71 125 johnson engine bucking at wot

"I have a 71 125hp electric sh

"I have a 71 125hp electric shift ob. I have checked compression and its 120 on all four cyl. I put new plugs in and replaced both carbs. When I get to wot, it is okay for about 2 minutes, then it starts bucking or cutting out like a major miss. So much so as to cause the engine head to jerk. I have been dealing with this since last year. I can't seem to find a decent outboard mechanic in this town (Grass Valley,Ca.) If I run it at about half the rpms it runs fine. I don't have a tach and I hear it takes a special kind. Today I took the fuel pump off and put another one on from a 73 135hp I blew a piston in. I knew that pump was good before frying the piston. my first question is this. Will a bad fuel pump cause my motor to buck like that? Second when I took the old pump off I could blow through the black plastic fitting on the pump its self and I couldn't blow through the black one on the pump I installed. What do you all think? Sorry this is sooo long. I'm taking it to Bullards Bar this weekend. I figure if I get lucky the pump was the problem. If not I think I will just do my best to blow the sob up!!!!!!!
Thanks Luana"

"Does it feel like you're

"Does it feel like you're hitting a underwater object? If so...........

(Jumping Out Of Gear - Manual Type)
(J. Reeves)

This pertains to lower units on all OMC manual shift outboard engines, or any OMC engine with lower units defined as a Shift Assist or a Hydro Electric Shift unit which incorporates a "Shifter Clutch Dog".

Within the lower unit, splined to the prop shaft is what is most often referred to as a clutch dog, hereafter simply called dog. The dog has at least two lobes protruding from it on both ends, facing both forward and reverse gear. The forward and reverse gears also have lobes built into them near their center area. When the engine is running, in neutral, the gears are spinning constantly via the driveshaft being connected directly to the powerhead crankshaft, but the propeller does not turn due to the fact that the dog is centered between the two gears, and the dog lobes are not touching either of the gear lobes.

When the unit is put into either gear, shift linkages force the dog (and its lobes of course) to engage the lobes of the gear. The lobes of the spinning gear grab the lobes of the dog, and since the dog is splined to the prop shaft, the propeller turns.

The lobes of the dog and gears are precisely machined, most with right angled edges that could be installed in either direction, and some with angles slightly varied that must be installed in one direction only (one end only must face the propeller). Dogs that can be installed in one direction only, if reversed, even if the dog and both gears were new.... would jump out of gear almost immediately. Keep in mind that the lobes are precisely machined with sharp angles!

Due to improper adjustment or worn shift linkages, but usually due to improper slow shifting, those precisely machined sharp edges of the lobes become slightly rounded. Now, with those lobes rounded, as the rpms increase, the pressure of the gear lobes upon the dog lobes increases to a point whereas they are forced apart (jumping out of gear), and due (usually) to the shift cable keeping tension on the engines shift linkages..... the unit is forced back into gear giving one the sensation that the engine has hit something, and the cycle continues.

Some boaters with manual shift engines have the mistaken belief that shifting slowly is taking it easy on all of the shifting components..... Wrong! Shifting slowly allows those precisely machined sharp edges of the dog and gears to click, clank, bang, slam against each other many times before they are finally forced into alignment with each other..... and this is what rounds those edges off! The proper way to shift is to snap the unit into gear as quickly as possible.

Thousands of parts in my remaining stock. Not able to list them all. Let me know what you need and I'll look it up for you. Visit my eBay store at:

http://stores.ebay.com/Evinrude-Johnson-Outboard-Parts-etc?refid=store"

not really sure and sorry for

not really sure and sorry for the extra long email I sent to you Joe. But one more question. I was hooking the evinrude electric shift box yesterday and looked at the carbs. Instead of having the adjustable low speed set up they have four regular screws with a gasket. Three of them were all the way in and one was backed out about
1\4 turn. Are these non adjustable carbs?