Just picked up my 1st Superjet... well two actually!

[Schmidty721]

As the title states I just picked up two SN's with a trailer and work stand. Besides a 3 week period this spring owning a js 550, These are my first skies. I drove just under 1500 miles round trip to get them, but I think it was well worth it.

Both are 1990's. I bought them from the second owner who used them very little. All the info I have as far as mods go are from the original owner/builder's emails with the gentleman I bought them from.

The black one has a 61x in it with the following mods:
Porting ? (unsure if this one was ported or not)
Riva red pipe
Skat-track impeller
Worx intake grate
AC racing aluminum handlepole
Greater Yamaha head with interchangeable domes (180 psi)
ProX forged pistons
Ocean pro intake
MSD ignition
Jet-armor trim
Arco starter
New Yamaha start/stop switch assembly

Blue one has the stock 650 engine with following mods:
Ported... (still trying to find out what the porting was geared for)
Riva red pipe
Riva toploader intake grate
Skat-trak impeller
MSD ignition
New Yamaha start/stop switch assembly

Both skies need a little work. The 701 started and ran good (out of the water), however it barely turns over with the plugs in. It has an Arco starter in it and turns over fine with the plugs out. I know the battery was fresh because it turns the 650 over just fine and we had a jump pack hooked up as well. Does this sound like a weak starter to you guys? I've read that the Arco's are rebuildable, is this true? If I need to replace, is a clean used OEM starter a good option or do I need something aftermarket due to the high compression?

The blue ski would not start. Previous owner said it ran when it was winterized last fall and he did not attempt to start until he decided to sell this summer. It fires but just won't start. It almost sounds like it's firing at the wrong time. It has a primer kit so I know some fuel is getting there. Can I get to the jets without pulling the carb and worring about gaskets? Any other ideas of the top of your heads?

I will update you as I make progress. I'm sure I'll be asking many questions as I trouble shoot these skies.

PS. I'm already working on getting rid of the purple!

 

[Matt_E]

Aftermarket starters can be a crap-shoot. You can remove it and try to spin the starter by hand. If it grinds or you feel much resistance to turning, replace it. Just my opinion, but a clean used OEM starter is better than a new aftermarket starter.
You could try getting a shop to rebuild it for you. Don't do it yourself unless you know what you're doing, otherwise you'll be wasting money and time.

Second: What do you mean, it "fires but won't start"? Does it turn over when you push the start button, but won't catch on and run on its own? Or do you mean the plugs show spark?
If the plugs have spark, try pouring some fuel down the carb. If it still won't fire, or misfires, the timing may be off because the flywheel key sheared. This is a simple fix, but be sure you know what's wrong before you start wrenching.

You cannot reasonably get to the jets without pulling the carburetor. The gasket costs maybe $10, and often, the old one can be reused. Again, try starting by pouring some fuel down the carb. If that does not work, your carburetor is likely just fine.

 

[Matt_E]

Btw,how much did you pay?

 

[jetkid]

I would also check the copmression once you can get the skis to turn over.

 

[Schmidty721]

quote:
Second: What do you mean, it "fires but won't start"? Does it turn over when you push the start button, but won't catch on and run on its own? Or do you mean the plugs show spark?
If the plugs have spark, try pouring some fuel down the carb. If it still won't fire, or misfires, the timing may be off because the flywheel key sheared. This is a simple fix, but be sure you know what's wrong before you start wrenching.


the 650 turns over just fine. It usually fires once or twice and then the starter disengages. The firing sounds harsh and thats why i was wondering if the timing could be off, but everyone once in a while it will fire smoothly and "run" for a half second or so which would indicate a fuel problem (only burning fuel from prime). I will try dumping some gas down the carb tomorrow and see where that gets me.

 

[Schmidty721]

I would also check the copmression once you can get the skis to turn over.

Compression was checked.

701 has 167ish on both cylinders. This was checked with a warm engine due to the forged pistons.

650 has just shy of 130 in both holes. An email from the original owner said that the exhaust port was 'raised" when it was ported and therefore some of the compressions was lost.

 

[Chompot]

I didnt notice the skis, but I did see a pretty awesome duck boat....

 

[Schmidty721]

Update:

I pulled the carb off and disassembled it. Everything looked good. Nothing was plugged. I believe it had a rebuild kit installed two seasons ago. The gasket at the base of the carb was hard and I will need to order new ones.

Jetting was 120, 125. High speed adjuster was out 1 3/4+, low speed was at 1 1/2. How do you determine which spring is in there. Are they denoted by different colors, length or something, or do need to physicaly test them via inches of pressure before it releases?

I also drained all of the old fuel out and put some fresh fuel in. The ski is still behaving the same so I think it is safe to rule out a fuel issue (or at least the carb).

I just pulled the ebox apart. Everything looked pretty clean in there. It does have an MSD box in it. I'm assuming this is the enhancer I see you guys talk about? There is a slight corrision build up around the mouting bolts for the enhancer (see pic). There were two wires cut and taped off; a black one and a pink one. Is this normal for the enhancer install? I have included pics of the ebox. How do I test these components or is my issue elsewhere?

 

[tipafew]

I haven't had the best luck with aftermarket starters. Try a OEM one.

On the 650.....The spark appears good???? It won't fire even with a little gas down the carb?
Like Matt said, it could be that your timing key sheared off. It could also be a bunch of other things though.........

 

[tipafew]

When you put that e box back together you will want to coat that rubber gasket with some wheel bearing grease to help it seal.

 

[SQUARE JOEL!!!]

Update:

I pulled the carb off and disassembled it. Everything looked good. Nothing was plugged. I believe it had a rebuild kit installed two seasons ago. The gasket at the base of the carb was hard and I will need to order new ones.

Jetting was 120, 125. High speed adjuster was out 1 3/4+, low speed was at 1 1/2. How do you determine which spring is in there. Are they denoted by different colors, length or something, or do need to physicaly test them via inches of pressure before it releases?

I also drained all of the old fuel out and put some fresh fuel in. The ski is still behaving the same so I think it is safe to rule out a fuel issue (or at least the carb).

I just pulled the ebox apart. Everything looked pretty clean in there. It does have an MSD box in it. I'm assuming this is the enhancer I see you guys talk about? There is a slight corrision build up around the mouting bolts for the enhancer (see pic). There were two wires cut and taped off; a black one and a pink one. Is this normal for the enhancer install? I have included pics of the ebox. How do I test these components or is my issue elsewhere?

Look up jetmaniac for all your gasket needs. Yes, the MSD is the enhancer. Treat the bolt corrosion how you wish but I wouldn't fool with them. The pink and black wires are for a stock temperature sensor that mounts in the head, removal is very common!

Have you grounded the plugs and checked spark?

BTW, I wouldn't leave your intake tract open like that too long. Definitely wouldn't disassemble anything over it being open...screen in place or not.

 

[motosicko]

Springs are rated by color.
Gold=115 Grams, Dull Silver=95 Grams, Black= 80 Grams, Shiny Silver=65 Grams.
Here's a tuning guide. http://www.mikuni.com/pdf/sbn_manual.pdf

 

[Schmidty721]

Thanks for the responses guys. I'm really trying to get this figured out ASAP so i can get them in the water before it gets too cold.

Sparks appears to be strong. The ski does fire but its usually only once and kicks the starter out. It almost sounds like its firing too early and stopping the cranking rotation. I think I will check the timing key next. Can an RTV sealant be used on the cover or will this require a new gasket as well.

 

[Big Kahuna]

Thanks for the responses guys. I'm really trying to get this figured out ASAP so i can get them in the water before it gets too cold.

Sparks appears to be strong. The ski does fire but its usually only once and kicks the starter out. It almost sounds like its firing too early and stopping the cranking rotation. I think I will check the timing key next. Can an RTV sealant be used on the cover or will this require a new gasket as well.

Sounds like you have a bad battery or cables, like it is not getting enough current or your starter is worn out.

 

[Schmidty721]

Well I pulled the flywheel off and indeed the timing key was sheared off. Thanks for the help guys, that would have been one of the last places I would have checked. Hopefully this takes care of the issue.

 

[Fro Diesel]

Thanks for the responses guys. I'm really trying to get this figured out ASAP so i can get them in the water before it gets too cold.

Sparks appears to be strong. The ski does fire but its usually only once and kicks the starter out. It almost sounds like its firing too early and stopping the cranking rotation. I think I will check the timing key next. Can an RTV sealant be used on the cover or will this require a new gasket as well.

had the flywheel out could be a sheered woodruff key

edit good !!!!! that should be it. now time 2 ride!!

 

[Matt_E]

Do yourself a favor and buy an OEM flywheel key. Don't try to mix & match from the hardware store (unless it is an EXACT fit)

 

[SQUARE JOEL!!!]

Do yourself a favor and buy an OEM flywheel key. Don't try to mix & match from the hardware store (unless it is an EXACT fit)

x a billion!!!!!

 

[superramjet]

did you get those out of kansas, they look familar?

 

[Schmidty721]

I will be ordering OEM keys tomorrow along with some gaskets.

Yes, the skies did come out of Kansas. Do you know the previous owner?