701 cylinders in a 650?

im not going to try this until i get all my bugs out but if i was to put in 701 cylinders in my 90 superjet 650 how much low end take off would that help? is it perty considerable or more of a waste of time? also does a dual carb setup help just in top end or does it do any good at low end? just want to jump wakes and someday hit a bf or br, i know im gunna need footholds and a helmet haha thanks
 
Actually, I was thinking of doing the same thing and from my research, it works really well! You do have smaller reeds than the 61X cases, but I've been told by several people that it hits hard.
You will have to have the 6m6 cases bored just a bit to allow the 701 cylinder slip in.

I have enough parts on the shelf, I just need some time to put it all together...
 

Midlake Crisis

Site Supporter
Location
Bakersfield, CA
I had the setup you are contemplating doing (650 cases / 62T 701 Cylinder).
Machining the cases to fit a 61x or 62T 701 cylinder or machining the cylinder to fit the cases works fine, but IMHO it is more cost effective to buy a used crank case/intake/reeds, especially if you are going to continue upgrading. The more mods you do the more you will want good breathing cases. Your old crankshaft will work in any of them.
 

yamanube

This Is The Way
Staff member
Location
Mandalor
Depending on how much you can get the machine work done for it may be cheaper to buy a set of 61x cases than have your 650 cases bored.
 
Location
dfw
A 650 case works very well with a 61x cyl. It just takes a few minutes with a Dremel to make room for the sleeves. Performance wise there is no noticeable difference between a 6m6 and 61x case, which is about the same as stock 38s on a 62T case. 6m6 cases will run slightly richer than a 61x with all else the same.
 

WFO Speedracer

A lifetime ban is like a lifetime warranty !
Location
Alabama
You can do it with a die grinder and a straight carbide bit , I have done them that way before on 701 cylinders on 6m6 cases and on 760 cylinders on 62t cases , you are not removing that much material. Mark it off on the cases with a new 701 base gasket then go slow keep the bit sprayed with WD40 so it doesn't clog up and finish it off with a cartridge roll on the die grinder to smooth everything out.


 
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It's my buddy ski he burnt the rear cylinder on the 650 cylinder. I might just get new pistons and have somebody bore it but I can't find anybody to bore it in my area.
 
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