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Discussion Starter · #1 ·
http://www.polarisatvforums.com/forums/atv-repair-maintenance/48083-checking-engine-oil-before-first-start-day.html

The above is the start of this thread actually but has since moved from crankcase full of gas to the subject of carburetor rebuilding.

We did remove the carburetor yesterday late and got the shop trailer cleaned up with the work bench space clear. Because we had to spend the afternoon doing some fencing and gate installation so the mini horses could gain access to the dry if they choose this winter it was 9 PM before I got to touch the carb.

We did get the diaphragm, float and all removable jets out of the carb tonight. The rubber tip on the float shut off needle was shot for sure. Had one jet that is recessed that I was concerned I was going to strip out the screw driver slot but after letting some PB Blaster soak in the hole I finally got it out. I think the treads were dirty.

The main jet was a 145 size. The moving parts showed some wear and it was dirty on the inside especially under the the pump diaphragm. I think a rebuild from time to time is good so one gets the carb very clean on the inside. With the jets, needles and float out one can get the carb cleaner blasting through out the carb passage ways. The O-rings were in bad condition too.

One thing that I have learned so far at least in the Magnum series that 89 octane gas is required unless it is alcohol free then 87 is permitted. The second thing from the manual is running an engine too lean will toast it over time.
 

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Discussion Starter · #2 · (Edited)
One thing I do not understand is where the carbon build up below the diaphragm compartment occurred. Is it natural, from back firing, etc?

I did not find an overflow path it the bowl over fills. There is the place where a hose can attach and gas will run out if the drain screw is backed out a couple turns. There is a brass looking rod sticking up that is the right height to drain off gas from the tank be for it stated flowing through the intake valve but it looks solid?
 

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Sounds like you've found the problem with the fuel overflowing (rubber tip on float needle) and filling up the crank case and mixing with the oil. Almost every Polaris manual I have says to run 89 octane min if it has ethanol in it, or step up one size on the main jet and you can stay with 87. On a 4 stroke there can by some carbon build up on the carb slide and in the areas around it, usually from worn cam lobes or misadjusted valves or piston ring wear causing some blowby and back pressure. Nothing to worry about, just clean it up and run it.
 

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Discussion Starter · #4 ·
When I removed the bowl drain screw completely it had a build up of something very hard on the under cut end that is to let the bowl overflow drain past it. I was able with the tube inserted in the carb cleaner can to spray cleaner into the pin hole on the side of the overflow tube near the top of the tube and spray out the bottom very well so I think we will be good to go next time because there is a new drain screw in the kit I see.

We did adjust the valves that were at about .020 when we got it. I guess extra .014 too wide came from cam wear perhaps.

Since it died and would hit some when we were warming it up to adjust the old carb we have another issue because we worked late last night putting the carb back on but it did not start but did back fire once. The plug lays a hot blue spark when cranking with the plug is out. It would not try to start when spraying carb cleaning into the filter side but we did not have the throttle open as I now think about it.

It is now in the lower 20's but this weekend it is to get back up to 60 during the day so we may take another look at it. We meant to put a compression reading before pulling the carb but will when it warms up. With it dying and seemed to have flooded out I thought it was due to the bad float needle valve. Yesterday I checked the oil that we changed after the crankcase flooded but before we started it and it was gas free after the 15 minute of riding before it died. I did check and the bowl had filled with gas last night. It would be nice to be rich enough to buy a new one but then we would miss all of the learning. :)
 
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