‘91 Superjet 6m6 to 62T/61x swap

[Yohan17]

Starting a new project on my ‘91 square nose to swap my 650 with a 701 and I’m hoping to get out on the water by the 4th of July (or sooner). The 701 has a 62T case with a 61X top end. Looking for some advice and recommendations on the following:

• Should I keep my 6m6 flywheel, electronics, and stator, or replace with 62T components?
• Is the exhaust manifold a direct swap? Can I use my original 6m6 muffler?
• Does anyone have an intake manifold and/or a dual carb setup that they’re looking to part with? Are 38mm or 44mm dual carbs recommended?
• The stamp on the case is “65R”. Is this a 701 or a 780? How will this alter my build?
• I’m looking to upgrade to a Factory B and MSD enhancer in the future but want to focus on getting the ski running first.
• Open to any and all recommendations as this is my first engine swap.

I’m located in White Bear Lake, MN. Thanks in advance!

 

[Kohldanielzimmer]

Pretty sure the rev limiter is lower on the 6m6 (6500 rpm)so if you already have all the 62t electronics (7100 rpm) then use those Or just modify your 6m6 cdi to remove rev limiter.

The 6m6 exhaust manifold may bolt on but the port alignment will be off as I recall.

65R cases are 760. Should have dual pulse fittings but crank cases are otherwise the same as “62T”

What head is on that 65R case with 61x cylinder?

 

[Yohan17]

@Kohldanielzimmer - I appreciate the info. I may end up modifying my current 6m6 CDI. To answer your question - I have a 64U head, please see the attached photo.

I am hoping to pick up a 701 exhaust manifold locally, but I have a few questions about the 61x vs. 62T components. Please let me know if this is the correct thinking:

62T case:
• 6m6/61x flywheel is recommended for a lighter bottom end. All electronics from my 6m6 may be used. Would a 61x CDI have a higher Rev limit than the 6m6 CDI?
• Reeds/intake manifold must be compatible with the 62T, not 6m6/61x.
• Yes - this has dual pulse fittings. Please see 2nd photo.
• Is this a 760 or 701?

6m6/61x:
• Exhaust manifold and muffler must be compatible with the 61x, not 6m6 or 62T?

 

[bored&stroked]

61x cylinder is 701. This is basically a standard 96+ superjet motor besides the extra pulse line. There isn't much of a difference between 6m6/61x/62t setups besides the rev limit. One isn't much lighter weight then the other.

 

[800750]

With out taking the head off it looks like someone put 701x cylinders on a set of t cases that came from a 760. Run a 62t cdi, has a better curve.

 

[Yohan17]

With out taking the head off it looks like someone put 701x cylinders on a set of t cases that came from a 760. Run a 62t cdi, has a better curve.

That's exactly what happened. Currently, all I have is a 6m6 flywheel, CDI and stator. Would you say it's worth it to track down the parts to do the 62T conversion/upgrade? I have read a few forums with people having issues with their 62T stator/flywheel setup, mainly intermittent spark and charging issues. If there is something local in MN from a trustworthy source, I would definitely pick the items up. I have a pretty tight budget until I can sell my 6m6 components

 

[WFO Speedracer]

yep that 6m6 CDI is going to have too low of a rev limit, it could work if you disable the rev limiter.

 

[800750]

I would just stick with the 650 stator and flywheel and find a cheap t cdi

 

[Yohan17]

I'm going pick up a 62T CDI and keep the 6m6/61x stator and flywheel from the 650. I found a trustworthy source selling a 62T OEM CDI for $75, I also found a Pro-Tec 62T CDI with an adjustable rev limiter for $60 (he said it worked fine before he pulled the engine). Open to recommendations on the OEM vs. Pro-Tec.

I am having a lot of trouble finding a 38mm Mikuni dual carb assembly under $200 (in decent condition). I have a rebuilt SBN 44 single carb from my 650 engine, and I'm wondering if it would be worth it to buy another single carb SBN 44 to convert to a dual carb setup. Has anyone had experience converting a single to a dual setup?

Hoping someone reading this may have a clean dual carb assembly laying around that I could purchase.

 

[WFO Speedracer]

Cconverting single carbs into duals is a big bag of snakes you probably don't want to open , to run a single 44 on that engine you need a special intake manifold, read expensive, put up a WTB post and see if maybe someone here can help you out on the 38's

 

[Yohan17]

Cconverting single carbs into duals is a big bag of snakes you probably don't want to open , to run a single 44 on that engine you need a special intake manifold, read expensive, put up a WTB post and see if maybe someone here can help you out on the 38's

I’m currently talking with someone 20 mins away from me with a Blowsion single carb adapter for a 48mm. He wants $50 for it, but I want to do some more research to see if my 44mm SBN will fit. Might just grab it to try it out.

 

[spinyard]

IMO get some stock 38's and rebuild them with OEM Mikuni kits, new needle and seats...

 

[WFO Speedracer]

I’m currently talking with someone 20 mins away from me with a Blowsion single carb adapter for a 48mm. He wants $50 for it, but I want to do some more research to see if my 44mm SBN will fit. Might just grab it to try it out.View attachment 437965

I would grab it for $50 regardless, you can always sell it later if you don't like the setup

 

[Yohan17]

IMO get some stock 38's and rebuild them with OEM Mikuni kits, new needle and seats...

Correct me if I'm wrong. The 38s for the 701 62T have a 3-bolt connection, and the 760 62t (what I have, shown in pic below) has a 4-bolt connection.

- Are dual 44s stock to the 760 62T with the 4 bolt setup?
- Is it possible to replace my intake manifold with a 62T 701 3 bolt base if I come across 38s with the same bolt arrangement, or should I stick with the 760 4-bolt setup?

 

[WFO Speedracer]

both 38 duals and 44 duals are held on by 4 bolts, a 760 engine is not a 62t it is a 64x , I think maybe you are confusing the flame arrestor bolts. on those 38's are three bolt and 44's are four bolts

 

[bored&stroked]

Either run a single 44-46mm carb or run the dual 38's. You don't have enough motor to use dual 44's really. Sure it would work, but not needed.

 

[800750]

@Yohan17 there is a crusty xl700 on marketplace for 500, see if he will take less. Then you can get carbs electric and sell off the rest and break even or make $100. And run 38s for this application and what you have going on it will be the best option hands down

 

[WFO Speedracer]

Troy boy over on PWC posted this this morning, you would need an intake (unless that is a 44 carb intake you have there) (I can't tell from the pics ) and you would have to rebuild those carbs but it is an option.

1998 Yamaha XL 760 parts carbs F/S FOR PARTS ONLY 44'S - PWCToday

These carbs are for parts, had water in them, selling for parts..all screws turn freely and they come with the speed plate $50 shipped US Trying to load pics now dual 44's

www.pwctoday.com

 

[subnsxr]

you should change the rear exit exhaust tube, Rad Dudes sells the whole kit and get a RN waterbox. Although the season has started, I would make it a winter project

 

[JC-SuperJet]

@MTRHEAD proved that the smaller Stock SN Exhaust does not have to be upsized, with his 60 mph SN and original Stock Exhaust...