What is really "needed"?

jap7t8

jap7t8

Spring Fever...
Location
St. Louis
I'm going down the checklist of what I should probably do to my 650 sj this winter. I'm planning on putting some new gaskets on it. For sure a head gasket, but what else is really "needed". I have no idea if any of them have been replaced in the past. I've only owned the ski for a year. I'm sure some go bad more often than others, so I look to you all for that info. Thanks for any advice!

Jake
 
MADMAT

MADMAT

Location
Ohio
Just check your motor mounts. I don't think I would do to much to a sealed SJ motor that runs great.

Put a prop on it! Pipe?
 
jap7t8

jap7t8

Spring Fever...
Location
St. Louis
If it ain't broke, dont fix it. I like your theory madmat! It would have just been preventative maint. anyway not really knowing what the previous owner has done. It has a prop - 7.4 Skat Trak which I am told is the old style sj 7/14 pitch. No pipe though. I have been told a pipe on a 650 doesnt make as much of a difference as you would think. I have a hard time believing that though...
 
MADMAT

MADMAT

Location
Ohio
Then get some 61x 701 cylinders and a pipe and a 180psi head! And a -3mm 13/16 prop!

That should keep you busy and kill the wallet. 2 birds...one stone..
 
nightrider05

nightrider05

Location
St.Louis Missouri
Nice to see another SJ rider in the StL area!

It all depends on what your goals are here. My buddy was recently in the same situation with his 1990 Superjet...he wanted to go bigger, but didn't want to do it with the 650 platform.

He ended up throwing a 61x 701 motor in there and building from that point. If you look around, you can find an older sitdown yamaha ski(or also a mastercraft..they have 701s in them) with a 701 in it and swap motors around...then sell the 650 for what you gave for the entire spare parts ski. Then from that point, throw a pipe, head and other parts on for a nice power increase.

However if you decide to keep your 650, I see no need in replacing ANY gaskets. Gaskets aren't really a regular maintenance type deal...Only time they need replaced is if you are either having issues(blown head gasket) or if you for some reason pull the motor apart. If your motor has good compression(which it appears it does), then don't worry about it.

Instead make sure you have a good electric bilge pump(one of the best mods you can have on a SJ) and maybe do some other mods such as aftermarket intake grate and ride plate. Also do general maintenance such as greasing your midshaft. Don't forget to winterize of course..
 
jap7t8

jap7t8

Spring Fever...
Location
St. Louis
Thanks to both of you for the advice. You have no idea how many times i've run through the scenarios of doing a conversion or just buying a rn. Unfortunately the finances just wont let it happen at the moment. Might be looking at another season on the sturdy ole' 650. Hey its better than nothing right?
 
nightrider05

nightrider05

Location
St.Louis Missouri
Like I said man..keep an eye out for a 701 donor ski.

I saw two of them up in your area last year for $250 each. They weren't snatched up quick either..both of them sat around for a few weeks.

You could turn around and sell your 650 for around $500 during the spring/summer months.

Have more Brap and also make a few dollars.
 
kevbo

kevbo

Location
dfw
Just check the torque of the head and exhaust manifold bolts. The factory gaskets seal better than any but can crush slightly over time.
 
chriselmore_1

chriselmore_1

high on resin
Location
san jose ca
i have some 6m6 cases that were bored to fit 701 cylinders that i would sell cheap. it would make for a cheap 701 conversion. all you would need to do is get the 701 top end which i have seen as low as 80$
 
jetski9010

jetski9010

Team RTYD
Location
Lancaster PA
you should send you cylinders, head and carb and manifold to group K for the sleeper kit. For $529.00 I think that should be some good bang for your buck.
 
tipafew

tipafew

Location
Grand Rapids, MI
yep, I agree, don't touch that motor unless you plan to build it.
Right now your money is best spent on things like a Worx intake grate, Impros Hooker prop, etc. Those are all things that will still be useful later when you go to a 701.

Otherwise, just save for a transplant when $$$$ permits.
 
jetski9010

jetski9010

Team RTYD
Location
Lancaster PA
jap7t8 said:
Oh the possibilities...

Thanks for the link!
Click to expand...
or you could step up and let Harry bore it out to a 701. I did this build for a friend about a year ago and ran it with a coffman pipe and a 9/17 prop and it hit just as hard as my other friends 701 with home porting and B pipe.
When I was talking to Harry about this 650 build before I did it he was telling me how the yamaha 650 motor has the worst port timing layout for power he has ever seen. So just by getting your 650 ported it should be night and day.
 
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