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Adjust Valves 2018 TRX500FA7 Rubicon Help

D

dook

Active Member
Aug 24, 2020
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montana
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I'm trying to adjust the valves on my 2018 Rubicon. Turned out to be a nightmare. The Honda service manual says to remove the crankshaft end cover and turn the crankshaft "clockwise". All engines turn both clockwise and counterclockwise. CLOCKWISE FROM FRONT = COUNTERCLOCKWISE FROM REAR. You have to specify front or rear or it doesn't mean anything.
I know over 90% of engines turn clockwise from front, but I don't want to make an assumption. Having been forced to make an assumption. Looking at picture of a recoil starter, it seems that this is one of those very unusual engines that turn counterclockwise from the front.
So I tried to adjust them by turning it clockwise from rear (counter-clockwise from front) watching valve position. I adjusted the intake when the exhaust valve was depressed, it was .002" loose. Then I try to adjust the exhaust with the intake depressed and the exhaust valve is tight, no slack at all. I loosened it up a half turn and it's still tight. It couldn't have been that tight, it ran perfectly when I rode it in the shop.
Reading further, it seems this engine has one of those automatic decompression devices like my 2020 P1K has, which makes it even more important to turn it the right direction.
Do I have to put the engine back together and start it to get the decompression reset or something? Anyone know for sure which rotation this engine turns?
 
H

HondaTech

Guest
Honda refers to "clockwise" as looking at the bolt your turning or the rear of the engine. When turning an engine with a starter you can feel and hear the one way bearing turning the start if your going the wrong way.

To adjust the valves on that engine you need to also remove the allen head plug on the right side of the engine near the same place your turning the engine from. The easiest way to do this is to remove the right floorboard.

Turn the engine over until the "T" mark is centered in the hole. You'll see an "F" mark first, the "T" is shortly after that. It helps to also remove the spark plug to keep the engine from spinning further.

Once you've centered the "T" mark you'll need to check and see if the rocker arms have freeplay. If they do NOT have freeplay then the enigne is on overlap and the valves are both slightly open. You'll need to rotate the engine 360 degrees until the "T" is lined up again. Then both rockers should have freeplay. This is Top Dead Center on the compression stroke and both valves are full closed. That is where you want to adjust them at. Never adjust the valves with either of them open.
 
D

dook

Active Member
Aug 24, 2020
65
160
33
montana
Ownership

  1. 1000-3
Your advice was very helpful, Honda Tech. The etched marks are barely perceptible. Pulling the right running board and using a headlamp and reading glasses is absolutely necessary. Too bad no one at the Honda factory had a hammer and chisel to mark it with.
 
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