2005 2stroke 70 HP

[Hank Austin]

Well people I feel like a babe in the woods here. I am purchasing a new G3 1860 SC boat with a Yamaha 70HP 2 stroke motor. I have never owned such a boat before plus I am new to the whole idea of the oil injection!

Is the oil injection reliable and what benifit does it offer over me pre mixing my owne fuel?

I ordered a 70 hp rather than the 60 because the weight was the same so the weight to power ratio was better. Will the boat be under powered?

All I have run before is small tiller handled out boards, I always put an anti gumming additive and the fuel system stayed very clean. Will such additives work in these larger motors?

As more questions come to me I will keep asking them. Being in the chemical plant business I have learned that the only stupid questions are the ones un-asked! Any general guidance on the nurture and maint of these motors will be greatly apreciated!

Hank

[Ken]

Hank,
The oil injection is more efficient than the pre-mix because it varies the ratio of oil/gas depending on the rpm and load. At idle, the motor only needs about 100/1 gas/oil and at full load about 50/1. When you pre-mix, you have to go with 50/1 to take care of full load, but that is too much at idle, and hence, a lot of fouled plugs if you run at idle or low rpm a lot.
Tho oil injection pumps are a lot more reliable than when first introduced.
As far as enough power, depends on the weight of the boat. My Pathfinder 1806 weighs approx 1100 pounds and I have a 115 Yammie on it. Could have gone with a 90, but the 115 does give me better performance. As long as you can get up on plane fast enough and top end is fast enough for you, then a 70 is ok.
I would not add any additives during break-in. Just follow break-in procedure per the owners manual. Then you can run something like Yamaha RingFree in the gas to keep carbon buildup at bay. (I use a product called Seafoam - just as effective and less costly).
Run your motor at least every two weeks in the off season - preferably every week. If you have to store your motor, follow the directions in your manual. The hardest thing you can do is just let the outboard sit for months at a time. The fuel evaporates and gums up the carbs/injectors/pumps,etc.
Good luck,
Ken K

[Hank Austin]

Thanks for the reply and info.

Another question, this motor will have an alluminum prop, what are the dvantages to buying with a black steel or ss steel prop? I was going to get an extra aluminum prop but if warranted i am not shy of buying a steel one and putting the aluminum aside as back up.

Hank

[Ken]

Hank,
Most boat owners eventually wind up with stainless steel props because of their durability.
The aluminum props are relatively fragile - hitting a small limb in the water will bend the blades (been there-done that).
Aluminum also will flex under heavy load, effectively changing the pitch.
"Black" stainless steel and polished stainless steel are made of the same material.
Make sure your dealer is going to work with you on prop selection. You want your outboard to be mid-range (5000) rpm at max throttle and trimmed out. Check your owners manual for max rpm range. Most dealers understand that if the prop they provide you with is not right, then they will provide another at no extra charge.
Good luck,
Ken K

[Hank Austin]

Thanks for your info Mr. Ken. It checks with what my dealer is telling me and what I suspected on my owne. So I ordered the upgrade to SS and am sure that was the right thing to do.

Hank