70hp carbs on a 50hp???

[all duck'd up]

I've seen a lot of guys in my area doing this conversion to there 40hp's and making them scream! well I bought a 1987 pro50 that runs pretty good but I want more speed. I've adjusted the jack-plate and prop to the best settings for my rig and i still want more.

I'm just curious as to why I've only heard of people doing this to 40s? my thoughts would be that a 50hp would be able to handle the strain a little better, being that it is already a higher hp.

I've got a lead on a set of 70 carbs at a local shop here and i would like any info before i put my money into this upgrade. Thanks!!!

 

[99yam40]

Re: 70hp carbs on a 50hp???

Have you even looked at the part numbers of the 40, 50 ,& 70

Nothing is even close between the 50 and 70

40 and 50 there is so you can turn your 50 into a 40 or you can go by you a bigger motor

 

[all duck'd up]

Re: 70hp carbs on a 50hp???

the 50 i bought was a deal i couldnt pass up. $1200 and it had a 3 month old rebuild; so i had to have it. and the place with the carbs are only asking $250. so I'm just looking at my options.

 

[mphelle8vld]

Re: 70hp carbs on a 50hp???

The 40 and 50 are the same motor with the exception of carbs and exhaust, here's a link to an old thread:http://forums.iboats.com/yamaha-suz...a-tuner-box-questions-286767.html#post1918620

Unless you're just competing with locals for the fastest 42.6 c.i.d. motor around, I would save your money for a bigger motor.

 

[all duck'd up]

Re: 70hp carbs on a 50hp???

that has some good points but the 5 mph has to be off. these guys are passing me like I'm tied on to the dock still lol. My boat at wot down river is 41-42mph gpsed. They have to be hitting high 50s mid 60s

and yes ive started browsing for a bigger motor

 

[mphelle8vld]

Re: 70hp carbs on a 50hp???

Every setup is different but your speed sounds right. My stock 88 pro50 with a 10x15 prop pushed my 1648 jon to just over 40mph at 5500rpm.

 

[all duck'd up]

Re: 70hp carbs on a 50hp???

thats whats funny about mine; its on a 1648 alumacraft also and i lost speed with my 15p chopper prop (topped out at 38) but with my cheap laser 13p it gets up to 41-42

are there any add-on's that i can put on it to get more speed if the carb's are out of the picture???

 

[mphelle8vld]

Re: 70hp carbs on a 50hp???

I just don't think there's a good, reliable substitute for cubic inches if your main purpose is hunting or fishing. I'm sure someone could bore it to the max oversize, port it, shave the head, stuff the crankcase, hang bigger carbs, add a tuned exhaust, and play with blended fuels, but like the old post, if I had to pull something 8 times to get it started and then spend my day watching a temp gauge, I would throw it over the side. This site might be interesting for you: Scream And Fly Powerboat and High Performance Powerboating Discussion Forums
Post your rpm for both props, if you don't have a meter there's a tiny tach knockoff on eb*y for around $12.