Engine-Tech 900 BIG BORE (polaris edge)

[BILTIT]

Here is my clutching but with a team tied so the helix is very different. I run 490 jets at 2100ft with twins and atacc so mine is different again. 30%avgas/premium.

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[2XM3]

i've ran slp 903's back to back with race twins vs there single, the single killed it for sure, may not be your issue but FYI

 

[Osborne Performance]

I have a set of race twins for a 910 they are for sale for the right price I rummy 910 with original Carl’s pipes

 

[lyspera]

Took the 900 engine out and installed the oem 800 engine, still have this problem. Wide open pulls up a hill then suddenly it drops from 8200 down to 7200-7500, but when i pump the throttle it will run strong again.

plugs look fine
fuel filter is changed
The cases is ported
clutches is fine
new belt
tried another temp sensor (no change)
tps is adjusted to 4 volts
case vaccume line is properly seated

maybe the fuel pump?

 

[BILTIT]

Remove case vacuum line and look for kink. Fuel pump next.

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[lyspera]

Remove case vacuum line and look for kink. Fuel pump next.

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Checked the vacuum line, no kinks in line just a little curve to it. yes i will replace the fuel pump next!

 

[lyspera]

fuel pump and fuel filter changed still drop in rpm. seems like it happens when the engine is hot, when i let the sled cool for a couple of minutes and then ride it again it works good for a few minutes then it drops in rpm again

 

[BILTIT]

Engine temp sensor?

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[lyspera]

Engine temp sensor?

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Tried that too, no luck

 

[whoisthatguy]

There are two nickel size clear plastic diaphragms in the fuel pump, that act as 1 way valves. They get rough on the side where they contact the aluminum, in a circular pattern around the outside edge of the diaphragm. After perhaps 2500 miles, they need to be flipped over so that the top smooth side is now in contact with the aluminum and makes a tight seal. Or you can buy a complete rebuilding kit on Ebay, which contains all of the other gaskets and diaphragms as well. The engine will run a lot smoother with this rebuild. Replacing one non-rebuilt 2500+ mile fuel pump with another non-rebuilt 2500+ mile fuel pump, will not help things.

 

[whoisthatguy]

Also, a defective hi-low beam switch can mess with the stator voltage, which will then mess with the engine voltage. You can unplug the hi-low beam switch, to take it out of the system, just to see whether that helps. Other items to substitute with the same electrical item from another working sled, include the CDI box and the coil. Also, at the coil leads to the spark plugs, you can remove the spark plug connectors and clip off about 1/2" of the wire, and then hand screw the connector back on. The copper wires inside the connector, get brittle and lose their conductivity.

 

[lyspera]

Also, a defective hi-low beam switch can mess with the stator voltage, which will then mess with the engine voltage. You can unplug the hi-low beam switch, to take it out of the system, just to see whether that helps. Other items to substitute with the same electrical item from another working sled, include the CDI box and the coil. Also, at the coil leads to the spark plugs, you can remove the spark plug connectors and clip off about 1/2" of the wire, and then hand screw the connector back on. The copper wires inside the connector, get brittle and lose their conductivity.

Will try the hi-low beam switch. thanks!

 

[lyspera]

There are two nickel size clear plastic diaphragms in the fuel pump, that act as 1 way valves. They get rough on the side where they contact the aluminum, in a circular pattern around the outside edge of the diaphragm. After perhaps 2500 miles, they need to be flipped over so that the top smooth side is now in contact with the aluminum and makes a tight seal. Or you can buy a complete rebuilding kit on Ebay, which contains all of the other gaskets and diaphragms as well. The engine will run a lot smoother with this rebuild. Replacing one non-rebuilt 2500+ mile fuel pump with another non-rebuilt 2500+ mile fuel pump, will not help things.

Brand new fuel pump installed, as mentioned no change!

 

[whoisthatguy]

Maybe the rear idler wheel bearings are toast and on long pulls, they really heat up and start to disintegrate, causing a horsepower demand. Same thing with the drive axle bearing on the front left side.