PLEASE HELP why are my motors shaking at speed?

**apporition77** · 04-12-2018, 05:43 PM

I took delivery of Competition 25 last summer. I have put about 70 hours on her and am trying to figure out the strange shakes the motors have while running. The shake are completely random and feel like they are getting turbulence. I have already reached out to Ken at prop gods and his suggestion was to try to lower the motors one hole. I lowered them and the shake has improved some but still present. I ironically did not loose any noticeable performance or fuel economy. I am running Yamaha Reliance props that I believe have been cupped when motors were hung. The boat performs great except for the very annoying shakes.

Please note that the videos and photos were taken before I lowered the motors one hole.

Can ventilation cause these shakes or is there something else causing this?

I am completely lost and hopefully some of you experts can help out.

https://www.youtube.com/watch?v=_IFjoSJ6C4s
https://www.youtube.com/watch?time_c...&v=zUG1eA7I630
https://www.youtube.com/watch?v=WpQN8tjpSRM

https://photos.app.goo.gl/rsS8x7cqhVIiPmlS2

**Charger20sv** · 04-12-2018, 06:06 PM

air in the hydraulic steering would be my first guess

**apporition77** · 04-13-2018, 07:28 AM

The steering ram does not move when the engine shakes. If it was air I would expect both engines to shake due to tie bar.

**mjw930** · 04-13-2018, 07:32 AM

It almost looks like the steering ram connection to the motors is using a rubber bushing and isn’t a hard connection like it should be. Hard to see in the video but it looks like the motors tillers are moving when the ram connection isn’t.

**XstreamVking** · 04-13-2018, 10:15 AM

Motors are moving independently. Best guess....Bad rubber on the engine mounts. May have been beat hard b-4 you got them?

**apporition77** · 04-13-2018, 10:28 AM

The boat is brand new. I only have 70 hours on her. If mounts are bad then they have been bad since day one.

**Dave Strong** · 04-13-2018, 10:35 AM

Props that are slipping or venting can cause vibration, when it does it try changing trim setting and see if vibration changes.

Dave

**XstreamVking** · 04-13-2018, 11:34 AM

It sure seems to be moving the cowls and power heads around. Steering is solid. When the boat is out of the water, try and move them around by stepping on the cav plate and springing up and down some and check for movement.

**apporition77** · 04-13-2018, 11:42 AM

Seems like the put really soft motor mounts on these new motor but something else has to bee going on to cause the shake.

**XstreamVking** · 04-13-2018, 12:14 PM

You might check for the alignment of the gear cases. Nose centers and prop shaft centers should be close (1/8'') Or....Turbulence from objects protruding from hull bottom that are making a bubble trail. Just guessing here...

**Dave Strong** · 04-13-2018, 12:42 PM

Originally Posted by XstreamVking

You might check for the alignment of the gear cases. Nose centers and prop shaft centers should be close (1/8'') Or....Turbulence from objects protruding from hull bottom that are making a bubble trail. Just guessing here...

intermittent and changes from motor to motor as steering angle changes.

Dave

**KIRCHNER** · 04-14-2018, 02:17 PM

Originally Posted by XstreamVking

Motors are moving independently. Best guess....Bad rubber on the engine mounts. May have been beat hard b-4 you got them?

IF the tiller isnt moving bad or broken part pwr hd to clamp connection agree!

**99fxst99** · 04-14-2018, 03:23 PM

I too would check the alignment of the engines. I've always felt that having them towed in somewhat such as 1/8 to 1/4 greater at the prop Shaft Center lines than at the nose you put tension on the steering tie bar and takes any slack and chatter out of it.

**mjw930** · 04-14-2018, 09:20 PM

Originally Posted by apporition77

The boat is brand new. I only have 70 hours on her. If mounts are bad then they have been bad since day one.

So why isn’t the dealer and manufacturer fixing it? This IS NOT your problem to solve, it’s there’s.

**phillnjack** · 04-15-2018, 11:30 AM

bad / soft upper and lower mounts.. dont matter if new or not, they can go bad so fast.
first time the motor is put under pressure the rubber can move inside its mount, plus they sometimes use soft crap for
smoother ride on the boat.. to me its crazy that rubber is still used. poly bushes would be much better, or solids.