Super Jet Engine upgrade questions 6m6 -> 61x/61x, 64x/62t

Location
NW PA
I have now a stock 93' 650 6m6 Superjet, I know a guy selling both a 701 61x/61x engine and a 760 64x/62t engine. What exactly would be required to upgrade to either of these engines? I'm specifically referring to the electrical systems, intake manifolds/reeds/cages and the exhaust. I'm leaning towards the 760 engine due to it having the 62t cases which from what I read are better in general. Buying both and mixing and matching aren't for me.

Keep in mind I've never removed or taken apart an engine but have a high degree of mechanical aptitude. My intentions are to go with the engine and carb/intake to have a great base for when I eventually get an aftermarket pipe. I know how to search so plumbing and alignment info is taken care of.
 
Location
NW PA
Let me make it easier to answer questions:
Will my 6m6 exhaust work on a 61x cylinder?
Will my 6m6 exhaust work on a 62t cylinder?
Will my 6m6 exhaust work on a 64x cylinder?
Will my 6m6 intake work on a 61x case?
Will my 6m6 intake work on a 61t case? Oops I meant 62t
Will my 6m6 electronics work with a 61x case?
Will my 6m6 electronics work with a 62t case?
 
Last edited:

Matt_E

steals hub caps from cars
Site Supporter
Location
at peace
Will my 6m6 exhaust work on a 61x cylinder? Yes, but the manifold runners are smaller.
Will my 6m6 exhaust work on a 62t cylinder? See above. Additionally, the 6M6 manifold uses 8mm bolts while the 62T cylinder uses 10mm bolts. Either put inserts into the cylinder or drill out the manifold holes. If you use a 62T head, the head mounting for the exhaust doesn't work.
Will my 6m6 exhaust work on a 64x cylinder? Same issues as 62T cylinder
Will my 6m6 intake work on a 61x case? Absolutely not
Will my 6m6 intake work on a 61t case? Easy answer: No such thing as a 61t case. Right answer: Absolutely not.
Will my 6m6 electronics work with a 61x case? Yes.
Will my 6m6 electronics work with a 62t case? Yes.
 
Location
NW PA
That's what I wanted to know, thanks. It appears I would need at a minimum a new intake regardless of what engine I use. I'm certain I will use a 62T case so I can use a single carb. So it then comes down to the cylinder, 61x has better bottom end but 62t is more promising after a port job. Now that I can make an informed decision, anyone else have input that I didn't specifically ask for related to an engine swap?
 

Matt_E

steals hub caps from cars
Site Supporter
Location
at peace
If you're set on using a single carb, don't waste your money on 62T cases.
You'll get the same performance much cheaper with 61X cases.
I wouldn't say that 62T cylinders are more promising after a port job than 61X cylinders after a port job.
Given what you've said here (single carb, maybe on a budget?), I'd go with the 61X/61X motor.
A single carb intake for T cases alone will set you back $200.
It's free on the X cases.
 
Location
NW PA
I thought the 61x case is intended for dual carbs only, no intake required. While the 62t case can be used with either a bual or single carb intake
X
40-402xf.jpg

T
40-402tf.jpg


What is the 701S engine on the SBT site?
 
Last edited:

Matt_E

steals hub caps from cars
Site Supporter
Location
at peace
61X cases are for single carbs. You can get aftermarket dual carb intakes for it, though.

Your pictures only show the case intakes. Since it's a dual cylinder motor, there are two intake tracts.
But the stock intake manifold is a single.
 
Location
dfw
If your 650 is in good condition then just get a good 701 cylinder and pipe. The 650 case will need a simple clearance cut for the sleeves or find a cheap 61x case/manifold assy. The cylinder and pipe make power not carbs and cases. A 61x or modified CDI will be needed.
 
Location
NW PA
After doing some more research I find now that the stock 61x was intended to have a single carb as Matt_E stated, It just seemed that the case intakes were situated perfectly for dual carbs. The 6m6+61x mod isn't recommended anymore due to the restrictive 6m6 reed opening, besides, better 61x and 62t cases are more available for reasonable prices now. I'd love to stay away from the machine shop for an engine upgrade, taking a visually good engine with good compression and dropping it in is optimal. Either way I will need a new intake setup and will have my 6m6 setup for sale eventually. Thanks for the help guys.
 
Location
dfw
After doing some more research I find now that the stock 61x was intended to have a single carb as Matt_E stated, It just seemed that the case intakes were situated perfectly for dual carbs. The 6m6+61x mod isn't recommended anymore due to the restrictive 6m6 reed opening, besides, better 61x and 62t cases are more available for reasonable prices now. I'd love to stay away from the machine shop for an engine upgrade, taking a visually good engine with good compression and dropping it in is optimal. Either way I will need a new intake setup and will have my 6m6 setup for sale eventually. Thanks for the help guys.

The 6m6 case mod doesnt need special machining, the performance is nearly identical to a 61x case.
 

McDog

Other Administrator
Staff member
Location
South Florida
I have a set of 6m6 cases that are already modded to accept a 701 cylinder. I will let them go for $40 plus actual shipping cost.
 
Location
Pa
61x motor and pipe make power, going from 650 to 701 piped motor is a good start. you can also look for a raider or something along those lines, with a solid motor and simply take the motor then part the extra parts. I went as far as to keep all the stainless bolts out of the last oem exhaust i pulled and have already used 8 bolts on another project. reduction nozzle and cone from the raider make a good CATS trim mod. swapping a complete motor in will do you the least struggle, especially if it is your first time. things line up and you have less things to worry about so if there is an issue later on you know that atleast the motor ran strongly before it leap frogged into your sj. you do not want to keep the 650 CDI as it will restrict your 61x or 62t's potential
 

BruceSki

Formerly Motoman25
Location
Long Island
If your 650 is in good condition then just get a good 701 cylinder and pipe. The 650 case will need a simple clearance cut for the sleeves or find a cheap 61x case/manifold assy. The cylinder and pipe make power not carbs and cases. A 61x or modified CDI will be needed.

Carbs and cases don't make power huh. Guess I wasted my money then. I'll go find a single 28mm. Maybe I can get some more grunt out of my setup.
 
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