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Discussion Starter · #1 ·
I had to tear down my engine to replace the crankshaft and connecting rod, piston, piston rings, and had to get a new cylinder due to it was already bored out to max. So I went back to stock piston size. I got it together today and primed it with oil and everything and when I went to go fire it up all it would do is back fire. I took it back out and tore it down to make sure all the alignment points were correct and they were. My question is since I went back to stock does the valves need to be adjusted because of the smaller size? Or could anyone have some things I should check or try? Everything was built by the book.
 

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I had to tear down my engine to replace the crankshaft and connecting rod, piston, piston rings, and had to get a new cylinder due to it was already bored out to max. So I went back to stock piston size. I got it together today and primed it with oil and everything and when I went to go fire it up all it would do is back fire. I took it back out and tore it down to make sure all the alignment points were correct and they were. My question is since I went back to stock does the valves need to be adjusted because of the smaller size? Or could anyone have some things I should check or try? Everything was built by the book.
The valve adjustment would still be the same. It sounds like you might not have it in time right. When you line the T mark up and the piston is at TDC, make sure the cam lobes are facing down.
 

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Discussion Starter · #3 ·
when it is at TDC all three of the internal markings are aligned but the exhaust valve is open just a bit at TDC. I don't know much on how it ran before I took it apart. I bought it for 800.00 and was going to change rings cause of smoking then found more problems I have maybe 1200-1300 in it now. I did test drive it and drove it around the yard a few times before I decided to take her down to keep from messing anything up worse. All it does now is backfire and I didn't do anything to the valve or valve springs
 

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I had to tear down my engine to replace the crankshaft and connecting rod, piston, piston rings, and had to get a new cylinder due to it was already bored out to max. So I went back to stock piston size. I got it together today and primed it with oil and everything and when I went to go fire it up all it would do is back fire. I took it back out and tore it down to make sure all the alignment points were correct and they were. My question is since I went back to stock does the valves need to be adjusted because of the smaller size? Or could anyone have some things I should check or try? Everything was built by the book.
I just did the same job on my '04 Rancher ES and I took the safe route and adjusted the valves. No telling what the PO or shops did. BTW, mine were out of spec. I will probably go back in and readjust them after a few rides.
 

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Discussion Starter · #5 ·
Did you adjust the lifters before cranking for the first time? Was one of the lifters open at TDC when you put it back together? What did you do to adjust the lifters?
 

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when it is at TDC all three of the internal markings are aligned but the exhaust valve is open just a bit at TDC. I don't know much on how it ran before I took it apart. I bought it for 800.00 and was going to change rings cause of smoking then found more problems I have maybe 1200-1300 in it now. I did test drive it and drove it around the yard a few times before I decided to take her down to keep from messing anything up worse. All it does now is backfire and I didn't do anything to the valve or valve springs
Both valves should be closed all the way when the piston is on TDC. Do you have the key groove in the crankshaft pointed straight up and parallel with the cylinder stud bolts like it shows in the picture below and do you have the other marks lined up like it shows below?

 

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Discussion Starter · #7 ·
yes I have all that correct and the exhaust valve is still slightly open. Should I adjust the lifter to be closed? Their is three different places that have to be aligned that I have found in my book.
 

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yes I have all that correct and the exhaust valve is still slightly open. Should I adjust the lifter to be closed? Their is three different places that have to be aligned that I have found in my book.
If the cam lobes are facing down, the valves should be closed unless somebody adjusted the valve adjustment way off. Are you sure the push rods are sitting in the center of the cam followers? Also, you may have a bent valve.
 

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Can you remove the valve cover and check and see if you have any valve clearance? If you have valve clearance and the valve is still open, then the valve must be bent.
 

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Discussion Starter · #10 ·
I am sure that they are in the center of the cam followers. once together they can't move from center right? I have ordered a new set of push rods today just in case. after all someone had been in the motor before me. I have clearance on the intake but none on the exhaust. That is what I can't figure out. everything is correct in the motor but at TDC the exhaust is pushed open by the lifter.
 

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I am sure that they are in the center of the cam followers. once together they can't move from center right?
Yeah, once you get it together, the push rods can't move out of place.

If the piston is on TDC and the cam lobes are facing down and all the timing marks are lined up correctly, then I don't know what it could be.

Can you tell by looking at the push rods if one is up higher than the other or if one of the rockers has been adjusted a lot more than the other one. Neither cam follower should be sitting on a lobe, so neither pushrod should be pushing the rocker arms up and opening the valves.
 

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Discussion Starter · #12 ·
Finally!!

I finally got my Rancher running again!!! I had to tear it back down and fix one alignment location, and had to adjust the valves. She is running like a champ. My next project is to replace the crash bars and front rack because the previous owner hit a tree. I'm just glad there was no frame damage. And buy a winch. If anyone has a Rancher in the same year range as my 2003 please tell me what winch plate you have if you like it and it mounts good. I don't want to go with a universal.
 

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That's great, glad you got it fixed!
 

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Discussion Starter · #14 ·
Thanks

Thanks to all that helped with my questions. first time rebuilding any motor other than a Chevy 350. No telling how much the shop would have charged in labor but they should charge more to rebuild a ATV engine than a car engine lol.
 
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