Do i need to remove the fuel tank to replace the top rocker box cover?

This is fairly easy on the Evo engines.

Remove top of rocker box cover.
Ease up old valve (not a good time for gorilla tactics here), being careful not to pull valve off of stem, leaving stem in the hole.
A little spritz of WD-40 down the stem might help.

Position new valve stem into hole, push down on center of valve until stem pops into hole.
If difficult, a dab of oil might help.
After insertion, GENTLY pull up on edges of valve to make sure stem stays in hole.

Replace rocker box top cover, repeat for other rocker box.

Go for a ride!

It sounds like the camshaft is going flat. The exhaust lobe on the camshaft is the first to wear. Basically the exhaust isn't opening the entire duration it needs to expel the exhaust. This will cause the bogging issue. Polaris uses an overhead camshaft, which fortunately, makes it easier to replace. To check the camshaft:
1. Remove spark plug
2. Remove the large bolt on top of the recoil starter
3. Rotate the engine with the pull rope until the "T" mark on the flywheel is visible through the hole the bolt was removed from
4. Remove 8 screws on valve cover, fuel tank removal is not necessary but gives you more room
5. Remove 4 bolts from rocker arms, lift rocker arms off camshaft
6. Rotate engine again with pull rope to inspect camshaft. The center of the camshaft is the exhaust lobe, intake lobes are on the outsides of cam. The exhaust lobe should be about the same height as the intake lobes, and will be noticeably flat
To replace the camshaft:
1. Remove camshaft gear access cover on right side of engine
2. Rotate engine again until the "T" mark on flywheel is visible, 2 dots on the camshaft gear should be at the top of the gear and will be parallel to the mating surface of the valve cover
3. Locate the chain tensioner, 2 small bolts holding tensioner to cylinder and 1 large bolt in the center. Remove the large center bolt to remove tension. There will be a spring and pin inside tensioner so be careful not to let it fly out.
4. Remove screws holding gear to camshaft, leave the gear on the chain
5. On the left side of the engine, clamp the coolant hose going into the thermostat cover
6. Remove thermostat cover, some coolant will come out but is ok
7. There will be a round cover on left side of engine with 3 screws, remove that cover and pull the camshaft out through that hole.
8. Install new camshaft, make sure the automatic decompression lever does not come out while handling. Keep pressure on decompression lever and hold cam so that the little ball inside the cam is facing downwards, this will help to keep the lever inside the cam
9. Install cover on the left side
10. Install cam gear on camshaft
11. Remove exhaust rocker arm from the shaft and replace with a new exhaust rocker arm
12. Install spring, pin, and bolt in tensioner once the gear is in place
13. Install rocker arms, set valve clearance to .006 in for intake and exhaust
14. Reinstall covers and thermostat cover
15. Option B is to take it to a Polaris dealer to avoid the hassle of trying to do it yourself!
Hope this helps, if you need any more assistance let me know, Daniel

To change the rocker box gaskets, simply take the bolts out of the top of the rocker boxed. You'll probably have to take the tank off to get to the bolts and there should be a hole in the frame to get the left side rear bolt out of the rear cylinder rocker box. Replace the "umbrella valve" in each center section while you're in there. Bolts torque to 100 inch pounds.

Good Luck

You probably haven't done anything wrong, it's just you've got an oil leak from your rocker boxes. Remove the fuel tank and take the top off the rocker boxes. Replace the gaskets between the upper and middle plate and the center gasket. Make sure everything is aligned correctly and tighten the bolts down to 100 INCH pounds.

Good Luck
Steve

To replace the rocker box gaskets, you'll have to remove the bolts on top of the rocker boxes to get them off. You may have to remove the fuel tank(s) and seat. You didn't tell me what year and model bike you're working on. Once you have these bolts off, you can replace the gaskets between the center and the upper parts, the inner gasket and the umbrella if your bike is equipped with them.

To replace the gaskets under the lower plate, work with one plate at the time. Remove the spark plugs and jack the rear wheel off the ground. Put the transmission in high gear and bump the engine over until the piston is at top dead center in the cylinder your working on with both vavles closed. Start by removing the three 1/4" hex head bolts and the two 1/4' socket head bolts. Then, remove the 5/16" bolts on the pushrod side of the engine. Tap the rocker shafts out and remove the rocker arms. Remove the other two 5/16" bolts. Lift the lower plate and replace the gaskets. Do not mix up the pushrods. They are usually color coded as to which position they go in.

To reinstall the lower plate, place the rocker box on top of the cylinder and start all bolts except the two 5/16" bolts on the push rod side of the engine. Put the rocker arms in place and push the shafts through them. Start the remaining two bolts. At this point, your lower rocker box plate is "floating" above the cylinder head. Tighten the four large bolts down until they are all flush with the top of the plate. Then, tighten them down 1/4 turn at the time until they are snug. Then, tighten the six smaller bolts down until they are barely snug. Torque the larger bolt to 15-18 foot pounds and the smaller bolts to 10-13 foot pounds. Wait for the tappest to bleed down to where you can turn them by hand to do the other cylinder. Do it the exact same way as you did the first one.

To install the middle and upper plates, put the center gasket and all other gaskets in place and align the plate. Install the socket head bolts in the top and torque to 100 Inch pounds.

Put the transmission in neutral and lower the bike. Reinstall the spark plugs, the tank(s) and the seat.

Good Luck
Steve

Simple fix. Take the fuel tank off and remove the four bolts that hold the rocker box covers on. If the rocker box is leaking there, simply put a new gasket in place, carefully align the top plate and put the bolts back in. Torque them to 100 inch pounds.

If the lower rocker is leaking remove the smaller 1/4" bolts and then remove the larger 5/16 inch bolts. Remove the larger bolts a turn at a time until they are completely loose. Lift the lower rocker plate and replace the gaskets. Reposition the lower plate and align the pushrods in the rocker arms. Do not mix up the push rods, mark them if necessary. Tighten the 5/16" bolts down evenly until just seated. Then put the 1/4" bolts in. Torque the 5/16" bolts to 15-18 ft. lbs and 1/4" 10-13 ft. pounds. Reinstall the middle and upper rocker boxes and torque those bolts.

Good Luck
Steve

The only thing under the rocker boxes is the rockers and the upper part of the heads with the valve springs. Getting to this area is not that difficult.

Remove the fuel tank and seat. Then, remove the six bolts that holt the top and middle rocker box covers on. Now, you're at the rocker plate with the rocker arms in it. You can also see the tops of the valve springs. Look and see if there is anything that might be causing your noise.

Now, keep in mind that a Harley engine is of an old design. It is a pushrod type engine with rocker arms that open and close the valves. They are going to make a little noise. Now, if you're having to get close to the rocker box to hear the noise, it's probably nothing to worry about. But, if you can hear the noise stand away from the bike a few feet, you may have a problem. But most things that might break or come loose under the rocker box will usually effect the way the engine runs.

Also, you could have an exhaust leak. It makes a "tick, tick, tick" type noise. Tighten the nuts on the two studs snugly but don't break them off.

Good Luck
Steve

To replace the upper rocker box gaskets is not too difficult. But, if you're replacing the gaskets between the head and the lower plate, this gets a bit more involved. You must remove the fuel tank as well.

To replace the top gaskets, simply remove the four bolts and lift the top and middle plate off the lower plate. The left rear bolt on the rear cylinder is the toughest bolt to get out. Sometimes there is a hole drilled in the frame to make access to this bolt easier. If not, you'll have to shorten a hex key wrench in order to get it out. With the top and middle plates our, replace the "umbrella valve" in the middle plate making sure you put it in from the correct side. Now place the outer gasket in the lower plate, the outer and middle gasket in the middle plate and set the top plate down on them. Wiggle the plates around a bit until you get them lined up properly with each other and tighten the top four bolts down a little at a time one each bolt until they're all tight. Torque to 80 inch pounds.

If you're going to remove the lower plate, first bring the piston of one cylinder up to top dead center on the compression stroke. Remove the spark plug and rotate the engine until both valves are fully closed. Remove the air filter assembly and backing plate. Remove the large bolts on the right side of the rocker arms Slide the rocker arm shaft out of the rocker arms one at the time and remove the rocker arm and it's pushrod. Notice that the rocker arm shaft have a recess ground into them. This is so the 5/16" acts as a lock to hold the shaft in place. It must be realigned on reassembly of the rocker plate. Once you get all the rocker arms and pushrods removed, you should have the pushrod tubes out as well. Remove the rest of the bolts and lift the lower rocker box plate. Clean the bottom of the rocker box plate and top of the head.

Assembly is the reverse of disassembly. Make sure you don't get the pushrods mixed up as they are all four of different lengths and will only work properly in their correct postitions. They are color coded for their proper positions. There is no adjustment of the pushrods.
Front intake --- YELLOW
Front exhaust -- GREEN
Rear Intake --- BLUE
Rear Exhaust --- PURPLE
Lower rocker box torque values are: 5/16" bolts 15-18 foot pounds
1/4" bolts 10-13 foot pounds

First off remove the spark plugs from both cylinders, this will make it easier to rotate the engine to the proper position for rocker box removal. Now drain and remove the fuel tanks. You will want to have a 3/16" ball allen wrench to remove the top cover from the rocker box. Next you need to be sure that both valves are closed on the rear cylinder. To do this put the bike in top gear(5th). With the rear wheel off the ground slightly rotate the rear tire slowly in the direction of normal rotation(like the bike was going down the road). Have a friend put their finger over the rear cylinder spark plug hole. When they feel their finger being pushed off the hole as your rotating the rear wheel, You will be close to TDC on the the compression stroke at this point both valves should be closed fully or very close to it. Now remove the top cover(it does fit very tight between the engine and frame). Once you can see the rocker arms rotate the rear wheel until you see the rocker arm closest to the center of the motor(intake) start to open and then close. At this point both valves are fully closed(this is crucial). If you dont have the valves closed when you remove the lower rocker box you will bend the valves and then your simple job becomes an expensive one. Now remove the 2 3/16" allen head screws from the left side of the lower rocker box. Then remove the 3 7/16" bolts from the inside of the rocker box. Now you can slowly remove the last 4 bolts these will be 1/2", back each one out about a full turn at a time, until all 4 bolts are completely out. The rear rocker box will now move around pretty freely on top of the cylinder head. You can now remove the covers from the pushrod tubes, use a flat blade screw driver and slip it into the little clip that is like a handle on the tube. Lift the lower part of the push rod tube and lift the pushrod until it clears the lifter block so you can remove it. Set each pushrod off to one side noting which one came from which cylinder. At this point you should be able to now push on the shaft that runs through the rear exhaust rocker arm this will allow the rocker arm its self to be removed. Now you can pull the lower rocker box from frame. Reassembly is the reverse of the disassembly. Honestly I do reccomend that you buy a service manual from your local dealership before attempting this though. Also when you are putting everything back together make sure to start all of your bolts a few turns before tightening everything down. As you are tightening the bolts for the lower rocker box you will notice that the pushrods are holding the rocker box up. This is normal, but be sure to tighten the bolts only a turn each at a time(1/2") The hydraulic lifters will need to bleed down before you start the bike and it may even clatter pretty good when you first start it up. This is the lifters building oil back up into them. Take your time and go slow. Let me know how it goes and feel free to get back to me with any questions. Its better to ask if you dont understand then to rush through it. Good luck and let me know how it goes.

wudyzpp2003: To replace the fuel pump entails removing the rear seat bottom to expose an inspection hole cover which is in the floor. You remove the inspection hole cover and that gives you access to the top of the fuel tank and the place where you remove the pump.
On the drivers side near your knee and the hood release, is the fuse block. Remove the cover and look at the box.
If you are facing the box from the driver's seat, the second row in from the out side and the third fuse up is a 15 amp fuse. REMOVE it. That is for the fuel pump. If the pump was running and you were wanting to remove it, you need to relieve the fuel pressure. You do this by starting the engine with the fuse out, any residual pressure will be bled off.
If you look at the top of the tank where the fitting is, the collar is threaded on there like a bottle cap. A special tool is called for in Nissan's instruction's however, most Nissan tech's as well as those in the aftermarket use large channel lock pliers and exercise care in rotating the collar.
Obviously there are fuel hoses and electrical connectors to address prior to removing the collar. Once the collar is removed, you can lift the pump and sending unit right out of the tank.
NOTE: There are some match marks or alignment marks on the tank and on the top which the collar hold down. Look for them before you remove the top.
Once the pump is out of the tank it should be pretty evident how to transfer the new part.