Clearance Spec Between Couplers

[TrueBlue]

I am finally dropping a 61x motor with the wetjet "reed stuffer" intake and 46 mm carb into my 90 Superjet and seem to have a 1/4" gap all the way around between the drive couplers. I am wondering what the spec is on this. I should have measured it with the stock 6m6, but in my haist forgot to. Like I mentioned, it is even all the way around so I know the shims are correct, but the gap bugs me. Please help, as I would like to be riding this weekend, rain or shine.

 

[jmeadlock]

Others may disagree but I think .25in is A-OK.

 

[augustaf]

The Yamaha shop manual shows 2-4mm clearance. .25" tends to tilt the rubber a bit but should still work. If you land the ski on it's tail while jumping, the engine moves back because the mounts can flex quite a bit. The mid shaft is sometimes even driven backwards.

 

[butti]

when run with too much clearance the plastic cap in the middle of the midshaft coupler can work its way out of there getting water in the midshaft,grease all over the place and possibly causing cavitation.

ask me how i know:clown:

 

[TrueBlue]

I will move it back some then. I had a comfortable gap when lining up the motor, but when I zipped down the motor mount bolts, the motor moved forward. I will get the wife to hold the motor back while I tighten the bolts; she loves helping me in the garage (yeah right).

 

[Mark44]

I run about a 1/8".

FYI
Also on the reed stuffers, I had them in my ported 701 with 44's and they made the carbs nearly impossible to tune. After I removed them the carbs tuned in seconds.

Mark44

 

[TrueBlue]

I just finished dropping in the motor and it fired right up multiple times and idled great with minimum adjustment. Seems to have better throttle response too. I will see what happens when I get a load on it this weekend, but it seems to be good right now. I hope the built in reed stuffers perform better for me than yours did. With only one carb, tuning should be a little easier and I just cleaned it and rebuilt it with OEM mikuni parts so I can eliminate faulty gaskets, diaphram, lodged debris, etc and focus on jets and High/Low air screws.