Runs rough after valve adjustment - Honda ATV Forum
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post #1 of 11 (permalink) Old 09-28-2010, 04:49 PM Thread Starter
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Runs rough after valve adjustment

I have a 1984 Honda TRX 200. It was running fine until I decided to adjust the valves on it because it hadn't been done in forever. I consulted the owner's manual and followed the valve adjustment procedures step for step. I aligned the two timing marks to make sure that the engine was at the top of the compression stroke. Once I had the marks aligned, I then wiggled the rocker arms by hand and they were loose, which would mean that the engine was indeed at the top of the compression stroke. I then adjusted both the intake and exhaust valves to the specs recommended by the manual, which was .05mm(.002in). After I put the quad back together, it was difficult to crank. I did eventually get it cranked and it idled fine. It also runs fine at lower rpms, but at upper rpms it loses power and runs extremely rough! It spits a lot of white smoke out of the tailpipe when it is running. Also, the quad has a compression release lever, which is supposed to make it easier to pull crank. After the valve adjustment the compression release lever no longer works. The lever won't stick at the top like it is supposed to. Does anyone have any idea what could be wrong with it? I am out of ideas. Any help will be greatly appreciated! Thanks.
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post #2 of 11 (permalink) Old 09-28-2010, 05:05 PM
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Originally Posted by bostthehause View Post
I have a 1984 Honda TRX 200. It was running fine until I decided to adjust the valves on it because it hadn't been done in forever. I consulted the owner's manual and followed the valve adjustment procedures step for step. I aligned the two timing marks to make sure that the engine was at the top of the compression stroke. Once I had the marks aligned, I then wiggled the rocker arms by hand and they were loose, which would mean that the engine was indeed at the top of the compression stroke. I then adjusted both the intake and exhaust valves to the specs recommended by the manual, which was .05mm(.002in). After I put the quad back together, it was difficult to crank. I did eventually get it cranked and it idled fine. It also runs fine at lower rpms, but at upper rpms it loses power and runs extremely rough! It spits a lot of white smoke out of the tailpipe when it is running. Also, the quad has a compression release lever, which is supposed to make it easier to pull crank. After the valve adjustment the compression release lever no longer works. The lever won't stick at the top like it is supposed to. Does anyone have any idea what could be wrong with it? I am out of ideas. Any help will be greatly appreciated! Thanks.
are you sure you adjusted the valves on the compression stroke ?..sounds to me you adjusted them on the ex stroke..you can line the T on the flywheel on both the compression and ex stroke..go back and re-check it..or your gonna bend or break a valve !
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post #3 of 11 (permalink) Old 09-28-2010, 07:42 PM Thread Starter
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No, I am not sure that it was on the compression stroke. I wondered about this myself. The only way the manual stated to ensure that it was on the compression stroke was to wiggle the rocker arms to see if they were loose when the "T" mark was lined up. I did wiggle the rocker arms and they were loose. Is there any other way to differentiate between the engine being on the compression versus the exhaust stroke? Thanks.
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post #4 of 11 (permalink) Old 09-28-2010, 08:00 PM
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Is there any other way to differentiate between the engine being on the compression versus the exhaust stroke?
Try to watch the rocker arms move as you are turning the flywheel. It might be easier if you get someone to turn the flywheel why you watch the rocker arms. The idea is to have the valves closed, when you are on the "T" mark, so the rocker arms won't be pushing down on the valve stem.

Most 4-wheeler problems are caused by a loose nut connecting the handlebars and the seat!!

You only need two tools in life -- WD-40 and duct tape. If it doesn't move and should, use the WD-40. If it shouldn't move and does, use the duct tape.
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post #5 of 11 (permalink) Old 09-28-2010, 10:26 PM
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I find that the easiest way to ensure that it is on the compression stroke TDC is to pull the spark plug and feel for compression with your finger as the piston rises. Then, with a blunt pointer I feel the piston reach its apex, at which time I can align the T1 mark. Then, the rockers will be loose--or should be loose if the timing is correct. Adjust away.
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post #6 of 11 (permalink) Old 09-29-2010, 03:37 PM
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I would start by looking at what is wrong with your decompression switch. If it worked before and now it doesn't, it's probably directly related to your problem. Pull off the inspection cover on the exhaust side, and look in there with a flashlight while moving the decomp switch. Try looking in while slowly turning it over too.

Another thing that comes to mind but may not be relevant. I used to have a 250sx and every time I flipped it, it would run like crap until I cleaned the carb. Has your bike been upside down lately?
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post #7 of 11 (permalink) Old 09-29-2010, 04:57 PM Thread Starter
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Potato Gun, I am also convinced that the compression release lever is directly related to my problem. However I don't know much about decompression systems in motors. My only understanding is that all a compression release lever does is hang a valve open during cranking...right? Is there a way that the lever could be jammed or something? Does anyone else know much about how these work or if it is related to my problem.

Also, the quad has not been flipped upside down lately and it was running fine before I tried to adjust the valves. Thanks.
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post #8 of 11 (permalink) Old 09-29-2010, 05:39 PM
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You are correct. The decompressor switch on most bikes just holds down the rocker arm on the exhaust valve until the cam actuates the valve and clicks the decomp off. Like I said, take a look through the inspection cap while moving the switch. It is a simple system and you should be able to see what's going on in there if you crank your neck just the right way.

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post #9 of 11 (permalink) Old 09-29-2010, 05:44 PM
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Click the image to open in full size.

Found an exploded view of your cylinder head if that helps you any.
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post #10 of 11 (permalink) Old 09-29-2010, 05:45 PM
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