10-25-2013, 05:37 PM #1
95 SLT 750 Rebuild - My Story And A Question
I bought a 95 750 SLT back in August. It had been completely disassembled in 1999. And just sat in baggies and boxes till I got it. Price $100. When I got to the guys house he said "Oh, that price was just for the hull!",(the ad didn't say hull only). Then I said "C'mon Man" He agreed to give me everything for $125.
So, I get on this forum and start researching and asking questions(Noob). Of course the reason it was disassembled was a broken rod and toasted piston, Mag cylinder. So I find an engine on ebay for $400. It's in really good shape. Compression 120 across. Then I start doing all the recommended upgrades and fixes. Triple pump, rebuilt carbs(mikuni) new fuel lines, new fuel selector etc. I saved the other engine I started to rebuild as a back up.
Well I finally put everything in the hull and fired it up for the first time yesterday! It started right up but then the engine raced to high rpm's and I shut it off. Looked on this forum for why that would happen. Answer: Probably an air leak.
Read a post that said check the carb synchronization. I tried starting a few more times. I noticed if I held the throttle on the carb really hard in the closed position it would idle fine. I remember when I did the sync someone recommended using a 1/16" drill bit(spacer) to sync the carbs which is what I used.
So, now I read the Clymer manual and it says to set Cen & PTO the same as the Mag. I closed the Cen & PTO butterfly valves to match the Mag. Which was practically all the way. Started it up and it idled fine. Around 2200RPM.
Haven't had a chance to get it in the water to test it out.
My question is, does everything I've described sound OK? Or, is there something else I should do before putting it in the water.
By the way. No drive in yet. It was in pieces too. If everything looks good then I'll install the jet drive and take her out the lake ramp for carb adjusting and hopefully a ride.
Sorry for the long story. But, it's been a long slow process learning how to work on this machine. But it's also been a lot of fun
Last edited by K447; 10-25-2013 at 07:30 PM.
10-25-2013, 07:34 PM #2
- Join Date
- Jul 2007
- near Toronto, Canada
How were you using the 1/16" drill bits to sync the three carburetors?
Sync means that all three carburetor blades begin to open together as you slowly squeeze the throttle lever and take up the slack in the throttle cable.
There should be a small amount of slack in the throttle cable at idle, so that the idle adjustment screw on the carb rack is what controls how closed the three carb blades are.
With engine off, the other check is that all three carbs are indeed completely open (blades rotated to vertical) when the throttle lever is fully squeezed.
10-25-2013, 09:57 PM #3
- Join Date
- Jun 2010
- Milwaukee WI
It could also be something as simple as the idle speed screw is turned in too much. All it takes is the throttle plates being open a little bit too much and they will really rev up with no load on them. I would try setting the idle speed in the water with it strapped to the trailer before you go tearing into it. It may be as simple as the idle being set too high. Rule that out first. I think 1300 RPM is about where you want to be in the water.
10-26-2013, 01:01 PM #4
I use the drill bit method to set all the butterflies to be open 1/16" with the idle speed screw holding them there. Once they are sync'd, I back off on the idle speed screw so they are closed. They start it up, adjust the idle speed screw to about 3300 RPM out of the water. Ideal in the water is around 1300 as Bryan mentioned. 3300 out of the water will be about 1300 in the water. If you didn't close the butterflies by backing off the idle speed screw after syncing the carbs, then yes, you would run up the RPMs.....
10-26-2013, 01:18 PM #5
- Join Date
- May 2008
- Elephant Butte New Mexico
sounds like you are ready for a trailer in the water test. Don't be all that fast to get on it and head out into deep water. Let her show you she can run and idle and restart at will on the trailer with a couple of full power blips and a couple of plug checks along the way. It doesn't take much to burn down a Polaris engine..and besides that you want to make sure the water is going where it should, and not appearing where it shouldn't. Make sure the drain plugs are in before you put her in the water and good luck!
Something you'll want to video for sure <hint>
10-26-2013, 03:34 PM #6
Thanks guys. Good advice. BFC, I guess I mis read the drill bit trick . Once i figured out the butterflies were open on the cen and pto cyls then I adjusted them to match the mag. After that idle good around 3300rpm. I have another problem now. The pto is not firing. It didn't fire when I first started the ski after install. Then later it did. Now nothing. How should I check spark and fuel? I'm thinking its one of three things. First, the fuel line for that cyl is a little flat in the middle. Is that enough to restrict flow? Second, may not be getting spark. But I used the plug wire for the center on it and still no fire. And I know that one is good. Third, when I was trying to figure out the problem and adjusting the butterflies I guess without realizing it i was rubbing the gasket on the intake against the side of the carb bowl on the pto. I can't tell if I got anything in there but the gasket looks a little torn up. How can I verify if pto is getting fuel without opening up the carbs?
10-26-2013, 05:09 PM #7
I got the pto firing. Clipped the plug wire tested spark on cyl head screwed back on. But, now It looks like there's air in the lines! See video for RPM's. Starts out fine then gradually increases. Where to start? Also, originally the Mag cyl was the warmest. Now it's the Cen. Do I have to remove and replace all the fuel lines? I did that already. How can I find out exactly where the air is getting in? Btw, I didn't touch the throttle.
Users Browsing this Thread
There are currently 1 users browsing this thread. (0 members and 1 guests)
By dtescher in forum Polaris Open DiscussionReplies: 9Last Post: 10-14-2013, 09:38 PM
By dtescher in forum Polaris Open DiscussionReplies: 3Last Post: 08-10-2013, 10:02 PM
By BlueFishCrisis in forum Polaris ProjectsReplies: 2Last Post: 09-05-2011, 07:53 PM
By Rodney in forum Polaris How To & FAQsReplies: 31Last Post: 08-10-2007, 12:25 AM
By daveo13 in forum Polaris Open DiscussionReplies: 7Last Post: 09-08-2006, 03:59 PM