Starting my top-end rebuild

[CAVPILOT]

Ok...got my ski back and now have time to start tearing into it.
If you remember, the shop wanted $3500 to replace my engine due to a 35psi compression in the aft cylinder. After thorough debating (all of 1 min. ), i've decided to save several thousand $$$ and do this myself.
I'm sure there will be steps where I'm going to be stuck, like how the F*** do you loosen/tighten the bolt UNDER the exhaust manifold??? Mine was slightly loose so I got it off but have no idea how to get to it upon reinstallation to tighten...the tolerance is soooooooo close in relation to the carbs.
Are there any tips or tricks to follow while performing this? From what I understand, a two-stroke top end is very simplistic.

Again, thanks to all you shadetree mechanics out there!!! :grouphug:

:hurray:

 

[CAVPILOT]

Top end pix

Ok all,
got the top end off today and started taking pix. How bad does this look to you? The sleeve on one piston is rusted slightly (from my viewpoint) and the other is fine. The crank is what I'm worried about...the counterweights are rusted. And now, with it tore down, the driveshaft won't spin freely! Does that indicate frozen crank bearings? The pistons don't freely rotate on the wrist pins either. If you look at the rings on the AFT piston you'll notice they are seized to the piston...the other piston rings expanded when I removed the housing.
I'm 99% certain I need a new engine but what about taking it in and having it sandblasted? Anyone have any luck with that in the past?

 

[gkm24]

I'm in the process of doing the same thing although I replaced my crank as it would not rotate freely. If your crank rotates freely and smoothly then I would say it's probably ok. With respect to the pistons, I would get the bores checked at a machine shop and if they are within tolerance get them honed and fit new pistons. The stuck rings are giving you low compression. It has obviously got some water in it at some time thats why there is some corrosion on the crank. It is very important that the crank rotates smoothly. Get plenty of oil around it to preserve it while working on it and remember to get any oil out before you re-assemble it. After every run, it would'nt hurt to put a drop of oil in it and spin it over to keep everything free and protected. Good luck. You will still be saving loads of money by doing it yourself.

 

[chuckydoo]

Cav, if you want to save yourself grief then either buy a rebuilt engine or rebuild your entire engine. One of the more common problems that these Rotax 2-stokes suffer from is the crank seals or rotary valve seals failing then running lean and tearing up the top end again. You can rebuild just the top end and gamble but its not worth it, I did and lost twice.

 

[riverrat88]

Cav, if you want to save yourself grief then either buy a rebuilt engine or rebuild your entire engine. One of the more common problems that these Rotax 2-stokes suffer from is the crank seals or rotary valve seals failing then running lean and tearing up the top end again. You can rebuild just the top end and gamble but its not worth it, I did and lost twice.

:agree:

I used these guys and they did a great job.

http://www.eastcoastcycle.com/

 

[rexsteiner]

if the crank wont turn its deffinate crank bearings. if theres any sign of rust in your engine you can be pretty certain its gona be in the bearings too. by the time you get a new crank pistons gaskets and what ever work your cylinders may need it may be to your benefit to look at rebuilds. but do your homework and include the time youll have into it both ways and youll make the right decision. heres a link to some guys i recommend.

http://www.seadooclinic.com/water_craft.htm

 

[CAVPILOT]

appreciate the input fella's!!
I've priced the top-end rebuild along with the bottom end and it looks like by the time I get all the parts, I will have invested damn near $1000. I've seen the rebuilt engines for $1400 so, as REX stated, I guess I need to evaluate my time & effort into the equation!
The crank bearings seem to be the recurring theme here which makes complete sense. Def don't want those to fail at 50+ mph!
Checking out the links now and I'll let you all know what I come up with.
Thanks for your help! :cheers:

 

[riverrat88]

Paid 895.00 plus shipping one-way (80.00) UPS in a Rubbermaid 18 gallon container. This is for a complete top and bottom end rebuild of my 951 (not a swap). Included bead-blasting and painting the motor plus shipping back to me.

Couldn't be happier with the service and support.

 

[CAVPILOT]

Paid 895.00 plus shipping one-way (80.00) UPS in a Rubbermaid 18 gallon container.

Under a $1000? :hurray: Looks like I'm boxing it up!!!
Thanks riverrat...tried calling yesterday, but of course no answer. Probably closed today (MON) as well.

atriot:

 

[riverrat88]

Cavpilot. Try dialing their direct phone instead of the 800 number. Speak with Alan.