Thread: Motor change

my Father-in-law has an 18ft Express with a 115 yamaha 4-stroke, maybe a little lighter than your Bumble-Bee, it will run 50-52 WOT and is VERY good on gas, probably as good or better than my 90 Optimax

I would go with the 150 Opti. It will double your fuel mileage and run the same or better on top end. Dropping down to a 115 i would think would have you always running full throttle just to maintain speeds you are used to and i dont care what type or size motor it is if ya run it wide open it will use the fuel. My 225 Opti gets great fuel mileage until i get in a hurry and run her hard then i might as well have an EFI motor cuase she will eat the fuel.

I probably would stay with a Merc. to keep from changing controls. I think the 115 will run in the mid to high 40's range WOT but should cruise in the mid to high 30's and save you a bunch of fuel cost with the V-4. The 150 Opti will do about the same as you have now with 30% better fuel economy. The Opti's are easy on fuel, and the 150 will cruise your rig easily, but you still have to feed a V-6 over a V-4. It all depends on how fast you REALLY want to go. Overall, I agree with Hogster on this one, but if speed isn't as important as fuel economy, I wouldn't hesitate to run the 115. The 115 will push a 17 1/2' glass boat just fine.

Would adding a jackplate (and you may already have one) make it easier to get on plane and keep it there with less fuel while keeping your same setup? If so, that might be the cheapest way to go. I used to have an old Hydrasport and I added fins to the back. Cost next to nothing and popped it right out of the hole using a 1978 115 Johnson.

Y'all are confirming what I had in mind. I already have a jackplate and fin on the decavitation plate, and the fuel economy is better when I behave, I guess I just need to do it more often. The prop is pretty tall so it does a slow but tolerable hole shot. I'm thinking that the 115 Yammy would carry about as much weight as my current motor, so no advantage there, but I know they run cheap. Thanks for the input everyone.

Hey Skeet,

I've got a 85 Merc Black Max 150 and she talks to me all the time. She sits in the drive crying (loudly) FEED ME! FFEEEEDD MMEEEEEE!! I can burn 6 gal very quickly at WOT, probably less than 1mpg it seems. At 4K, I'm around 45mph and my fuel consumption triples easily. I think my prop's a 23* and WOT in the summer is 5.2K and 5.5K in cold water. I have good hole shot and when traveling any distance I try cruising 4K, but always 'drop the hammer' a bit on a run. My buddies 225 Opti goes faster and gets far better mpg. I'll eat him in a 1/4 mile, but that's it. Do a little math, the costs to repower can't be recouped for at least 5yrs or more and you'll probably be in a different boat by then anyway. Just saying