Exploder SX

Mars

Mars

New member
Joined
Oct 12, 2005
Messages
86
Age
40
Location
Chelmsford, ON
Well, as of today, with 12 000 miles showing, I blew a piston on the SX.

I was riding with a buddy which had his 670 MXZ, we were cruising along the lake, all of a sudden his MXZ comes to a stop, I circle around, and laugh at his broke down sled. We pop a plug off and find out that it's all full of chunks of aluminum on there. So I bust out the tow rope, and pull him about 1 mile down the lake (it was slushy, and a mild day, few degrees above freezing anyways.), but the Exciter just didn't make it. Just died on me.

So, 2 machines blown in one day.

I doubt it will be worth sinking more money into my Exciter, A part of me wants to fix it, yet a part of me wants to just part it out...

The "damage" doesn't look bad, It's the mag. side piston that went. This thing was all original, so it was bound to happen. It wasn't running lean, the plugs have a nice dark brown colour to them, but you can see chuncks of alum. on that mag. side plug... I will tear into it tomorrow.

Now the SX has special cylinders, with Nikasil, and different pistons, I am sure yamaha will want a good 1000-1500 for parts only. (gaskets, pistons, rings...ect) So, I dunno, I guess I will make sure I am sitting down when calling the dealer for a quote. heh

:o| :o|

If anyone has some rebuild tips for the Exciters, I am all ears, I am told to stay away from Wisecos for the SX?...

Thanks.
 
Last edited:
The cylinder can be replated, but it may not even need to be. If there are no grooves and it has aluminum stuck to the wall, it can be removed with acid. And if you are trying to fix it as cheaply as possible, the other cylinder can be left alone.
 
Sorry to hear about your motor man.
Great sled. I had one before I bought the srx.
How is the rest of the sled?
Are you going to part it or sell it outright maybe?
Got a bud that is looking for a parts sled.

Maybe a little karma was workin there when you had a chuckle about your buds sled.
Just something to think about.
 
just buy mine for 500 bucks lol

now it goes pretty good but only after 5000 rpm

frig those sled are pretty fast so hope you fix it!
:bling:
 
Well, I opened it up, and here's the deal.

MAG side :

One piece of the piston is gone on the top. A piece of ring blew into the top end and scored the cylinders pretty bad in 2 places.

Clutch Side :

Cylinder has quite a bit of scoring in it. And a piece of piston is also gone. (just a piece between the rings blew right out the exhaust). This cylinder still had good compression I think. Just that piece was missing.

What would cause that part of the piston to break off like that. The same thing happened to both sides... Just a chunck between both rings was blown out...?

So, now, to get them re-nicasiled ould be around 300 each. Which is nuts cause the sled isn't really worth it.

It didn't lean out, and it didn't run out of coolant. I am not sure what caused this to happen...

I will look for a 600, 500, or an older 570 iron bore cylinders... A nice 600 reed inducted top end would be pretty cool to find...

The pistons have good wash on them, and it didn't lean out I am sure. The sled was always down on power though, and I had no idea why..?

Oh well, hopefully I can find some parts and get back on the trail.
 
I bet it was just age. Its always cool to be able to get a ton of miles on your stock/never opened motor but, sometimes it just ends up worse in the end. Replacing the rings after X amount of miles might have saved the cylinders ...then again it could have ran another 6000 miles without a problem.

Everyone has their own view on replacing rings before they go bad....sometimes its just luck.
 
Your buddies 670 also melted down, have you drained your fuel tanks?
I have a machine that I road for 10+ years and never touched the jetting. One day it started to ping and melted a piston. I never did find the reason. Nothing in the carb, no leaking crank seals,nothing in the fuel. Replaced one piston and rerung the other side and have been using it for a guess sled for 5 years now without a hitch. Go figure???????????
 
rruser said:
I bet it was just age. Its always cool to be able to get a ton of miles on your stock/never opened motor but, sometimes it just ends up worse in the end. Replacing the rings after X amount of miles might have saved the cylinders ...then again it could have ran another 6000 miles without a problem.

Everyone has their own view on replacing rings before they go bad....sometimes its just luck.
Click to expand...

I agree a gasket set and rings are inexspensive !
 
For the future...

Nicasil cylinders.

If I wanted to replace the piston and rings, would I need a quick hone job? or do you not hone Nicasil? I wouldn't mind putting in new pistions every 2 years at all. Specially if I get it done in the warm months...

Found a 2000 VMAX 600 I may pick up... Would be good information to know.
 
to hone nickasil, you need to use a ball hone and the appropriate honing oil. I think it just scratches them enough to aid in ring seating.
 
Well, I got the thing running. Used some 88 cylinders, and kept the flatslides, as well as the PSI single pipe.

It has alot more on the bottom end than it did before... at 5000 rpm, when you puch it, it will loft the skis and make an awsome whine, sounds excellent.

The only thing now is that I wonder what RPM I should shoot for, I am thinking the 88 cylinders will like 7200, but the SX digital ignition, and PSI pipe want more RPM.

It's just under 8000 now...
 
You must log in or register to reply here.


Back
Top