61x on 6m6?

SuperjetSteve

Go Big or Go Home
Location
Macomb michigan
Im looking replacing my complete 6m6 with 61x cylinders.I plan on leaving the 6m6 crank case.What kinda power will I be putting out with this set up? and will everything fit right?
 

keefer

T1
Location
Tennessee
I think you will have to machine the cases a little to make clearance for the bigger sleeves on the 61x 701 cylinder. A friend of mine built one of these some years back and he had to do this before it would work. I remember it ran decent but went flat on power on top end due to the small 6m6 intake tract & reeds. You might consider finding some cheap 61x cases and run your crank. Either way you will have to split the cases and replace crank seals.
 
switching to a 61x case will mean getting 61x reeds and manifold. also, the exhaust ports/shapes are different = different ex manifold..
 
Location
dfw
The 6m6 case will not affect power as much as any other part will. 6M6 reeds are only 10% smaller than 61X reeds and the power difference is less than that. You will need to hog out some material to clear the 61X sleeves, everything else will work.
 

jetskiking

Im done sanding!!!
Location
Dallas Georgia
If your gonna spend the money on the topend getting new cylinder,pistons,rings,head and exhuast mani then just spend the extra hundred and get some cases and intake. It will be well worth it. I went from a 81mm bigbore ported 6m6 last winter to a non ported b-piped 61x and it was a big difference. The intake tract is alot smaller on the 6m6 when you look at them side by side. When you put the 61x with larger displacement and alot bigger exhaust port then the 6m6 cases are not gonna flow enough. It will probably have good bottom end snap then fall on its face up top.

I'm pretty sure you need to machine the cases. Mine was a 6m6 that had been resleeved and had thinner sidewalls then a 61x and it had to be machined. So since you would be splitting the cases you might as well just spend the extra money and do it right.
 

john zigler

Vendor Account
Location
wisconsin
have you thought of just changing the complete motor out?

i have a good 61X short block here for sale. you could then just sell your existing motor.

or, take it one step further, i have a good 62T 701 here for sale too.
 
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