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Hi: The dirty fuel filter can cause the bike to over heat and slow down -- and back firer -- jerk climbing hills. Burning oil is something one has to find by checking things.
Is there a trick to remove the line off of the fuel pump with the green clip? It says to remove it first to relieve fuel pressure. I got a buddy to push in one side of the green clip with a small screwdriver while I did on the other side while pulling up. It isn’t budging. I’m worried I’m going to break it.
You may need to read the manual again. To relieve the fuel pressure you first disconnect the FUEL PUMP UNIT 4P CONNECTOR. It's the big square plugin electrical connection. It sits on top of the plastic covering over the fuel tank. Then, crank and let it run until it stalls. Then, DISCONNECT the negative terminal on the battery, THEN, you can disconnect the fuel pump hose.

I'm more concerned about the black/gray smoke you saw and the engine compression.
@retro has a great post about checking compression to be sure it's done correctly. He discusses the need for the right gauge parts to get the proper seal while checking. Sorry, I don't have it bookmarked, but a search will find it.
Also, just want to be sure we both have the same definition of "throttle open". By throttle open the manual is telling you to hold the throttle DOWN/IN, as if you're giving it all the gas you can and hold it there while checking the compression. Some people misread this to mean you don't touch the throttle while checking compression. If you DID hold the throttle down it does not necessarily mean your compression reading is correct. Again, read the post by @retro.

Based upon everything you've said I agree with @misterclean59 that your overheating problem may be solved with the radiator cleaning/coolant change.
So, if it were me, I would:
1. check the compression correctly
2. do leak down test
3. pull the top end and check the valves

Lastly, I bet you may have sunk that Rancher at some point. If not, I bet you've enjoyed some good mud more than once. You don't get a radiator that clogged if you're just riding on dirt trails. :)
 

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Discussion Starter #22
Hi: The dirty fuel filter can cause the bike to over heat and slow down -- and back firer -- jerk climbing hills. Burning oil is something one has to find by checking things.
Is there a trick to remove the line off of the fuel pump with the green clip? It says to remove it first to relieve fuel pressure. I got a buddy to push in one side of the green clip with a small screwdriver while I did on the other side while pulling up. It isn’t budging. I’m worried I’m going to break it.
You may need to read the manual again. To relieve the fuel pressure you first disconnect the FUEL PUMP UNIT 4P CONNECTOR. It's the big square plugin electrical connection. It sits on top of the plastic covering over the fuel tank. Then, crank and let it run until it stalls. Then, DISCONNECT the negative terminal on the battery, THEN, you can disconnect the fuel pump hose.

I'm more concerned about the black/gray smoke you saw and the engine compression.
@retro has a great post about checking compression to be sure it's done correctly. He discusses the need for the right gauge parts to get the proper seal while checking. Sorry, I don't have it bookmarked, but a search will find it.
Also, just want to be sure we both have the same definition of "throttle open". By throttle open the manual is telling you to hold the throttle DOWN/IN, as if you're giving it all the gas you can and hold it there while checking the compression. Some people misread this to mean you don't touch the throttle while checking compression. If you DID hold the throttle down it does not necessarily mean your compression reading is correct. Again, read the post by @retro.

Based upon everything you've said I agree with @misterclean59 that your overheating problem may be solved with the radiator cleaning/coolant change.
So, if it were me, I would:
1. check the compression correctly
2. do leak down test
3. pull the top end and check the valves

Lastly, I bet you may have sunk that Rancher at some point. If not, I bet you've enjoyed some good mud more than once. You don't get a radiator that clogged if you're just riding on dirt trails. :)


I haven’t sunk it before. Haven’t even gotten any water in the air box. I do ride muddy trails occasionally, but at my cottage we don’t have a hose so I can’t clean the atv as much as I would like. Any time I bring it home I clean it very well. Yes I understand throttle open, and I followed the service manual on how to do a compression test. My second test was done correctly. Besides warming the engine up, which I could not do because there is no coolant at the moment. Once I inspect the fuel filter (and replace it if needed) I will refill the cooling system and do a compression test following the service manual completely. I did a quick look to find that post by retro on compression testing, but I couldn’t find anything I’ll look more tomorrow.

As for removing the fuel pump, I didn’t feel comfortable starting the engine with no coolant (even for a few seconds) to relieve pressure in the fuel system. I turned the fuel valve to “off” and then removed the lines and minimal gas came out.


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Discussion Starter #23
I got the filter out. How can I tell if it needs to be replaced?


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The compression on your engine can be higher or lower for many reasons. First it can be higher than normal if the valves are too loose which partially or entirely disables the decompression release function. Secondly, oil in the combustion chamber can boost the numbers in relative to how much oil is there. Low compression can be a result of valves that are too tight. The tighter the valve, the more compression loss experienced. Of course worn rings and burned valves will lower the compression. Hope this helps. Ps. I posted this response before I saw the most recent posts from you. Now concerning the fuel filter, I'd replace it as a maintenance procedure......at least you will know for sure it's good then.
 

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Discussion Starter #25
The compression on your engine can be higher or lower for many reasons. First it can be higher than normal if the valves are too loose which partially or entirely disables the decompression release function. Secondly, oil in the combustion chamber can boost the numbers in relative to how much oil is there. Low compression can be a result of valves that are too tight. The tighter the valve, the more compression loss experienced. Of course worn rings and burned valves will lower the compression. Hope this helps. Ps. I posted this response before I saw the most recent posts from you. Now concerning the fuel filter, I'd replace it as a maintenance procedure......at least you will know for sure it's good then.


So I suppose I could adjust my valves and then do another compression test and this would rule out my valves being to loose. As for the oil in the combustion chamber, I don’t think there is much because I don’t see any black or grey smoke at idle and lower rpm it was only at 3/4 to full throttle. After doing a dry compression test I could also add some oil into the cylinder to see how much of a difference there is, to determine if the rings are bad.


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The compression on your engine can be higher or lower for many reasons. First it can be higher than normal if the valves are too loose which partially or entirely disables the decompression release function. Secondly, oil in the combustion chamber can boost the numbers in relative to how much oil is there. Low compression can be a result of valves that are too tight. The tighter the valve, the more compression loss experienced. Of course worn rings and burned valves will lower the compression. Hope this helps. Ps. I posted this response before I saw the most recent posts from you. Now concerning the fuel filter, I'd replace it as a maintenance procedure......at least you will know for sure it's good then.

So I suppose I could adjust my valves and then do another compression test and this would rule out my valves being to loose. As for the oil in the combustion chamber, I don’t think there is much because I don’t see any black or grey smoke at idle and lower rpm it was only at 3/4 to full throttle. After doing a dry compression test I could also add some oil into the cylinder to see how much of a difference there is, to determine if the rings are bad.

Please reread what @misterclean59 told you. The bottom line is that you are going to have to check the valves for wear, leakage, and the adjustment. Adjustment alone is most likely not the answer.

There's no way to know about the amount of oil in the chamber based on when it smokes. If it blows grey/black smoke, that's not good, period. In addition to checking the valves, you'll need to check the head gasket, piston ring and cylinder.

Here is the first page of a great thread where @retro talks about using a Shrader valve to check compression and other tips:
https://www.hondaatvforums.net/forums/repair-maintenance/129172-back-more-advise-my-98-450es-blowing-smoke.html
You need to read at least the first few pages of this thread because it may help you.
Just so you will know for future repairs, turning off the gas did not relieve the pressure on the fuel system. It's not just about the fuel in the fuel line, but also about the fuel injector.
Working on a Rancher is not like working on older bikes. The Rancher has so many electrical connections and parts that must be handled carefully because they are interrelated. You can mess things up pretty quickly. So keep following the manual.
 

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I am sticking to my initial theory. It overheated due to the radiator etc and the top end is worn out. It was probably on the threshold of burning oil and the overheating just sped up the process. Many here will support the statement that "it was not burning oil one day then all of the sudden I noticed it smoking". I would tear down the top end and inspect everything. As I stated previously, you may just need rings and valve seals.
 

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Hi: Yes that fuel filter is dirty -- I don't know if you can just replace that filter -- they have a filter kit that mounts the filter to the side of the fuel pump.
 

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Discussion Starter #29
Hi: Yes that fuel filter is dirty -- I don't know if you can just replace that filter -- they have a filter kit that mounts the filter to the side of the fuel pump.


Yeah I’m going to order the updated filter kit.


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Discussion Starter #30 (Edited)
Taking apart the top end now. Before you take off the valve cover it says to bring the engine to TDC on the compression stroke. So in order to do that it says to remove the intake and exhaust covers, timing hole cover and crankshaft cover. I have everything removed except the crankshaft cover, which is held on with 3 bolts, according to the service manual. My atv has a recoil starter, so I figured the 3 bolts are inside the recoil starter housing. It doesn’t say anything about removing your recoil starter in the service manual to get to the 3 crankshaft cover bolts. I have 3 of the 4 recoil housing bolts off and I can see inside. I don’t see any bolts for the crankshaft cover, but I can see where they would go.

So do I have to take the recoil off and then the metal part attached to the crankshaft which the recoil starter pawl grabs onto?



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Discussion Starter #31
I read the part that explains how to get the engine to TDC again and it doesn’t mention anything about using the crankshaft hole. Isn’t the flywheel mark viewed through the timing cover inspection hole? If that’s the case then why do you need to remove the crankshaft hole cover?


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Discussion Starter #32
Is the crankshaft hole just to rotate the crankshaft to line up the “T” mark? I’ve been trying to line it up with the recoil starter but it isn’t precise enough so I’m going to take the recoil starter off.


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Discussion Starter #33
I got the recoil starter off, got the T mark lined up and doubled checked that each rocker could move (both valves closed). Then I got the valve cover off, and moved onto the cylinder. I started with the exhaust first and got the two nuts off, but one of the bolts on the muffler clamp broke. The clamp is loose, but the header is seized inside the muffler section of pipe. I tried heating the joint up and pulling the muffler from the back of the atv, but didn’t budge. I’m going to call it a night and finish disassembly tomorrow.



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Looks like you are doing well. That broken bolt can be repaired later......with much patience and correct procedure. I think the pipe joint can be separated by hitting one piece with a rubber mallet of hammer on a piece of wood. I'd use penetrating oil first. Good luck.
 

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Discussion Starter #35
Got the exhaust off. Sprayed some wd 40 inside the joint an hour before hand. Got a buddy to hold the header while I pulled on the muffler. I’ll probably be able to remove the broken bolt out of the exhaust clamp and get some new bolts for it.

I was able to remove the cylinder head without taking apart the throttle body. I just loosened the clamp and I was able to pull it off. I removed the cylinder and cylinder head together and I couldn’t find the base gasket. Not on the bottom of the cylinder, not on the crankcase. Checked all over my garage floor and in the atv frame. Couldn’t find anything. None of the rings are stuck, no scoring on piston or cylinder. I don’t think that’s a lot of carbon on the valves or piston top?



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Discussion Starter #36
Base gasket is metal and blended in with the crankcase really well. It’s rtv’d down so going to leave it on for now.


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Discussion Starter #37
So I guess I should start by removing the rings and measuring end gap? Should I get new gaskets? Since valve seals could be causing the problem, I'll replace them too.
 

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All rings are out of spec. So rings, valve seals anything else to check?


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That piston looks scuffed. If so replace it too. A quick method to check piston to cylinder clearance is to measure with a feeler gauge. It's not perfectly accurate but it is good enough for your job. Just install the feeler gauge anywhere you want on the piston and cylinder. Measure different combinations. Try the worst scuff on the piston and in the middle of the front or rear of the cylinder. This should be the area of most wear. Then measure somewhere below the rings on the piston around the pin area and and on the cylinder above where the rings stopped their upward stroke. This area is narrow ring, look for it and it becomes obvious. This measurement should be the least wear. I'm not sure of the maximum clearance allowed between the new piston and cylinder but I'd guess three thousanths or just a little less. Use a good ball hone and resurface as little as you can get away with. The cross hatch pattern should be about thirty degrees. If you aren't sure of your assessment skills take it to a shop. I think there is a 50/50 chance you may need a bore and oversized piston.
 

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base gasket is held on with rtv sealant ?..this is a big NO NO !!!. I also see scoring on piston and on cylinder wall. I hope you checked your connecting rod for any play where the wrist pin rides ?, as well as any up and down play on the lower rod to crank ?. if there is any play ?, your new top end wont last long at all until you fix the crank/connecting rod !.
 
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