006
- Messages
- 461
- Reaction score
- 87
- Points
- 28
- Location
- San Marcos, CA
- Model
- Adventure
It's either/or. There is a mechanical choke on the cowling and an electronic choke that is activated by a momentary toggle switch at the helm. I use the mechanical choke for cold starts. The electronic choke doesn't provide enough choke when the motor is cold. It will eventually start, but it usually takes 5 or 6 attempts. Easier to use the mechanical choke and have it start first try.
Disconnect the throttle linkage and use a hand to close the throttle.if the throttle terminal fitting needs to be adjusted then do it .