vibration in 93 johnson 150 fast strike

[188ranger]

I have a seat of the pants vibration or miss at app 35mph and 3500 rpms. I have tried lowering and raising the engine to no avail. It has a new set of plugs and Ive run two different props it does it worse with the raker. THe engine height has been everywhere between 3 in to 3 3/4 in below the pad. Ihave a 9 in plate and both props have been reworked. Please advise. I also notice a miss ot stutter at a constant 1200 rpms. The engine is on a 354 Ranger. Initally I was told th prop was ventilating and thats why I was doing the above changes, It did not help.


Modified by 354ranger at 9:39 AM 7/10/2005

[RUSTY63]

Welcome to the BBC.

Have you tried pushing the choke at the RPM where the problem occurs?

This would help to figure out whether this is fuel or ignition related.

When the motor starts to miss push in on the choke and count to 3, if the motor bogs then we are looking for a ignition problem, if the motor speeds up or the miss goes away then we are looking for a fuel problem.

[188ranger]

what can you tell me about prop slip as related to this situation if it isnt fuel or ignition related? Also would you recommend a 6 or 8 in hydralic plate ,that is my next purchase.

[RUSTY63]

If you changed the prop and it still does it I would think it would not be prop slip.

I don't have info on the Rangers as far as jack plate size, check with the guys on the Ranger boards.