Thread: New Guy with a 95 SL 750.
05-14-2010, 11:20 PM #1
New Guy with a 95 SL 750.
Hey everybody, I have been lurking for a few days, but now it is time for me to join in.
Fist, a little background on myself. I am self taught on everything I do and I am not afraid to tackle anything, and I love new things. I am no stranger to water and have been restoring boats (see my latest resto thread at iboats.com http://forums.iboats.com/showthread.php?t=358277) for a couple of years now. Last week I got the itch to restore a Jetski, and that is what brings me here.
I picked up a 95 SL750 for a smoking deal in my area and I am ready to dive in. I have been reading for a few days and I know how to use the search function, and I will not ask the same questions that get asked over and over.
Here is a list of what has been done
The PO burned the magnito piston last year and did a tear down. He replaced the fuel pump, switched to premix and replaced all the fuel lines. He took it out to the lake and said it still did not have power. That is when he gave up and how I have it now. He showed me the old piston and it was scared on one side. I asked if he replaced the jug and he stated no. Hmmmm. First of all that cylinder has very low compression, and so I took the head off. You could actually see where the scaring was on the wall and there there was a small gap between the wall and the ring. Hence the no compression. I also noticed what looked to be welding slag on top of the piston and head.
So here is my game plan. I am going to yank the engine and replace that jug, piston and head, and then check the entire crankcase, and make sure the crank is indexed. I have a question about indexing. If you are out of index, do you have to replace the crank? Also I cannot find the thread where is talks about how to do this. After that I will check all the fuel lines and then see if she works.
I was planning on starting a resto thread in in the project forum. I take tons of pics and post lots of youtube videos. I did this on my last boat build and people loved it.
You guys game?
05-14-2010, 11:31 PM #2
- Join Date
- Jul 2007
- near Toronto, Canada
Welcome to the Hulk
You seem to be coming up to speed nicely
If the crank is out of index, then a crank shop would need to adjust it. Depending on what they find, they may need to pull the crank webs apart.
Polaris PWC cranks are a press fit, and a 20+ ton press is used to take them apart and put them together.
There are a bunch of threads discussing crank index checking;
Number one thing to do is make sure the carburetors are 100% internally clean and in good condition.
Is the replacement fuel pump a triple outlet pump?
Make sure the small flow restrictor is present inside the return fuel line. Without it, the fuel pump will not develop enough fuel pressure to run the carbs properly.
Clean and internally check the fuel selector valve. It is important that the fuel system have no air leaks between tank and fuel pump. Replace the O-ring and lightly grease.
Polaris Fuji (blue) engine
05-15-2010, 07:53 AM #3
- Join Date
- Oct 2006
- Cleveland OH
Welcome to the Hulk frisco.
It does sound like your educating yourself quite nicely, and we appreciate the courtesy of not asking the same questions that are asked regularly.
By all means PLEASE start a new build thread with pics. Alot of new guys like yourself are picking up the same ski and have no clue what needs to be done or is involved. That would be a good thing for sure.
My biggest concern is the material that's left inside the crankcase from the damaged piston. It makes its way into the crank bearings and decreases their life tremendously. The crank is the heart of the engine and is quite expensive to repair/replace.
If the crank is out of phase (index), it must be removed and repaired by a good machine shop. The crank is a press fit that must be realigned using crank truing stands. If it's just a re-index, it won't cost too much. It's when the bearings and rods need replaced is when the price goes up. And shipping a heavy crank both ways gets a bit pricey too.
The MAG cannot come out of phase. It's physically mounted to the flywheel, The CEN and PTO can.
Normally the pistons burn because a lack of fuel or fuel pressure. Make sure to re-install the restrictor in the return hose when you replace the fuel lines. Also replace the pulse hose going from the case to the fuel pump. Keep the fuel pump elevated above the case fitting, and the hose as short as possible.
Did the PO install the triple outlet fuel pump?
05-15-2010, 09:30 AM #4
Now I am really scared about the crank index. How often in that a problem with the Mag burning through? Isn't that most of time a fuel issue?
05-15-2010, 09:32 AM #5
- Join Date
- Jul 2007
- near Toronto, Canada
05-15-2010, 09:41 AM #6
That is what I thought. The other cylinders are perfect.
Remember the PO put the scared Mag jug back on. I will post some video later.
Users Browsing this Thread
There are currently 1 users browsing this thread. (0 members and 1 guests)
By afr in forum Open DiscussionReplies: 7Last Post: 04-28-2008, 05:05 AM
By Pags in forum Open DiscussionReplies: 15Last Post: 04-23-2008, 07:08 PM
By NeverEndn in forum Yamaha PWC Performance (2-stroke)Replies: 31Last Post: 07-15-2007, 11:41 PM
By jcc011185 in forum Sea Doo Open DiscussionReplies: 0Last Post: 12-18-2006, 08:42 PM
By jcc011185 in forum Polaris Open DiscussionReplies: 0Last Post: 12-18-2006, 08:41 PM