Super Jet Need some help with a 61x SN

[SVTPete83]

Hello all..I am new here but having been using this site for info for years. I raced my SN back in the early 2000 in limited class and my 61x has seen some miles. It was last rebuilt in 2000 with a bore and one size up pro x pistons. It was a bolt on ski with dual carbs using an r and d intake and stock 44 mikunis with a factory b pipe. The ski has been dead reliable for years and still cranks 170 psi in each cylinder. I have ridden it about 60-100 hours a year until last year when it started running like crap. I rebuilt the carbs, assembled everything and when I took it to the lake for tuning it was deiseling bad. I had an air leak. Took it apart this morn and got saw this..

As you can see the corner of my case intake there is material missing... So my question to you all is what should I do? If I have to replace the lower cases should I do a full rebuild. I dont want to blow a whole bunch of money on a ski that has been raced and beat on pretty hard over the years, but if I did rebuild it I feel I SHOULD make it faster. On a side not I am decent and mechanical stuff but have never pulled a motor before? How tough is it? I have no port work or anything on this ski as it was illegal to do so in limited class? What do you all recommend?

 

[BruceSki]

I have a set of 61x stock cases that are mint. Comes with all the hardware for it also. 50 shipped.

the best thing would be for you to go through that motor, especially if it has a lot of hours on it. Inspect the crank and replace the crank seals. Also inspect the clearances on the pistons and rings.

 

[Dustin Mustangs]

Pulling a motor and tearing it down is easy. Get another set of cases, as posted above, they are cheap. If you want more power I would recommend a simple port job. You are looking at about 350 for that plus another 300 if you need a bore and new pistons (I would bet you do). Of course you should inspect the crank to but chances are it is fine. Assembly is also easy, there is a thread here that covers it in detail and another thread with a link to the service manual.

YOU CAN DOOOOOOO ITTTTTT!

 

[SVTPete83]

Well I am going to give it a shot...I might take you up on those cases. Gonna do one step at a time. Motor pull first. Thanks for the encouragement..I will keep you all posted on the pregress

 

[SVTPete83]

Ok..kinda stuck...Got everything out of the ski and am working on tearing down the motor. I opened the flywheel cover and things are looking great. No water, just grease on everything. Stator and flywheel look perfect. I grab some 8mm bolts and my pulley puller to remove the flywheel and the thing wont budge. It is not even thinking about moving. Is there anything special I have to do to get this thing off the stator?

 

[BruceSki]

you should hit the flywheel with a dead blow hammer after you put some torque on the center bolt of the puller.

Or use an impact gun on the center bolt if you have one and it will pop right off.

 

[eeerieski]

I tap the center stud of the balancer puller with a normal hammer. I leave the flywheel bolt in but unscrewed 1/8" stick a 17mm open end wrench on the bolt head then crank on the center stud of the puller, I did this to apply as much pulling force as I could then hit the center stud lightly then harder and harder till it popped free. Leaving the bolt in will keep the flywheel from flying across the room as many others have had done.

On a side note, I got my top end bored and honed for under $100 with another $70 for rings and pistons. A port cleanup job would help a bunch and you can do it yourself. Look up sport port, it is a template for you to port the exhaust on your own. You would need fluted long shaft carbide porting dies to do a good job. But then again most of the guys will say have a pro do it, why have a pro do it when I can learn how to do it on my own. I enjoy wrenching on them.

 

[SVTPete83]

Thanks for the tip guys...I will give it a shot tomorrow morn and let you know how it goes. As for the porting, I was already reading up on it a bit today and might give it a shot. It sounds like fun and if I am going to all this trouble I might as well try to make it faster to keep up with my sxr!

 

[MileHighJSC]

So your saying you have over 1000 hours on your crank? 95-2010 60 to 100 hours per season? you may look at investing in a new crankshaft. You can spend alot of time rebuilding your motor only to have a rod bearing destroy your cases and ported cylinder, pistons, every piece of your sweet rebuild. I've seen it so many times, I don't recommend doing that much work over a crank with alot of hours on it. Even if all the bearings check out, Crankshaft only last so long. Most of the time You are only building a time bomb. JMO. Hate to see you throw good time and money away.

 

[SVTPete83]

Damn it! I was just logging in to tell you all I got the whole thing apart..Pistons were scored badly. Crank looks perfect and I was pumped about that until I read miles post lol! There is only very little side to side play in the rods and its spinning smooth. No discoleration either. Damn...I will prob order up a new crank just to be safe. Quick question...How do you tell what size pistons to order? I know I have had this cylynder bored over once. Is there a way I can measure it? A tool I need to buy perhaps? Also, can any ol machine shop bore it out, do I need to bore it? I just wanna do it right!

 

[BruceSki]

You need to order the pistons before you take it to the machine shop. Measure it with a caliper and figure out how much bigger you need to go. Then order the pistons and give them to the machinist when he bores it.

Certain piston companies require a certain clearance between the piston and wall. They require the piston to determine this measurement.

 

[SVTPete83]

Cool..ty for the tip. I need to buy a caliper then...Sorry I am new to this engine building stuff... More questions to come!!! Thanks for the help everyone