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A valve gapping proposal...

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During a lengthy conversation concerning the valve racket my friend's XR4 was making another friend of mine brought up an alternate (an much easier IMO) method for setting valve gap.

He said rather than worrying about TDC and which stroke the bike was on simply crank over the motor until one set of valves is at full lift then gap the other pair. Then switch and repeat. Having the intake at the top of the lobe means the exhaust is at the bottom of the lobe.

Just a thought...sounds a lot easier to me. This method doesnt even require removal of the inspection caps.

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That would work as well, but if you only want to rotate the engine once, do it the std way.

Another hint. I use two feeler gauges. One above and one below the required setting to insure I get the correct gap(Go No-Go Gauge). :cry: Don't have to worry about that "feel".

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The trick would be to make sure it is at TDC and not a bit off. I don't recommend doing it this way.

Dwight

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at tdc the F mark is present in the viewing window, ALL valves should be closed since its on the compression stroke, the rockers should ALL be loose at this point .It is possible that a valve be tight but all four highly unlikely.

The most common valves to tighten up are the intake valves.

If you check the valves regularly you will get to "feel" the gap on the rocker arm.

As a rule if the piston is on the wrong stroke when the flywheel tends to want to chase off of the F mark.

Keep in mind that you can ONLY rotate the flywheel the same rotation as the kick starter rotates the engine... you have an auto decompressor system which engages as the flywheel is rotated opposite to the starting rotation, it causes the rh exhaust valve to remain opened a tad. It you gap this valve with the decomp system activated you will end up with 1/16" of gap and noisy as hell.

stu

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Removing the two inspection caps is how difficult?

Vs screwing up the valve adjustment procedure.

Switch and repeat? All of the valves are adjusted at the same time.

Also, Honda recommends turning the crank, not using the kickstarter, so the automatic decompression is not engaged.

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He said rather than worrying about TDC and which stroke the bike was on simply crank over the motor until one set of valves is at full lift then gap the other pair. Then switch and repeat. Having the intake at the top of the lobe means the exhaust is at the bottom of the lobe.

Just a thought...sounds a lot easier to me. This method doesnt even require removal of the inspection caps.

I do something similar, the the TDC way is fine if your exactly on TDC, the way you describe is the way I always adjusted valves on cars with solid lifters when I drag raced, so I just stayed with it. I do pull the plug and turn engine with a socket. It's like discussing oil brands or air filters, the main thing is JUST DO IT.

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Believe it or not, there are two different procedures for checking XR valve clearances! It depends which model you have. All XR600's from '88 on, all XR400's/650's and '96 on XR250's have a camshaft integrated decompression system which flicks open the R/H exhaust valve at cranking speed just on TDC. On these models it is required to crank the engine JUST AFTER TDC so the decomp is not flicking the valve open, otherwise you'll end up with a valve that has HEAPS of clearance and will rattle loudly! The procedure is as normal (you can check them at the same engine position as the aforemontioned valve) for the other three valves. With all other models, the valves would be checked right on TDC which is easier but once you get the drill nailed with the other bikes its still easy- an easier job than on a lot of newer rockets I could speak of!!

Hope this helps, cheers,

Mark.

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