1996 Polaris 440 Sport Touring.... time for a top end?

[absteed]

My old 440 with 3000 miles has been acting up. It starts fine when it's cold. But if you shut it off or it dies while running, it won't start warm. I have to wait for it to get cool again.

I cleaned the carburetors and synchronized them to factory settings. No change in the way the machine runs.

I installed a brand new fuel pump. The machine behaves in exactly the same way.

So I pulled the carbs off and did the upside down dry pressure test--both needles and seats hold pressure just fine.

This morning I did the upright wet test--pumped fuel into the carbs to see if they hold pressure--and both carburetors hold pressure just fine.

I've tested the compression and it came in at 70 lbs per cylinder exactly, but this tester has a tendency read way low. What I've read here on the forum and in talking to others is to focus more on if there is a difference in compression between the two cylinders of 10 percent or more rather than what the compression reading itself is because compression readings will depend on who is cranking the pull cord? Is that right?

The question is, based on what I've tested, is there anything else I should be looking at or is the top end the next step?

 

[Lake Powell]

My old 440 with 3000 miles has been acting up. It starts fine when it's cold. But if you shut it off or it dies while running, it won't start warm. I have to wait for it to get cool again.

I cleaned the carburetors and synchronized them to factory settings. No change in the way the machine runs.

I installed a brand new fuel pump. The machine behaves in exactly the same way.

So I pulled the carbs off and did the upside down dry pressure test--both needles and seats hold pressure just fine.

This morning I did the upright wet test--pumped fuel into the carbs to see if they hold pressure--and both carburetors hold pressure just fine.

I've tested the compression and it came in at 70 lbs per cylinder exactly, but this tester has a tendency read way low. What I've read here on the forum and in talking to others is to focus more on if there is a difference in compression between the two cylinders of 10 percent or more rather than what the compression reading itself is because compression readings will depend on who is cranking the pull cord? Is that right?

The question is, based on what I've tested, is there anything else I should be looking at or is the top end the next step?

Definitly time for a top end. Peter

 

[davesilb]

If your compression is in fact below 100 it is time for a upper rebuild. But if 100 or better I would look for some other reason for the hard start warm. Maybe fuel getting to warm at some point in the fuel system.

 

[absteed]

I've seen a number of aftermarket top end kits. But if I'm going to tear into the engine, I'd like to do bearings too. Do any kits come with bearings that you know of?

 

[BBP]

If the compression is good, I would run it at half throttle for a few seconds & hit the kill switch without letting off the throttle. The spark plugs should be a very light tan. If not, is it rich or lean? Are they burning even on both sides? The answers should give you a direction to go.