PRC Polaris Ranger Club banner
21 - 32 of 32 Posts

·
Registered
2015 Polaris ranger 570 XP
Joined
·
4,089 Posts
It's possible that the reason the old engine died had nothing to do with a mechanical problem. An oil leak at the cylinder base wouldn't prevent starting or running, Most of the time when an engine gets really tired it begins to lose power, is hard to start, develops knocks or other sounds and continues to run until a final failure (usually at the worst possible moment) or catastrophic event such as locking up or something breaks internally and may or may not come through the block.

With regard to spark timing, on most engines I've worked on I set a preliminary timing by putting the engine at TDC (all valves closed) and set the timing marks to line up at the firing point, approximately firing at TDC. Usually an engine will run with timing set like that even if it is sluggish on acceleration and doesn't want to idle well. You can even guess at 5 degrees or so before TDC. I've never seen a 500 or how timing is set on one, however I have seen manufacturers use several marks on the flywheel for timing purposes. Some are for setting timing at idle or initial timing, others are for full advance timing checks and some will include a TDC mark. In short, be certain you are using the right mark if there is more than one.

I suggest going back to basics. Since, as you know, engines need only fuel, air, ignition and compression (all at the correct time) to run, I suggest you troubleshoot by spraying some CRC carb spray (some carb cleaners won't burn like the CRC stuff does) into the intake and crank it over to see if it pops off and dies. If it does you've got a fuel problem. If not, it's probably either valve timing or spark timing.

The problem with rebuilders, even reputable ones, is that they can make mistakes. Check to see that the valves are opening and closing when the should and that valve clearance is correct. A cam sprocket that was accidentally installed with the cam timing chain one tooth off will put cam timing way off.
 

·
Registered
Joined
·
128 Posts
Discussion Starter · #22 · (Edited)
On this flywheel there is one mark with TDC stamped next to it. There are 3 marks at 32°, 30° and 28°. Service manual says to time it at 30° ± 2° at 5000 rpm. Only timing adjustment is very little on the stator plate rotation. Then it is a guessing game as cannot make any adjustments with the engine running. Been working with the carb. Double checked the float height. When set per specs the fuel level is about 1/2 " + above the top of the bowl. Service manual says it is to be right at the top of the bowl with the bowl held level, not the actual carb. Have that adjusted by fuel level now. Will do some adjusting on the pilot screw as that control how much fuel goes through the carb on start up, idle. I appreciate the input you guys are providing. I know it is hard to diagnose a problem from a computer screen many miles away from the issue.
 

·
Registered
Joined
·
1,790 Posts
I really think the timing and carb are not your problem. If either is a little off the engine should at least show some life and run a bit rough.

Have you tried spraying a little ether in the intake with the carb removed. If it doesn't fire that eliminates the carb. That would indicate no spark or the timing being way off, as in 180 degrees.

For clarification, was this engine simply pulled from a running machine or was it rebuilt?
 

·
Registered
Joined
·
128 Posts
Discussion Starter · #24 ·
Engine was pulled from a running machine as I understand it. Came out of a Sportsman, which is the same engine. Odometer picture they provided showed 555 miles. Of course if you want an engine with 500 hours on it that is exactly what it will have. Been that route before other small engines. Will give the ether a shot this afternoon. Have a bathroom stool to change out now. Thanks for the input.
 

·
Registered
Joined
·
128 Posts
Discussion Starter · #25 ·
Thanks very much BPS. Gave it a shot of ether this morning and it fired and ran a couple seconds. Got to be the carb.. The Makuni is at the Polaris shop now for a rebuild. Hopefully they can get it done right as the other two guys that tried failed. Should hear something today or tomorrow.
 

·
Registered
Joined
·
128 Posts
Discussion Starter · #29 ·
On the aftermarket carb that was on it the fuel was coming out the overflow and into a quart oil bottle by the battery. Ran that way for a year or more but never good, short on power, etc. The OEM pump is supposed to have max 5 PSI output. The aftermarket carb needle can only handle 4 PSI max, 3 is better but hard to come up with pumps that size. Once I got the float set to put the fuel level at the top of the bowl the overflow stopped and the catch bottle was no longer needed. Cannot go by what the rating is listed at on fuel pumps. Have to actually put the gauge on them and let them pump up to pressure to know where they are at. The pump on the Ranger now is a 4 lb pump.
 

·
Registered
Joined
·
128 Posts
Discussion Starter · #30 · (Edited)
So was fuel coming out the overflow on the carb?

Reason I asked about pump is that would make sense on why it died the first time.

Sent from my SM-S901U using Tapatalk
Fuel pump was/is good. Not sure why the old engine died other than lot of hard use & well over1K hours before I got it. Hr meter not working showed 1048 hr.

Fuel was coming out the overflow. Thought the drain valve was bad. Was sent another carb and it did the same thing. Then I figured out it was an overflow issue. Have 2 aftermarket carbs for a Makuni BST 34.
 

·
Registered
Joined
·
128 Posts
Discussion Starter · #31 ·
Hired a young man to do the grunt work and got the replacement engine installed. The company I got it from said it came out of a 2015 Sportsman with 555miles on it.
Fast forward. Got the carb back and on the engine. Engine fires off and runs good. Oil pup primed right off first try. But the carb is dripping gas from the pilot adjustment. Dealer that rebuilt the carb said I would have to bring the machine in to get the carb adjusted properly to the engine. Mean time been working on trying to get all the air out of the system. It has had a heater installed prior which is higher than the rest of the system. Not sure of the flow direction of this add on but it sure cannot be helping to get the air out. I removed the hose from the thermostat block and when coolant started to trickle out I put it back on the fitting. I think tomorrow I will do away with that heater as it to small and to many open areas to do much good anyway. It is an 18 year old machine but after a lot of work it is in good mcehcnical condition. High gear is about gone but very seldom use it anyway.
 

·
Registered
Joined
·
128 Posts
Discussion Starter · #32 ·
UPDATE: This morning I removed the heater hoses from the cooling system. OEM hoses hooked up as original. 10 min and had the air all out. Took it up the road 1/4 mile and back. Ran great and NO GAS DRIP !! Never touched a thing on the carb till after it was back in the shop when I turned the idle speed down a bit. Have no clue what was going on to make it drip a bunch and then after being parked overnight it quit. I think I am back up and running again. Been down since last October.
 
21 - 32 of 32 Posts
Top